Study on high efficiency nutrient use and regulation of soil nutrient dynamics for high yield rice

IPNI-2010-CHN-HN16

14 Feb 2011

2010 Annual Interpretive Summary

Highly Efficient Use and Dynamic Regulation of Soil Nutrients in High Yielding Rice

Rice is the most important grain crop in China. It occupies only 25% of the grain crop area, but represents 50% of its total grain food output. High yielding, super hybrid rice has spread quickly in recent years in China. As the largest rice production province, the planting area of super hybrid rice in Hunan has reached 4 million ha with an average yield of 12 t/ha in 2006. Super hybrid rice has different nutrient demand characteristics compared with conventional rice. The Soil and Fertilizer Institute of Hunan established this project in 2009 to study the soil fertility limiting factors and better nutrient management strategies for super hybrid rice.

The project gathered 24 rice field soil samples from eight main rice planting counties within Hunan Province. Results showed that high yielding rice soils have good physical, chemical, and biochemical qualities. Rice soil with moderate yields (10 to 13.5 t/ha) had good physical and biochemical qualities, but poor chemical qualities. The physical, chemical, and biochemical qualities in low yielding (< 10 t/ha) rice soils were all poor, which is mainly reflected in low organic matter, nutrient supply, and buffering ability. The main factor affecting moderately yielding rice soils was unbalanced soil nutrient supply. Highly productive soils (>14 t/ha) usually had soil bulk densities below 1.2 g/cm3, soil particle density about 2.0 g/cm3, and 20% of water soluble macro-aggregates between 0.5 to 5 mm. No significant difference was observed in most of the physical property indicators between highly productive and moderately productive rice soils, but significant differences were observed between the high and low producing soils. Hunan-16