Spatio-Temporal Variations of Fertilizer Contribution Rate for Rice in China and Its Influencing Factors

Spatio-temporal variations and driving factors of fertilizer contribution rate were conducted for the paddy soil in China, so as to provide a theoretical basis for the sustainable development of rice and scientific recommended application of fertilizers in rice cultivation areas.

Data was cited from a total of 338 long-term paddy soil monitoring sites located in rice-producing provinces of China for this study. The effects of fertilizer contribution rate for cropping system, climate, regions, soil texture and its driving factors were evaluated.

In the past 30 years (1988-2017), the fertilizer contribution rate for rice increased first and then levelled off in China in the condition of same rice variety and cultivation techniques both in fertilization and none-fertilization plots. The variable range of fertilizer contribution rate for rice was from 41.20% to 51.89%. The fertilizer contribution rate for rice was 38.58%-55.49%, 41.96%-51.05%, and 42.34%-53.43% in single, double rice, and rice and other cropping systems, respectively. After 30 years, the fertilizer contribution rate for rice from high to low was as follows: Southwest China (55.82%), Middle of Yangtze River (46.73%), North China (46.27%), North east China (45.90%), South China (45.83%) and Lower of Yangtze River (44.25%). According to the fitting equation, it was found that the stable fertilization years of fertilizer contribution rate for rice was 15.2 a, 18.5 a, 19.0 a, 15.3 a, 15.3 a and 14.5 a in the Northeast China, North China, Southwest China, Middle of Yangtze River, Lower of Yangtze River and South China, respectively. The fertilizer contribution rate for rice in subtropical monsoon (49.23%) was much higher than temperate monsoon (45.90%) and tropical monsoon (34.57%). The fertilizer contribution rate for rice with different soil texture was 43.25%-64.80% for clay soil, 40.65%-48.46% for loam soil, and 26.20%- 45.98% for sand soil. Among the fertilization factors, nitrogen and phosphate fertilizer were the main factors affecting fertilizer contribution rate. Among the climatic factors, frost-free period, mean annual rainfall and mean annual temperature were the main factors and soil organic matter was the most important one among the soil factors.

The fertilizer contribution rate for rice was increased first and then levelled off in 1988-2017, and there was different for fertilizer contribution rate for rice under different rice cropping systems, regions, climate and texture. Nitrogen and phosphate fertilizers were main factors of fertilizer contribution rate for rice in China. Moreover, the soil organic matter in paddy soil was the most important to fertilizer contribution rate for rice in soil fertility indexes.