Balancing Agricultural Production and the Environment in China: Strategies for Fertilizer Use.

China’s agricultural production relies heavily on inorganic fertilizer input to support the continuous increase in crop production. This dependence on inorganic fertilizers reflects a large food demand, limited land area, relatively low soil fertility and productivity, and historic use of organic manure only to recycle nutrients and maintain soil fertility. Since 1993 China has been the largest fertilizer user in the world, and now accounts for about one third of the world total fertilizer nutrient consumption.

Fertilizer use has not only provided additional nutrients and energy to the cropping systems, but has supported a continuous increase in annual crop production. Research has shown that fertilizer input contributes about 40-50% of total yield increase for main grain crops in the last 60 year in China. Combining fertilizer use with advanced science and technology, improved management in crop production, and a favorable policy environment to support farmers, China has successfully managed to increase total grain production in the last 8 years since 2004. However, achieving balanced nutrient management remains a challenge in many regions for various reasons. In those regions with high yielding intensified cropping systems, over use of N is common and accumulation of P, and in some cases K, has occurred. These N and P nutrient accumulations have resulted in relatively low fertilizer use efficiency and in some cases had negative environmental impact.

High pressure for crop products to support the growing population and to improve the countries standard of living continues. In 2008, China released its “Mid and Long Term Plans to Ensure Food Security in China”, and set out the target of increasing grain production to 540 million tonnes by 2020, a 95% increase in domestic production. And at the same time, there is growing awareness that high fertilizer rates required to achieve high, or super high yields, and the irrational (unbalanced) use of fertilizers will continue to create environmental challenges. The first official report from the national survey on pollution in 2010, by Ministry of Environment Protection, National Statistics Bureau and Ministry of Agriculture of China, indicated that total N and P discharge from agricultural sources, including crop production, animal husbandry and fishery, to surface water reached 2,704,600 and 284700 tonnes, accounting for 57.2% and 76.4% of total N and P discharge, respectively. Although fertilization is only one of many factors in agriculture contributing to this high N and P discharge into surface water, it does bring needed attention to the fact that fertilizer practices have become a critical issue and need to be managed to reduce environmental pollution.

Organic nutrient resources in China have not been used properly. It was estimated that in 2008, the total nutrient content in organic resources (including night soil, animal manure, crop straw and green manure) was 74.06 million tonnes with 30.51 million tonnes of N, 14.04 million tonnes of P₂O₅ and 29.51million tonnes of K₂O. However, it was also estimated that only 41% of the total organic nutrient resources were return to agricultural land and recycled. This has also contributed to surface water environmental problems.

Facing pressure to both increase yields and improve the environment, a new strategy is required to bring attention on improving fertilizer use efficiency. Considering the fact that most crop production systems in China are highly intensified with high fertilizer input, and the fact that China has to further increase crop production to support a growing population and rapid economic growth, increasing fertilizer use efficiency actually becomes an important task to ensure food security, social stability and environment quality. This goal can only be reached with advances in soil science and fertilization technology. The strategy to reach this goal will be discussed including: 1) Using all available organic nutrient resources wherever possible; 2) Realizing balanced fertilization to support increased crop yields; 3) Develop advanced technology to improve fertilizer use efficiency, such as slow release fertilizers, site specific nutrient management, fertigation technology, etc.; 4) Developing best management practices with fertilization, irrigation, cultivation and other management practices necessary to address the move to larger farm size and mechanization.