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Poland 
Overview
Land resources
Water resources (AQUASTAT)
Plant nutrient resources
Hot spots
Bright spots
Challenges and viewpoints
References / Related internet links |
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Note 1: Note 2: |
1. Country overview
1.1 Geography and administrative units 1.3 Climate 1. > top |
1.1 Geography and administrative units
1.1 > 1. 1.2 Socio-economic features
Due to all these reasons the structure of agriculture in Poland with respect to ownership rights, size and economical conditions of farm holdings is extremely differentiated. According to the last inventory made in 1996 the total number of farm holdings in Poland is 3.066.535, mostly in the private sector and only 2016 farms in public sector. From the number of private farm holdings 66.6 % i.e. roughly 2 million own the area over 1 ha and are classified as individual farms. The remaining 33.4 % with the area below 1 ha each are classified as the agricultural plots. With respect to numbers most of the individual farms fall in the 1- 7 ha category 68.2 %) and only 8.5 % of the farms in the category of more than 15 ha (Chart 1.2.1). In respect to the area the small farms (1-7 ha) occupy 30.8 % of the agricultural land and the big ones (above 15 ha) – 35.5 % of the agricultural land (Chart 1.2.2). The average size of an individual farm in Poland is about 7 ha whereas the average size of a farm in the public sector is roughly 600 ha. The productive farmland of ca 18 million ha supports a population of 38.67 million people (about 0.46 ha per person). Private farms remain the major land holders, occupying 76 % of the farmland, the remainder belonging to the Agency of State Treasury Fund for Land Ownership and the few co-operatives. About 28 % of the total labour is currently employed in agriculture and one farmer produces food to support about six non-farming persons. [Chart 1.2.1: Structure of individual farms acc. to number] [Chart 1.2.2: Structure of individual
farms acc. to area] 1.2 > 1. |
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2. Land resources
2.1 Physiography 2.2 Soils 2.4 Wetlands, mangroves and inland valley bottoms 2.5 Inundation Land Types 2.6 Natural hazards 2.7 Land cover 2.8 Land use 2.9 Land use change 2.10 Land Productivity 2.11 Environmental Impact of land uses 2. > top |
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2.2 Soils
Natural farming conditions are poor due to the prevalence of light, sandy soils and the unfavourable climate. The agricultural landscape originates from the period of glaciation (Map 2.2.1). The Scandinavian glacier three times covered the present day Polish territory , shaping the oldest soils in the southern part of the country (Mindel glaciation) and the youngest in the northern part of the country (Wurm glaciation). Due to the high diversity of the parent rocks (see Table 2.2.1) and in course of different geological and pedological processes a substantial number of soil types and sub-types has been developed in Poland. The most common soil types are brown soils, acid brown soils, grey brown podsolic soils, rusty soils and podsolic soils. Much smaller area is covered by chernozem soils, rendzina soils, black soils and alluwial soils. Grasslands are located mainly on alluwial muck soils, muck soils and peat soils. Most of the soils have developed from loose, post–glacial rocks and only a small area is covered by massive rock derived soils. The soils classified as very good or good cover only 23 % of arable land, those classified as medium value – about 47 % land and the weak or weakest soils account for 30 % of the land. The weakest Polish soils are not cultivated elsewhere in continental Europe. The soils in Poland are commonly acidified and poor in organic matter (see Table 2.2.2). Unfertile and acid soils account for 40 – 60 % of arable land and only 16 – 34 % of soils can be rated as highly fertile. The soil acidity, correlated with the low content of available magnesium , is one of the most limiting factors of soil productivity in Poland. The climatic conditions also do not favour the agricultural production. The length of the growing period averages 210 days and is comparable to that in Scandinavian countries. During May to September evapotranspiration in Poland exceeds rainfall, resulting in a continuos water deficit, especially on light soils with low water-holding capacity. Generally the rating index for the soils in Poland is ca 75 – 80 points, and for the soils also ca 75 – 80 points , as compared with the average 100 points for Western Europe. As a result of combined soil and climate ratings , the average value of the agricultural production area accounts for 57 – 64 points (see Table 2.2.3).
2.2 > 2. 2.3 Agroecological systemsThe natural, economical and socio–technical conditions of agriculture are highly differentiated across Poland. Consequently, there is a large number of systems of dividing the country’s territory into several regions or zones. According to the geographic approach Poland is divided into 6 big regions (Map 2.3.1). This system is not very useful for agriculture because it reflects the general geological and climatic conditions only. In another system, commonly used for cereals varieties testing, the country is split into 8 regions running latitudinally (Map 2.3.2). This system is based on climate, particularly on the length of the vegetation period. It does not reflect the economical and socio-technical conditions of agriculture and, therefore, does not reflect the developmental strategy for this sector. The most serviceable seems to be the system used for production-economic analysis in agriculture and food production. In this system 9 macro-regions (agro-ecological zone) are defined, each covering few provinces (Map 2.3.3). The boundaries of the macro-regions run along the borders of provinces which makes the system feasible in respect to the availability of statistical data. Most of the statistical date concerning agriculture are published for the highest ranking administrative regions, i.e., provinces. The number of provinces was 49 but as of the beginning of 1999 Poland was divided into 16 provinces only. The general characteristic of these regions is presented in Table 2.3.1. The central and eastern regions (I, V, VI and VII) are characterized by extensive farm management practices expressed in low consumption of mineral fertilizers, bad soil fertility status and small farms. The public sector in agriculture is practically non existing and few farms only cover the area over 50 ha. The positive feature is high stocking level of animals and high production of manure. The agriculture in central–western region, as well as in Opole province (the southern region), is fully developed and matches the Western Europe standards. The consumption of mineral fertilizers is pretty high, soil fertility status rather good and the farm size higher than the average for Poland. A substantial area of the soil belongs to the public sector which makes possible the enlargement of individual farms. The lowest crop production is recorded in northern and east–northern regions. Agriculture in these regions is going through a particularly difficult time. The former state farms prevailing in this area collapsed and are still undergoing restructurization processes which have negative influences on farming. In the northern region a serious drawback is low stocking rate of animals and correspondingly low production of manure. The highest share of arable land in Poland is under cereals cultivation (see Table 2.3.2). Cereals cover over 65 % of arable land in central–eastern and central–western regions, known as the cereal belt of Poland. Only in the south–eastern region is the share of cereals as low as 50 %. Winter and spring wheat are in foreground followed by rye, cereals mixture and winter and spring barley. Triticale and oats are grown in smaller areas. Since 1991 the trend of increasing the area of cereals on behalf of potato and fodder crops has been quite remarkable. Among the cereal species, wheat, cereals mixtures and triticale are gaining importance and the main losers are rye and oats. The share of potato and fodder crops is decreasing. In regions I, V and VII potato crop is grown on an area over 15 % of arable land and in northern and south–western regions the share of potato is already close to 6% of arable land. Sugar beet and canola cultivation maintains the highest concentration in southern, central–western and south–western regions (see Table 2.3.3).
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4. Plant nutrient resources
4.1 Plant nutrient use and nutrient balance 4.2 Fertilizer production and costs 4. > top |
4.1 Plant nutrient use and nutrient balanceIntroduction
Prior to 1991 the fertilizer industry was a very important part of the central planned economy and its production capacity matched the demand for fertilizers from Polish agriculture, leaving little or no product for export. Fertilizer production and distribution was subsidized by the State and the demand for cheap products exceeded the production substantially. Mineral fertilizers were more easily available to state farms than to individual ones. State farms covering about 17 % of the agricultural land consumed more than 30 % of the total fertilizers sold in the country. During 1991 the transformation to market oriented economy led to the subsidy for fertilizers being lifted and the demand from impoverished agriculture dropped dramatically (Table 4.1.1). The consumption of nutrients, both in mineral and organic forms is very different among the agro-ecological zones of Poland. The average figures for the years 1993 – 1997 are shown in Table 4.1.2. The highest doses of mineral fertilizers are applied in western Poland ( Regions III, IV, VIII and IX). Animal stock, however, is low in this part of the country and consequently, the nutrients provided by manure are proportionally smaller than the average for the country as a whole. The central-western zone, covering 8 provinces (see Map 2.3.3), is generally characterized by well-developed agricultural areas which meet Western European standards. Nitrogen Consumption and Balance The actual doses of nitrogen are the highest for sugar and fodder beets, maize, canola and wheat (Table 4.1.3). High doses of nitrogen were also applied to grasses and mixtures of leguminous grasses. The lowest doses were applied to rye, oats, potato and vegetables. The predicted doses of nitrogen for fertilized areas were 9–30 % higher than applied. This difference between effective and predicted average doses depends on the proportion of non-fertilized area within the total agricultural area. In the model, it was presumed that non-fertilized area corresponded to the total area of fallow and set-aside land, the whole area of pastures and the area of plots up to 1 ha not classified as the farm holdings. Table 4.1.4 illustrates some elements of nitrogen balance. These elements are the relation of nitrogen input in mineral and organic fertilizers to the nitrogen output with the crop yields, and the input of nitrogen in mineral and/or organic fertilizers for grain units of the crops yield. In regions I, VI, VII, VIII the soil surface balance of nitrogen indicated neither surpluses nor deficits, demonstrating that the fertilizer doses (both mineral and organic) match the crop demands. In these regions the uptake of nitrogen per grain unit was found to be 2.40 which corresponds to the typical uptake of well nourished crops. In regions IV and V the soil surface balance of nitrogen showed a deficit of about 20 %; the doses of fertilizers were low to satisfy the demands of the present crops present yield. The unit uptake of nitrogen was found to be 2.00 kg N/grain unit only and is too low with respect to crop demands. In regions II and III the nitrogen balance showed a surplus and the unit uptake of nitrogen is close to 3.00 kg N/grain units. Thus, the fertilizer doses were too high for the low crop yield. The low yield was thought to be due to some other factors which are yield limiting. A similar situation was seen in region IX. In Poland, as a whole, the total input of nitrogen in both organic and inorganic fertilizers was found to have an input/output ration of 0.94 and is, therefore, inadequate in relation to the crop uptake of the present yield levels. Phosphorus Consumption and BalanceCurrent phosphorus doses are the highest for sugar-fodder beets, maize, canola and grasses/leguminous crops. In order to calculate the phosphorus dosages, the entire areas of fodder pulses and grasses/leguminous were taken into consideration (see Table 4.1.6). Phosphorus doses in mineral fertilizers were found to be lowest in regions V and VI. Low input of mineral phosphorus was here partly compensated by higher than average amounts of manure. The elements of phosphorus balance are presented in Table 4.1.7 which illustrates that the demand is the product of phosphorus uptake with the actual crops yield and the phosphorus balance equivalent. The balance equivalent is a factor used in fertilizer recommendation schemes to calculate the amount of phosphorus uptake necessary to increase the content of available phosphorus in the soil to asatisfactory level. The value of this equivalent reflects the soil fertility status with respect to phosphorus. In all regions of Poland the soil surface balance of potassium shows a serious deficit. The doses of potassium fertilizers are at least 60 % lower than necessary to meet the demands by crops and soils. The input of potassium in mineral and organic fertilizers for a grain unit is about 1.6 kg K2O only, while the minimum value is calculated in Poland for 3.5 kg K2O/grain unit. Potassium deficit seems to be one of the most limiting factors of crop production in Poland. Due to the unavailability of statistical data concerning the consumption of fertilizers by crops an indirect approach was applied. The approach is based on the assumption that each agro-ecological zone (and Poland as a whole) is a single farm managed by an educated farmer who adheres to official fertilizer recommendations. The hypothetical farmer is expected to grow all crops on a given area (Table 2.3.2) and to record the yield (Table 2.3.3) in the Statistical Yearbook. The farm land value, soil fertility indices and the doses of nutrients in mineral and organic fertilizers (per ha of agricultural land) correspond to the zone averages (Table 2.3.1). This data was entered into a computer program and the recommended mineral fertilizers doses (nitrogen, phosphorus and potassium) calculated separately for each crop. Mineral fertilizers doses were multiplied by the given crop area, added up and expressed as the total demand for mineral nutrients for the whole agro–ecological zone. The total demand for nutrients was related to the actual consumption of nutrients and the correction coefficient has been calculated for nitrogen, phosphorus and potassium. The recommended doses of nutrients for each crop were multiplied correction coefficients (the ratio of the actual amount of nutrients and the optimal amount of nutrients calculated by the computer programme) and the result gave the actual dose of nutrients in mineral fertilizers. The actual doses of nitrogen, phosphorus and potassium are presented in Table 4.1.5, Table 4.1.6 and Table 4.1.7. As the share of different crops in total agricultural production is reasonably constant, the nutrient uptake of NPK per grain unit may be calculated as the weighted average of the uptake of several crops and the share of a particular crop in crop rotations. This is reportedly a useful parameter for differential internal and external comparisons. The typical uptake for well-nourished crops was found to be 2.4 kg N, 1.0 kg of P2O5 and 5.2 kg of K2O.
4.1 > 4. 4.2 Fertilizer production and costsIntroduction
Until 1990 the sale and distribution of fertilizers were organized uniformly and the retail prices were lower than the production costs. The ratio of prices to production costs was 0.51, 0.17 and 0.43 for nitrogen, phosphorus and potassium fertilizers respectively. During recent years, however, the prices of fertilizers are ruled by market forces. During the years 1989 – 1993 the prices of nitrogen fertilizers (N) increased 30 times, phosphorus (P2O5) 36 times and potassium (K2O) 44 times. In the years 1993 – 97 the prices of fertilizers increased at the rate comparable to the rate of inflation (Table 4.2.1). The prices are the same for all regions as a consequence of the policy of the fertilizer factories. During the same period of time prices of agricultural products increased as well, though at a slower pace than the prices of fertilizers. Between 1994-97 the rate of increasing the prices of wheat grain was slightly higher than the rate of increasing the fertilizer prices. As a consequence of these processes the ratio of fertilizer/grain prices widened at the beginning of the 90ties and slowly narrowed in the second half of this decade (Table 4.2.2). It should be emphasized that for buying 1 kg of N a farmer must sell 2.6 kg wheat grain, for 1 kg of P2O5 3.0 kg of grain and for 1 kg of K2O 1.3 kg of grain. Taking into consideration that the profitability of nitrogen fertilizers is 3 to 4 times higher than that of phosphorus and potassium, the reason for the drop in potassium and phosphorus consumption is evident when compared to that of nitrogen. The only fertilizer product still subsidized by the State is limestone but the share of subsidy in the total cost of production and distribution of limestone and dolomite limestone shows a decreasing trend (Table 4.2.3) At the end of the central planning period the share of subsidy in the total cost of soil liming exceeded 70 % and in 1993 still amounted to 66%. In 1997 this share was cut down to 44 % and in 1998 to mere 20 % of the total cost of soil liming. It is a crucial problem for Polish agriculture because high acidity is one of the most limiting factors of soil fertility and crop yields in the country. Assessment of fertilizer use profitability The basic set of data from 49 provinces (Table 4.2.4) was used for creating the model of crop yields, expressed in yield units. In the full model, calculated by step-wise regression analysis, three independent variables : NPK in mineral fertilizers, NPK in manure and valorization factor , were included. Soil fertility index did not influence significantly the yield level and was not included in the model. The model (I) was described by the following equation : Yield = -1.243 + 0.0713 NPK(mineral) + 0.1058 NPK(manure) + 0.3098 valorization factor R2= 0.70 The fitted yield values for this model are presented in column 8 of Table 4.2.4. Mineral fertilizers (NPK doses) explained the greatest part of the total yield variability. Therefore it seems justifiable to calculate the simple relation between the yields and the NPK doses in mineral fertilizers. This model (II) was described by the equation : Yield = 23.825 + 0.091 NPK (mineral) R = 0.56 The fitted yield values for simplified yield model are presented in the last column of Table 4.2.4 The yields calculated from the 2nd regression equation were significantly overestimated in seven provinces, which implies that the input of fertilizers is too high in relation to the actual yield expressed in grain units. All of the seven provinces are characterized by high proportions of land belonging to the former state farms and the impoverished, existing state of agriculture not recovering after the transformation. In another nine provinces the yields were significantly underestimated which means that the comparatively low input of fertilizers does not explain the high level of actual yield. These provinces are characterized by well developed agriculture, with a long tradition for good management practices concentrated in individual farms. Few of these provinces show high valorization factor for agricultural land. The slope of 2nd the regression equation is 0.09 which indicates that the average efficiency of mineral fertilizers in Poland is 9 kg of grain units per 1 kg of NPK. The average price of 1 kg NPK for the years 1993-97 was 0.93 PLN, and the average price of 1 kg of wheat grain (supposed to be equivalent to the value of 1 kg of grain unit) was 0.40 PLN. The profitability of mineral fertilization in Poland is, therefore, pretty high and can be roughly estimated at 3.8 PLN yield value per 1 PLN spend on fertilizers. Even if the slope for NPK is calculated based on the the more comprehensive 1st regression equation (i.e. 7 kg of grain units per 1 kg of NPK), the profitability of mineral fertilization would still be 3 PLN of the yield value per 1 PLN spend on fertilizers. Similar calculations have been performed for crops. The actual (or most probable doses) of mineral fertilizers for all crops grown in 49 provinces were calculated using the methodology described above. The basic set of data from 49 provinces was used for creating the model of a given crop yield. In the full model given by step-wise regression analysis two variables were included: (i) actual NPK dose for a crop, and, (ii) valorisation factor for the agricultural land in a province. Mineral fertilizers (actual NPK) dosages explained the greatest part of the yield variability and therefore a simplified model (simple regression) was performed in addition. The regression coefficients for both models are presented in Table 4.2.5 The slope of regression from simplified model corresponds to the average mineral fertilizers efficiency , i.e., 6.6 – 9.8 kg of seeds (grain) per 1 kg NPK and 30 – 50 kg tubers/roots per 1 kg NPK. From this model the profitability of mineral fertilizers can be easily calculated (Table 4.2.6). Profitability of mineral fertilization for the actual nutrients doses is in the range 2–5 PLN per 1 PLN spent of fertilizers and depends mainly on the prices for plant products. Distribution system of fertilizers Until 1989 fertilizer industry distribution system were components of the centrally planned economy with sales monopolized by a company known as "Agrochem ". The bulk of produced and imported (potassium salt) fertilizers were centrally distributed among the provinces and channeled by Agrochem either directly to the state farms, or to the marketing cooperatives with outlets in each commune (the smallest administrative unit covering a few to several villages). This system collapsed in few months after introducing the market-oriented economy system in 1989/1990. Most of the marketing cooperatives went bankrupt and Agrochem was partly dissolved and partly privatized. The prices increased rapidly at the rate 5-7 kg of wheat grain for 1 kg of nutrient and fertilizers were practically inaccessible to most farmers. In 1991/92 wholesale centers and dealer networks were implemented and uniform factory prices for the whole country were established by each big producer . The details of trade policy are not revealed but according to estimation at present most of the big factories were selling similar amounts of fertilizers (see Map 4.2.1). There are presently more than 3000 retailers connected with the main producers and are active on the fertilizer market thereby intensifying competition. The estimated number of dealers related to the nitrogen works is : 1000, 1100, 160, 120 and 650 for the Zaklady Azotowe Pulawy S.A., Zaklady Chemiczne Police S.A., Zaklady Azotowe Kedzierzyn S.A., Zaklady Azotowe Tarnów-Moscice S.A. and Anvil Zaklady Azotowe Wloclawek S.A. respectively. The prices of fertilizers for farmers are equal at the factory gate as well as the local retailer due to discounts given by producers to distributors. The common margin of profit offered to retailers is 5–10 % of the fertilizer value. The payment system for delivered fertilizers is flexible. In the case of wholesale to the commercial companies the immediate remittance system is commonly used but in clearings with dealers the payment is executed when the dealer acquires the dues from the farmer. In the last 4 years the State has intervened slightly on the fertilizer market by so-called preferential credit offered to farmers. The credit for purchasing the fixed amount of fertilizers at a low interest rate (half of the common one) is launched for the period from planting to harvest. The amount of money secured for this kind of credit by the banks is limited and only partly matches the farmers demand. Until 1994 practically the whole amount of fertilizers was distributed in solid form. A new product of urea–ammonium nitrate solution (UAN, launched by Zaklady Azotowe, Pulawy S.A. works) challenged the established distribution system for fertilizers. At the beginning of 90s UAN was sold exclusively on foreign markets. The export of this product in 1993 and 1994 reached the level of about 600*10 3 tones. Since 1994 with the logistic and financial support of ZA Pulawy works’, networks of liquid fertilizer storage and distribution stations have been built, mainly in the Northern and Western regions of Poland. The storage stations are usually provided with 2 tanks of 20 m3 capacity each located on a pad securing against the accidental leakage of UAN. Due to the lower production and transport costs the price of nitrogen unit in UAN is by a few to several percent lower in comparison to solid nitrogen fertilizers. The consumption of UAN starting from 25*103 tones in 1994 has been increasing steadily to the estimated amount of over 100*103 tones in the last years. The structure of nitrogen and phosphorus fertilizer consumption in Poland for 1996 is shown in Chart 4.2.1 and Chart 4.2.2.
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8. References and related internet links
8.1 References 8. > top |
8.1 ReferencesAnonymous , edited by A. Wos.1998. Analiza produkcyjno ekonomicznej sytuacji rolnictwa i gospodarki zywnosciowej w 1997r. IERiGZ Warszawa Anonymous .1993 - 1997. Rynek srodków produkcji i uslug dla rolnictwa, IERiGZ , Warszawa Anonymous 1990. Zalecenia nawozowe czesc I. Liczby graniczne do wyceny zawartosci w glebach makro- i mikroelementów. IUNG Pulawy Anonymous, edited by T. Witek . 1975. Rolnicza przestrzen produkcyjna Polski w liczbach . Suplement. IUNG Pulawy Anonymous. edited by T. Witek .1981. Waloryzacja rolniczej przestrzeni produkcyjnej Polski wedlug gmin. IUNG Pulawy Bilski E. 1992. Genetyczne uwarunkowania produkcyjnosci roslin . w Zalecenia Agrotechniczne IUNG tom I : 61-96. IUNG , Pulawy Fotyma M. , Gosek S. 1998. Long term phosphorus balance in Poland. Bibliotheca Fragmenta Agronomica . 3 : 317-326. Fotyma M. edited. 1994. Komputerowy program doradztwa nawozowego NAW-2. IUNG Pulawy. Fotyma M., Terelak H. 1994. Environmental challenges in Polish agriculture covering a main area of the Baltic Sea basin. Marine Pollution Bulletin, 29. 6-12 : 455-463. Gorecki H.J., Biskupski A.1998. Production and consumption of fertilizer in Poland. Bibliotheca Fragmenta Agronomica 3 :19 - 34 Gosek S., Fotyma M. 1998. Long term potassium balance in Poland. Bibliotheca Fragmenta Agronomica . 3 : 443-453. GUS Powszechny spis rolny. 1996. GUS, Warszawa GUS Produkcja podstawowych upraw pastewnych wedlug województw i grup producentów w Polsce. 1993 - 1997. GUS, Warszawa. GUS Produkcja podstawowych upraw rolnych w Polsce . 1993 - 1997. GUS, Warszawa. GUS Roczniki statystyczne Rzeczypospolitej Polskiej .1994 - 98. GUS ,Warszawa. GUS Wyniki produkcji roslinnej - Powierzchnia, plony i zbiory roslin uprawnych.1993 - 1997. GUS Warszawa Jadczyszyn T., Kowalczyk J., Sroczynski W. 1996. Zalecenia nawozowe dla gospodarstw korzystajacych z oznaczen odczynu i zasobnosci gleb Stacji Chemiczno- Rolniczych. IUNG Pulawy Lekan Sz., Terelak H. 1997. Zróznicowanie srodowiska glebowo - rolniczego w Polsce. W Ochrona i wykorzystanie rolniczej przestrzeni produkcyjnej Polski . IUNG, Pulaw. Malinowski M. 1997. The Polish nitrogen fertilizer industry- present status and future trends. IFA Production and International Trade Committee meeting, Warszawa, Poland October 14-16. Malinowski M., Schimmelfennig Z. 1996. Polish fertilizers
market- present status and development trends. EFMA , East-West Workshop,
Pulawy, Poland October 10-11 : Strzemski M., Siuta J., Witek T. 1973. Przydatnosc rolnicza gleb Polski PWRiL, Warszawa Systematyka gleb Polski. 1988. Roczniki Gleboznawcze 40.3/4 : 7 - 103. Witek T. 1992. Produktywnosc gruntów ornych i uzytków zielonych . 1992. W Zalecenia Agrotechniczne IUNG tom I : 41-60. IUNG , Pulawy Witek T., Górski T. 1977. Evaluation of the natural capability of agricultural areas in Poland. Wydawnictwo Geologiczne Warszawa 8.1 > 8. 8.2 Related internet linksPoland natural resources European Environment Agency: Poland Land management in Poland in the period of transformation
- Banski J., 1997 Problem areas in Polish agriculture - Banski J., 1999 Green Brigades (Poland) Fertilizer Use by Crop in Poland |
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History :
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