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Presented at AFA 7th International Annual Conference

30 January - 01 February 2001, Cairo, Egypt

Demographic development and its implication for fertilizer use

by Dr. A. Krauss, Director, International Potash Institute, IPI, POB 1609, CH-4001 Basel, Switzerland
Tel +41 61 261 29 22; Fax +41 61 261 29 25; e-mail: ipi@ipipotash.org; www: www.ipipotash.org

Contents

Summary

Population growth and urbanization become a major problem in developing countries. This not only forces the planners to provide increasingly more adequate dwellings, water and power supply, traffic and transport opportunities, but also more food, price-wise affordable for the low income class, diverse and of high quality for the emerging middle/upper class. On the other hand, the remaining rural society, being confronted with the migration of the younger generation into towns, not only needs the means to maintain land productivity with less labour force, but also has to feed more people not involved in agriculture. Some of these aspects are discussed in the following chapters:

  • A steadily growing population demands more food, but the natural resources to produce it become scarce.
  • Urbanization affects the diet.
  • Quality becomes an important trait in crop marketing.
  • What is quality?
  • More and better food, what are the consequences for nutrient management?
  • Carrying food to towns transfers nutrients.
  • Change in the food habits affects the crop spectrum and thus, the nutrient requirement and management.
  • Focus on quality necessitates balanced fertilization.

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A steadily growing population demands more food, but the natural resources to produce it become scarce

Global population increases annually by almost 80 million people. Although the growth rate will decline, it is expected that the global population will hit the 8 billion mark within the next 20 years.

Half of the additional 2 billion people will grow up in Asia. FAO (1998) estimates that the current population of about 3.7 billion will increase to 4.6 billion in the next 2 decades. In the West Asia North African region, the current population of about 400 million will increase according to FAO to 600 million in twenty years from now and to 900 million in the middle of this century.

More people need more food. As an example, Argenti (2000) estimates that food requirement of urban centers like Isfahan, Iran will increase by 7 million t to more than 20 million t in the next 10 years, and Karachi, Pakistan by more than 20 million to almost 64 million t of food. Assuming that 80% of the diet is based on cereals, the future food demand for Karachi would contain nutrients equivalent to more than 2 million t of urea, almost 1 million t of DAP and half a million t potash fertilizers, which have been removed from the field.

On a global scale, the current cereal production of about 2.1 billion t has to be increased within the next 20 years to 3.4 billion t to meet the expected demand for food and feed. However, horizontal expansion in production is hardly possible. The per capita availability of arable land and water for irrigation is decreasing. Most striking is the situation in Asia where, in 20 years from now, only 800 m2 per caput will be available for crop production. A similar trend is expected in India. The per capita land availability will decline from currently 0.14 ha to 0.10 ha in 2025. Moreover, "… the quality of land (in India) likely to remain available for agriculture due to severe competition from urbanization, industrialization and civic needs, will be poor…" (Kanwar & Sekhon, 1998). The situation of land availability in the WANA Region follows the general trend although being less drastic than in Asia or in developing countries (Figure 1).

What has been said for land availability also applies for water. Withdrawal of water in developing countries will increase by 43% between now and the year 2020, in developed countries by 22%. But, in developing countries, the demand for domestic and industrial uses will double, reducing the supply for agriculture (Pinstrup-Andersen et al., 1997).

Growing scarcity of land and water and increasing demand for food imply that the productivity of the cultivated land has to be increased accordingly. In order to ensure the "minimum food crop production requirement", the cereal yield in Asia for instance has to be increased from presently 2.8 t/ha to 3.2 t/ha in 2010 and 4.75 t/ha in 2030 (Ange, 1992). A corresponding development is seen in Near-East, where cereal production more than doubled in the last 30 years, whereas the area increased by only 26% (Figure 2). This corresponds with a yield increase from 1.13 t/ha in 1970 to currently 1.83 t/ha (FAO, 2000). However, figure 2 also shows that the domestic cereal production in Near-East cannot cope with the population growth in this region. Increasing cereal imports are necessary to meet the demand of the growing population.

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Urbanization affects the diet

It is a common observation that progressively more people leave the rural area searching for jobs and food. Urbanization in the WANA region will increase from currently 60% to almost 80% within the next 25 years. Urbanization in Turkey progressed more than for instance in Egypt (Figure 3).

Living conditions and income usually affect the food habits of the population. Low-income inhabitants of rural and urban centers mostly consume low value subsistence crops like cereals and root/tuber crops (Figure 4). But, with increasing income, the diet changes to include more animal protein, high quality vegetables and fruits. Urbanites in China for instance eat more meat (27 kg per capita) and less rice (68 kg) than their rural counterparts (17 kg meat and 103 kg cereals) (Rozelle & Jikun Huang, 1999).

In due course, the wealthy 'high-tech' society spends less time on food preparation and looks for packed and processed food. Furthermore, there is considerable public concern about nitrate in vegetables, growth hormones and antibiotics in meat products, which ultimately increases the desire for safe food of 'bio' origin. The market share of bio-food, although still rather small, will grow. In 1997, the US market for organic products was $4 billion, up from $78 million in 1980; European consumers spend about $4.5 billion in organic products and Japan about $2 billion per year (Swezey & Broome, 2000).

In addition to that, there is increasing interest in functional food, which may have a potential to lower body fat, cure gut maladies, provide gender and age-related medical needs, improve skeletal strength, lower cholesterol or improve the optical vision, etc. (Kern, 2000). Ingredients such as lycopene in tomato, allicin in garlic or isoflavones in soybean are associated with prevention or treatment of cancer, diabetes, hypertension, and heart disease (Bruulsema, 2000).

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Quality becomes an important trait in crop marketing

A survey in 7 European countries shows that quality, though largely a subjective property, is rated as the most important determinant of acceptability by 25% of consumers, followed by price (16%), brand name/reputation (14%) and freshness (9%) (Traill, 1999).

The quality of the produce determines also the success in the export market. Hammer (1999) from FAO says that "… in order to be a successful food exporter, a country must produce foods that are both sought after and be acceptable in quality. Compliance with the statutory, compulsory or mandatory requirements of importing countries is an unavoidable and essential prerequisite…". In this context, it is worth to mention that export of fruits and vegetables is an important source of foreign exchange income for the Near-East. This trebled the export from 2 million t 30 years ago to currently more than 6 million t, representing a value of about 4 $ billion (FAO, 2001).

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What is quality?

According to Abalaka (1999) "… an intrinsic property of food by which it meets pre-defined standard requirements. Determinants of food quality can be grouped into several properties. Food quality therefore refers to the value, which is subjectively or objectively attached to food with respect of quality properties…".

  Nutritional properties Functional properties  
   
Hygienic properties
FOOD QUALITY
organoleptic properties
   
  environmental compatibility safe food  

Nutritional properties are characterized by the content of certain constituents such as protein, oil/fat or starch, mineral components and vitamins. Functional properties are related to the crops' suitability in processing like sugar content in beets or cane, starch in potatoes, content and spectrum of fatty acids in oil seeds. The resistance of crop plants to biotic and abiotic stress such as salinity, drought, heat and cold or the tolerance to weedizides as implanted into transgenic plants can be grouped into this category.

Hygienic properties are linked to freedom from pests and diseases and their metabolic by-products, which might be toxic or initiate food allergy. Organoleptic properties are highly subjective. They describe the appearance, color, structure, smell or taste. The preference of many customers for a shiny dark red apple compared to yellowish or green one is well-known although there might be no difference in nutritive value.

Environmental compatibility of production will become an important quality parameter used by consumers when selecting food at the market or by processors in their quality management. The rather rapidly expanding market with a growth rate of 25% p.a. for 'organic products' refers to the desire of consumers for 'safe' food, that is no contamination with nitrate or heavy metals, residues from agrochemicals, etc.

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More and better food, what are the consequences for nutrient management?

Kern (2000) sees 4 main input groups, which warrant food supply of future generations, namely fertilizers, irrigation, use of high potential seeds together with plant protection and biotechnology.

The close relationship between fertilizer use and yield formation has been demonstrated worldwide in numerous field trials. It is also well established that plants absorb during development substantial amounts of nutrients. An average cereal crop takes up around 170-75-175 kg/ha N-P2O5-K2O. Potatoes or sugar beet absorb about 200 kg/ha N, 80-90 kg P2O5 and some 300 kg/ha K2O. On principle, uptake of potassium during the vegetation is similar to that of nitrogen or even higher.

Nutrient removal by crop at harvest differs on whether only the marketable part (seeds, tubers, roots, etc.) or the whole crop including plant residues like straw is removed from the field. Harvest of one ton of wheat removes for instance about 18 kg N, 8 kg P2O5 and 5 kg K2O. Harvest of straw together with the grains increases the removal to 27 kg N, 12 kg P2O5 and 30 kg K2O. An average wheat yield in Egypt of 6.3 t/ha would therefore remove - grain and straw - about 170 kg N, 75 kg P2O5 and 190 kg K2O or the equivalent of almost 370 kg urea, more than 160 kg DAP and 380 kg potash.

However, fertilizer use in Near East differs substantially from the nutrient removal by crops. As shown in figure 5, use of nitrogen exceeds by far that of potassium, although both nutrients are absorbed by plants in a similar ratio. Current N use with mineral fertilizers is in the same order of magnitude than N removal by cops. The same applies to phosphorus although use of phosphate was reduced in the recent past. In contrast to N and P, use of potash only covers less than 10% of K removed by crops from the soil with harvest.

A negative K balance as indicated in figure 5 is without doubt contradictory with the need to increase crop production to feed a still growing population. Due to the multi-functional role of potassium in the metabolism of plants, an inadequate K supply prevents full exploitation of the genetic yield potential. This lowers use efficiency of natural resources such as land, water and energy and of inputs like fertilizers, which in turn increases production costs and reduces farm income. In addition to that, low use efficiency of N fertilizers also contributes to pollution of the environment.

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Carrying food to towns transfers nutrients

Carrying food to towns transfers nutrients from the agricultural area to the urban centers. The nutrient transfer increases with urbanization. In the WANA region, about 9.6 million t N + P2O5 + K2O are removed annually with the harvested crop. Assuming a current rate of urbanization of 60%, this means that at least 5.8 million t NPK nutrients are transferred to towns. Globally, about 175 million t N + P2O5 + K2O are removed by crops. At a global rate of urbanization of 47.5%, therefore at least 83 million t NPK nutrients are transferred into towns.

Usually, the nutrients excreted after digesting the food in towns are deposited in urban dumping sites. Health concerns, mixing with toxic and/or heavy metals are some of the reasons for farmers to hesitate to use sludge from urban water treatment plants. However, agriculture in Western Europe for instance is put increasingly more under pressure to accept and recycle urban sewage sludge because alternative disposals on dumping sites or in waste incineration plants become quite expensive. Estimates from EFMA (2000) show that, at present, merely 2.6% of nitrogen, 3.5% of P2O5 and 1.1% of K2O used in EU agriculture derive from non-livestock urban waste.

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Change in the food habits affects the crop spectrum and thus, the nutrient requirement and management

More vegetables and fruits in the diet at increasing income and more oilseeds to feed animals affect the crop spectrum and thus the nutrient management.

In Egypt for instance, the area with vegetables and fruits increased almost 3 times in the last 40 years. The same trend is seen in whole Asia. There is also a substantial increase in the acreage and production of soybean and other oil crops. The global area with soybean trebled in the last 40 years from 24 million ha in 1961 to currently more than 70 million ha. Most of the acreage was added in Argentina and Brazil, which increased the area with soybean from almost nil 40 years ago to currently 7 and 13 million ha, respectively.

Some of the consequences for nutrient management, as derived from the changes in crop spectrum, can be summarized as follows:

i) Fruits and vegetables remove considerably more nutrients from the field than cereal grains (Figure 6). The transferred nutrients have to be replaced to close the balance.

j) Oilseeds have a particular requirement for potassium. The K content in soybean seeds is about 5 times higher than that in cereal grains. The poor root system of soybean has a specific high demand on K concentration in soil solution. In return, adequate supply of potash to soybean and other leguminous crops improves nodulation and therefore the biological nitrogen fixation. Sunflower absorbs during the vegetation up to 500 kg/ha K2O, winter oilseed rape up to 400 kg/ha K2O. This implies a rather high daily K uptake intensity and thus K supply through fertilizers.

aa) The rather short vegetation period and the rapid biomass development of vegetables on the one hand and the rather poor root system on the other require a much higher soil nutrient release intensity and a higher soil nutrient concentration than necessary for cereals (Figure 7). This requires split application, especially on light textured soils and additional fertilizer nutrients on heavy soils to overcome fixation and/or interference of the absorption complex of the soil.

bb) Micro-irrigation of field grown and protected vegetables, became common practice. However, micro-irrigation requires fertigation, the injection of fertilizer nutrients into the irrigation system. In Israel for instance, 80% of the total irrigated land (200'000 ha) is fertilized through fertigation (Imas, 1999). With this system, the nutrient management has to consider aspects such as:

  • the daily nutrient uptake and nutrient requirement of the crop,
  • the NK ratio in nutrient supply to meet the physiological requirement of the crop, which needs a N-oriented nutrient ratio during the vegetative stage and a K-oriented nutrient ratio during fruit development,
  • the compatibility of fertilizer nutrients in the liquid phase (clogging, precipitation),
  • the concentration of the stock solution (salting out),
  • the concentration of the irrigation water (osmotic effects in the rhizosphere).

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Focus on quality necessitates balanced fertilization

As indicated earlier, food quality is determined by several properties such as nutritional, functional, organoleptic properties, etc. Field trials conducted throughout the world by IPI and other fertilizer associations repeatedly show the close relationship between balanced fertilization and quality of the crop. The following few examples are given:

  • Balanced fertilization increases the protein content in wheat, oil content in soybean, groundnut and rape seed or the vitamin C content in vegetables and fruits. This refers to nutritional properties of food. The example in figure 8 on the effect of potash on yield and protein content of wheat also shows that balanced fertilization contributes to use efficiency of other inputs like N fertilizers because, at the same level of N, yields could be increased through potash by 24%.

  • Functional properties refer to traits such as sugar content in beets and cane, fiber content and quality in cotton, flax, jute, starch content in potato, etc. Improving the soil K status in Egypt resulted in higher stalk yield and higher sucrose contents (Figure 9). In consequence, to produce the same amount of white sugar, less high quality stalks have to be transported to and crushed in the sugar mill than in case of poor quality cane stalks. Therefore, balanced fertilization also contributes to save natural resources such as energy.

  • Organoleptic and hygienic properties are related to taste and appearance and the freedom from pests and diseases. Increase of the content of aromatic compounds in tea is one example of the beneficial effect of balanced fertilization on quality. Less diseases attached to marketable crops at balanced fertilization comply with sanitary and phytosanitary regulations in international trade (Figure 10). Better crop resistance to pests and diseases would also reduce the input of agrochemicals and thus minimize the concern on residual effects. Less agrochemicals for crop protection would at the same time lower production costs and increase the farm profit.

  • Environmental compatibility: consumers will ask more than before whether the crop has been produced in context with environmentally friendly practice. The substantial decrease of residual N at balanced fertilization, as observed in IPI trials in China, is a step towards the required environmental compatibility of crop production (Figure 11). Less nitrate in the system would also comply with the demand of consumers for 'safe' food, especially now in an atmosphere of uncertainties on food safety in context with nitrate in food, residues of agrochemicals, beef and BSE, etc. Quality auditing of production could bring back confidence of consumers. And, balanced fertilization in an integrated approach is one of the most important components in quality auditing. It also adds a particular image to the produce, the added value increases the competitiveness.

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Conclusion

A steadily growing global and regional population demands more food and feed. At present, there are about 1 billion well nourished people, about 4 billion less and/or poorly fed and about 1 billion hungry people worldwide (Braun, 1999). To which group should be added the expected 2 billion inhabitants who will be born within the next 20 years? To the well nourished or to the hungry one? It will be a great challenge for the agriculture to produce on a shrinking natural base more food than before. And balanced fertilization can contribute to produce more on the same acreage of land.

The farmers have also to take care of the changing food habits and the focus on quality of a steadily increasing urban population. Majority of the consumers rate quality as the most important determinant of acceptability of goods at the market. Balanced fertilization is an important step to meet the demand. The fertilizer industry should also take the challenge and provide the farmers with the necessary input and knowledge. To adjust production to verifiable quality norms would not only secure old and open new markets to the farmers, but also indirectly contribute to a positive image of the fertilizer industry, provided the industry would be in the position to assist the farmers accordingly. The benefits for the farmers when using balanced fertilization in an integrated approach are clear: they can certify quality and origin of their produce, they prove compliance with legislative rules and will not have problems with product liability.

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References

Abalaka, J.A. (1999): Assuring food quality and safety: Back to the basis-quality control throughout the food chain. FAO/WHO/WTO Conf. on Int. Food Trade beyond 2000, Melbourne, Australia, 11-15 Oct. 1999.

Ange, A.L. (1992): Environmental risks of fertilizer use, overuse or misuse. FADINAP Regional Seminar Fertilization and the Environment, 7-11 Sept. 1992, Chiang Mai, Thailand.

Argenti, O. (2000): Feeding the cities: food supply and distribution. IFPRI 2020 Vision, Focus 3, August 2000.

Braun von, J. (1999): pers. communication. ZEF, University Bonn, Germany.

Bruulsema, T.W. (2000): Functional food components: a role for mineral nutrients? Better Crops 84(2), pp. 4-5.

FAO (2001): FAOSTAT.

Hammer, W.C.K. (1999): Food trade and implementation of the SPS and TBT agreements: current status of food trade, including food quality and safety problems. FAO/WHO/WTO Conference on Int. Food Trade beyond 2000, Melbourne, Australia, 11-15 Oct. 1999.

Imas, P. (1999): Recent techniques in fertigation of horticultural crops in Israel. IPI-PRII-KKV Workshop on 'Recent trends in nutrition management in horticultural crops'. 11-12 Feb. 1999, Dapoli, Maharastra, India.

Johnston, A.E., Barraclough, P.B., Poulton, P.R. and Dawson, C.J. (1998): Assessment of some spatially variable factors limiting crop yield. Proceedings No. 419, The International Fertiliser Society, York, UK.

Kanwar, J.S. and Sekhon, G.S. (1998): Nutrient management for sustainable intensive agriculture. Fertiliser News 43(2): 33-40.

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.

Pinstrup-Andersen, P., Pandya-Lorch, R. and Rosegrant, M.W. (1995): The world food situation: recent developments, emerging issues, and long-term prospects. Food policy report, IFPRI, Washington DC, USA.

Rosegrant, M.W. (1997): Water resources in the twenty-first century: Challenges and implications for action. Food, agriculture, and the environment, Discussion Paper 20, IFPRI, Washington DC, USA.

Rozelle, S. and Jikun Huang (1999): Supply, demand and trade of agricultural commodities in China. Marketing opportunities: World trade competition. Agricultural Outlook Forum, 23 Feb. 1999.

Shrotriya, G.C. (2000): Fertiliser promotion in fruit and vegetable crops. Fertiliser Marketing News, FAI, Vol. 31 (8), pp.1-7.

Swezey, S.L. and Broome, J.C. (2000): Growth predicted in biologically integrated and organic farming. Cal. Agric. Vol. 54 (4), pp. 26-35.

Traill, W.B. (1999): Prospects for the future: Nutritional, environmental and sustainable food production considerations - changes in cultural and consumer habits. FAO/WHO/WTO Conference on Int. Food Trade beyond 2000, Melbourne, Australia, 11-15 Oct. 1999.

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