Study On The Distribution And High Efficient Utilization Of Resources For Double Cropping System In The Huang-huai-hai Plain

In the Huang-huai-hai Plain, the increasing of grain yield and resource efficiency of irrigated wheat-maize cropping system has been restricted by a significant warming climate and imbalance application of water and nitrogen. In this study, based on the analysis of a large database from high yield field experiments of winter wheat-summer maize and double maize cropping system, we clarify the characteristic of resources distribution between two seasons, and introduce the index of quantitative assessment. And then, study the effect of sowing date, irrigation and nitrogen management, and tillage practice on grain yield and nitrogen efficiency of maize, eventually establish the winter wheat-summer maize and double maize cropping sytem with high yield and high efficiency. The main results are as follows:(1) We clarify the characteristic of resources distribution between two seasons for the winter wheat-summer maize and double maize cropping system with high yield, and introduce the index of quantitative assessment, such as resources distribution rate and resouces rate. The accumulated temperature distribution rate (TDR) of wheat and maize are43%and57%, respectively, and the accumulated temperature rate between two seasons (TR) is0.7; The accumulated temperature distribution rate (TDR) of two seasons in double maize are50%and50%, the rate of accumulated temperature between two seasons was1:1. According to the indexes, the resources distribution between seasons can be chanaged by chanaging sowing date. In addition, compared with wheat, maize has high efficient utilization of resources, which is important for increasing yield and resources use efficient of double cropping system in Huang-huai-hai plain.(2) In order to explore the yield potential of maize, the relationship between maize yield and climatic factors was investigated. Post-silking dry matter and kernel weight are the main factors influencing the variation of yield. Temperature and radiation are the determinging climatic factors for post-silking dry matter accumulation and grain filling. When the accumulated temperature, daily mean temperature, daily maximum temperature, and daily minimum temperature from sowing to maturity were1939℃,25.9℃,30.6℃, and21.6℃, respectively, and the accumulated temperature and radiation during post-silking stage were980v and1005MJ m-2, respectively, namely, the sowing date was from May22to June10, the yield was the greatest.(3) We have preliminarily researched the effect and mechanism of sub-soiling tillage, application of nitrogrn by drip fertigation on maize growth and development, and nitrogen accumulation. The use of slow release fertilizer with subsoiling and drip fertigation significnatly increased maize yield and nitrogen use efficiency. Yield increase was mainly attributed to post-silking dry matter accumulation. For drip fertigaion, higher plants N concentration and more N accumulation during pre-silking stage was mainly contributed to the increased dry matter during post-silking stage. For application of slow release fertilizer with subsoiling, post-silking N accumulation is the main factor influencing dry matter accumulation. (4) The winter wheat-summer maize and double maize cropping system with high yield and high effcieny have beeen established in our study by using integrated technology, including "double delay", subsoiling tillage, and drip fertigation. Compared to the traditional cropping system, the annual yield of winter wheat-summer maize increased by10.8%, and its benefit increased2113.2Yuan hm-2; the annual yield of double maize increased by3.4%, the benefits increased2313.6Yuan hm"2.