Effects Of Nitrogen Supply Levels And Wheat Intercropping Maize On Soil Carbon And Nitrogen Of Straw Mulching Farmland In Hexi Oasis Irrigation Area

Carbon, nitrogen is not only the organisms essential nutrients are also important ecologicalelements. Conservational tillage measures, organic carbon and nitrogen are concerned intensively atpresent in the world because of the changes of climate and environment. Wheat/maize intercroppingis an important multi cropping pattern in Hexi oasis irrigation area, In order to understand thevariation of soil carbon and nitrogen in wheat maize interplanting system, the experimental inGansu Agricultural University Experimental Station in Wuwei city in the Shiyang River basin,Gansu province during2011in China, to study the effect of N fertilizer application rates (0,140,221,300kg N hm2) on soil carbon and nitrogen of mono wheat, mono maize and wheat/maizeintercropping after harvest on Straw Mulching Farmland. The results showed as following:1.On the straw mulching farmland, in the same nitrogen level, the mono wheat were thehighest soil organic carbon and total nitrogen content, mono maize were followed, intercroppingmaiz were low, the lowest is intercropping wheat, the soil organic carbon and total nitrogen contentof mono wheat than mono maize, intercropping maiz and intercropping wheat with3.8%and1.1%,4.1%and6.7%,9.4%and8.8%2. On the straw mulching farmland, With the increase of nitrogen rates, total nitrogen andorganic carbon contents were obvious increased in soil. However, when the nitrogen rate was higherthan140kg N hm2, soil total nitrogen did not continously incresased with the increase of nitrogenrates, the organic carbon even showed a trendancy to decrease.3.On the straw mulching farmland, the NO3N increased with the increase in nitrogenapplication to deep contaminant mass, in the100120cm depth, compared to no nitrogen, on thethe300kg N hm2level, NO3N accumulation in mono wheat increased by9.3kg hm2, an increaseof10.3kg hm2on mono maize, intercropping wheat an increase of1.3kg hm2, intercropping maiz4.1kg hm2. in the same planting mode, except6080cm depth, the rest of the soil content ofNO3N increased with increasing amount of nitrogen.4.In the same planting mode, the vertical distrbution of nitrate content is surface of thehighest(5.47mg kg1), the soil nitrate content is surface of the lowest(1.81mg kg1) in the6080cm depth, in the80120cm depth, the nitrate content increased slowly with the soil increase. thevertical distrbution of soil nitrate content is expressed as:first reduce and then increased with theincreased in soil.5.On the mono wheat farmland, crops growth stages were prolonged as soil provides enoughnitrogen, an grain yields and WUE increased with nitrogen supply levels. When the nitrogenapplication rate exceeds a certain range, the grain yield and WUE will be reduced, a nitrogen rate of221kg N hm2,obtained the highest values of grain yields(6714kg hm2) and WUE(11.43kg mm1 hm2) among other nitrogen levels. With the increase of nitrogen rates, the grain yield and WUE willbe increased in mono maize and wheat/maize intercropping farmland.