Effect Of Different Planting Mode And Straw Returning On Soil Fertility And Soil Organic Carbon In Dry Land

The rainfed cultivated land area in Shanxi is2.228million hm2, which accounting for65.13%of the total arable land in the province. Because of less annual rainfall and the soil isbarren, the production is very low. As reported, straw returned can replenish and balance soilnutrients effectively, increase the accumulation of soil organic matter, have obvious effect onimproving soil physical and chemical properties, improve the soil fertility and finally canimprove crop output significantly. So we start a long-term experiment at Heyang County onthe Weibei dryland to explore the influence of soil nutrient and soil organic carbon by strawreturned under different planting patterns. Comparing soil fertility and produce performanceunder different planting patterns comprehensivly and provide a basis for putting forward areasonable solution of dryland farm production and management. There’s a very importanttheoretical and practical significance on sustainable production, improving soil fertility aswell as the improvement of production efficiency on dry farmland. The main conclusions areas follows:1. Effects of soil available and full nutrients under different modes of straw returnedThe content of soil available nutrient increased under various planting patterns aftergrowing crops for five years consecutively. There is a significant increasing on availablephosphorus and available potassium by straw returned，but can’t see the beneficial effects ofavailable nitrogen conten between straw returned and straw out of the field. The pattern whichhas the highest available p content is the rotation+straw returned pattern and the highestavailable potassium content is for the MS spring corn straw returned pattern. The test cannotincrease the content of total nitrogen and total potassium in soil total while have somepositive effects on total phosphorus in soil.2. Effects of soil organic carbon under different modes of straw returnedIn all these patterns after five years which the content of soil organic carbon increasedare the straw returned patterns, especially the two tests WS-S and WS-SS were higherwhich is the of rotation+straw returned，their contents are8.42g/kg and8.43g/kgrespectively,while the minimum content is7.06g/kg for NF. It showed that the plant strawcould increase the content of soil organic carbon obviously as it was higher than blank leisure when there is some crops planted and some straw will leave behind.3. Effects of soil organic carbon and CIM under different modes of straw returnedAfter five years, the content of soil organic carbon is increased while the content ofactive organic carbon is decreased instead. Through this we can see that under the testcondition, planting of crops for a long time can only increase the content of soil organiccarbon but can not improve the quality of soil whether the straw was returned or not. ButUnderin the process of straw returned descend range of soil active organic carbon under strawreturned plantting patterns is small, so we can say that the straw returned have some positiveeffects on replenishing soil active organic carbon and improving soil quality.4. Effects of crop production under different modes of straw returnedThe production of WS winter wheat straw returned is the highest of wheat singlecropping while the lowest is WS-S winter wheat straw returned-catch soybean processingin2010，but in2011the result is opposite. There maybe two reasons: one is the differentfarming modes of continuous cropping and crop rotation for years makes the autotoxicity ofwheat continuous cropping shown while the culture left by roots of leguminous plants arebeneficial to the crop next season; the other is wheat straw returned separately makes thecarbon nitrogen ratio of soil imbalanced. The rest of the results are consistent of two years:the production of maize changes is not much different from different treatments while thehighest has been the treatment MS maize straw returned; under the treatments crop rotation ofwinter wheat-summer maize WN-SN and WS-in SS, the result is the production of WS-SS for straw returned higher than WN-SN straw out.