5PATHAK H,SINGH R,BHATIA A, et al. Recycling of rice straw to improve wheat yield and soil fertility and re- duce atmospheric pollution[J]. Paddy and Water Environ- ment ,2006,4(2) :111-117.
6KUMADA K,SATO O,OHSUMI Y,et al. Humus com- position of maintain soil in central Japan with special refer- ence to the distribution of P type humic acid [J]. Soil Sci- ence and Plant Nutrition, 1967,13 : 151-1581.