| The areas of winter fallow fields in North China containing Tianjin are gradually increasing because of the lack of water in the maize-producing areas and the decrease of wheat area.It is a challenge how to improve the farmland ecological environment and maintain the soil fertility in winter fallow field.On the basis of winter green manure screening,Orychophragmus violaceus,Hairy vetch,Rye and Ryegrass.were selected.The present study investigated the nutrient accumulation,decomposition and release process of winter green manure,maize growth and development,nutrient cycle transformation process,and the effect of rotation mode on soil fertility effect,maize production through field positioning experiments.The comprehensive fertility evaluation,maize productivity and ecological value were carried out in the rotation system.The main results are as follows:(1)Winter green manure had high carbon accumulation and nutrient absorption,and reduced therisk of soil nitrogen loss in winter and spring,and increased the effective utilization of soil phosphorus and potassium fixation.The total biomass of winter green manure was 4991.9-7262.0 kg/hm~2,and the total amount of nitrogen(N),phosphorus(P)and potassium(K)provided by winter green manure was334.5-423.2 kg/hm~2.The N absorption of Hairy Vetch was the highest,which was 183.3 kg/hm~2;the P and K absorption of Rye was the highest,which was 39.9 kg/hm~2 and 261.4 kg/hm~2,respectively.High N absorption was observed for Hairy vetch,and high P and K absorption was in Rye Winter green manure before turning pressure decrease soil nitrate nitrogen,inorganic nitrogen and available phosphorus contents and increase available potassium content.(2)After turning pressure of winter green manure,the decomposition rate increased firstly and then decreased over time.And,the decomposition rate was 79.78-92.47%.Mineralization research showed that mineralization rate of C,N,P,K was 83.99%,88.72%,82.03%,91.04%,respectively.Compared to individual Hairy vetch,its mixed planting delayed the nutrients release of C,N,P,K,and promoted nutrient supply,especially for N.(3)The rotation system of winter green manure and spring maize significantly improved soil physical and chemical properties.The rotation system significantly increased the contents of soil organic matter,TN,TP,TK by 14.63-21.50%,3.31-12.40%,4.05-20.27%,0.63-4.44%,respectively.And,the rotation system significantly increased the contents of soil alkali hydrolyzed nitrogen,available phosphorus,available potassium,increased the soil buffer capacity to acid and alkali and decreased EC Value.The rotation increased soil water content and saturated water capacity by3.24-13.58%and 8.5-20.8%,respectively.Orychophragmus violaceus and Ryegrass decreased soil bulk density and increased soil total porosity.Soil active organic carbon and carbon pool management index increased by>16.46%and>5.22%respectively.Soil carbon stock and carbon stability coefficient were increased,and the effect of winter green manure mixed maize rotation was the most obvious.The rotation significantly increased soil enzyme activity by 6.59-20.47%,Rye+Hairy vetch,Rye and Hairy vetch significantly increased the soil phosphatase activity.Rye and Ryegrass significantly increased soil invertase activity.Orychophragmus violaceus+Hairy vetch,Hairy vetch significantly increased soil catalase activity.4 green manure significantly increased soil polyphenol oxidase activity.The rotation increased the quantities of soil bacteria,actinomycetes and fungi.Green manure increased soil bacterial community diversity,and could increase special bacterial species under planting green manure.The rotation increased the soil microbial carbon and microbial nitrogen by 57.44%and 36.94%on average respectively.The effect of mixed planting was the largest.The comprehensive evaluation of soil fertility showed that the soil fertility of winter green manure mixture-spring maize rotation was the highest,and that of maize monoculture was the worst.(4)The rotation improved maize growth,increased yield and nutrient absorption and utilization efficiency.Compared with the control,the leaf area index,leaf chlorophyll content and leaf photosynthetic rate value of winter green manure maize rotation at all growth stages(excluding seedling stage)were increased;maize grain yield was increased by 4.94-11.62%,and the contents of nitrogen,phosphorus and potassium in maize grain was significantly increased;the accumulation of n and P in maize grain were significant.The agronomic utilization efficiency of nitrogen,phosphorus and potassium in maize was increased by 16.6-22.72%,9.29-23.81%and 9.25-23.82%,respectively.The highest was in the Hairy vetch-maize rotation.(5)Total value of the ecological service function of the rotation system was 1.87-2.31 times that of the spring maize monoculture ecosystem,up to 67600-83400 yuan/hm~2,which included the net output value of the ecosystem,the total accumulated value of soil nutrients,the value of the farmland to maintain the soil function,the value of water conservation,the value of the gas regulation function.In a word,the rotation significantly increased the surface coverage of winter and spring arable land,improved the physical and chemical properties,biological characteristics and comprehensive fertility of soil,improved the productivity of spring maize and the efficiency of fertilizer agronomy utilization,and greatly improved the value of ecological service function.Therefore,the winter green manure-maize rotation system is worth popularizing. |
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