Effects Of Fertilization On Crop Yields And Soil Microbiological Proterties Based On The Returning Straw Under Wheat-Maize Cropping System

A field trial was carried out in lime concretion black soil of northern Anhui province to study the effects of different fertilization on crop yields and soil microbiological properties. The 9 treatments at the site included no fertilizer (CK), conventional NPK (NPK), conventional NPK with straw (ST1), conventional NPK with straw and straw effective microorganism 150 kg hum-2 (ST2), conventional NPK with straw and straw effective microorganism 300 kg hm"2 (ST3), reduced 30% conventional NPK with straw and pig manure 3000 kg hm-2 (ST4), reduced 30% conventional NPK with straw and cow manure 3000 kg hm-2 (ST5), reduced 50% conventional NPK with straw and pig manure 6000 kg hm-2 (ST6), reduced 50% conventional NPK with straw and cow manure 6000 kg hm 2 (ST7), crop yields, soil nutrients, soil carbon pool capacity, soil enzyme activity, soil microbial quantity and soil microbial biomass were analyzed for comparison, aiming to improve straw returning technique and provide a theoretical basis to construct high yield and health soil microflora. The main conclusions of trial were as the following:1. The straw incorporation with different fertilizers could increase yields of wheat and maize, and the effect of yield increased significantly year by year. Yield of wheat and maize under ST6, ST7 were higher relatively. Yield stability under ST6 was better than others. Fertilizer 3000 kg pig or cow manure to replace 30% conventional NPK could meet crop regular growing.2. Straw returning to field could improve soil total nitrogen, phosphorus, alkali solution nitrogen, rapidly available phosphorus and rapidly available potassium content. ST6 treatment got the best effect on soil alkali nitrogen, rapidly available phosphorus and total phosphorus whether wheat season or maize season. Rapidly available potassium of ST7 treatment increased up to 13.96% during wheat season and 20.53% during maize season compared with ST1 treatment.3. Soil organic matter and soil active organic carbon could increase at varying degrees under straw returning incorporation with different fertilizers compared with NPK treatment between wheat and maize season, and ST6 treatment had the most significant than others, as well as ST7 treatment could improve CMPI.4. Under condition of straw returning to field, fertilizing treatments could improve soil enzyme activities. Soil invertase activity, soil cellulose activity, soil urease activity and soil neutral phosphatase activity increased with increasing application rate of organic manure. Correlation analysis showed that, soil enzyme activities could reflect soil fertility to a certain degree.5. Soil bacterial, actinomycets and total microbial communities increased which treated with straw returning. Soil bacterial under ST7 increased up 2.06 times during wheat season and 2.33 times during maize season, and also significantly enhanced soil microbial biomass C、N and soil microbial quotient. Correlation analysis showed that soil microbiological properties were related to soil fertility under certain condition.Above all, based on the straw returning to field, incorporation with 50% common fertilizer and 6000 kg hm-2 organic manure could improve soil quality, and they were more effective to construct high yield and health soil microflora.