Effects Of Different Crop Straw Return And Fertilizer Input On Crop Growth In High-Yielding Agro-ecosystem

A series of environment problems have appeared as a result of the excessive application of fertilizer and pesticide in highly intensive modern agriculture in China. The study is a part of NSFC project of "Modeling approach to evaluation the environmental cost based on the budget of carbon and nitrogen in agro-ecosystem ". The experiment was located in a typical Northern China Plain with high productivity - Huantai County, Shandong Province. Crop growth and carbon-nitrogen budget in ago-ecosystem of this region were studied by the methods of investigation and field experiment. Because Huantai County have been characterized by its crop straw return and high fertilizer input, field experiment focused on different crop straw models and N fertilizer input levels. Three types of crop straw return, i.e. wheat-maize straw return, wheat straw return alone and zero straw return, four levels of N fertilizer, i.e. N1 (600 kg.hm-2), N2 (400 kg.hm-2), N3(200 kg.hm-2) and N0 (no fertilizer), and organic fertilizer were treated. There were eight treatment selected. The research results are as the followings:For winter wheat season, the peak of yield was 5.49t.hm-2, with treatment of both straw return and NO level; the lowest yield was 5.13t.hm-2, it was 7% reduction of output. But, all treatments yield showed no significant variation. In same wheat straw return condition, the highest yield was the N2 level treatment. It was found that the both straw return pattern was more efficient to increase yield. However, higher N fertilizer input decrease yield.For summer maize season, the peak of yield was 5.93t.hm~2, treated with wheat straw return and N3 level. In same condition, N1- N2 and N0 treatments decreased yield 16%, 27%, 17% respectively, however, having no significant difference, either.From the point of sustainable development, the regional farmers should increase the manure input and decrease the N fertilizer application and use crop straw more efficiently in order to improve crop production economic benefit in the future.