Tuesday, November 6, 2007 - 2:30 PM
147-1

Present and Perspective of Nutrient Management in the Irrigated Rice Systems in China.

Jianbo Shen1, Fusuo Zhang1, Jingying Jing1, Jianchang Yang2, Yingbin Zou3, Guanghuo Wang4, Yuanying Liu5, Rengang Li6, Xuhua Zhong7, and Jianliang Huang8. (1) China Agricultural University, College of Resources and Environmental Sciences, No. 2, Yuanmingyuan West Road, Beijing, 100094, China, (2) Yangzhou University, Yangzhou, China, (3) Hunan Agricultural University, Changsha, China, (4) Zhejiang University, Hangzhou, China, (5) Northeast Agricultural University, Haerbin, China, (6) Hebei Agricultural University, Baoding, China, (7) Guangdong Academy of Agricultural Sciences, Guangzhou, China, (8) Huazhong Agricultural University, Wuhan, China

Rice is one of the most important grain crops in China. The lack of effective cultivation technology and fertilizer application method led to a very low rice production before 1960s. From 1961 to 1976, the planting area increased by 37.8% whereas total yield increased by 134.5%. Application of N and P fertilizers significantly enhanced rice production. After 1976, despite the decreased planting areas, rice production steadily increased till 1990, showing a good correlation with fertilizer application rates (r = 0.966). From 1991 to 1998, the correlation coefficient between rice production and fertilizer application rates was declined to 0.852, and even to 0.199 from 1999 to 2006, indicating a rapidly decreasing response of crop yield to fertilization. During the past two decades, extension of some strategies of fertilizer recommendation definitely played an important role in improving rice production, particularly soil or plant testing, balanced fertilization, fertilizer-yield response model development and the combined application of organic and inorganic fertilizers. Since 1990s, highly intensive farming system and rapid development in economy stimulated farmers to overuse chemical fertilizers in rice ecosystem, particularly N fertilizer, resulting in a series of problems such as rice yield decrease, low nitrogen use efficiency, low rice quality and increasing environmental pollution. Optimizing nutrient resource management in rice ecosystem through integrating optimal nutrient management, efficient water and nutrient resource utilization, high-yield crop management and environmental risk evaluation system becomes more and more important for the development of sustainable rice production in China.