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【目的】黄土高原旱地土壤贫瘠,夏闲期雨热资源难以被充分利用。本文通过田间试验研究不同夏季绿肥品种及其种植方式对绿肥鲜重、绿肥养分还田量、土壤养分含量、土壤酶活性、土壤水溶性有机碳和微生物量碳含量的影响,旨在筛选出适宜当地夏闲期种植的绿肥品种及种植方式,为促进黄土高原地区农业可持续发展提供理论依据和技术支持。【方法】本研究采用随机区组设计,以夏季裸地休闲为对照,设绿肥(绿豆、长武怀豆、毛叶苕子、油菜)和绿肥种植方式(麦后播种、麦田套种)为研究因素,共9个处理。绿肥盛花期全区齐地收割地上部并称重计鲜草产量,分析绿肥地上部氮磷钾含量;每个小区采集50株绿肥下长、宽、均为20 cm的土体中的根系,称重并进行分析;绿肥收获翻压20天后,于各小区采集0—20 cm土壤样品,测定土壤养分含量、土壤微生物量碳、土壤水溶性有机碳含量以及主要酶含量。【结果】绿肥麦后播种生物量要高于麦田套种;麦后播种以怀豆和油菜生物量较高,套种以油菜生物量显著高于其他处理。不同种植方式下绿肥总养分还田量与生物量规律类似;麦后播种长武怀豆显著提高了氮素和磷素还田量,麦后播种油菜显著提高了磷素和钾素还田量;套种时氮、磷和钾还田量由高到低顺序为:油菜>毛叶苕子>绿豆>长武怀豆,不同绿肥间差异达到显著水平。翻压油菜土壤有机质、速效磷及速效钾含量都要显著高于休闲处理;麦后播种长武怀豆并翻压2年后,0—20 cm土壤有机质、总氮、矿质氮、速效磷及速效钾含量较休闲分别提高了12.4%、22.2%、95.9%、28.6%和11.2%。种植绿肥与休闲相比,土壤水溶性有机碳和微生物量碳含量均有所提高,其中套种油菜增加达显著水平,麦后播种各绿肥间土壤微生物量碳含量差异不显著,但都显著高于休闲。与休闲相比,麦后播种绿肥均提高了土壤酶活性;套种绿肥除绿豆处理的脲酶和过氧化氢酶低于休闲外,其他处理均提高了土壤酶活性。土壤各测定指标与绿肥生物量之间均有显著或极显著的正相关关系,表明土壤肥力的提高主要取决于还田绿肥的生物量。【结论】长武怀豆和油菜翻压入土后,能够增加土壤的养分含量和酶活性,培肥效果优于绿豆和毛叶苕子。麦后播种绿肥的生物量、养分还田量显著高于套种,土壤养分含量及土壤酶活性也较高。所以在黄土旱塬地区可选择麦后播种长武怀豆和油菜来有效改善土壤肥力。
【Objective】 The soil in the dry land of the Loess Plateau is barren and rain and heat resources in the summer can not be fully utilized. In this paper, field experiments were conducted to study the effects of summer green manure varieties and their planting methods on fresh weight of green manure, return of green manure, soil nutrient content, soil enzyme activities, soil water-soluble organic carbon and microbial biomass carbon content. The local green manure cultivars and planting methods during the summer and winter fallow provide theoretical basis and technical support for the sustainable development of agriculture in the Loess Plateau. 【Method】 Randomized block design was used in this study. Green manure (Mung bean, Changwuxuandou, Mudaojianzi, Rapeseed) and planting mode of green manure (wheat sowing and wheat intercropping) A deal. In the whole area of green flowering, the shoots were harvested and weighed, the yield of fresh grass was analyzed, and the content of NPK in the upper part of green manure was analyzed. Fifty green manures were collected in each plot with root length of 20 cm, Weighing and analysis; green manure harvest 20 days after the pressure, in each plot 0-20 cm soil samples were collected to measure soil nutrient content, soil microbial biomass carbon, soil water-soluble organic carbon content and the main enzyme content. 【Result】 The results showed that the sowing biomass of green manure was higher than that of wheat intercropping. After sowing wheat, the biomass of sowing beans and rape were higher than that of other treatments. Under different planting modes, the total nutrient return to green manure was similar to that of biomass; sowing Changwuowuodeng from wheat significantly increased the return of nitrogen and phosphorus to wheat and the sowing of rape after wheat significantly increased the return of phosphorus and potassium; When nitrogen, phosphorus and potassium were in the descending order, the order of rapeseed, rapeseed mungbean, mung bean, Changwuhuowu and different green manure reached the significant level. The contents of soil organic matter, available phosphorus and available potassium in turnip rape were significantly higher than those in leisure treatment. After sowing Changwuhuoyou 2 years after transplanting, the soil organic matter, total nitrogen, mineral nitrogen, available phosphorus and available potassium Compared with leisure, their contents increased by 12.4%, 22.2%, 95.9%, 28.6% and 11.2% respectively. Compared with recreation, green manure increased soil water-soluble organic carbon and microbial biomass carbon, of which rapeseed intercropping increased significantly, but there was no significant difference in soil microbial biomass carbon Leisure. Compared with leisure, the sowing of green manure after wheat postemergence increased the soil enzyme activity; The intercropping green manure except mungbean treatment of urease and catalase were lower than leisure, and other treatments increased soil enzyme activity. There was a significant or extremely significant positive correlation between each index of soil and green manure biomass, indicating that the increase of soil fertility mainly depends on the biomass of returned green manure. 【Conclusion】 The results showed that Changwuhuodou and rapeseed could increase the soil nutrient content and enzyme activity after turning into soil, and the effect of fertilizing was better than that of mung bean and hazelnut. After sowing green manure after wheat biomass, nutrient return was significantly higher than interplanting, soil nutrient content and soil enzyme activity is also higher. So in the loess plateau area can be selected after sowing Changwuhoubian and rapeseed to effectively improve soil fertility.