Abstract:

【Objective】 The effect of long-term application of nitrogen (N), phosphate (P) and potassium (K) fertilizer and rice straw (RS) on change trends of soil fertility and productivity sustainability of double rice (Oryza Sativa L.) cropping system were investigated in a reddish paddy soil of subtropical climate region in China. 【Method】 This study evaluated the soil fertility and productivity sustainability in five treatments composed of N, P and K fertilizer and combined application of fertilizer with RS in a long-term experimental field established in 1981 designed to examine the effects of fertilization on soil properties and rice crop productivity of a reddish paddy soil (classified as typical stagnic Anthrosol) derived from parent materials of Quaternary red clay. 【Result】 Results showed that long-term balanced application of N, P and K fertilizers and in combination with RS could increase significantly soil organic matter (SOM), total N (TN), total P (TP), potentially mineralizable N (PMN), available P and K compared with their initial value in 1981. Rice yield, N and K content in soil were lowered year by year in NP treatment without K fertilizer, and productivity sustainability of rice crop and soil fertility could not be maintained. Rice straw returned into soil significantly increased rice yield. Average rice yield with 27 years rice straw-returned treatment (NP+RS and NPK+RS) were increased by 12.2% and 6.7%, respectively, compared with NP and NPK application alone. 【Conclusion】 Rice straw could partly replace chemical K fertilizer as the nutrient of K brought by rice straw had the same function as that of chemical K fertilizer.

Key words: long-term fertilizer application, reddish paddy soil, soil fertility, productivity sustainability