| Around the world,China is a major agricultural producer,with the largest amount of straw resources.In agricultural production,crop straw is one of the most valuable and valuable renewable resources,but at present our country has not been rationally and effectively utilized the straw resources.Every year,a large number of crop straws are burned directly.This is not only a waste of resources,but also a serious pollution of the environment,but also affects human health.For crop growth,soil environment is the most important.For a long time,in order to pursue yield,excessive application of chemical fertilizers has led to soil pollution,organic matter reduction,fertilizer and water conservation capacity declined sharply,and black land degradation capacity is serious.Straw is the most important source of organic fertilizer.Using straw as fertilizer can not only improve soil organic matter,physical and chemical properties,but also improve soil water and fertilizer conservation capacity,thus increasing crop yield.If straw is directly used as fertilizer,there are also some disadvantages,such as slow decomposition,poor seedling emergence,low maturity,increased pests and weeds.In order to solve the above problems,we adopt straw extrusion technology to improve the utilization of straw.Through the extrusion treatment of straw,we add highly active decomposing agent,and accumulate fermentation to degrade and produce organic fertilizer.Therefore,straw extrusion technology has become the focus of current straw returning research,which can improve soil structure and reduce waste of resources.The main research work is as follows:1.According to the observation of SEM,extrusion,expansion and fermentation of straw can effectively break down the dense structure of cellulose,hemicellulose and lignin,decompose part of hemicellulose,increase the contact area of straw with microorganisms and cellulase,increase the rate of enzymatic hydrolysis,and then increase the utilization rate of straw.The characteristic peaks of hemicellulose decreased obviously,the characteristic peaks of lignin changed slightly,and the bond C?O?C of some cellulose was broken.The composition analysis of the structure of corn straw showed that the corn straw after extrusion fermentation was helpful to increase the contact area with cellulase,which provided a basis for the subsequent enzymatic hydrolysis to reflect the production of reducing sugar.2.The results indicated that the organic matter content of expanded fermented straw after 7 days and 35 days culture was higher than that of expanded non-fermented straw,showing significant difference.However,the organic matter content of expanded fermented straw after 56 days,77 days and 98 days of culture decreased.The results of available nitrogen culture were consistent with the results of organic matter content,indicating that the macromolecular organic matter degraded the small molecular organic matter and inorganic nitrogen after the expansion fermentation of straw.After 98 days of incubation,the available nitrogen content of the extruded fermented straw and the extruded non-fermented straw decreased,but still maintained a higher cumulative amount;on the 56 th day,the available phosphorus content of each treatment was lower than CK;on the 98 th day,the available phosphorus content of each treatment fluctuated compared with the value of 56 d,and the available phosphorus content was higher than CK,the same amount.The content of available phosphorus in the extruded fermented straw was higher than that in the non-fermented straw.Among them,the content of available potassium decreased at 77 d,98D and 56 d.In addition,the content of available potassium in the extruded non-fermented straw was significantly different at 77 d and 98 D with the increase of incubation time compared with that in the extruded fermented straw.3.Effects of different treatments on soil physical properties:Straw could effectively reduce soil bulk density in tillage layer after expansive fermentation.Soil porosity: Returning straw to the field can effectively improve the soil porosity of tillage layer,which is closely related to crop root system and tillage mode,and the improvement effect of 5 tons/ha dilatation fermentation straw + fertilizer constant(A4B1)is obvious.Soil moisture content is absorbed and consumed by returning straw to the field in the early stage of maize growth.As maize enters the mature stage,in the process of decomposition of maize straw,the moisture content of maize straw itself and the soil moisture absorbed in the early stage return to the soil,playing a role of soil moisture conservation.Soil water-stable aggregates showed as follows: A4B1 treatment increased soil porosity,increased soil organic matter content,and humus formed during straw decomposition,which was conducive to the formation of large aggregates;A4B1 treatment had a significant effect on improving soil organic matter content;A4B1 treatment had a trend of increasing soil nitrogen;the change of soil available phosphorus content in each treatment was not obvious,only the content of soil available phosphorus in A4B1 treatment increased by 0.9%;each treatment could improve the content of soil available potassium.The soil PH value showed a downward trend.The number of soil bacteria showed that the treatments of straw + 70% chemical fertilizer constant(A4B2)and straw + 80% chemical fertilizer constant(A3B3)after 5 tons/ha puffing fermentation and 3 tons/ha puffing fermentation were significantly higher than those of the control.There was no significant difference between the treatments of straw + chemical fertilizer constant(A4B1)after 5 tons/ha puffing fermentation and straw + chemical fertilizer constant(A3B1)after 3 tons/ha puffing fermentation.The number of soil actinomycetes showed no significant difference between jointing stage and tasseling stage.In the middle and late stage of maize growth,the number of soil actinomycetes treated with A4B2 and A3B3 was significantly higher than CK,while the number of soil actinomycetes treated with A4B1 was significantly lower than CK.In the early growth stage,the number of soil fungi in each treatment had little effect,but in the middle and late growth stage of maize,the number of soil fungi in each treatment showed a decreasing trend;in the whole growth period of maize,the number of soil ammoniated bacteria and aerobic nitrogen fixing bacteria in each treatment was significantly higher than that in the control,and in the late growth stage of maize,the number of soil aerobic cellulose decomposing bacteria and nitrifying bacteria was significantly higher A4B2 and A3B3 treatments significantly increased the number of ammoniated bacteria,but had little effect on the number of aerobic cellulose decomposing bacteria and nitrifying bacteria.Soil enzymes activities showed that the invertase,catalase and urease activities were similar in all treatments.The activities of urease,invertase and catalase were increased in A4B1 and A3B1 treatments.4.The plant height and spike height of maize under different treatments were as follows:A4B1>A3B1>A3B3>A4B2>A2B1>A1B1>CK,plant height and spike height under A4B1 treatment were higher than those under other treatments.The barren tip length in different treamengts was as follows:CK>A1B1>A2B1>A4B2>A3B3>A3B1>A4B1,the barren tip length in A4B1 treatment was lower than that in other treatments.The variation of ear length was not obvious between different treatments because ear length was mainly influenced by genetic factors.The leaf area of maize(trifolium cordata)under different treatments was showns as follows A4B1>A3B1>A3B3>A4B2>A2B1>A1B1>CK.The hundred?grain weight and yield of corn under different treatments are shown as A4B1>A3B1>A3B3>A4B2>A2B1>A1B1>CK in turn.It can be seen that the treatment of corn straw returning to the field by A4B1 can effectively change the soil environment,thus significantly improving the quality and yield of corn seeds. |
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