[Present situation of maize straw resource utilization and its effect in main maize production regions of China].

A survey was carried out in three main maize production regions in Northeast, North, and Southwest China, including 720 villages of 125 counties, with the purpose of investigating the present situation of maize straw resource utilization and its effect. Among the present utilization ways of maize straw resource, the main ones were returning to soil, feeding livestock, and using as fuel, their proportions being 30.8%, 26.2%, and 24.6%, respectively. In Northeast China, the top three utilization ways were fuel, livestock feed, and returning to soil, with the proportions being 35.4%, 30.8% and 19.8%; in North China, the top three were returning to soil, livestock feed, and fuel, with the proportions being 43.6%, 19.9%, and 17.9%; and in Southwest China, they were returning to soil, livestock feed, and fuel, with the proportions being 29.0%, 27.9%, and 20.5%, respectively. In the survey areas, the proportion of using maize straw as fuel was smaller (12.8%), and that of using as industrial raw material was only 0.7%. Returning maize straw to soil increased maize yield (the increment in Northeast, North, and Southwest China was 632.0, 371.6, and 290.4 kg x hm(-2), respectively), improved soil condition, and decreased the application rates of manure, nitrogen, phosphorus, and potassium fertilizers by 20% -30%, 16%-30%, 24%-34%, and 33%-38%, respectively. The maize yield increased with increasing straw mass and its returning amount and proportion. However, because of wanting complete sets of available machines, straw returning was low in quality, which increased the difficulty in weed controlling and promoted the occurrence of some diseases and insect pests, giving impacts on maize seedlings growth. It would be necessary to strengthen the researches on the related complete set maize straw returning techniques.