Software development environment of FCC3
Description of the software (FCC3)
Further linkages between Databases and Decision-aids
Table 1. Some observations of the FCCas implementation of the FCC (Fertility Capability Classification system).
Table 2.Appendix Table 2. Errata list for the WISE database
Table 3. Database schema of fccwise.dbf, the output database containing the
intermediate calculated data and all of the FCC3 codes.
Table 4. FCC Modifiers, soil depth, and sequence in which they may be evaluated in
automated systems, and shortcut evaluations.
Table 6. Algorithm pseudocode with approximate description given in "/* ... */"
Surface Condition-Modifiers (C. M. 1)
Subsurface Condition-Modifiers (C. M. 2)
Table 7.List of recommendations associated with each of the FCC3 codes
Table 8. Example data input for FCCas, site data of the 0-100 cm depth (sam0100.dat).
Table 9. Example data input for FCCas, profile data of the 0-20 cm depth (sam020.dat).
Table 10. Example data input for FCCas, profile data of the 20-60 cm depth (sam060.dat).
Figure 1. Main Form output, program FCC3.
Figure 2. Worksheet Form output, program FCC3.
Figure 3. Recommendation Form output, program FCC3.
FAO Scientists repeatedly provide advice and guidance on identifying major limitations in Natural Resource Planning and Management, especially in reference to crop-related limitations of broad regions of land resources. Often there are regional limitations that have major policy implications while specific recommendation details can be handled by other forms of assistance to local scientists. One framework that identifies probable crop growth and productivity limitations is the Fertility Capability Classification System (FCC).
An early version of this system was found useful for the regional assessment of crop limitations of soils and was, therefore, selected for an integrated decision-aid and database system that would provide a diagnosis of major limitations and make suggestions arising from the assignment of some 22 modifiers in 5 categories of limitations: 1) Soil texture in the root zone, 2) Water and temperature status, 3) Mineralogy of soil materials, 4) Soil pH and acidity status, and 5) Cation status of the rooting zone. A new version of the FCC was selected to interface with the WISE (World Inventory of Soil Emission Potentials) database, which is a integration of 1) The FAO Soils database, 2) ISRIC (International Soil Reference and Information Centre), and 3) NRCS (Natural Resource Conservation Service) foreign soil database. A revised FCC 3rd approximation algorithm was developed that was tuned to the WISE database in order to maximize use of the information it contains. A revision of the algorithm is now being planned that fully exploits the NRCS database (NASIS, National Soil Information System). Multiple alternatives were developed to ascertain whether or not or whether there was sufficient data of the quality needed to even evaluate the modifier. As many as 4 or 5 alternatives were provided for some modifiers. Missing data was tolerated with criteria that depended on the modifier -- for depth-averaged variables as much as 50% of the data could be missing while the presence of as little as 10 cm of data was sufficient for some of the highly detrimental properties. In this way missing data were handled in a manner to maximize the use of the information that was present.
A menu-driven interface was developed that displayed all of the pedon data, a form with the intermediate worksheet calculations such as the depth-averaged values, and a recommendation form that grouped the recommendations from the 5 categories of modifier codes. Recommendations are those presented in Smith's dissertation and need some review and discussion before the software is released for extensive or mission-critical use by scientists who cannot judge the results. This suggestion for review and discussion is suggested because of the vastly different purposes of the recommendations and potential use by non-experts. Finally, the program includes an option to record the results of the code assignment and selected intermediate results to a general purpose database for use in linkage and display with a GIS.
The Food and Agriculture Organization of the United Nations is repeatedly called upon to provide assistance in natural resource development, particularly related to improved use of soils and soil resources for development. Over the years FAO scientists have identified a pattern in these requests. Usually they require an accurate assessment of current conditions and limitations -- essentially an inventory. This inventory often begins with soil characterization by means of specific measurements that experience has shown to be important in identifying limitations to plant growth and development. These measurements include factors that quantify nutrient levels as well as soil water characteristics in terms of limits to plant growth, effects on leaching, nutrient runoff, loss of nutrients, as well as loss of the soil itself through soil erosion.
FAO has recognized this pattern of information needs and has supported the development of a series of databases that provide the basic data required to support natural resource assessments. One of these databases includes the WISE database that was developed at the International Soil Reference and Information Centre (ISRIC) in support of a broader research effort on Global Air Pollution and Climate Change. The central aim of WISE was a "...geographical quantification of soil factors that control the fluxes of greenhouse gases and other processes of global environmental change by developing a global soil database." The data stored in the soil profile tables of the WISE database have been derived from various sources including: a) FAO's Soil Database (SDB), b) The ISRIC Soil Information Systems (ISIS), c) The Natural Resource Conservation Service (USDA-NRCS, formerly the SCS) database at Lincoln, Nebraska, d) Soil profile descriptions extracted from the ISRIC library collection, and e) responses to a questionnaire sent to soil scientists from various countries of the world, whose names are documented individually in the WISE database.
To be fully utilized, soil data must be interpreted to identify probable management limitations and suggestions for further management attention by those developing specific, on-site nutrient management recommendations. Broad scale, regional and country level identification of these limitations are an important first step in developing a complete management plan. While specific recommendations require site-specific interpretation of field data, farmer management, intended crop and economic goals, infrastructure and policy must be developed so that such detailed management can take place. It is the purpose of the Fertility Capability Classification System (FCC) (Buol, 1972; Sanchez et al., 1982) to identify, on a broad scale, such probable soil management issues and zones of analogous soil and terrain factors that affect management and development. Other decision-aids have been developed for specific recommendations and suggestions for individual farmers (ADSS, PDSS, NDSS, QUEFTS, NLEAP and DSSAT). A useful implementation of the 1982 revision of the FCC, known as FCCas, was developed by the CSIC, Sevilla, Spain (CSIC, 1995). This initial implementation of the FCC illustrated the potential of decision-aids to provide systematic support for decision-making in natural resource management.
1. Facilitate the use of an updated FCC (Fertility Capability Classification System) to diagnose soil and land constraints to improved land use through computer implementation.
2. Improve the diagnosis of potential soil and crop management problems by linking an improved FCC with existing databases so that non-experts can obtain management suggestions.
3. Suggest opportunities for further integration of existing FAO databases and decision-aids.
Our procedure was to review the existing implementation of FCC, FCCas, which was nicely developed by the CSIC, Sevilla, Spain (CSIC, 1995). We also wished to the revised FCC software system, we are calling FCC3, to directly access existing soil databases. The WISE soil database seemed particularly attractive for three reasons: 1) It represented a valiant effort to merge minimum datasets by very diverse institutions with different mandates but all with keen interest in soil management on a broad regional, national, and sometimes multinational scale.2) It included three of the major international soil databases in existence, providing excellent initial coverage for proof of concept of linking a decision-aid with a large database, and 3) These two software development efforts were independently key to meeting the FAO mandate to provide useful, timely, and critical regional natural resource management information throughout the world. How much more helpful might they be when joined in a single unified decision-aid tool.
Consequently we reviewed the FCCas developed by colleagues in CSIC, Spain, seeking to building on their innovative effort by expanding the utility through Windows programming environment and by implementing a new revision to the FCC (Smith, 1989).
In addition we sought to adapt the decision-aid portion of the system to facilitate the use of alternative information in the event that the primary criteria for a modifier code was missing or incomplete.
Lastly, to facilitate other uses of our effort we built in an output routine into FCC3 that will write out the modifiers and the major computations needed to arrive at their evaluation into a general purpose relational database that would facilitate the mapping of the modifer codes to ascertain the areal extent of various modifiers and combinations of modifiers with the specific geographic database. In this sense the linkage can continue after this software is implemented.
Results
Preliminary analysis of FCCas:
The objectives of FCCas, the initial FAO computerization of the 1982 FCC algorithm, were to evaluate the natural soil fertility, maintain the input data in a database, and obtain output results in a variety of formats including reports and graphics. Some observations regarding the use of FCCas are noted in Appendix Table 1.
The menu format that was developed for FCCas identifies continents, regions, countries, and soil pedons seemed useful and was adopted for the new FCC3 system. This system, however, usually breaks down at the country level because most countries include several geographic regions. For example, Burkina Faso is in the Sudano-Sahelian region, while it includes subhumid to humid regions in the southern part of the country.
Software development environment of FCC3
The proposed revisions of FCC (Smith, 1989) were implemented using the Objectvision® programming environment (developed by Borland International®) for the following reasons:
1. This programming environment was designed to support a form-based data entry and reporting that was similar to existing data sheets and was extremely easy to use. It would display pedon data in a form fairly typical of that used by several organizations, including the NRCS (Figure 1). The software does have some new forms that are not possible in the conventional soil review and displays such as the WORKSHEET form (a form that display intermediate calculations and assumptions in the extensive calculations performed in FCC3) and the RECOMMENDATION form (a form that displays general recommendations and observations of typical constraints associated with the modifiers assigned to the pedon).
2. The programming environment was designed to support work with large and complex databases with many linked tables and multiple indexes (Li, 1993) and has been used by the authors to develop several decision-aids (CSAS as discussed in Li, 1993; FACS as discussed in Chen et al, 1995; and Yost et al., 1997).
Pseudocode We have developed a "pseudo-code" version of the calculation algorithm, which is a somewhat simplified attempt to describe the algorithm in simple English. This should facilitate later updating or, if necessary, conversion into another software development framework (Appendix Table 3).
User evaluation During software development users were asked to evaluate prototypes along the way so that they were aware of the progress of the software development. As in many projects, there are many unforseen situations that occur in the course of software development and FCC3 was no exception. .
Implementation of the revisions to the second version of FCC (Sanchez et al., 1982) was facilitated by the form in which the dissertation (Smith, 1989) was organized. In further developing and implementing the algorithm, several fundamental revisions were discussed and implemented. These updates are also reflected in the "pseudocode" listed in Appendix Table 3. While there were alternative data for some FCC modifiers described in the 1982 algorithm, the third revision (FCC3) contains many more and sometimes in a different priority than that implemented in the 1982 algorithm. In the present implementation there are often 3 or 4 alternative methods to ascertain whether a modifier is to be assigned or not (see "ah modifier" criteria in Appendix Table 3, for example). Sometimes we sought to infer the presence of modifier characteristics by a synthesis of several other observations and measurements. Examples are numerous and are clearly illustrated in the comment or italicized section of the general algorithm presented in the Appendix Table 3.
Consequently, we urge caution in the interpretation and review of the WORKSHEET form of the software in addition to review of the list of "modifiers" and "Types" and "Subtypes".
In the course of FCC revision and software development the following considerations became important:
1. It was implicit that there was some order and sequence implied in the application of the criteria for Type, Subtype, and modifiers. This was clarified and documented in the algorithm. It is clear that the overriding consideration is the Type and Subtype and that consideration of modifier status must follow this initial determination. The query of certain modifiers also needs to occur before others which renders selected subsequent modifiers unnecessary to query. The relationship among modifier also depends on the world's soils -- some combinations do not, based on our knowledge to exist. It is probable that some of these combinations will occur in broader, more extensive use of the software. The approximately 1200 pedons in the WISE database have been used in initial testing of the software.
2. We present the users with more information that previous implementations of the FCC. We found that it was important to determine not only whether the modifier was true or false, but also whether there was sufficient data to evaluate the modifier. The current algorithm not only determines whether the critical variables were measured, but also whether there were sufficient data of the critical variables present in the database. The FCC3 algorithm is designed to operate even if some data are missing from the pedon. For example, if data from a horizon or 10-12 cm are missing the algorithm will still successfully process the remaining data to arrive at a modifier. However, if too much data is missing the algorithm will so indicate with no assignment of true or false to the modifier code. Consequently, each modifier now has three possible outcomes -- true, false, or insufficient data. This assessment is important, we think, because it informs the user that some of the criteria could not be applied with the current data gaps. This gives FCC3 maximum flexibility in striving to use all possible data to draw all warranted conclusions, yet informing users if additional data would be helpful in some assessments.
Clearly assessment of the performance of the algorithm as implemented is critical to the success of the operation of FCC3. It was also clear that there were no completely closed form solutions to the algorithm and we, therefore, could not prove that the algorithm was internally consistent and that it will always produce correct assessments. Consequently, we chose a knowledge-based validation approach in which test data sets were subjected to the algorithm and also given to expert soil scientists at the same time. The resulting assignment of codes were compared and studied. The results of this comparison were used to revise and update the algorithm and gradually approximate the knowledge of the soil scientist. This process consumed approximately 75% of the approximately 9 months of development time. The method led to many insights into how soil scientists think and organize their knowledge, which will not be presented here. We also found that the feedback to the soil scientist was instructive for their evaluation as well. As will be noted in the WORKSHEET, the amount of calculation and computation involved in some complex pedons is enormous. It is unlikely that human expert determination of the modifiers will be as extensive in the depth-averaging and calculation of alternative estimates conducted by this algorithm. In implementing the algorithm, we also found that the sequence of modifier evaluation becomes critical to proper operation of the algorithm.
We caution the user and point out that although the evaluation produced a high success rate of correct FCC classifications, all possible results of the algorithm have not been determined and each new soil can provide a new combination of data that may result in an incorrect assessment and assignment of modifiers. Consequently, we recommend cross-checking of results, review of the WORKSHEET, and a healthy skepticism, particularly when significant decisions are likely to be made from the results.
Description of the software (FCC3).
Installation. The FCC3 software is a windows program. It has been tested under Windows 3.1, 3.11, 95, and Windows NT version 3.51 and 4.0. Because of the complex calculation, best results are obtained with a Pentium-based machine. Even so, some pedons with many near- limiting criteria may take as long as a minute to calculate and assign the FCC modifier codes.
The FCC3 software is an Objectvision(1)® file that is executed by the Objectvision Runtime® system. Consequently, the first step in installation is to install the Objectvision Runtime®, which usually also installs the Borland Database Engine® that is used by FCC3. The Objectvision Runtime® is "zipped" in the ovr.zip file that is part of the fcc.zip compressed file.
1. The procedure to install then is to place the fcc.zip compressed file in a new directory and "unzip" it -- producing three files: fccwise.zip (the entire WISE database, and the fcctest7.ovd, plus all the supporting utility files (over 100), ovr.zip (the run-time installation of Objectvision), and fccdoc.pdf (which is a documentation file in Acrobat PDF format).
2. "Unzip" the fccwise.zip and also the ovr.zip (Objectvision Runtime System).
3. Install the Objectvision Runtime System, which will take several minutes will give you a graphic description of Objectvision.
4. Be sure to read the "Readme.txt" file that is included in the fccwise.zip compressed file. It has the last minute directions for installation.
There are three main forms in FCC3 that provide the output of the software -- Main, Worksheet, and Recommendations Forms.
Main Form (Soil Profile Data Sheet) FCC3 generates, in the windows environment, an initial form (Fig. 1) that resembles the Soil Profile Data Sheet used by the Natural Resources Conservation Service, except it is more elaborate, particularly at the bottom of the form. This is a "live" form that has several buttons that operate the software. The buttons New Pedon, Worksheet, Recommendations, Store Results and Print All forms open up auxiliary forms and menus. The Store Results button creates a data table "fccwise.dbf" that includes the necessary information to link the latitude and longitude of the pedon with a Geographic Information System in order to plot the intermediate data such as the depth-averaged values (from the WORKSHEET form, any or all of the FCC codes, including Type, Condition modifier, Subtype, Condition modifier, and individual fields for each of the 22 modifiers so that either 0 (false), 1 (true), or blank (insufficient information) can be plotted using vector-based GIS software such as Arcview, Arcinfo, etc. (Appendix Table 3).
Worksheet form The WORKSHEET form (Fig. 2) was developed to assist those interested in reviewing the depth-averaged data used in the assessment of particular modifiers. For example, the calculations become complex if there are 8 horizons in the 0 to 50 cm depth of the profile, yet the algorithm depends on the average of 0-20cm. The horizons must be counted to find out how many must be pooled to form the 0-20 depth-averaged value that the algorithm must have to test against the criteria. Other modifiers use "any occurrence" of the soil property -- such as Al toxicity and the assignment of "a" and / or "h" modifiers, which means that if there is any horizon (> 10 cm in thickness) of the pedon with the criteria then the entire pedon is labeled as an "a" or "h" depending on the severity of the acidity.
The WORKSHEET form indicates what depths of horizons were found in the pedon and gives the intermediate values that were calculated for use in determining which modifiers were applicable. Each specific Type, Type modifier, Subtype, Subtype modifier, and modifier (expanded from 13 (Sanchez et al., 1982) to a total of 22 (Smith, 1989)) are given in the WORKSHEET form. The WORKSHEET form also gives the true, false, or insufficient information (blank field) for each modifier. A brief explanation of the modifier is also available when the cursor is placed over the field and the F1 key is pressed.
The fourth line in the WORKSHEET form gives the overall grouping of modifiers into categories of limitations, which are also used to organize the general recommendations section in the RECOMMENDATIONS form (Fig. 3). The categories that were developed for FCC3 were the surface and subsurface, which are of major importance and the following four groups:
1. Water, Temperature modifiers: g, g+, d, d+, t, t-
2. Mineralogy: v, x, x-, i, i-, i+
3. Soil pH & Acidity: a, h, b, c
4. Cation status: e, k, s, s-, n, n-
Recommendation Form: The RECOMMENDATION form (Fig. 3) gives a summary of the FCC codes and the general recommendations developed by Smith (1989). These recommendations arose from personal experience of the original developers as well as from Smith (1989) and reflect experience in tropical and temperate America more than that in other continents. Future versions of the software should seek to broaden this background of experience and knowledge.
Further linkages between Databases and Decision-aids
While FCC3 represents the merging of the FCC algorithm with an FAO database, there are many additional options for merging and linking decision-aids and databases. One of those is represented by the ECOCROP1 database of crop characteristics and requirements.
A fundamental characteristic needed in establishing linkages between databases or between databases and decision-aids is to ensure both systems carry some of the same "linking variables" that are common in both databases, for example, soil nutrient levels. If the soil database has extractable phosphorus data and the crop database has the critical extractable phosphorus for the plant, the two can be matched and conclusions drawn concerning the need for added amendment. For example, we recommend including estimates of soil nutrient critical levels and plant tissue critical levels where available.
Furthermore it is usually helpful if the two databases contribute to a common objective i.e. assessing likelihood of salinity-limitations to growth in a particular soil. If the crop database could indicate a critical salinity level for the crop (using the same methods and reporting units) and the soil database had the values for the major soils a useful merging is possible. Most databases tend to be incompatible with those generated by other disciplines because it is probably more convenient for the disciplinary scientist to record their information using the disciplinary jargon. Effective information systems require using similar measures and units as much as possible, but to be sure the problem is not just a question of slight changes in recording methods. These methods and approaches are deep-seated preferences for some disciplines and usually conscious effort must be expended in order to bring about the merging. Often there is a need for scientists with training and experience in the respective disciplines to jointly discuss and ascertain common objectives and together propose measurements that can satisfy both disciplines represented in the databases. Working together jointly to identify data needs in order to solve the problem or to prepare the predictions needed for the planning is useful to lay a foundation for linking the databases and knowledge bases.
Batjes, N.H. 1995. World Inventory of Soil Emission Potentials (WISE 2.1), Profile Database User Manual and Coding Protocols. International Soil Reference and Information Centre, Wageningen, The Netherlands.
Buol, S. W., P.A. Sanchez, R.B. Cate, Jr., and M.A. Granger (1973). Soil fertility capability classification. Soil Management in Tropical America. E.Bornemiza (ed) pp. 126-141.
Chen, G., R.S. Yost, Z.Li, Y. Tamimi, J. Silva, N.V. Hue, and R. Uchida. 1995. FACS (Fertility and Advice Consulting System). Unpublished manuscript.
CSIC/IRNAS, 1995. FCCas: Automated System for Soil Fertility Capability Classification, Version 00.9.95, FAO, Land and Water Development Division, Rome, and CSIC, Instituto de Recursos Naturales y Agrobiologia, Sevilla, Spain.
FAO, 1995. ECOCROP 1, The adaptability level of the FAO crop environmental requirements database. FAO, Rome, Italy.
FAO, 1993. CLIMWAT for CROPWAT: A climatic database for irrigation planning and management. FAO Irrigation and Drainage Paper 49. FAO, Rome, Italy.
Li, John Zhi Cheng. 1993. CSAS: Crop Suitability Analysis System. Manual. University of Hawaii at Manoa, Honolulu, Hawaii.
Sanchez, P. A., W. Couto, and S.W. Buol. 1982. The fertility capability soil classification system: Interpretation, applicability, and modification. Geoderma 27: 283-309.
Smith, C.W. 1989. The Fertility Capability Classification System (FCC) 3rd Approximation: A technical soil classification system relating pedon characterization data to inherent fertility characteristics. Dissertation, North Carolina State University, Department of Soil Science, Raleigh, North Carolina.
Smith, C.W, S.W. Buol, P.A. Sanchez and R.S. Yost. 1997. Soil Fertility Capability Classification system (FCC), 3rd approximation: The link between pedologist and soil fertility manager. (in preparation).
WISE database...
Yost, R.S., S. Itoga, Z.C. Li, and P. Kilham. 1986. Soil acidity management with expert systems. pp. 225-236. In M. Latham (ed) Proceedings of the first Regional Seminar on Soil Management under Humid Conditions in Asia. International Board for Soil Research and Management, Bangkok, Thailand.
Yost, R.S., Y.N. Tamimi, J. A. Silva, N.V. Hue, and C. I. Evensen. 1997. How Fertilizer Recommendations are Made in the FACS software (Fertilizer Advice and Consulting System), Hawaii Soil Fertility Manual, 1997.
Appendix Table 1. Some observations of the FCCas implementation of the FCC (Fertility Capability Classification system).
The software has a userfriendly interface. Of particular use is the attempt to guide the users to the Continent, Region, Country, and Pedon. The outputting of codes and the areas associated with the codes is useful, but requires a database with such areas already estimated for the region of interest. This would likely be difficult to obtain of regions without an existing soil map and without already having the map digitized and recorded in a data table.
The software estimates the FCC codes based on assignments of soil map units to FAO 74 or FAO 90 codes. This probably leads to considerably more generalization and approximation than interpreting original laboratory data as is done in the FCC3 software developed by this project and described in this report. Moreover, the FCCas implements the 1982 algorithm that contains considerably fewer modifiers than the present revised algorithm.
The FCCas operates in a DOS environment and thus becomes limited in size and complexity of the algorithm that can be supported. The present algorithm and its considerable complexity could not be implemented in such an environment.
Appendix Table 2. Errata list for the WISE database:
1. Soils BR075, CO058, KR017, US136, WS012, ZM068. These pedons are examples in which Al is apparently not included in the Al sat. Perhaps because Al+H was missing??
2. There are many soils in which estimates of ECEC appear incorrect, in some cases this was traced to the dBASE software's inability to represent missing data and as a result, either -1 or -9 values were used as a key to missing values, which were then inadvertently used in the calucation. Consequently, we recalculated all of the ECEC used in FCC3 to be sure that they were the best possible. Strictly speaking, ECEC should include the extractable H associated with the KCl extraction, but this value was sometimes missing and sometime present in the WISE database. Consequently, we included the Al+H whenever it was present and included only Al when it was present. These preliminary calculations were necessary to ensure accurate computation of the Al saturation, one of the most important criteria in the FCC.
3. We found a number of incorrect or incorrectly indexed Laboratory Identification codes. This results in Pedon CR001 (Costa Rica) being linked with the Laboratory ID with data originating from the FAO Soil Map of Africa, which is obviously in error. We found a number of such incorrect linkages between the horizon data table and the supporting tables such as the Laboratory Identification table. A similar number of inconsistencies were found in the linkage between the analytical method and the methods data table.
Several variables were usually or almost always missing, one example was depth to ground water (grwhi, and grwlo).
These comments should not be construed in anyway to negatively reflect on the WISE database, these are typical database maintenance problems and need to be pointed out by users in order to eventually make the corrections.
Appendix Table 3. Database schema of fccwise.dbf, the output database containing the intermediate calculated data and all of the FCC3 codes.
| Field Name | Type | Size | Dec. Pts. | Field ID | |
| WISE_ID | C | 5 | †NA | 1 | |
| COUNTRY | C | 2 | NA | 2 | |
| LOCATION | C | 50 | NA | 3 | |
| LATITUDE | C | 1 | NA | 4 | |
| LATDEG | C | 2 | NA | 5 | |
| LATMIN | C | 2 | NA | 6 | |
| LATSEC | C | 2 | NA | 7 | |
| LONGITUDE | C | 1 | NA | 8 | |
| LOGDEG | C | 3 | NA | 9 | |
| LONMIN | C | 2 | NA | 10 | |
| LOGSEC | C | 2 | NA | 11 | |
| OC1A | N | 5 | 2 | 12 | |
| OC2A | N | 5 | 2 | 13 | |
| SAND1A | N | 5 | 2 | 14 | |
| SAND2A | N | 5 | 2 | 15 | |
| SILT1A | N | 5 | 2 | 16 | |
| SILT2A | N | 5 | 2 | 17 | |
| CLAY1A | N | 5 | 2 | 18 | |
| CLAY2A | N | 5 | 2 | 19 | |
| PHW1A | N | 5 | 2 | 20 | |
| PHW2A | N | 5 | 2 | 21 | |
| PHKCL1A | N | 5 | 2 | 22 | |
| PHKCL2A | N | 5 | 2 | 23 | |
| PHCACL1A | N | 5 | 2 | 24 | |
| PHCACL2A | N | 5 | 2 | 25 | |
| CEC1A | N | 5 | 2 | 26 | |
| CEC2A | N | 5 | 2 | 27 | |
| PF42A1 | N | 5 | 2 | 28 | |
| PF42A2 | N | 5 | 2 | 29 | |
| GR1A | N | 5 | 2 | 30 | |
| GR2A | N | 5 | 2 | 31 | |
| ECEC1A | N | 5 | 2 | 32 | |
| P1A | N | 5 | 2 | 33 | |
| SURFACE | C | 5 | NA | 34 | |
| CM1 | C | 1 | NA | 35 | |
| SUBSURFACE | C | 5 | NA | 36 | |
| CM2 | C | 1 | NA | 37 | |
| A | C | 1 | NA | 38 | |
| B | C | 1 | NA | 39 | |
| C | C | 1 | NA | 40 | |
| D | C | 1 | NA | 41 | |
| D_PLUS | C | 1 | NA | 42 | |
| E | C | 1 | NA | 43 | |
| G | C | 1 | NA | 44 | |
| G_PLUS | C | 1 | NA | 45 | |
| H | C | 1 | NA | 46 | |
| I | C | 1 | NA | 47 | |
| I_PLUS | C | 1 | NA | 48 | |
| I_MINUS | C | 1 | NA | 49 | |
| N | C | 1 | NA | 50 | |
| N_MIMUS | C | 1 | NA | 51 | |
| S | C | 1 | NA | 52 | |
| S_MINUS | C | 1 | NA | 53 | |
| T | C | 1 | NA | 54 | |
| T_MINUS | C | 1 | NA | 55 | |
| V | C | 1 | NA | 56 | |
| X | C | 1 | NA | 57 | |
| X_MINUS | C | 1 | NA | 58 | |
| K | C | 1 | NA | 59 |
† NA - Not applicable, i.e. with character variables there are no decimals.
Appendix Table 4. FCC Modifiers, soil depth, and sequence in which they may be evaluated in automated systems, and shortcut evaluations.
| Modifier | Depth (cm) | Predecessor | Shortcuts |
| b | 20. Any occurrence | No | No |
| c | 50. Any occurrence | No | c = 2 if Surface = R or b = 1 |
| a | 50. Any occurrence | No | a = 2 if b = 1 or c = 1 |
| h | 50. Any occurrence | No | h = 2 if b=1, c = 1 or a =1 |
| s | 100. Any occurrence | No | s = 2 if a = 1 or h = 1 |
| s | 100. Any occurrence | No | s = 2 if a = 1, h = 1 or s = 1 |
| n | 50. Any occurrence | b, s, s. | n = 2 if a = 1 or h = 1 |
| n | 50. Any occurrence | No | n = 2 if a = 1, h = 1 or n = 1 |
| g+ | 50. Any occurrence | No | No |
| v | 20. Any occurrence | No | v = 2 if Surface = R, O, or S |
| x | 20. Depth averaged | v | x = 2 if Surface = S, or v = 1 |
| i+ | 20. Depth averaged. Horizons are not checked. | g+ | i+ = 2 if x = 1 |
| g | 50. Any occurrence | v | g = 2 if g+ = 1 or i+ = 1 |
| d+ | 50. Horizons are not checked. | No | No |
| d | 50. Horizons are not checked. | No | d = 2 if d+ = 1 |
| t | 50. Horizons are not checked. | No | No |
| t | 50. Horizons are not checked. | No | t = 2 if t = 1 |
| x | 20. Depth averaged
(Horizons are not checked.) |
x | x = 2 if x = 1 |
| i | 20. Depth averaged | No |
Appendix Table 5. Overview of algorithm checking sequence of Surface and Subsurface tests
(I) Surface and subsurface tests are performed in the following sequence :
R R F O S L C
(II) Modifiers are tested in the following sequence:
(1) b : If true then NOT c, a, h
(2) c : If true then NOT a, h
(3) a : If true then NOT h, n, n -, s, s -
(4) h : If true then NOT n, n -, s, s -
(5) s : If true then NOT s -
(6) s - :
(7) n : If true then NOT n -
(8) n - :
(9) g + : If true then NOT g, i, i -
(10) v : If true then NOT x, e, x-
(11) x : If true then NOT x -, i, i -, i +
(12) i + : If true then NOT g
(13) g :
(14) d + : If true then NOT d
(15) d :
(16) t - : If true then NOT t
(17) t :
(18) x - : If true then NOT i, i -
(19) i : If false then NOT i -
(20) i - :
(21) e : If true then NOT v
(22) k :
Appendix Table 6. Algorithm pseudocode with approximate description given in "/* ... */"
If [Max. Soil Depth] 20 cm then / the maximum depth of soil horizons/
{
If [parmat] = "UC" then
{Type = "F"; goto Condition-Modifiers-test}
else If [parmat] = "SO2"/"UX" then
{Type = "R"; goto Condition-Modifiers-test}
else If [parmat] = "I*"/"M*"/"SC*"/"SE*"/"SO1"/"SO3" then
{Type = "R"; Exit}.
}
/* Surface Type criteria: We first check to see that the soil is greater than 20 cm in depth if so exit this section and go to the O-test. If the soil is 20 cm or shallower we ask if the parent material is "unconsolidated colluvium"(UC) (WISE, 1995, p.39). If so then the soil type is F (fragmental). If the parent material is sulfidic (SO2) or contains unconsolidated amorphous materials it will be called R- (rippable bedrock or pan). Otherwise if the soil parent material is I (igneous), M(Metamorphic), SC(clastic sediments), SE(Evaporites such as gypsum or halites), SO1(limestone or other carbonates) or SO3(coals, bitumen, and related rocks) then the Type is R (hard bedrock). */
O-test: /[Max. Soil Depth] > 20cm, or [parmat] = "-"/"UO"/"UF"/"UL"/"UM" /"UE"/"UG"/"UY" /
If [oca1] >= 20% OR ([oca1] >= 15% AND [drain] = "V"/ "P") then
{Type = "O"; goto Condition-Modifiers-test}
If [oca1] = -1 then
{
If [desig] = "O[*]" AND ([botdep] - [topdep]) >= 10 cm then
{Type = "O"; goto Condition-Modifiers-test}
If [drain] = "V" / "P" AND [cecsoil] > 50 AND ([FAO_74] = "Humic Gleysol" OR [FAO_90] = "Humic Gleysol" OR [uscl] = "IST") then
{Type = "O"; goto Condition-Modifiers-test}
Type = "?"; Warn; goto Condition-Modifiers-test
}
/* O-test criteria: Check for organic Type if the soil is more than 20 cm in depth: If the organic carbon content is greater than 20% or if both the organic layer contains more than 15% organic carbon and drainage is very poor to poor then the Type is O.
However, if the organic carbon content is missing, then apply the following criteria. If any horizon designation begins with the letter O in the top 20 cm and the horizon thickness is equal to or greater than 10 cm then the Type is O.
If ( the drainage is very poor or poor and the soil CEC (pH 7) is greater than 50 and FAO 1974 classification is Humic Gleysol) or FAO 90 classification is Humic Gleysol or US Taxonomy order is Histosol then the Type is O. Otherwise the Type is "?".
*/
If [clay] = -1 AND [sand] <> -1 AND [silt] <> -1 then
[clay] = 100 - [sand] - [silt]
(1) If [clay] <> -1 AND [clay] =< 27% AND [sand] - [clay] > 70 then
{Type = "S"; goto Condition-Modifiers-test}
(2) If [uscl] = "OX " AND [pf42] <> -1 then /a space after OX for soil order/
{
[clay] = min ([pf42] * 3, 100)
If [clay] =< 35% then Type = "L" else Type = "C"
goto Condition-Modifiers-test
}
(3) If [uscl] = "ANDEPTS" / "AND " OR [FAO_74] = "ANDOSOL" OR
[FAO_90] = "ANDOSOL" then /a space after AND for soil order/
{
If "Hydr" / "Hydric" then Type = "C" else Type = "L"
goto Condition-Modifiers-test
}
(4) If [pf42]<> -1 AND [clay]<> -1 AND [clay]<> 0 AND [pf42] / [clay] >= 0.6 then
[clay] = min([pf42] * 2.5, 100)
If [clay] > 35% then Type = "C" else Type = "L"
(5) If [clay] = -1 then {Type = "?"; Warn}
/* Surface Type: SLC-test criteria: Determine if the Type should be S (sandy), L (loamy), or C (clayey). First determine the clay % if it is missing and sand and silt data are both not missing. Clay = 100-sand-silt.
(1) If clay data is not missing and clay is less than or equal to 27% and sand - clay is greater than 70% then the Type is S (sandy).
(2) If the US Taxonomy Order is Oxisol and the 15-bar water is not missing then calculate the clay percentage as 3 times the 15-bar percent water, not to exceed 100%. If the clay % calculated in this way is less than or equal to 35% then the Type is L (silt) otherwise the Type is C (clayey).
(3) If the US Taxonomy is "Andepts" or "And" as in Andisol or the FAO 1974 or the FAO 1990 grouping is "Andosol" then do the following:
If there is a "Hydr" or "Hydric" text in the description then the Type should be C (Clayey) otherwise the Type should be L (loamy).
(4) If there still is no definitive assignment of the soil Type look at the following:
If the 15-bar water is not missing and clay percentage is not missing and the clay percentage is not zero and the ratio of 15-bar water to percent clay is greater or equal to 0.6 then recalculate the clay as follows: clay% = 15-bar water * 2.5, not to exceed 100%. Now if clay% (either recalculated or originally measured) is greater than 35% then the Type is C (clayey) if the clay % is less than or equal to 35% then the Type is L (loamy). If the clay can still not be calculated assign a ? to the Type and warn the user.
*/
Surface Condition-Modifiers (C. M. 1):
If [gr1a] > 35% then [C.M.1] = " `` "
If [gr1a] > 15% then [C.M.1] = " ` "
/* Surface condition modifiers: If gravel content of the 0-20 cm depth-averaged layer is greater than 35% then the condition modifier is " `` ". If it is less or equal to 35% and greater than 15% then the condition modifier is " ` ".
*/
Subsurface: Similar to Surface but the criteria are applied to a different depth (20 - 50 cm).
If Type = "R" then SubType = ""
else
If [desig] = "R" AND [topdep] <=50 then SubType = "R" /@LINKMAX("wiselayer","r50desig")=1/
else
If [desig] = "CR*" AND [topdep] <=50 then SubType = "R-" /@LINKMAX("wiselayer","cr50desig")=1/
else
If [Max. Soil Depth]=< 50 AND [parmat]="I*"|"M*"|"SC*"|"SE*"|"SO1"|"SO3" then SubType = "R"
else
If [Max. Soil Depth]50 AND [parmat]="SO2"|"UX" then SubType = "R-"
else
If [Max. Soil Depth]50 AND [parmat]="UC" then SubType = "F"
else
If [oca2] > 20 then SubType = "O" /[oca2] is the depth-averaged OC over top 50 cm/
else
If [oca2] 15 AND [drain]="V"|"P" then SubType = "O"
else
If [oca2]= -1 AND ([desig] = "O[*]" AND ([botdep] - [topdep]) >= 10cm))
then SubType = "O" /@LINKMAX("wiselayer","o20desig")=1)/
else
If [oca2]= -1 [drain] = "V"|"P"AND [cec2a] >50 AND ([fao_74] = "Gh" OR [fao_90] = "GLu" OR "IST" in [uscl])
then SubType = "O"
else
If [oca2]= -1 then SubType = "?[O]"
else
If [clay2a]-1 AND [clay2a] =< 27 AND [sand2a] - [clay2a] > 70
then SubType = "S"
else
If "OX " in [uscl] AND [pf422a]-1 then /a space after OX for soil order/
If min ([pf422a] * 3, 100) =< 35 then SubType = "L" else SubType = "C"
else
If "ANDEPTS"|"AND " in [uscl] then /a space after AND for soil order/
If "Hydr" in [uscl] then SubType = "C" else SubType = "L"
else
If [fao_74] = "T*" OR [fao_90] = "AN*" then
If [fao_74] = "Tv" OR [fao_90] = "Anz" then SubType = "L" else SubType = "C"
else
If [pf422a]<> -1 AND [clay2a]> 0 AND [pf422a] / [clay2a] >= 0.6 then
If min([pf422a] * 2.5, 100) > 35 then SubType = "C" else SubType = "L"
else
If [clay2a] > 35 then SubType = "C"
else
If [clay2a] = -1 then SubType = "?[CL]"
else
SubType = "L"
/* Subsurface: Subtype criteria: Subtype criteria are similar to those applied to the surface (Type) but are applied only to the 20-50 cm depth. If the Type is R then there is no Subtype. If there is an R designated horizon and the depth is less than 50 cm then assign the Subtype to R. If the horizon has the designation of CR* and the depth is less than 50 cm then the Subtype is R-. If the soil depth is less than 50 cm and parent material is Metamorphic, Sedimentary clastic, sedimentary evaporties, sedimentary organic (limestone and other carbonatic rocks) or coals, bitumen and related rocks then also assign Subtype R. If the soil depth is less than 50 cm and parent material is marl and other mixtures or soft laterite or ferruginuous materials then the Subtype is R-. If the depth is less than 50 cm and parent material is colluvium then the Subtype is F.
If organic carbon is > 20% then the Subtype is O. If the organic carbon is greater than or equal to 15% and drainage is very poor to poorly drained then the Subtype is O. If organic carbon is missing and the horizon designation begins with the letter O and the depth is greater than 10cm then the Subtype is O. If the organic carbon is missing and drainage is very poor to poor and the CEC at pH7 is greater than 50 and any one of the following is true: (FAO74 code is 'Gh" or FAO90 code is "Glu" or the US Taxonomy soil order is Histosol) then the Subtype is O. If the organic carbon of the 20-50 cm zone is missing then the Subtype is "?[O]".
If the clay content of the 20-50 cm zone is not missing and is less than 27% and the sand-clay percentage in the 20-50 cm zone is greater than 70% then the Subtype is S.
If the soil taxonomy order is Oxisol and the 15-bar water content is not missing and the 15-bar water*3, not to exceed 100, is less than 35 then the Subtype is L. If the soil taxonomy order is Oxisol and the 15-bar water*3, not to exceed 100, is greater than 35 then the Subtype is C.
If the US Taxonomy is Andepts or Andisols and if there is a "Hydr" in the taxonomic name then the Subtype is C, otherwise it is L.
If the FAO74 code has the first letter of T or the FAO90 code has the first letters of AN
then if FAO74 code is "Tv" or the FAO90 code is "Anz" then Subtype is L otherwise it is C. If the FAO74 code has the first letter of T or the FAO90 code has the first letters of AN but FAO74 code is not "Tv" FAO90 is not "Anz" then check if the 15-bar water is not missing and the clay percentage in the 20-50 cm zone is not zero and the 15-bar water to clay ratio is greater or equal to 0.6 then if 15-bar water*2.5, not to exceed 100, is greater than 35 then the Subtype is C, if it is less or equal to 35% then Subtype is L.
If the clay percentage in the 20-50 cm zone is greater than 35% then the Subtype is C, else if the clay percentage in the 20-50 cm zone is missing then the Subtype is "?[CL]", otherwise the Subtype is L.
Subsurface Condition-Modifiers (C. M. 2):
If [gr2a] > 35% then [C.M.2] = " `` "
If [gr2a] > 15% then [C.M.2] = " ` "
/* Subsurface Condition-Modifier Criteria: If gravel content of the 20-50 cm depth-averaged layer is greater than 35% then the condition modifier is " `` ". If it is less or equal to 35% and greater than 15% then the condition modifier is " ` ".
*/
b-test: /depth = 20cm, any occurrence, no predecessor/
/default -- 0 means undecided, 1 true, 2 false/
If [caco3] in any layer >= 0.5% then b = 1
else if NOT all [caco3] = -1 then b = 2
else if [phh2o] in any layer PRESENT [7.3, 8.5] then b = 1 / all [caco3] = -1 /
else if NOT all [phh2o] = -1 then b = 2
else b = 0 / all [caco3] = -1 and all [phh2o] = -1/
/*b-test criteria: For any horizon, if there are CaCO3 data, then if CaCO3 percentage is greater or equal to 0.5% the b modifier is true else the b modifier is false and exit to test the next modifier. If all the CaCO3 data in the top 20 cm are missing and there are water pH values and it is between 7.3 and 8.5 then the b modifier is true. If the water pH data are present but not in the interval 7.3 to 8.5 then the b is false. If both CaCO3 data and the water pH data are missing then the b is "unknown".
*/
c-test: /depth = 50cm, any occurrence, no predecessor. The shortcut is c = 2 if Surface = R- or
b = 1/
c = 0
If Type = "R" OR b = 1 then {c = 2, goto end-c}
If "Sulf" in [uscl]OR "Thio" in [fao_74]OR "JT" in [fao_90] then
{c = 1, goto end-c}
If [phh2o]<> -1 AND [phh2o =< 3.5 then {c=1, goto end-c}
c = 2
end-c:.
/* c-test criteria: First check for other modifiers that may exclude c: If b is true or Surface is R- then c is false. Otherwise check whether the US classification has "Sulf" or the FAO74 code has "Thio" or the FAO90 code has "JT", if so then the c modifier ("cat" clay, or acid sulfate soil) is true and exit. If none of these three text variables are present then revert to soil pH. For any horizon in the surface 50 cm, if water pH is not missing and is less than pH 3.5 then the c modifier is true, but if water pH is missing or is equal to or greater than 3.5 then the c modifier is false.
*/
ah-test: /depth = 50cm, any occurrence, no predecessor for a. Shortcuts are: a = 2 if b = 1 or c = 1, and h = 2 if b=1, c = 1 or a =1/
a = 0; h = 0
If b = 1 OR c = 1 then {a = 2; h= 2; goto end-ah}
If [exalum]<> -1 AND [ecec]<> -1 AND [ecec]<> 0 then /if alsat for any layer exists/
If [exalum] / [ecec] >= 0.6 then
{a = 1; h = 2; goto end-ah}
else if [exalum] / [ecec] PRESENT [0.1, 0.6) then
{a = 2; h = 1; goto end-ah}
else {a =2; h = 2; goto end-ah}
If [bsat] <> -1 AND [bsat] =< .12 then /use bsat only if alsat for ALL layers are missing/
{a = 1; h = 2; goto end-ah]
else if [bsat] PRESENT (0.12, 0.4] then
{h = 1; a = 2; goto end-ah}
else if [bsat] > 0.4 then
{h = 2; a = 2; goto end-ah}
/Use pH only if alsat and bsat for ALL layers are missing/
If (Type = "S"/"L"/"C" OR Subtype = "S"/"L"/"C") AND [phh2o] <> -1 then
If [phh2o] =< 4.6 then
{a = 1; h = 2; goto end-ah}
else If [phh2o] PRESENT (4.6, 5.4] then
{h = 1; a = 2; goto end-ah}
else If [phh2o] > 5.4 then
{a = 2; h = 2; goto end-ah}
If (Type = "O"OR Subtype = "O") then
{
If [phh2o] > 4.6 then {a = 2; h = 2; goto end-ah}
If [phh2o] <> -1 AND [phh2o] =< 4.2 then
{a = 1; h = 2; goto end-ah}
else if [phh2o] PRESENT (4.2, 4.6] then
{a = 2; h = 1; goto end-ah}
If [phkcl] <> -1 AND [phkcl] =< 3.8 then
{a = 1; h = 2; goto end-ah}
else if [phkcl] PRESENT (3.8, 4.2] then
{a = 2; h = 1; goto end-ah}
else if [phkcl] > 4.2 then
{a = 2; h = 2; goto end-ah}
If [phcacl2] <> -1 AND [phcacl2] =< 4.0 then
{a = 1; h = 2; goto end-ah}
else if [phcacl2] PRESENT (4.0, 4.4] then
{a = 2; h = 1; goto end-ah}
else if [phcacl2] > 4.4 then
{a = 2; h = 2; goto end-ah}
If "Dysic" in [uscl] then {h = 1; a = 2; goto end-ah}
}
If limed then check 50cm-100 cm (not implemented)
end-ah:
/* ah-test criteria: First check for other modifiers: if modifier b (excess bases) is true or c ("cat" clay) is true, then both a (extremely acid) and h (very acid) modifiers are false and exit. Otherwise search the criteria in the following order: 1) Aluminum saturation and exit, 2) base saturation, then exit, 3) lastly revert to soil pH only if aluminum saturation and base saturation are missing in ALL soil horizons.
If extractable Al (KCL-extractable Al) data are present and effective CEC data are present and not equal to zero then calculate the fraction (extractable Al / ECEC) and do the following test with the fraction: 1) If the Al fraction of ECEC is not less than 0.6 then modifier a is true and modifier h is false and exit, 2) If the fraction is between 0.1 and 0.6 then the modifier a is false and modifier h is true and exit, and finally 3) If the fraction can be calculated but is none of the above then both modifiers a and h are false and exit the algorithm.
If both extractable Al and effective CEC are missing in all horizons then check for base saturation (based on pH 7). If bsat is not missing and 1) not greater than 0.12 then modifier a is true and modifier h is false and exit, 2) between 0.12 and 0.4 then modifier h is true and a is false and exit, 3) greater than 0.4 then both modifiers a and h are false and exit the algorithm.
However, if both the fraction of ECEC that is Al and the base saturation data are missing for all layers then revert to soil pH as follows. Check for Surface and Subsurface textures are not organic and water pH is present then apply the following rules: 1) if water pH is not greater than 4.6 then modifier a is true and modifier h is false and exit, 2) if water pH is between 4.6 and 5.4 then a is false and h is true and exit, and finally 3) if water pH is greater than 5.4 then both modifiers a and h are false and exit.
However, if the soil is organic in the surface (Type = "O") or subsurface (Subtype = "O") then apply the following criteria for soil pH. First try to use water pH, then KCL pH, and then CaCl2 pH: 1) if water pH is greater than 4.6 then both modifiers a and h are false and exit, 2) If water pH is less than 4.2 then a is true and h is false, 3) If water pH is between 4.2 and 4.6 then a is false and h is true, and exit.
If water pH is not present but there are KCl-pH data then apply the following criteria: 1) If KCl-pH is not greater than 3.8 then a is true and h is false and exit, 2) If KCl pH is between 3.8 and 4.2 then modifier a is false and h is true and exit, 3) If KCl pH is greater than 4.2 then both modifiers a and h are false, and exit.
If KCl pH is not present but there are CaCl2-pH data then apply the following criteria: 1) If CaCl2-pH is not greater than 4 then modifier a is true and h is false and exit, 2) If CaCl2-pH is between 4.0 and 4.4 then modifier a is false and h is true and exit, and 3) If CaCl2-pH is greater than 4.4 then both modifiers a and h are false and exit.
If all the above data are missing then as a last resort check for the Dysic prefix in the Soil Taxonomy name and modifier a is false and h is true if that is the case.
*/
s-test: /depth = 1m, any occurrence, no predecessor. Shortcuts are s = 2 if a = 1 or h = 1/
s = 0
If a = 1 OR h = 1 then {s = 2, goto end-s}
If [ECE] are all missing AND [uscl] = "-" then {s = 0, goto end-s}
If [ECE]>= 4 OR "SAL" in [uscl] then {s = 1, goto end-s}
s = 2
/* s-test criteria: First check for other modifiers: if modifier a or h is true then s is false. For any horizon in the 50 cm depth to find if there are any ECE (electrical conductivity) data. If all ECE data are missing and all taxonomy is missing then s is unknown and exit. If ECE is greater than 4 mmhos / cm or if there is an "SAL" word group in the Soil Taxonomy text then s is true and exit. Otherwise s is false and exit.
*/
end-s:
s-test: /depth = 1m, any occurrence, no predecessor. Shortcuts are s = 2 if a = 1, h = 1 or s = 1/
s = 0
If a = 1 OR h = 1 OR s = 1 then {s = 2, goto end-s }
If [ECE] are all missing then {s = 0, goto end-s }
If [ECE]PRESENT [2, 4) then {s = 1, goto end-s }
s = 2
/* s--test criteria: First check for other modifiers: if modifier a, h, or s is true then s- is false and exit. If all ECE data are missing then s- is unknown and exit. If any ECE is present and is in the range of 2 to 4 then s- is true and exit. Otherwise s is false and exit.
*/
end-s:
n-test: /depth = 50cm, any occurrence. Predecessors include b, s, s. Shortcuts are n = 2 if a = 1 or h = 1/
n = 0
If a = 1 OR h = 1 then {n = 2, goto end-n}
If [exna] <> -1 AND [ex ca]+[ex mg] > 0 AND [exna] / ([ex ca]+[ex mg]) >= .15 then
{n = 1, goto end-n}
If b <> 1 AND s <> 1 AND s <> 1 AND [phh2o] >= 8.5 then {n = 1, goto end-n}
If "NATR" in [uscl] OR "Sodic" in [FAO_74] then {n = 1, goto end-n}
If [altit] PRESENT [0, 2m] AND [drain] = "V"/"P" AND [parmat] = "UM"/"UF"/"-" then
{n = 1, goto end-n} /UM,UF,-: marine,fluvial, or missing/
n = 2
/* n-test criteria: First check for other modifiers: if modifier a or h is true then n is false and exit. Otherwise check for any occurrence in any horizon to 50 cm depth. If exchangeable Na data are present and exchangeable Ca plus exchangeable Mg are greater than zero and the ratio of exchangeable Na to exchangeable Ca plus exchangeable Mg is greater than 0.15 then n is true and exit.
Otherwise if b is not true, s is not true, and s- is not true then check water pH. If water pH is greater than 8.5 then n is true and exit.
Otherwise check for code phrases of "Natr" in the USDA Soil Taxonomy field or for "Sodic" in the FAO74 text, if either is present then n is true and exit
Otherwise check whether altitude is 0 to 2m and drainage is "very poor" or "poor" and parent material is marine or missing then n is true and exit.
Otherwise n is false and exit.
*/
end-n:
n-test: /depth = 50cm, any occurrence, no predecessor. Shortcuts are n = 2 if a = 1, h = 1
or n = 1/
n = 0
If a = 1 OR h = 1 OR n = 1 then {n = 2, goto end-n }
If [exna] <> -1 AND [ex ca]+[ex mg] > 0 AND [exna] / ([ex ca]+[ex mg])PRESENT [.06, .15) then
{n = 1, goto end-n}
n = 2
/* n-test criteria: First check for other modifiers: if modifier a , h or n is true then n is false and exit. Otherwise if exchangeable Na data are present and exchangeable Ca plus exchangeable Mg are greater than zero and if exchangeable Na / (exchangeable Ca + exchangeable Mg) is greater than 0.06 and less than 0.15 then n is true and exit.
Otherwise n is false and exit.
*/
end-n:
g+-test: /depth = 50cm, any occurrence, no predecessor/
g+ = 0
If [crops] = "RB" OR [vegcod] = "HE" then {g+ = 1; goto end-g+}
/"RB" - flooded rice, "HE" - hydromorphic vegetation /
If [drain] = "V" then {g+ = 1; goto end-g+}
If [drain] = "-"/"P" AND [horiz] <> "E Horizon" then
{
If [mottle] = "N"/"V"/"F" then /the soil is not mottled/
If [Chroma mcolor] =< 1 [Value mcolor] >= 4 then
{g+ = 1; goto end-g+}
If [mottle] = "C"/"M"/"A" then /the soil is mottled/
If [Chroma mcolor] =< 2 then /must be so in 5 cm - 50 cm/
If [Value mcolor] >= 4 then {g+ = 1; goto end-g+}
Else do the same search for next deeper layer until 75 cm deep
}
If "Sulfi" in [uscl] then {g+ = 1; goto end-g+}
g+ = 2
/* g+-test criteria: Check for crops: If flooded rice is grown or there is hydromorphic vegetation then g+ is true and exit.
Otherwise if drainage is "very poor" then g+ is true and exit.
Otherwise if drainage is "missing" or "poor" and there are no "E" horizons in the top 50 cm then check the following:
If there is any horizon with mottles are "N", "V", or "F" (i.e. the soil is not mottled) then check the following:
If chroma of the moist matrix is less than or equal to 1 and the value of the moist matrix is greater or equal to 4 then g+ is true and exit.
Otherwise check the whole 5 - 50 cm depth for any horizon in which mottles are "C","M", or "A"(i.e. the soil is mottled) and chroma of the moist matrix is less than or equal to 2 then check the value for any horizon to the depth of 75 cm and if it is greater than or equal to 4 then g+ is true and exit.
If the Soil Taxonomy text contains the string "Sulfi" then g+ is true and exit.
Otherwise g+ is false.
*/
end-g+:
v-test: /depth = 20cm, any occurrence, no predecessor. Shortcuts are v = 2 if Surface = R-, O,
or S/
v = 0
If Surface = R/O/S then {v = 2, goto end-v}
If "ERT " in [uscl] OR ("ERT" in [uscl] AND Type = "C") then {v = 1; goto end-v}
/ a space after the first ERT for the soil order; no space after
the second ERT for any occurrence/
If [clay] >= 35% AND [cec7] > 30meq/100g soil AND [condsat] =< 0.5 cm/hr then
{v = 1; goto end-v}
If [clay] >= .35 AND [struct] = "PR"/"AB"/"AW"/"AP" then {v = 1; goto end-v}
If [clay1a]<> -1 then v = 2
/* v-test criteria: First check for surface type, if R -, O, or S then v is false and exit.
If the order is Vertisol or there is a phrase "ERT" in the Soil Taxonomy text and the surface soil is of Type C (Clayey) then v is true and exit.
If for any occurrence in the surface 20 cm of the following:
If clay percentage is greater or equal to 35% and CEC pH 7 is greater than 30 meq / 100 g and the saturated conductivity is less than 0.5 cm per hour then v is true and exit.
Otherwise if clay percentage is greater or equal to 35% and the soil structure is "prismatic", "angular blocky", "angular blocky wedge-shaped", or "angular blocky parallelopiped" then v is true and exit.
Otherwise if surface clay is not all missing then v is false and exit.
*/
end-v:
g-test: /depth = 50 cm, any occurrence. A predecessor , v. Shortcuts are g = 2 if g+ = 1 or
i+ = 1/
g = 0
If g+ = 1 OR i+ = 1 then {g = 2, goto end-g}
If [grwlo] <> -1 AND [grwhi] <> -1 then
{
xx = ([grwlo] + [grwhi]) /2
yy = -1
If (Type = "S"OR Subtype = "S") then yy = xx -10
If (Type = "L"/"C"OR Subtype = "L"/"C") then yy = xx -30
If (Type = "C"OR Subtype = "C") AND v = 1 then yy = xx - 50
If yy <> -1 AND yy =< 50 then {g = 1; goto end-g}
}
If [mottle] = "N"/"V"/"F" then /the soil is not mottled/
If [Chroma mcolor] =< 1 [Value mcolor] >= 4 then
{g = 1; goto end-g}
If [mottle] = "C"/"M"/"A" then /the soil is mottled/
If [Chroma mcolor] =< 2 AND [Value mcolor] >= 4 then
{g = 1; goto end-g}
Else do the same search for any occurrence in next deeper layer until 75cm deep
If [drain] = "P" then g = 1 else g = 2
/* g-test criteria: First check for other modifiers: if modifier g+=1 or i+=1 then g is false and exit.
Search for any horizon within the top 50 cm for the following:
If the depth to the highest average groundwater depth (grwhi) is present and also the depth to the lowest average groundwater depth (grwlo) then do the following depending on surface texture:
If the Type(surface) is S (sandy) or the Subtype (subsurface) is S (sandy) then calculate yy as [grwhi + grwlo]/2 - 10
If the Type(surface) is L (loamy) or C (clayey) or the Subtype (subsurface) is L (loamy) or C (clayey) then calculate yy as [grwhi + grwlo]/2 - 30
If either (the Type(surface) is C (clayey) or the Subtype (subsurface) is C (clayey) ) and v is true (vertic properties) then calculate yy as [grwhi + grwlo]/2 - 50
If yy in the above cases is less than or equal to 50 then g is true and exit.
Otherwise test for mottles: If the mottles are "N", "V", or "F" (no mottles) then check:
The first horizon for chromas of the moist matrix of less than or equal to 1 and values of greater or equal to 4 then g is true and exit.
If mottles are present ("C","M", or "A") then check:
The first horizon for chromas of the moist matrix of less than or equal to 2 and values of greater or equal to 4 then g is true and exit.
Continue this sequence of tests for all horizons until 75 cm depth.
Otherwise if drainage is "P" (poor) then g is true and exit.
*/
end-g:
x-test: /depth = 20cm, depth-averaging. Predecessors include v. Shortcuts are x = 2 if
Surface = S, or v = 1/
x = 0
If Type = "S" OR v = 1 then {x = 2, goto end-x}
If [parmat] = "UP" AND Type = "L"/"C" AND [pf42] >= 30 then {x = 1; goto end-x}
If [phh2o]<> -1 AND [phh2o] =< 6.2 AND [cec7]<> -1 AND [ecec]<> -1 then
If ([cec7] - [ecec]) / (7 - [phh2o]) >= 12 then
{x = 1; goto end-x}
else
{x = 2; goto end-x}
If v = 2 AND Type <> "O" AND [pf42] > 30 AND [oc1a] > 5 then {x = 1; goto end-x}
If "Vitr" in [uscl] then {x = 2; goto end-x}
/* x-test criteria: First check for Type and other modifiers: if Type is S (sandy) or modifier v is true then x is false and exit.
If parent material is "unconsolidated pyroclastics" and Type (surface texture) is L or C (loamy or clayey) and pF4.2 or 15-bar water is greater or equal to 30% then x is true and exit.
Otherwise if pH in water is present and is less than pH 6.2 and CEC pH7 is present and effective CEC (ECEC) is present then calculate (CECpH7 - ECEC)/(7 - pH in water). If this value is not less than 12 then x is true else x is false and exit. (This is a ratio developed by Vollrath and Smith, NRCS, Hawaii).
Otherwise if v is false (soil does not have vertic properties), and if the Type is not O (organic) and the pF4.2 (15-bar water) is greater than 30%, and organic carbon in the surface horizon is greater than 5% then x is true and exit.
Otherwise test for the letters "Vitr" in the text of the Soil Taxonomy name, if present then x is false and exit.
*/
end-x:
i+-test: /depth = 20cm, depth-averaging but not related to horizons. A predecessor, g+. Shortcuts are i+ = 2 if x = 1/
i+ = 0
If x = 1 then {i+ = 2, goto end-i+}
If g+ = 1 AND Type = "C" AND Subtype = "C" AND [cec]/[clay] =< .16 then i+ = 1 else i+ = 2
/* i+-test criteria: First check for other modifiers: if modifier x is true then i+ is false and exit. If g+ is true and Type (surface) is C (clayey) and Subtype (subsurface soil) is C (clayey) and CEC/(clay percentage) is less than or equal to 16 then i+ is true and exit. Otherwise i+ is false.
*/
end-i+:
x-test: /depth = 20cm, depth averaging but not related to horizons. Predecessors include x.
Shortcut is x = 2 if x = 1/
x = 0
If x = 1 then {x = 2, goto end-x }
If "Vitr" NOT in [uscl] AND "And" in [uscl] AND "Kand" NOT in [uscl] then
{x = 1, goto end-x}
x = 2
/* x--test criteria: First check for other modifiers: if modifier x is true then x- is false and exit. Otherwise if the letters "Vitr" are not present in the text of the Soil Taxonomy name but "And" is and "Kand" is not present in the text then x- is true and exit. Otherwise x- is false and exit.
*/
end-x :
i-test: /depth = 20cm, depth-averaging, no predecessor. Shortcuts are i = 2 if Surface = S/O,
x = 1, x = 1, or g+ = 1/
i = 0
If Type = "S" OR Type = "O" OR x = 1 OR x = 1 OR g+ = 1 then {i = 2, goto end-i}
If "OX " in [uscl] OR (Type = "C" AND ("KAN" in [uscl] OR
([clay] <> -1 AND [cec7] <> -1 [clay] <> 0 AND [cec7] / [clay] =< 0.16))) then
{i = 1; goto end-i}
/A blank after OX - search for the soil order OXISOL, but not for any other kinds (such as OXIC, etc). Alternatively, the suffixes can be listed as AQUOX, UDOX, HUMOX, ORTHOX, TORROX, USTOX, PEROX/ /The cec7 and clay ratio is the ratio of their averages/
If [uscl] = "-" AND [clay1a] = -1 then {I = 0; goto end-I}
i = 2
/* i-test criteria: First check for Type (surface texture) is S (sandy) or O (organic) and other modifiers: if modifier x=1 or x- =1 or g+ = 1 then i is false and exit.
If the letters "Ox" are present in the Soil Taxonomy text or (Type is C (clayey) and either there is the letters "Kan" in the Soil Taxonomy text or the CECpH7 / clay ratio is less than 0.16) then i is true and exit.
Otherwise if the Soil Taxonomy classification text is missing and surface clay is missing then i is unknown and exit.
Otherwise i is false and exit.
*/
end-i:
i-test: /depth = 20cm, depth averaging. Predecessors include i. Shortcuts are i = 2 if Surface = O/S, i = 2, x = 1, x = 1, or g+ = 1/
i = 0
If Type = O/S OR i = 2 OR x = 1 OR x = 1 OR g+ = 1 then {i = 2, goto end-i }
If i = 1 AND ([phh2o] < 7.3 OR ([phh2o]>= 7.3 AND [method] = "Olsen")) AND [totp] >= 10 ppm then i = 1
/[method] can be derived from [lab_id] in wisesite/
/* i--test criteria: First check for Type (surface texture) is S (sandy) or O (organic) and other modifiers: if modifier i=1, x=1 or x- =1 or g+ = 1 then i- is false and exit.
If i = 1 and pH in water is less than 7.3 ( or pH in water is greater than or equal to 7.3 and Soil test method is Olsen P) and P is greater than 10 ppm then i- is true and exit.
*/
end-i :
d+-test: /depth = 50cm, not related to horizons, no predecessor/
d+ = 0
If "TOR"/"ID" in [uscl] then {d+ = 1; goto end-d+}
If [koppen] = "BWh"/"BWk" then {d+ = 1; goto end-d+}
If [uscl] = "-" AND [koppen] = "-" then {d+ = 0; goto end-d+}
d+ = 2
/* d+-test criteria: Not related to horizons.
If Soil Taxonomy text contains the letters "Tor" or "id" then d+ is true and exit.
If the Koppen climate classification is "Bwh" or "Bwk" then d+ is true and exit
If the Soil Taxonomy text description of the code is missing and the Koppen code is missing then d+ is unknown and exit.
Otherwise d+ is false.
*/
end-d+:
d-test: /depth = 50cm, not related to horizons, no predecessor. The shortcut is d = 2 if d+ = 1/
d = 0
If "XER"/"UST" in [uscl] then {d = 1; goto end-d}
If [koppen] = "BSh"/"BSk"/"Cs"/"Csa"/"Csb"/"Cbw"/"Dd"/"ET"/"Daw"/"Ddw" then
{d = 1; goto end-d}
If [uscl] = "-" AND [koppen] = "-" then {d = 0, goto end-d}
d = 2
/* d-test criteria: First check for other modifiers: if d+ is true then d is false and exit.
Otherwise if the letters "XER" or "UST" are present in Soil Taxonomy text then d is true and exit
Otherwise if Koppen classification is Bsh, Bsk, Cs, Csa, Csb, Cbw, Dd, ET, Daw, or Ddw then d is true and exit.
Otherwise if the Soil Taxonomy text is missing and the Koppen classification is missing then d is unknown and exit.
Otherwise d is false.
*/
end-d:
e-test: /depth = 20cm, depth-averaged values. Predecessors include v, b, s, s, n, x, x, a, h .
Shortcuts are e = 2 if v = 1/
e = 0
If v = 1 OR (x = 1 AND (b = 1 OR s = 1 OR s = 1 OR n = 1)) OR (b= 1 AND Type <> "S") then
{e = 2; goto end-e}
If [ecec]<> -1 AND [ecec] =< 4 then {e = 1; goto end-e}
If [ecec] > 4 then {e = 2; goto end-e}
If (x = 1 OR x = 1) AND (a = 1OR h = 1) AND [cec7]<> -1 AND [cec7] =< 16 then {e = 1; goto end-e}
If (x = 1 OR x = 1) AND (a = 1OR h = 1) AND [cec7] >16 then {e = 2; goto end-e}
If (a = 1OR h = 1) AND [cec7]<> -1 AND [cec7] =< 7 then {e = 1; goto end-e}
If (a = 1OR h = 1) AND [cec7] > 7 then {e = 2; goto end-e}
If [cec7]<> -1 AND [cec7] =< 4 then {e = 1; goto end-e}
If [cec7] > 4 then {e = 2; goto end-e}
/* e-test criteria: Depth 20cm, depth-averaged values. First check for other modifiers: If b is true (high base status) and Type (surface texture) is not S (sandy) or x is true (x-ray amorphous materials and one of the following modifiers is true (b, s, s-, n) or, lastly, if v (vertic properties) is true then e is false and exit.
Otherwise if ECEC (effective cation exchange capacity) data are present and the ECEC is less than or equal to 4 then e is true and exit.
Otherwise if ECEC is greater than 4 then e is false and exit.
Otherwise if x or x- is true and a or h is true, and CECpH7 is present and less than or equal to 16 then e is true and exit.
Otherwise if x or x- is true and a or h is true, and CECpH7 is present and greater than 16 then e is false and exit.
Otherwise if a or h is true and CECpH7 is less than or equal to 7 then e is true and exit.
Otherwise if a or h is true and CECpH7 is greater than 7 then assign e to false and exit.
Otherwise if CECpH7 is present but is less than 4 then e is true and exit.
Otherwise if CECpH7 is greater than or equal to 4 then e is false and exit.
Otherwise e is unknown and exit.
*/
end-e:
k-test: /depth = 50cm, any occurrence with cumulative thickness of qualified layers >= 10cm. Predecessors include e, i, d+, g+, b, v, g, x, x /
k = 0
If "Quartzipsamment" in [uscl] then {k = 1; goto end-k}
If [horiz] = "E horizon" AND [botdep] - [topdep] >= 10cm then {k = 1; goto end-k}
If e = 1 AND i = 1 then {k = 1; goto end-k}
If [exk] <> -1 then /min of vk's is used here/
{
If Type = "S" OR Subtype = "S" then
If d+ <> 1 then /S except d+/
If [exk] =< 0.14 then {k = 1; goto end-k} /sum of k1/
else /Sd+/
If [exk] =< 0.2 then {k = 1; goto end-k} /sum of k2/
If Type = "L" OR Subtype = "L" then
If e = 1 OR g = 1 OR g+ = 1 then /Le, Lg, Lg+/
If [exk] =< 0.14 then {k = 1; goto end-k} /sum of k1/
else /L except Le, Lg, Lg+/
If [exk] =< 0.24 then {k = 1; goto end-k} /sum of k3/
If Type = "C" OR Subtype = "C" then
If b = 1 AND v = 1 then /Cbv/
If [exk] =< 0.54 then {k = 1; goto end-k} /sum of k6/
else If b = 1 OR v = 1 then /Cb, Cv/
If [exk] =< 0.44 then {k = 1; goto end-k} /sum of k5/
else If g = 1OR I = 1 OR x = 1 OR x = 1 then /Cg, Ci, Cx, Cx/
If [exk] =< 0.2 then {k = 1; goto end-k} /sum of k2/
else If g+ = 1 AND v = 1 then /Cg+v/
[exk] =< 0.24 then {k = 1; goto end-k} /sum of k3/
else If [exk] =< 0.34 then {k = 1; goto end-k} /the rest of C/
If (Type = "O" OR Subtype = "O") AND [exk] =< 0.14 then k = 1 /sum of k4/
}
/* k-test criteria: The potassium modifier is more complex than many. Initial screening for taxonomy is that if the soil is a Quartzipsamment then it most likely is K deficient. It also is likely if there is an E-horizon (eluviated horizon) and the thickness of this horizon is greater than 10cm. Also it is most likely that if the soil has an e modifier (low exchange capacity) and has a lot of iron (I modifier) then it is also K deficient). If none of these conditions hold then the algorithm goes through a fairly complicated decision tree:
First we check to be sure that there are exchangeable K data. If not we exit the algorithm indicating that we cannot determine the K status. However if exchangeable K is present we evaluate it with the soil texture and e modifier status in mind:
We first take soils that have either an S Type or an S Subtype and check for the K levels; If the soil is not extremely arid (d+ is false) and the exk (exchangeable K) is not greater than 0.14 then the k modifier is true. If the soil is extremely arid and exk is less then 0.2 then k is true.
Next we take soils that have either L Type or Subtype. If the soil has either the e modifier, is poorly drained g modifier or is extremely poorly drained g+ modifier, and exk is not greater than 0.14 then the k modifier is true. If the soil has an L Type or subtype but has neither the e, g, nor the g+ modifier and exk is no greater than 0.24 the k modifier is true.
Next we take the soils that have either C Type or Subtype and check for base status (b=1) and whether the soil has vertic properties. If it has both of these then if exk is less than 0.54 then the k modifier is true. If the C Type or Subtype soil is not both b=1 and v=1 but one of them then if exk is less than 0.44 the k modifier is true. If the soil (still clayey surface or subsurface) has the g modifier or the i modifier or has some andic properties then if the exk is less than 0.2 the k modifier is true. We next check to see if the soil is both extremely poorly drained (g+ modifer is true) and has vertic properties then if exk is less than 0.24 then the k modifier is true. If none of the above conditions hold and the soil is still clayey Type or Subtype then if exk is less than 0.34 then the k modifier is true.
Lastly we check for organic soils, those with O Type or subtype, if exk is less than 0.14 then the k modifier is true.
*/
end-k:
t-test: /depth = 50cm, not related to horizons, no predecessor/
t = 0
If [latdeg] + [latmin]/60 >66.5 then {t = 1, goto end-t }
t = 2
/* t--test criteria: The t- modifier indicates permafrost -- and it is assumed that this occurs at least at latitudes greater than 66.5 degrees latitude, including both the Arctic and Antarctic.
*/
end-t:
t-test: /depth = 50cm, not related to horizons, no predecessor. Shortcut is t = 2 if t = 1/
t = 0
If t = 1 then {t = 2, goto end-t}
If [latdeg] + [latmin]/60 < 23.5 then {t = 2, goto end-t}
If [latdeg] + [latmin]/60 PRESENT [23.5, 66.5] then t = 1
/* t-test criteria: Purpose of the t-test is to determine whether there is a seasonal temperature limitation in the soils with this modifier. The criteria are that if there is a t- then there cannot be a t modifier. The t- modifier is for colder temperatures than t+. This algorithm assigns the t modifier to a yes if the location (latitude) of the sample is within 23.5 and 66.5 degrees latitude. */
end-t:
Appendix Table 7. List of recommendations associated with each of the FCC3 codes.
Types (Surface layer and the first letter in the one or two letter code), Subtypes (Subsurface layer and second letter, if different). (S - sandy, L - silty, and C - clayey)
O: - In spite of high organic carbon contents, these soils can have high nitrification rates and may not require N fertilizers for one or more crops after clearing (Brady, 1984).
- The effectiveness of some herbicides is greatly reduced by the presence of high organic matter contents (Weber, personal communication).
- If this soil has sapric materials (muck), hydraulic conductivity values are typically low. Where artificial drainage is required to maintain good aeration, ditches and/or tiles may need to be closely spaced (about 100 m) and the soil surface graded to remove surface water (Buol et al., 1980).
- Micronutrient deficiencies including copper, molybdenum, boron, zinc, manganese, and chloride commonly occur (Brady, 1984; CIAT, 1978).
- The low bulk density and strength of the soil favors well shaped root crops (Buol, 1980).
OS:- In spite of high organic carbon contents, these soils can have high nitrification rates and may not require N fertilizers for one or more crops after clearing (Brady, 1984).
- The effectiveness of some herbicides is greatly reduced by the presence of high organic matter contents (Weber, personal communication).
- If this soil has sapric materials (muck), hydraulic conductivity values are typically low. Where artificial drainage is required to maintain good aeration, ditches and/or tiles may need to be closely spaced (about 100 m) and the soil surface graded to remove surface water (Buol et al., 1980).
- The possibility of micronutrient deficiencies (including copper, molybdenum, boron, zinc, manganese, and chloride) is high in this soil because of the presence of both the organic and the sandy material.
- Unless the organic material is a muck, rapid infiltration rates cause excessive leaching of nutrents, especially nitrate, potassium, and sulfate. These fertilizers should be applied in split applications.
OL: - In spite of high organic carbon contents, these soils can have high nitrification rates and may not require N fertilizers for one or more crops after clearing (Brady, 1984).
- The effectiveness of some herbicides is greatly reduced by the presence of high organic matter contents (Weber, personal communication).
- If this soil has sapric materials (muck), hydraulic conductivity values are typically low. Where artificial drainage is required to maintain good aeration, ditches and/or tiles may need to be closely spaced (about 100 m) and the soil surface graded to remove surface water (Buol et al., 1980).
OC: - In spite of high organic carbon contents, these soils can have high nitrification rates and may not require N fertilizers for one or more crops after clearing (Brady, 1984).
- The effectiveness of some herbicides is greatly reduced by the presence of high organic matter contents (Weber, personal communication).
- If this soil has sapric materials (muck), hydraulic conductivity values are typically low. Where artificial drainage is required to maintain good aeration, ditches and/or tiles may need to be closely spaced (about 100 m) and the soil surface graded to remove surface water (Buol et al., 1980).
S: - The ability of the soil to supply nutrients is relatively low and the possibilities of nutrient deficiencies are increased as moisture contents decrease from field capacity. Excessive leaching of nutrients, especially nitrate, potassium, and sulfate (Oates and Kamprath, 1985; Renau and Hawkins, 1980), is common. The crop should be carefully monitored for nutrient deficiency symptoms. Fertilizers should be applied in split applications.
S: - Surface and subsurface, without d or d+ modifier
The soil moisture regime is udic or perudic but in most locations, irrigation may be required for maximum yields. The quantities of irrigation water and timing of application should be carefully calculated to reduce leaching losses. Seedling wilt due to a rapidly drying surface layer can be a problem. Planting when moisture stress hazard is lowest or planting in the furrow may be required to reduce seedling wilt where non-irrigated.
Infiltration is rapid and runoff is unlikely. During short drought periods, soil blowing can occur. Bedding usually creates sufficient surface roughness to minimize the problem.
This soil is susceptible to traffic pan formation. Significant yield increases can be obtained with periodic subsoiling (Denton et al., 1986). Tillage operations when the soil is drier decrease the hazard of pan formation.
SL:- The ability of the soil to supply nutrients is relatively low and the possibilities of nutrient deficiencies are increased as moisture contents decrease from field capacity. Excessive leaching of nutrients, especially nitrate, potassium, and sulfate (Oates and Kamprath, 1985; Renau and Hawkins, 1980), is common. The crop should be carefully monitored for nutrient deficiency symptoms. Fertilizers should be applied in split applications.
SC:- The ability of the soil to supply nutrients is relatively low and the possibilities of nutrient deficiencies are increased as moisture contents decrease from field capacity. Excessive leaching of nutrients, especially nitrate, potassium, and sulfate (Oates and Kamprath, 1985; Renau and Hawkins, 1980), is common. The crop should be carefully monitored for nutrient deficiency symptoms. Fertilizers should be applied in split applications.
SC: without d+ and g+ - The ability of the soil to supply nutrients is relatively low and the possibilities of nutrient deficiencies are increased as moisture contents decrease from field capacity. Excessive leaching of nutrients, especially nitrate, potassium, and sulfate (Oates and Kamprath, 1985; Renau and Hawkins, 1980), is common. The crop should be carefully monitored for nutrient deficiency symptoms. Fertilizers should be applied in split applications.
- Infiltration is rapid and runoff is unlikely if the surface material is thick enough to accept expected rain event amounts. Water can temporarily perch on the clayey material and cause short term waterlogging in lower areas of sloping fields.
SO:- The ability of the soil to supply nutrients is relatively low and the possibilities of nutrient deficiencies are increased as moisture contents decrease from field capacity. Excessive leaching of nutrients, especially nitrate, potassium, and sulfate (Oates and Kamprath, 1985; Renau and Hawkins, 1980), is common. The crop should be carefully monitored for nutrient deficiency symptoms. Fertilizers should be applied in split applications.
L: - Very fine sandy loam, silt, and silt loam surface textures can be the most highly water erodible textures.
LS: - In the surface layer, very fine sandy loam, loam, clay loam, silt, silt loam and silty clay loam textures usually have a high AWC (available water capacity). The remaining textures within the loamy surface type have a medium AWC. The AWC of the sandy subsurface type is generally, low and drought stress becomes an increasing concern as the sandy material is encountered nearer the surface. A very fine sand texture, however, can have a medium AWC.
LC: - Surface textures including very fine sandy loam, loam, clay loam, silt, silt loam, and silty clay loam usually have a high available water content (AWC). The remaining textures within the loamy surface type usually have a medium AWC. The AWC of the C subsurface type textures is variable. A sandy clay texture typically exhibits a medium AWC. Clay loam, silty clay loam and silty clay textures generally have a high AWC. A clay texture can have a low or medium AWC if the clay content is greater than 60% and medium to high AWC if the clay content is less than 60%.
LO: - Very fine sandy loam, silt, and silt loam surface textures can be the most highly water erodible textures.
C: - This soil usually has a medium to high available water content as long as the clay content is 60% or less. Soil structure may deteriorate by compaction from tilling when the soil is too moist or from excessive tillage, resulting in decreased aeration and root proliferation.
C: - without I or I- modifiers
- Tillage may be delayed because of high moisture contents from an untimely rainfall event.
- without I or x modifiers
- The available water capacity (AWC) of C Type soils is variable. A sandy clay texture typically exhibits a medium AWC. Clay loam, silty clay loam, and silty clay textures generally have a high AWC. A clay texture can have a low or medium AWC if the clay content is greater than 60% and medium or high AWC if the clay content is less than 60%.
CS: - The available water content (AWC) of the clayey surface type is variable. A sandy clay texture typically exhibits a medium AWC. Clay loam, silty clay loam and silty clay textures generally have a high AWC. A clay texture can have a low or medium AWC if the clay content is greater than 60% and medium or high AWC if the clay content is less than 60%. Tillage may be delayed because of high moisture contents from an untimely rainfall event. The AWC of the sandy subsurface type is generally low. A very fine sand texture can have a medium AWC.
CL:- The AWC of the clayey surface type is variable. A sandy clay texture typically exhibits a medium AWC. Clay loam, silty clay loam and silty clay textures generally have a high AWC. A clay texture can have a low or medium AWC if the clay content is greater than 60% and medium or high AWC if the clay content is less than 60%. Tillage may be delayed because of high moisture contents from an untimely rainfall event. The AWC of the loamy subsurface type is high for very fine sandy loam, loam, clay loam, silt, silt loam and silty clay loam textures and medium for the remaining textures.
CO: - The AWC of the clayey surface type is variable. A sandy clay texture typically exhibits a medium AWC. Clay loam, silty clay loam and silty clay textures generally have a high AWC. A clay texture can have a low or medium AWC if the clay content is greater than 60% and medium or high AWC if the clay content is less than 60%. Tillage may be delayed because of high moisture contents from an untimely rainfall event. Micronutrient deficiencies of copper, molybdenum, boron, zinc, manganese, and chloride are common if the organic layer predominates.
R- (in subsurface) - This soil has a rooting depth limitation because of the present of an indurated layer, pan or rippable bedrock. If the limiting layer is broken, the soil should be reclassified considering the resulting subsurface type texture and coarse fragment content in order to obtain the appropriate interpretation.
Modifiers:
(statements will be made in groups: 1) Water and climate conditions (d, d+), (g, g+, i+), (t, t-), 2) Mineralogy, (i, i-), (x, x-), 3) Soil pH, acidity, (a, h, b, c), 4) Cation abundance (s,s-), (n, n-), (e, k).
Group 3: Soil pH, acidity
a - Lime particle size is important in determining reactivity. Optimum size distribution includes at least 50% of the grains that will pass a 50 mesh sieve. A few regions have access to corraline sand as a lime source. This material is porous and need only pass a 2 mm sieve (Latham, personal communication).
- Where lime is difficult to obtain or is expensive, selection of Al tolerant cultivars alone or in combination with reduced liming is recommeded depending on the cultivar and severity of Al toxicity.
- Where acid tolerant cultivars are grown and liming the soil does not increase the pH values to over 5.5, rock phosphate may be effectively used (Barnes and Kamprath, 1975).
h - Aluminum presence reduces uptake of magnesium (Kamprath and Foy, 1971) and liming can lower