Practices for controlling desertification and improving livestock production
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Grazing systems
Common use
Supplemental
pastures
Many range management practices have been developed since the science was born some fifty years ago and new ones are being developed. These practices are aimed at controlling desertification and at obtaining maximum sustained economic animal production. While specifics will vary, the application of these practices, in principle, is badly needed in the Region. Desertification symptoms are widespread and average ruminant production is pitifully low. Of the regions where meat is eaten, only Africa has lower production levels than the Latin America and Caribbean region. A brief review of the livestock production situation is given to reiterate the urgent need for the implementation of sound range and livestock management practices.
Cattle are by far the most important component of the Region's livestock industry. This is mainly due to the vast grazing areas which are more conducive to the production of cattle than other ruminants. Preference has also traditionally been given to cattle over the small ruminants. About 85% of the Region's 324 million head of cattle are in Argentina, Brazil, Colombia, Mexico, Paraguay, Uruguay and Venezuela. Average production per head of cattle is only 30 kgs carcass equivalent. This low level of productivity is due mainly to low reproductive rates, high mortality rates and prolonged fattening. A review of the information from eleven countries at the FAO Expert Consultation for Improving the Reproductive Efficiency of Cattle in Latin America showed that average calf crops were between 50 and 55% with a range as low as 40% in northeastern Brazil to a high of 63% in Argentina. First calving normally occurs at 3 to 4 years of age and the calving interval exceeds 400 days. This low reproductive efficiency combined with high calf mortality makes it almost impossible to raise productivity because it results in: (1) an insufficient number of animals for sale to justify investments for the better management of the herd; and (2) too small a number of replacement females limits genetic progress.
This is aggravated by prolonged fattening periods of four to six years for animals fattened on pasture, especially tropical ones, to attain slaughter weights. Consequently, herds tend to comprise a large percentage of growing males. As a result, the percentage of breeding cows in the national herds tends to be low. Extraction rates are low, varying from around 10% in Paraguay to 20% in Argentina. Low reproductive efficiency is due to a multitude of interrelated factors such as inadequate nutrition, climatic stress, poor herd management, diseases, breeds, and poor reproductive physiological development in the form of sterility, late puberty and others. Man can have an influence on all of these, except climatic stress. There are many examples of well managed herds in the Region which have reproductive rates of 80% or more and annual extraction rates of 20% and above. This was achieved by improved nutrition, utilization of hybrid vigor and proper herd management.
Productivity indices for dairy cattle, sheep and goats and probably alpacas and llamas are similar to those for beef cattle. There are approximately 34 million dairy cows in the Region yielding an average of only 1,000 liters of milk per cow. Most of the dairy farms in the tropical zone do not specialize in milk because most cows utilized are dual purpose, milked seasonally and in many instances only once a day. There is, however, a notable trend, especially near consumption centers, to establish intensive and specialized dairy operations. Average meat and scoured wool production per head for sheep is 3.5 and 1.6 kg, respectively. Sheep production and husbandry practices vary. In many countries it is mostly at the subsistence level. Sheep are kept in small herds and are grazed during the day mainly by women and children or by tethering. Systematic shearing is not commonly practiced. Wool is plucked throughout the year and spun, weaved and made into cloth by the small farmer and his family.
Commercial sheep enterprises for wool and meat production exist mainly in Argentina, southern Brazil, Chile, Uruguay and Mexico which have 75% of the Region's sheep population. Argentina is by far the Region's largest sheep producer, most of which are raised in the Patagonia and Tierra del Fuego. Low reproductive efficiency and high perinatal mortality of lambs owing to malnutrition and harsh climatic conditions are major constraints to production in this zone. There are many breeds of hair sheep adapted to tropical conditions. These are encountered on small farms in the Caribbean countries, Venezuela, northeastern Brazil and Mexico. Outstanding qualities of these sheep are their high prolificacy and fecundity. They represent a valuable resource for meat production in tropical areas. However, lamb death losses are very high, which offsets the advantage of multiple births.
Goat numbers per farm vary from two or three on small farms up to several hundred in large enterprises or in semi-nomadic flocks such as those of the Guajira peninsula of Colombia and the Pacific coast of Chile and Peru. Production per animal is generally low owing to inadequate nutrition and management. Lactation periods of around 160 days and daily milk yields between 200 and 300 gr are common. This amounts to only 32 to 48 kg of milk per doe per year. Kid death losses of 50% or more during the first weeks of life are also common as well as average weaning weights of 5 to 8 kg.
The alpaca and llama are of great economic importance to Peru and Bolivia because of their ability to utilize grasslands of the Andean Altiplano at altitudes over 4,000 m where it is difficult to raise sheep and cattle. Llamas, of which there are about 3 million in Bolivia, are used as pack animals, slaughtered for meat and their hair is used in the cottage industry for rug making. The alpaca are valuable for their fibre, meat and skins. Peru, with some 2.9 million head, is the leading alpaca producer followed by Bolivia with 300,000 head. Around 80% of the alpacas in Peru and all of the llamas in Bolivia are reared by small farmers. At least 200,000 Peruvian campesino families depend in one way or another on the raising of alpaca. Data regarding the productivities of these animals were not available. However, it is known that they are below potential.
Proper Stocking
It has been previously mentioned that two ways to increase livestock production and to control desertification are to: (1) increase grazing capacity and (2) improve individual animal performance. The former was described in the section, "Range Condition as Related to Desertification and Livestock Production." The influence of degree of utilization on individual animal production was illustrated in Figure 8 in the section, "Range Plant Nutrition." However, if one had to select one single factor that affects animal productivity the most, that factor would have to be stocking rate as related to degree of use. For this reason, this subject is presented in greater detail here.
Proper use is a degree of utilization of current year's growth which, if continued, will achieve management objectives and maintain or improve the long-term productivity of the site (SRM, 1989). Our objectives are to arrest and reverse desertification and to obtain maximum sustained livestock production. Proper stocking is placing a number of animals on a given area that will result in proper use at the end of the planned grazing season. Continued proper stocking will lead to proper grazing.
The relationship between stocking rate and animal performance is difficult for livestockmen to understand. Yet, it is so simple. Animals wake up every morning with an appetite and a need for nourishment just like people. They need to consume enough forage during the day to satisfy their appetites and to meet their nutritional needs. On the other hand, a range can only produce so much forage. If the number of animals exceeds the forage supply, an animal against animal competition for forage is created and al] go to bed at night with partially filled stomachs. These daily deficiencies accumulate, resulting eventually in poor performance. The general axiom that good management and nutrition will lead to more productive animals better able to resist diseases, temporary periods of undernourishment and adverse climatic conditions cannot be achieved with continual overuse.
Individual animal production decreases with increases in stocking rate as shown in Figure 8, Table 13 and in Figure 16. Table 13 shows the results of a long-term stocking rate study on an experiment station in the United States. The percent calf crop for overgrazing was 20 percentage points less than for undergrazing and 19 less than for proper grazing. The 205 day calf weights for overgrazing was 56 kg and 50 kg less than for undergrazing and proper grazing respectively. While the highest production per animal was obtained with under utilization, the highest per hectare was obtained with proper use. Interpretations of stocking rate studies with qualitative classifications such as heavy, intermediate (moderate) and light (under) can be misleading. Researchers seem to avoid destructive grazing in their studies, probably because they know what the results will be. Thus, "heavy" is usually around 75 to 80% of utilization and destructive grazing would result in drastic and even more reductions in individual production (See Figure 8). Moderate is usually around 50 to 60% use and light is less than 50%.
Table 13. Long-term influence of degree of use on cattle production at the Miles City, Montana (U.S.A.) Experimental Station. (From Valentine, et al., 1965)
| ITEMS | DEGREE OF USE | ||
| Over | Proper | Under | |
| % Calf Crop1 | 70 | 89 | 90 |
| 205 Day Calf Weights - Kg | 143 | 193 | 199 |
| Production/Ha - Kg | 10.6 | 13.9 | 11.5 |
1 Percent weaned based on number of cows bred.
The influence of stocking rate on cow fertility and percent calf crop shown in Figure 16 was provided by a Venezuelan rancher (Carrero Necker, 1990). The ranch was stocked with slightly less than 3,900 cows in 1978 and the calf crop was less than 35%. A serious stocking reduction programme was commenced in 1979 and percent calf crops began to increase. It peaked at around 65% in 1983, almost double that in 1979 with around 600 less cows. The reduction of cow numbers and calf crop in 1984 was due to an outbreak of disease, which is ample evidence why disease control must be an integral part of herd management. With disease control and range improvement due to proper stocking and other measures, a programme to increase stocking rates began in 1985. Calf crops have remained above the 1978 level with many less cows.
Maximum individual animal productivity might not be the most economical. Production per unit area of land is probably a better measure. The interrelationships between production per animal and area as related to stocking rates results in a bell-shaped curve revealing an optimum rate regarding production per unit of land. This is illustrated in Table 13, Figure 8 and again in Figure 17. This relationship can also be shown mathematically. Jones and Sandland (1974) calculated that zero gains per animal can be expected when stocking rate is double that required for optimum gain per hectare resulting in zero production per hectare, as shown in Figure 17.
The principles of proper stocking also apply to sheep, goats, alpacas and llamas. On a farm in Chile, milk production from "Criollo" goats increased 77% with better management, nutrition and disease control. Total wool production increased from around 85 thousand tons to around 95 thousand tons with 13 thousand less sheep on a ranch in Argentina's Patagonia. The reduction was gradual over a fifty year period and the increases in wool production were not only due to adjustments in stocking rates, but also to better management and genetic improvement.
Facing declining animal production and declining economic gains with overuse and lacking technical knowledge, one can understand why livestock owners think that additional stock is a solution to their problems, when in reality it makes things worse. The adage "more livestock - more produce" simply does not work when over utilization is involved. On the other hand, one cannot understand how national or regional progress can be measured by increases in livestock numbers without provision for adequate nutrition. As strange as it might sound, meat, milk and fiber production will increase with less livestock on the Region's rangelands. A great step towards desertification control will also be made.
A grazing system can be defined as a specialization of grazing management which defines the periods of grazing and non-grazing. It can also be defined as the manipulation of livestock grazing to accomplish a desired result. Scientists and even livestockmen have spent a lot of time designing and testing various grazing systems with varied results.
Many different factors are considered in the design of grazing systems. One is to avoid as far as possible the deleterious effects of defoliation during a plant's most vulnerable stage of growth such as those shown in Figure 7. Plants are almost completely dependent on carbohydrate reserves during these periods and the reserves will not be replaced until there is an adequate amount of leaf area to do so. Defoliation during these vulnerable periods has an adverse effect on plant health and on both current and future year's growth and forage production.
Systems that will enhance secondary succession and range condition improvement is another important consideration. As previously described, succession cannot take place without migration, ecesis and aggregation. In the first place, some sort of rest is needed in order for the desirable and less desirable species to produce seeds or vegetative reproduction organs. In the second place, some rest is needed in order to have successful migration, ecesis and aggregation.
Other considerations are systems that will (1) reduce grazing frequency, (2) result in more efficient use of the forage resources, (3) create forage reserves for use during the non-growing season, (4) reduce costs, (5) favour wildlife and (6) assure acceptable livestock production levels. Of course, desertification arrestment and reversal is a major objective.
Grazing systems are not a panacea. Proper stocking is the backbone of all systems and no system will be successful without it. The consultant has seen many deferred-rotation grazing systems that did more harm than good because they were improperly stocked. There is no one ideal system suitable for all situations. It is not the purpose of this paper to compare the merits and faults of some of the systems, especially the systematic ones. Some of the better known systems are presented which are applicable somewhere in the Region depending on the circumstance. Modifications to fit local conditions will be required and even better systems can be developed.
Yearlong Grazing
This refers to yearlong rangelands which are, or can be, grazed yearlong. Yearlong grazing is the continuous grazing of these ranges for a calendar year. There is evidence that good and excellent range condition can be maintained with continuous proper stocking. This is also true for poor and fair condition, but maintenance of these should not be an objective. Improvement through secondary succession should be the objective. Continuous proper, or even lighter, grazing is not conducive to progressive succession. The amount of less desirable plants is limited and desirable plants are even more limited. Since animals eat what they like first, the desirable species are sought out and are continually grazed, preventing their reproduction. The same is true with less desirable plants to a lesser extent. Thus, some sort of deferment is needed to allow the spread of desirable and less desirable species.
Seasonal Grazing
Some ranges cannot, or should not, be grazed yearlong for various reasons; topography, snow, flooding, seasonal growth patterns and others. A seasonal grazing system is one in which utilization is, or should be, restricted to specific seasons. Examples of seasonal rangelands can be found in the Region's mountainous areas and wet savannahs (llanos). The proper grazing period for a seasonal range is short and attempts to graze it for longer periods results in deterioration and poor livestock performance.
Proper seasonal grazing systems are not systematic in the sense that livestock are moved on fixed dates. They should not be placed on a seasonal range until a state of range readiness is attained which is a stage of growth at which grazing may begin without damage to vegetation or soil. By the same token, they should not remain on a seasonal range until the forage is completely consumed. Some growth must be left for the plants' benefit and for the environment's benefit. Rotation or deferred-rotation grazing systems can be superimposed on some units of a seasonal grazing system to assure timely use and to promote vegetation improvement.
Decision Deferment
It has already been seen that some decision making is involved in seasonal grazing systems. Deferred or deferred-rotation grazing systems based on decisions can also be an effective and inexpensive way to utilize and improve yearlong ranges. Decisions can be based on various measures or observations such as range condition, range condition trend, degree of utilization, range readiness, livestock condition, plant vigor and rainfall. Rainfall is not uniform in the arid and semiarid regions. It may rain quite a lot in one spot and very little or none at all in other spots. One part of a ranch can have more rain that other parts. Decision deferment can be made accordingly. Deferment following some physical improvement practices such as reseeding and brush control is mandatory.
Decision deferment requires trained eyes which most livestock owners do not have. Technical assistance and rancher training is normally needed for the wide-scale implementation of sound decision grazing systems and such services are not available in the Region. This is most unfortunate because this range and livestock management method can be a very effective way to control desertification and improve production at low cost. One reason for designing costly systematic grazing systems is because the "trained and understanding eyes" are lacking.
Systematic Systems
A systematic grazing system is one in which the different pastures or units of the system are either grazed or non-grazed on a fixed schedule or specified calendar dates. These go by many names such as rotation, deferred grazing, deferred-rotation, rest-rotation, high intensity-low frequency, short duration grazing, cell grazing and perhaps many more. Sometimes the system goes by the name of the original designer such as Hormay, Merril or Savory. The wealth of names often creates confusion.
A well designed systematic grazing system requires pastures of more or less equal grazing capacity. This does not necessarily mean equal size depending on the range sites and conditions involved. For example, 143 ha of a slope site in poor condition as shown in Table 7 would be equal to 100 ha of an ordinary upland site in the same condition. Planners must therefore take range sites and condition into consideration when designing systematic systems. Each pasture must also have drinking water and this must be considered as well.
The total grazing capacity for all of the pastures in a system is divided equally into the number of herds involved. A three-herd-four-pasture-deferred-rotation system is taken to illustrate the point. Assume that each pasture has a capacity of 60 A.U.s. This would be divided into three herds consisting of 80 A.U.s each. This creates some overuse of the pastures that are grazed, but this is not continued over the years. Thus, the frequency of over utilization is not serious and any temporary damage that might have been done is repaired with subsequent deferment. The deferment periods are based on the seasons when plants are most vulnerable to defoliation (Figure 7) and when secondary succession is most likely to take place.
Current divisions of many ranches are not compatible to immediate implementation of most systematic systems. This is also true of water development. The cost of additional fences and water might be prohibitive, but considering the success of many systematic systems, the cost could be amortized in the long term. Costs could also be reduced with the use of suspension and/or living fences.
The three herd-four pasture, two herd-three pasture and one herd-two pasture deferred-rotation systems have given good results under certain circumstances. Their fundamental designs are given in Annex I. Hormay and Talbot (1961) found that some grazing after seed formation helped to disseminate and bury the seed and that removal of cured leaves and stems stimulated tiller formation. Hence, the Hormay one herd rest-rotation grazing system evolved, involving three treatments in one year. It is widely used with success on the arid and semiarid seasonal rangelands of western United States. It can be executed without fencing with good planning and with herding. It is felt that the system is applicable on many of the Region's seasonal ranges. The design is given in Annex II.
An example of the high intensity-low frequency systems comes from the Texas Range Station and was designed by the consultant. Six pastures were established and the total grazing capacity of all six was placed into one herd of sheep and cattle. The total A.U.s was composed of 60% cattle and 40% sheep. A pasture was grazed for 25 days and rested 125 before being grazed again. Consequently, each pasture was grazed for 75 days and rested 290 days during the year. There was spectacular and rapid range improvement, but livestock production, especially cattle, was low. Similar results have been obtained in other trials in other locations. It is a good system for rapid improvement if one is willing to sacrifice some animal production. It can be modified in future to take advantage of the improved range condition and at the same time obtain higher livestock production levels. The feasibility and economics of systems involving many more pastures and reduced grazing frequency are questionable.
This is in effect a grazing system as it refers to the use of a range by more than one kind of livestock either at the same time or at different times within the same growing season. It is also called "dual use." Examples are grazing either cattle and sheep; cattle and goats; sheep and goats; cattle, sheep and goats; alpaca and llama or sheep, alpaca and llama together. Single use refers to the grazing of only one kind of livestock, cattle only, sheep only, etc. Common use is not applicable on all rangelands for climatic, vegetation and cultural reasons. Some cattlemen will not raise either sheep or goats although these species could contribute significantly to increased came productivity and net income.
Where common use is applicable, it results in more efficient use of the forage resources (grass, fortes, browse), greater total animal production and more secure income than single use. The latter is because of greater versatility regarding markets. When prices for the products of one kind of animal are down, they may be up for the products of the other kind or kinds. Total grazing capacity can often be increased up to 20 or 25% with common use compared with single use. Proper stocking rates are based on the total animal units and the ratio between the different kinds of livestock depends on the vegetation components.
Stocking Rate Flexibility
It is reiterated that any grazing system must be accompanied with proper stocking. If not, it will surely fail. Flexibility refers to the characteristics of a management plan which allows it to accommodate to changing conditions (SRM, 1989). This particularly refers to changes in grazing capacities owing to weather fluctuations. Minor fluctuations in forage production are not of major concern. These tend to offset each other with proper stocking. Major fluctuations, especially those associated with prolonged droughts, are of great concern. Even average proper stocking rates can result in severe over use during these periods resulting in damage to the vegetation that will take years to overcome. Under use during above average rainfall years results in unused forage. While this might represent a slight economic loss, it does not represent an environmental loss. The additional litter and mulch plus increased plant vigor and reproduction better prepares the range for the oncoming dry years.
Griffiths and Orton (1968) calculated that the probabilities of receiving average and above rainfall in both the semiarid and humid climatic areas of Texas is 40%, i.e., 60% of the years will have below average rainfall. Thus, stocking based on average rainfall would result in over use, varying from slight to severe, 60 years out of 100 which will contribute significantly to desertification.
A mode in a series of statistical data is an average of items that occur the oftenest. Rainfall mode in arid and semiarid zones is always below the average, being around 20% less. Consequently, there is also a forage production and a grazing capacity mode. Stocking according to the mode would reduce the probabilities of over use to around 30 to 40 years out of a hundred rather than 60 or more years. The formation of an elite reproducing herd based on the mode grazing capacity is an important step towards the establishment of a flexible grazing system and the avoidance of desertification. Nothing is lost. Maximum production for the elite herd will be assured for many more years than otherwise. Animals that can be readily sold could be kept during good years to increase profits. Old and poor productive and non-productive animals would be culled during bad years.
Supplementation
The lack of supplementation can be an indirect desertification causal factor. Superior animal productivity requires adequate yearlong nutrition which range forage alone does not always provide. Mineral and, during certain seasons, protein supplementation is often needed. The lack of supplementation adversely affects productivity. Not being aware of this, livestockmen, as with overgrazing, think that more animals are needed to increase total production which in turn causes desertification and poorer animal performance. Appropriate supplementation is needed in order to reap the full benefits of increased grazing capacity and proper stocking.
Range-Cultivated Pasture Integration
Establishment of cultivated pastures in zones with favourable climates and soils is receiving increasing attention. The technologies are known and they are being applied. The grazing capacity of these pastures is several times greater than native vegetation, but establishment and maintenance costs are high. Analyses in Venezuela indicate that cow/calf operations on cultivated pastures are not economical.
Demonstrations in Venezuela indicate that an overall production system in which rangelands are used as breeding grounds and cultivated pastures are used as growing and fattening grounds is not only economical, but is also a more efficient way to use the forage resources. With timely supplementation, heifers on cultivated pastures reach a suitable size for first breeding at an earlier age than usual. Bulls also reach slaughter weights at an earlier age than those on range. Currently, cattle herds on rangelands tend to comprise a large percentage of growing males and females. This would be eliminated with the integration of these two kinds of pastures allowing more space for reproducing cows and an opportunity to establish proper stocking rates on rangelands. Total animal production would also be greater and more efficient.
By-Product Utilization
Better use of the Region's by-products as supplements or feed can reduce the use of grains by the livestock sector. Research has shown that the Region is richer in feed resources than is probably realized. While limitations of space do not permit a comprehensive review of this subject, some examples are highlighted to illustrate the point. The by-products from oil crops such as cotton, sesame, groundnuts, coconuts, African palm, castor beans and sunflowers are excellent sources of protein, as are the inedible parts of fish and livestock.
The fibrous products (leaves, stems, etc.) and/or the non-fibrous products (fruit, pulp, molasses, etc.) of bananas, plantains, coffee, cocoa, pineapple, citrus fruits and sugarcane can all be used as feed and the supply is quite large. Sugarcane has received special scientific attention in this respect because of its high feed yields in the form of whole cane (which is either chopped or derinded for feeding), bagasse or molasses. Roots and tubers and fibrous by-products of many crops also make excellent feeds, especially for small farmers. Particular attention has been paid to cassava (yucca) because of its efficiency in converting solar energy into high yields of starch in the roots and crude protein in the leaves. Manure and poultry litter make good feeds. These are easily collected in production systems where chickens and livestock are concentrated. Animal waste represents a valuable source of energy in that it can be processed into biogas, the residue of which can be fed or used as fertilizer.
The purpose of a supplemental pasture is to quantitatively or qualitatively augment range forage, particularly during dry seasons. These are popularly called either "protein banks, " "energy banks" or "proteinenergy banks." A supplemental pasture is an area of pasture of forage which is not utilized during the season when there is plenty of animal feed available, but is saved for use during times of scarcity. It is a reserve of forage which is left in the field until it is required by the animals. It therefore represents a form of deferred grazing, since the animals are not allowed access to it until they actually need it. If the bank is large enough, the whole herd or flock can take advantage of it during the worst part of the year. If it is too small to benefit all the animals, it should be given only to the most valuable or most productive ones. In any case, it must be protected from grazing for a large part of the year so that it can accumulate material which will be utilized later. To be effective, a fodder bank must be securely fenced to keep out all grazing animals during the growth phase (Paterson, et al., 1987).
The fodder shrubs leucaena (Leucaena leucocephala) and quickstick (Gliricidia septum) and highly productive grasses such as sugarcane (Saccharum officinarum) and elephant grass (Pennisetum purpureum) can be used in the tropics. Various saltbush species (Atriplex spp.) can be used in the arid and semiarid areas. Supplementation pastures reduce grazing pressure on ranges to some extent. Better yet, they can be used as incentives for the formation of grazing cooperatives.
Grazing cooperatives
Public and community grazing lands are subjected to destructive grazing owing to the lack of rules and regulations and an authority to enforce them. This is a very complex problem and its solution requires governmental leadership and support. Although it will not be easy, the formation of self-governing grazing cooperatives or associations will be a beginning towards the solution of this problem. These cannot just be formed by governments. The members must be involved in every stage of formation from the start to the end and during its operation. The members, with technical assistance, make the rules and regulations and they enforce them. They must have power to assess penalties for violations.
The formation of grazing cooperatives is made easier with the provision of incentives. The designation of certain range areas for their exclusive use is a very good one. Another is the establishment of protein and energy banks for their exclusive use. The individuals will develop a pride of "ownership" which tends to lead to better care of the land and they are amenable to extension and assistance activities.
There are many other advantages to grazing cooperatives. They pave the way for the more rapid development of other necessities such as marketing facilities, supplementation, livestock improvement and management and many others. A key to the success of a grazing cooperative is a sound and properly executed range and livestock management and improvement plan. Once the members see and gain from the benefits of a cooperative, they will develop more confidence in the range specialist and will therefore be more prone to accept programmes aimed at rationalizing the use of their designated rangelands.
Alternative Fuels
In light of the fact that fuel gathering contributes significantly to desertification on both rangelands and forests, the need for alternative fuel supplies is apparent. Fossil fuels are generally not available to the fuel gatherers and even if they could be made available, they would be too expensive. One solution that has been used successfully in the Near East, is the establishment of "fuel woodlands." However, the users of this fuel reserve must control harvesting to assure sustained production which is not always possible. Supplemental pastures composed of fodder shrubs also produce some fuel which is another advantage of this practice.
The real solution to the problem is the development and implementation of energy resources other than wood and fossil fuels suitable for individual and/or rural village use. Methane generation using animal and agricultural wastes and solar energy offer the best possibilities. The technologies for methane generation are known and the process is widely used in India and China. Small one-burner generators using pig manure have been developed. The technologies for using solar energy for heat are also known. Small inexpensive cooking ovens using solar energy can be made. The subject of alternative fuel supplies deserves greater consideration.
Artificial Reseeding
All too often, the benefits of artificial reseeding of rangeland, as a range improvement practice, have been overemphasized in most parts of the world. Many times, a sparse though highly potential cover of native vegetation has been completely destroyed in efforts, many of them unsuccessful, to reseed. Artificial reseeding should be undertaken only when no source of seed or vegetative reproduction organs remain to naturally start another generation of desirable native forage plants. This is demonstrated in Figure 18 which is a range that had been recommended for artificial reseeding. The recommendation was based on cursory observations. A critical analysis showed that reseeding was not necessary because there were enough severely overgrazed desirable and less desirable shrubs and grasses for secondary succession. Deferment and proper stocking was all that was needed. If one thinks that artificial seeding is needed, it is wise to first defer the area to see if this is true.
Reseeding is costly and risky, especially in arid and semiarid zones. As a general rule, seeding should not be attempted in areas with less than 300 mm of average annual rainfall because they are apt to fail. However, successful seedings have been made in low rainfall areas when made in connection with water harvesting techniques such as pitting, contour furrows and water spreading although these give only shortterm water harvesting benefits. Gifford (1975) concluded that these and other mechanical "improvement" practices are not beneficial from the long-term standpoint of runoff and sediment production. Most research has shown that improvement practices which involve severe mechanical disturbance should not be expected to improve hydrologic conditions. Since the life of most mechanical treatments is relatively short, it is imperative that a desirable vegetative cover be established and properly maintained.
Assuming that artificial seeding is really needed, it should first be attempted on range sites with the highest potential and on favourable soils. Abandoned cultivated fields must be reseeded to restore productivity.
Poor seedbed preparation and seeding practices have been the cause of reseeding failures much more often than has adverse weather, although the latter is usually blamed. But in most years, only the really well prepared seedbed will yield results. Generally speaking, a reseeding will be only as good as the preparation and planting work that went into the seeding operation. This applies not only to arid and semiarid areas but also to high rainfall areas.
Brush Control
Many of the Region's rangelands have been invaded by undesirable brush species. Improper utilization has permitted this invasion in almost all cases and cessation of burning along with excessive use has permitted it in many cases. Brush control is not deforestation. It is the reduction of undesirable woody species on rangelands to reduce their competition with the desirable forage species for water, light, space and nutrients. In a way, the name "brush control" is a misnomer. It is really "species replacement" because the objective is to reduce brush and replace it with desirable and less desirable species. However, brush control is not "eradication" as some think. First, the technologies for eradication do not exist and if they did, they would probably be too expensive. Second, brush has some desirable attributes. It provides food and cover for many wildlife species and some species provide forage for certain livestock enterprises such as goat production. Thus, the planning of brush control programmes is important. Grasses are by far the Region's most important forage producers and environmental stabilizers. Most species are sun lovers as they simply do not grow well under shade. Moreover, grasses that do grow under shade, even desirable species, are not liked by livestock. Thus, the interception of light by brush greatly reduces forage production and one of the reasons for brush control is to reduce this competition. The competition between woody and herbaceous plants for nutrients is debatable, but there likely is some.
Dense brush takes a lot of space, leaving very little for grazing. Furthermore, it is difficult to manage livestock in dense brush. Grazing capacities have been increased several fold with brush control merely because it provides more space for grazing. A good management plan, however, would leave some brush for wildlife. Brush species in general are inefficient users of water. Dwyer and De Garmo (1970) showed that desert shrubs require about 2.5 times more water per unit of growth than do desert grasses and some grass species required more than others. It has been estimated that some short grass species require from 300 to 400 kg of water to produce one kilo of air-dry forage, whereas the mesquite (Prosopsis juliflora) requires from 1,700 to 1,900 kg to produce one kilo of growth. Only a fraction, if any, of this growth is forage. This excessive use of water by non-economical plants is in effect desertification. It upsets desired water regimes by reducing underground recharge and by increasing runoff. Ingebo and Hibbert (1974) reported that annual streamflow increased 22% after the chemical suppression of brush on two small watersheds in Arizona. Sturges (1973) reported that brush control in Wyoming reduced soil moisture loss 24%. As previously mentioned, the consultant has witnessed the rebirth of springs after brush control. Control definitely makes more water available for forage growth. Thus, brush control followed with good management is also a desertification control practice as well as a practice for increasing animal production.
Brush control methods can be divided into four categories: mechanical, chemical, burning and biological. The following descriptions of these are intended as general information and much of these have been taken from Welch (undated).
Mechanical Methods
Equipment used for mechanical brush management is designed to remove either the top growth or the entire plant. Methods that remove only top growth generally provide short term woody plant control because most species will resprout. Methods that effectively remove part of the root system with the top provide longer term control. Some of the methods are hand grubbing, power grubbing, mowing, rollerchopping, root plowing, chaining and railing. Each has its place.
Prescribed or Controlled Burning
This is the use of fire for burning a predetermined area to accomplish a desired result, the fire to be confined to said area. This is more than striking a match. Such burns must be planned and proper preparations made to confine the fire.
A major constraint to effective prescribed burning is the amount and distribution of fuel required to carry the fire. Generally, from 2,000 to 3,000 kg/ha of evenly distributed grass, dead leaves and litter are needed. Grazing deferment during the growing season before burning is normally required to achieve an adequate fuel load. In many situations, the degree of brush infestation limits the area's capability to support a fire. Some brush control treatment before burning may be required to produce adequate amounts and distribution of fuel. Therefore, prescribed burning often is used in combination with other brush control practices and as a maintenance measure. An ideal situation for burning following roller-chopping, and herbicide control is shown in Figure 20. Burns must be deferred to allow recovery of the grass and other forage species.
Biological Methods
Goats prefer browse to other kinds of forage and for this reason they have been successfully used to control brush without damage to grasses and fortes. Goats do not eat any and everything as commonly believed. To the contrary, they are selective browsers or grazers. Therefore, the brush to be controlled must be palatable to them. The control process is in effect frequent over defoliation. Consequently, all leaves and stems must be accessible to grazing and for this reason, control with goats is usually an adjunct to other brush control methods which reduce brush height. Finally, they must be grazed in a two pasture high intensity-high frequency rotation based on decision. They are moved when the browse is heavily consumed and when they commence eating grass by necessity. The goat stocking rate is reduced in accordance with brush decline.
