IPI International Potash Institute
IPI International Potash Institute

Balanced fertilization in WANA Region

Presented at the IPI-NCARTT Regional Workshop on

Potassium and water management in West Asia and North Africa

November 05-08, 2001, Amman, Jordan

Balanced fertilization in WANA Region

by Dr. A. Krauss

Contents

Food security in the WANA region, a burning issue
Mineral fertilizers play a dominant role in increasing productivity of the cultivated land
Unbalanced fertilization results in soil nutrient mining
What is the effect of soil K mining?
What are the benefits of balanced fertilization for the society?
Conclusion
References

Food security in the WANA region, a burning issue

West Asia North Africa, the WANA Region, is characterised by a steadily growing population. It is expected that the population will increase by a further 60% till 2030 (figure 1). It is also assumed that, by the year 2030, more than 2/3rd of the population will live in urban centres without the possibility of producing their own food.

Figure 1: Evolution of the population in the WANA Region
Figure 1: Evolution of the population in the WANA Region

More people need more food and urbanization changes the diet. With increasing income, people demand more animal protein, fruits and vegetables. Quality and safety of food becomes an important determinant when selecting food from the market (figure 2). ROSEGRANT et al. (1995) prognoses that demand for meat and eggs in WANA will increase till 2020 by 47%, whereas the demand for wheat and rice will increase by 24% only. To supply the population adequately with food, the countries of the WANA region have to increase imports of wheat from currently 28.2 million tons (mt) to 41.6 mt within the next 20 years. Meat imports are expected to increase even more drastically from currently 1.05 mt to 3.6 mt in 2020, adding substantially to the budget requirement of the concerned countries.

Figure 2
Figure 2
after KERN 2000

In consequence of the increasing demand for food and feed, the crop production in WANA has to be increased substantially, also to control the expenses needed to import food.

However, availability of land and water is scarce in WANA. The acreage of arable land and permanent crops increased only slightly in the last two decades by about 13% to currently 94 million ha. At the same time, the population increased by 64% to currently 352 million inhabitants, which reduces the per capita land availability from 0.38 ha in 1980 to currently 0.26 ha. In other words, to feed the growing population, the productivity of the existing cropped land has to be increased because horizontal expansion of crop production is hardly possible. But in recent years, there has been little increase in cereal yields in WANA, and yields have become more variable. Consequently, the per capita cereal production is declining (figure 3) and this widens the gap between cereal production and demand.

Figure 3: Cereal yield and per capita production in the WANA region
Figure 3: Cereal yield and per capita production in the WANA region
 

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Mineral fertilizers play a dominant role in increasing productivity of the cultivated land

In the past, fertilizer use and cereal production in WANA developed fairly parallel (figure 4). Use of mineral fertilizers increased rapidly in the last three decades from 1 to currently 6 mt N+P2O5+K2O. During the same period, cereal production rose from some 40 to about 70-90 mt but with signs of stagnation during the last years. There is also a rather serious decline in the apparent fertilizer use efficiency, FUE, which decreased from some 35 kg cereals per kg NPK to currently 15 kg.

Figure 4: Fertilizer use, cereal production and fertilizer use efficiency FUE in WANA
Figure 4: Fertilizer use, cereal production and fertilizer use efficiency FUE in WANA
FAOweb 2002

One of the factors responsible for stagnating yields and decreasing FUE is the current unbalanced fertilizer use (figure 5). This refers in particular to the ratio of nitrogen to potassium. About 2/3rd of the applied nutrients consists of nitrogen, 25-30% of P2O5 and a meagre 5-7% of K2O. On average, the countries of WANA applied 39 kg/ha N, 17 kg/ha P2O5 and 4 kg/ha K2O (mean 1997-99). The highest N use is seen in Egypt with 289 kg/ha, applied together with 41 and 10 kg/ha P2O5 and K2O, respectively. Lebanon applied the highest P rates with 104 kg/ha (together with 72 kg/ha N and 21 kg/ha K2O), and Israel the highest K rates of 55 kg/ha K2O with 93 kg/ha N and 34 kg/ha P2O5 (mean 1997-99).

Figure 5: Development of fertilizer use in WANA
Figure 5: Development of fertilizer use in WANA

The current N:K ratio in the fertilizers used is 1:0.08 that is 12 times more N than K2O. This contrasts sharply with the ratio at which plants absorb these two nutrients. The N:K ratio is 1:1 in cereals and up to 1:1.5 in crops such as potatoes, vegetables or sugar beet. The very wide N:K ratio in the WANA region is wider than the average ratio of developing countries (N:K = 1:0.21) or the global average (N:K = 1:0.26).

But, the N:K ratio differs substantially between the countries of the WANA region (figure 6). Turkey and Egypt, the biggest fertilizer consumers, apply N and K at a ratio of about 1:0.03. Iran improved considerably fertilizer use within the last few years and changed the N:K ratio from 1:0.04 in 1997 to a current ratio of 1:0.23 (1999). Morocco (1:0.32) and Israel (1:0.59) have a fairly balanced N:K ratio, and Algeria even a very close ratio of 1:0.77 (average of 1997-99).

Figure 6: N:K ratio in fertilizer use in selected countries of the WANA region in relation to nutrient uptake by crops (fertilizer use mean 1997-99)
Figure 6: N:K ratio in fertilizer use in selected countries of the WANA region in relation to nutrient uptake by crops

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Unbalanced fertilization results in soil nutrient mining

In figure 7, there is a comparison between N removal by crops and N fertilizer use in WANA. It shows that, during the 70ies, N removal by crops exceeded N use, the deriving N balance was negative. The situation changed rapidly during the last two decades, which shows N fertilizer use and N removal by crops in almost similar quantities.

Figure 7: N removal by crops in relation to N use in WANA
Figure 7: N removal by crops in relation to N use in WANA

A comparable situation appears in phosphorus (not shown). After an early period of a negative balance, P use and P removal appear to be in equilibrium.

A completely different picture is obtained when K removal by crops is related to the use of potash (figure 8). K input with potash fertilizers represents less than 10% of potassium that is taken up by plants and removed with the harvest. The apparent K deficit is estimated at almost 4 million t K2O annually or the equivalent of 37 kg/ha K2O. It can be doubted that organic manure, although locally used for horticultural crops, can close this gap in the K balance.

Figure 8: K removal by crops in relation to K use in WANA
Figure 8: K removal by crops in relation to K use in WANA

The K balance is worst in Egypt with a deficit of 195 kg/ha K2O. Farmers apply with potash fertilizers only a fraction (5%) of potassium that is removed by the harvested crops. The K balance in other countries of WANA, albeit being negative, is less serious than in Egypt. Farmers in Turkey and Lebanon apply about 50 kg/ha K2O less than what is removed by crops, the K deficit in the other countries range between 15 and 30 kg/ha K2O. The exception is Israel, where potash use is well in balance with K removal by crops.

Negative nutrient balances indicate soil nutrient mining and thus loss in soil fertility.

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What is the effect of soil K mining?

  • Sustainability of soil fertility: Potassium in soils can be differentiated into several fractions according to the availability. The soil K fractions are interrelated to each other by dynamic exchange processes. K in soil solution is immediately available to plant roots. After removing solution K either by uptake or leaching, it is replenished by K from the exchangeable fraction, which is a readily available pool. With exhaustion of this fraction, namely at negative K balances and soil K mining, the plant has to rely on K released from the less readily available pool of the non-exchangeable fraction. However, the release rate of K from the non-exchangeable fraction is much smaller than from the exchangeable fraction.
    A high yielding crop absorbs K at a rate of up to 10 kg K2O/ha/day. Failing to match K release from the soil into the solution with the demand of the crop restricts plant growth and yield formation. The more the plant has to rely on K release from the non-exchangeable fraction, the lower becomes the yield.
    Simultaneously, with depletion of the readily available K fraction, the clay minerals start to fix potassium, which makes soil K less available (figure 9).
    The same applies to ammonium. Plants grown on K fixing soils require a much higher potash supply than on non-fixing soils and thus, have higher production costs. NH4 fixation of K depleted soils lowers the N fertilizer use efficiency, which is also a cost factor.
Figure 9: Effect of exhaustive cropping on K fixation
Figure 9: Effect of exhaustive cropping on K fixation
after TRIBUTH et al., 1987
  • Yield: Numerous field trials with a wide range of crops and soil types could demonstrate that, with soil K mining, the yields decrease because of deteriorating soil fertility. The results in figure 10 also show that the response of crops to soil K mining differs with the genotype. Cereal, with its extended root system, is obviously more efficient to extract soil K than dicots such as potato or sugar beet, which have a rather lax root system. This also signals differences in potash requirement and should lead to differentiate critical soil K limits according to the crop type and/or crop rotation.
    Significant yield responses to potash are also known in the WANA region. EL HADI and ETOURNEAUD (1995) could demonstrate already in the early 90ies that use of 60 kg/feddan K2O increased in the Nile delta of Egypt yields of berseem, cotton, beans and several cereals by 4 to almost 10% although those soils contain up to 500 ppm exchangeable potassium. Similar results were obtained in Upper Egypt. BADRAOUI et al. (1997) showed with sugar beet that investing one $ in potash returned up to eight $ through higher yield.
Figure 10: Genotypical yield responses to soil K mining
Figure 10: Genotypical yield responses to soil K mining
after MERBACH et al., 1999
  • Quality: Quality of agricultural products became the dominant factor in selecting food at the market. Quality can be expressed according to the nutritive value, hygienic and organoleptic properties, the functional properties, and the compatibility with the environment at its production. Due to its multi-functionality in the plant, potassium is considered as the nutrient being most involved in quality production. Higher protein content in wheat, oil content in soybean and groundnut, fibre content in cotton, better shelf-life of fruits and vegetables are some of the findings from field trials with potash (Figure 11). AGBANI et al. (1999) reported from Morocco that applying 150 kg/ha N and 300 kg/ha K2O has proved to be the most effective combination for the highest extractable sugar content.
Figure 11: Effect of balanced fertilization with K and Mg on yield and quality of sugar beet
Figure 11: Effect of balanced fertilization with K and Mg on yield and quality of sugar beet
IPI trials Hungary, 2000
  • Stress tolerance: Nutrition of plants has a substantial impact on the predisposition of plants to be attacked by pests and diseases. By affecting the growth pattern, the anatomy, morphology and particularly the chemical composition, the nutrition of plants may contribute either to an increase or decrease the resistance and/or tolerance to pests and diseases. The ratio between nitrogen and potassium plays obviously a particular role in the host/pathogen relationship.
    PERRENOUD (1990) reviewed almost 2450 literature references on this subject and concluded that the use of potassium decreased the incidence of fungal diseases in 70% of cases. The corresponding decrease of other pests was bacteria 69%, insects and mites 63% and viruses 41%. Simultaneously, K increased the yield of plants infested with fungal diseases by 42%, with bacteria by 57%, with insects and mites by 36%, and with viruses by 78% (Figure 12).
    The function of potassium in plants as an osmotically active cation and its involvement in controlling the water household gives balanced fertilization with potash the unique opportunity to improve the tolerance of plants to drought, frost and to salinity. WYRWA et al. (1998) could demonstrate that drought reduced grain yield of triticale by 54% on soils low in K whereas, at adequate potash supply, the grain yield was reduced only marginally by 16%. This refers to the function of potassium to control stomata movement and thus, the water release at drought stress.
    BOGDEVITCH (2000) showed that oat grown on soils with 234 ppm K could survive late frost without obvious damage whereas oat on K deficient soil (132 ppm K) was almost wiped out. K in plant cells lowers the freezing point that protects the plant from frost damage provided there is adequate supply to the plant.
    Shoot weight of salt affected barley was increased when additional K was applied (HELAL & MENGEL, 1979). The plants treated with extra K had also a higher K and lower Na content in the shoot and showed a much better N conversion into protein than the salt affected plants without the “meliorative” extra K.
Figure 12: Effect of potassium on yield increase and pest incidences
Figure 12: Effect of potassium on yield increase and pest incidences
PERRENOUD, 1990
  • Compatibility with the environment: Lower yields in field trials at unbalanced fertilization with inadequate potash imply that the use efficiency of the other fertilizer nutrients is decreased. In this context, DOBERMANN (1999) showed in field trials with rice that the recovery efficiency of N increased from 26% at low K (20 kg/ha K2O) to 36% at adequate K (80 kg/ha K2O). This means that less N is left in the rooting zone at adequate K supply, which otherwise could pollute the groundwater when leached or contribute to global warming when volatilized. With lower yield, use efficiency of other inputs such as land, water and energy decreases as well. Therefore, insufficient supply of potash leads to waste of natural resources, it is a threat to the environment and reduces the profit of the farmer.

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What are the benefits of balanced fertilization for the society?

  • Yield and income: Lower yield at insufficient potash supply is synonymous to loosing opportunity yield and income (Figure 10). The farmer could obtain higher yields and income with adequate potash supply. With higher income, the farmer is inclined to spend more money for non-agricultural products. This attracts other business, creates jobs and contributes to the development of the rural area. He also may stay on his farm and will not migrate into urban area because, with higher income, he gains in social security.
  • Quality and competitiveness: In most of the crop markets, the procurement price is based on quality criteria, such as protein or oil content in cereal and oil seeds, sugar content in beets and cane, or simply by freshness and appearance of fruits and vegetables. Farmers being paid according to the quality will loose their competitiveness at the market when producing crops with inferior quality. Lower procurement prices for crops poor in nutritive value shrink his income and profit from farming. Apart from the direct impact, there is also an indirect benefit of quality-oriented production to the society, for instance in sugar production: each percent sugar less in sugar beets requires about 6% more beets to be transported and extracted to yield the same amount of white sugar. The higher energy consumption and lower profitability in extracting low quality beets are obvious. Furthermore, the higher content of noxious N in sugar beets at unbalanced fertilization with inadequate potash lowers in addition the sugar extraction.
  • Stress tolerance: Less pest and disease incidences at balanced fertilization reduce the need for agrochemicals, reduce the storage losses, especially in fruits and vegetables, and the marketable crops have a better appearance. This lowers the production costs and increases the competitiveness at the market when offering healthy and safe products. One should also not forget that, in an age of globalization and liberalized international trade, quality such as freedom from pests and diseases became an important non-tariff trade barrier. In not complying with the hygienic standards set by the importing country, the market is quickly lost.
    Variable yields when plants are vulnerable to climatic and soil-borne stress are not only a financial risk for the producer but also impair the planning of the food supply of the nation.
  • Compatibility with the environment: Consumers will ask more than before whether food is produced in accordance with the environment. This refers in particular to agricultural products. The rapidly increasing market of so-called ‘bio’-product gives evidence of this development. A higher N fertilizer use efficiency, less pest and disease incidences at balanced fertilization with adequate potash comply with the requirement of safeguarding the environment in agricultural production.

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Conclusion

Extended soil K mining as practised in WANA is a time bomb. It prevents the full exploitation of the genetic potential that modern high yielding varieties contain. By that, unbalanced fertilization deprives the farmer to gain maximum profit from his cultivated fields, which in turn might force him to abandon his fields and to migrate into towns where he adds to the growing number of the poor.

Prevention of full exploitation of the genetic potential of crops at unbalanced fertilization also means missing the opportunity to improve food supply of the population and to lower the bill for costly imports. The money saved on imports at higher domestic crop production could be spent for other purposes.

Preventing better crop quality due to unbalanced fertilization lowers the competitiveness at the local and international market. Export of fruits and vegetables from Near East increased in the last 20 years from 3.11 mt worth $1.46 billion to currently 6.5 million t worth $4.26 billion (mean 1997-99, FAO-web 2002). It would be interesting to estimate the gain in export quantity and value if balanced fertilization would be applied to all crops.

On the other hand, better quality of conventionally cultivated crops at balanced fertilization helps the farmer to comply with the demand to produce enough as well as “healthy” and safe food. Good governance also in respect of nutrient management proves his reliability and gives him advantages at the market.

Furthermore, balanced fertilization and by that, improving use efficiency of fertilizers, nitrogen in particular, would not only contribute to protect the environment and to safeguard natural resource. It, if promoted by the whole fertilizer industry, would also improve the image of an industry, which is under close observation from the public. This refers in the same way to the farmer and the fertilizer producer.

It is high time to turn to balanced fertilization in WANA.

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References

Agbani, M., Badraoui, M. and Soudi, B. (1997): Effects of potassium and nitrogen on sugar beet yield and quality in the Doukkala region in Morocco. In: Proc. Regional Workshop of IPI on ‘Food security in the WANA region, the essential need for balanced fertilization’, May 26-30, Bornova, Izmir/Turkey, pp. 203-212.

Badraoui, M., Agbani, M. and Soudi, B. (1997): Potassium status in soils and crops, recommendations and present use in Morocco. In: Proc. Regional Workshop of IPI on ‘Food security in the WANA region, the essential need for balanced fertilization’, May 26-30, Bornova, Izmir/Turkey, pp. 115-124.

Bogdevitch, I. (2000): IPI internal report. BRISSA Minsk, Belarus.

Dobermann, A. (1999): Reversing diminishing growth of rice yields in Asia. 67th Annual Conference of the International Fertilizer Industry Association, IFA, May 17-20, Manila, Philippines.

El Hadi, A. and Etourneaud, F. (1995): From natural manuring in the days of the Pharaohs to modern nutrient management with fertilizers since the High Dam. In: International Fertilizer Correspondent Vol. 36, 3/1995. International Potash Institute, Basel, Switzerland.

FAO web (2002): Web site of the Food and Agriculture Organization of UN, Rome, Italy, www.fao.org

Helal, H.M. and Mengel, K. (1979): Nitrogen metabolism of young barley plants as affected by NaCl-salinity and potassium. Plant & Soil 51: 457-462.

Kern, M. (2000): Future of agriculture. Global dialogue EXPO 2000, the role of the village in the 21st Century: crops, jobs and livelihood. 15-17 Aug. 2000, Hanover, Germany.

Merbach, W., Schmidt, L. and Wittenmayer, L. (1999): Die Dauerdüngungsversuche in Halle (Saale). B.G. Teubner, Stuttgart-Leipzig, pp. 56-65.

Perrenoud, S. (1990): Potassium and plant health. IPI Research Topics No. 3, 2nd rev. edition. Basel/Switzerland.

Rosegrant, M.W., Agcaoili-Sombilla, M. and Perez, N.D. (1995): Global food projections to 2020: Implications for investment. Food, agriculture, and the environment, Discussion paper 5, International Food Policy Research Institute.

Tributh, H., von Boguslawski, E., von Lieres, A., Steffens, D. and Mengel, K. (1987): Effect of potassium removal by crop on transformation of illitic clay minerals. Soil Sci. 143: 404-409.

Wyrwa, P., Diatta, J.B. and Grzebisz, W. (1998): Spring triticale reaction to simulated drought and potassium fertilization. In: Proc. 11th Int. Symposium on Codes of good fertilizer practice and balanced fertilization, Pulawy, Poland, September 27-29, pp. 255-259.

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