| In order to solve the serious environmental pollution caused by straw burning and improve the utilization efficiency of straw returning to the field,discuss how to reduce fertilizer input,improve soil structure,improve soil fertility,and increase production and income while taking advantage of straw’s own advantages,and put forward feasible methods The compound application mode of biochar-based fertilizer can provide a scientific basis for the resource utilization of solid waste and the improvement of saline-alkali land in Hetao irrigation area.In this thesis,sunflower was used as the test material,and blank control(CK),biochar compounded with organic fertilizer(SY,Biochar22.5 t/hm~2,Organic fertilizer 15 t/hm~2),biochar compounded with desulfurized gypsum(ST,Biochar 22.5 t/hm~2,Desulfurization gypsum 3600 kg/hm~2),biochar compounded with humic acid(SS,Biochar 22.5 t/hm~2,Humic acid 500 kg/hm~2),and biochar compounded with compound Fertilizer(SF,Biochar 22.5 t/hm~2,Compound fertilizer 75 kg/hm~2)5treatments were used to explore the effects of applying different biochar-based fertilizers on soil physical and chemical properties,nutrients,soil microorganisms,crop growth indicators and yield under the conditions of saline-alkali land and drip irrigation in the Hetao irrigation area.The following main conclusions were obtained:(1)Biochar compound desulfurization gypsum(ST)can significantly increase soil moisture content,with a maximum increase of 40.77%.Biochar compound fertilizer(SY)can effectively reduce soil p H,and the p H value of 0～20 cm and 20～40 cm soil layer is about 5.2%and 2.6%.Biochar compound humic acid(SS)reduced soil conductivity the most,about 7.56%～38.79%,and had obvious desalination effect,and the maximum desalination rate was 34.02%.(2)There were obvious differences in the effects of different biochar-based fertilizers on soil nutrient content(total nitrogen,total phosphorus,total potassium,organic matter),but there were significant improvements in all aspects.Biochar compound desulfurization gypsum(ST)has the most obvious effect on soil total nitrogen and soil organic matter in 0～20 cm soil layer,biochar compound humic acid(SS)on total phosphorus and soil organic matter in 20～40 cm soil layer,and biochar compound organic fertilizer(SY)on soil total phosphorus and soil total potassium content in 20～40 cm soil layer.The application of biochar-based fertilizer will reduce the soil carbon and nitrogen ratio,and the C/N between the treatments is between 5.24～10.62,and the soil nitrogen increase is greater than the soil carbon increase range,among which the 0～20 cm soil layer has the most significant effect.Compared with the blank control,the carbon-to-nitrogen ratio of biochar compound desulfurized gypsum(ST)was significantly reduced.(3)The number of soil microorganisms increased first and then decreased with the change of growth period,and the soil activity of microorganisms in the 0～20 cm soil layer was frequent and the most active.The number of soil microorganisms under the treatment of biochar compound organic fertilizer(SY)was about 1.69 times that of the control treatment.At the same time,soil microorganisms were positively correlated with water content,total potassium,organic matter and carbon-nitrogen ratio,and negatively correlated with soil conductivity.(4)Application of different biochar-based fertilizers can promote sunflower growth to varying degrees,increase dry matter accumulation,100-seed weight and yield.Among them,biochar compounded with desulfurized gypsum(ST)had the most significant effect on plant height,and biochar compounded with humic acid(SS)had the most significant effects on stem diameter,dry matter accumulation and 100-grain weight.Biochar compounded with humic acid(SS)and biochar compounded with desulfurized gypsum(ST)had a significant effect on increasing production,which increased by 16.49%and13.4%respectively compared with the blank control,while the economic benefits increased by 10.88%and 7.78%respectively.On the whole,the improvement effect of biochar-based fertilizer on the physical and chemical properties of 0～20 cm soil layer was better than that of 20～40 cm soil layer.Different biochar-based fertilizers could improve soil moisture content,reduce soil p H value and conductivity,increase soil nutrients,microbial number and crop growth,and finally achieve high crop yield.For the improvement effect of saline-alkali soil,biochar compound desulfurization gypsum(ST)is more suitable.Biochar compound humic acid(SS)has a better effect on increasing sunflower yield. |
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