| Contains a large number of mineral elements,such as straw carbon,nitrogen,phosphorus,potassium,calcium,magnesium,sulfur and silicon and other elements,but also contains a lot of cellulose,hemicellulose,lignin and protein such as organic matter,is a kind of resource utilization of solid waste resources.The number of straw gradients in this experiment was 0?3750?7500?11250.1500 kg·Hm-2,respectively,and no straw was used as the contrast.The design of micro,micro area 5m2,repeated three times.According to experiment scheme,the corn straw evenly spread in the area,the depth of 12-15cm with conventional rotary tilling.Spring sowing fertilizer compound fertilizer 600kg-hm2(-N-P205-K20 25-15-15),planting density of 60000 plants hm-2.The surface soil was collected during the growing period of maize.The soil physical properties,soil nutrients,soil microorganisms,soil enzymes and their correlations were analyzed,Test results show that:1.Straw returning can obviously improve soil nutrient,the 7500 kg/hm-2 treatment works best,when the corn was ripe,the soil alkaline hydrolyzable nitrogen was increased 38.9%?AP increased 8.97%?AK increased27.31%?OM increased21.3%compared with the control.2.Straw returning can obviously decrease soil bulk density,increase soil porosity,increase soil water holding capacity and relieve moisture loss.This effect will increase with the increase of straw returning amount;The soil bulk density of 1125015000 kg·hm-2 treatment were lower than control for 11.4%,14.2%,for soil porosity,control,3570,7500,J4,J5,the overall upward trend,3570,7500 increased compared to the control of the total porosity of soil had no significant difference,J4,J5 had significant difference compared with the control,were increased by 8.2%,8.8%.The field capacity,the results of variance analysis showed that 3570,J5 compared with the control of field capacity increased without significant difference(P>0.05),7500,J4 compared with the control of field capacity increased significantly,increased by 10.2%,11.9%.for capillary porosity,with the increase of corn straw quantity,the soil porosity does not change too much.3.The straw can significantly reduce the loss of water and evaporation,irrigation after 15000 kg·hm-2 treatment of soil moisture in 120 hours after irrigation has been showing rapid decline,3750 kg · hm-2 in 24 to 48 hours after irrigation and control are the same as the rapid decline,48 hours to 120 hours slow 7500 11250 kg·hm-2 treatment decreased has been showing a slow downward trend.Thus,the straw can reduce soil water loss,and increase the amount of maize straw,the mitigation effect is better,but when the straw amount exceeds a certain range,the straw can accelerate soil moisture loss.4.Straw mulching could obviously increase the number of soil microorganisms,soil fungi quantity at the jointing stage with the increase of amount of maize straw decreased,then increased,and then decreased,11250 kg-hm-2 treatment most,then decreased rapidly.The amount of soil actinomycetes in Maize Jointing Stage with the increase of amount of maize straw were increased and then downward trend,up to 11250 kg · hm-2,in the milk stage and ripe stage,the number of actinomycetes.The overall performance for the rising trend of ripe period soil actinomycetes was increased after the downward trend,7500kg · hm-2 the most.The number of soil bacteria in the jointing stage with the increase of amount of maize straw were increased and then downward trend,11250 Kg·hm-2 the most,the number of soil bacteria after ripening was first increased and then decreased,7500 kg · hm-2 treatment most.The soil at the jointing stage with cellulolytic bacteria amount of maize straw increased decreased,then increased,and then decreased,11250 kg · hm-2 treatment in most initial tasseling stage and ripe stage with the increase of amount of maize straw were increased and then downward trend,the 11250 kg · hm-2 most treatment.5.Straw mulching could enhance soil enzyme activity,and with the increase of straw quantity,soil enzyme activity was higher when the straw quantity reaches a certain value,the activity no longer increases.Straw returning increased invertase content in corn growth stage in soil,but increased with straw returning time,the content of each treatment soil invertase will slowly decrease over the same period,soil invertase content of each treatment was higher than that of the control.The straw can increase the content of urease.The early growth of corn in the soil,but increased with straw returning time,the content of soil urease among different treatments will slowly decrease over the same period,soil urease activity in each treatment was higher than that of the control.Soil cellulase and phosphatase in the late period of maize growth with increased first and then decreased the trend of increasing the amount of straw.6.The appropriate amount of straw returning can effectively increase crop yield,and the effect of crop yield increase is the best at 7500kg·hm-2. |
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