【作者】 汪娟；

【导师】 张仁陟；

【作者基本信息】 甘肃农业大学 ， 生态学， 2009， 硕士

【摘要】 本文通过设置在陇中黄土高原半干旱区连续7年的长期定位试验,研究了不同农作方式对耕层土壤微生物特性的影响,旨在结合定西的生产实际,进行保护性耕作的试验研究,寻求能够提高土壤结构稳定性及肥力的耕作模式,以减少水土流失,维持土壤的持续生产力。本试验设4个处理,即T:传统耕作;NT:免耕不覆盖;TS:传统耕作结合秸秆还田;NTS:免耕秸秆覆盖。采用春小麦豌豆双序列轮作,分别于2008年3月18日、4月6日对春小麦、豌豆双序列轮作下的土壤微生物量碳、土壤微生物量氮含量及土壤酶活性和土壤基础呼吸进行了采样测定,主要研究结论如下:1保护性耕作提高了土壤微生物量碳、氮含量1)不同耕作方式下0～30 cm土层的微生物量碳含量,小麦地和豌豆地均表现为:NTS>TS>NT>T;而微生物量氮含量小麦地和豌豆地则分别表现为:NTS>TS>T>NT和NTS>TS>NT>T。2)不同耕作方式下,0～5 cm、5～10 cm、10～30 cm三个土层土壤微生物量碳、微生物量氮不同处理都表现为随着土层加深递减,即0～5 cm > 5～10 cm > 10～30 cm。3)长期保护性耕作使土壤微生物量C、N较之传统耕作均有不同程度的增加,占有机C、全N的比例也增加,并且与有机C、全N呈良好的平行关系,相关达显著水平。2各处理下土壤基础呼吸的差异与土壤SMBC和SMBN的总体趋势类似,免耕秸秆覆盖处理显著提高土壤基础呼吸3保护性耕作能够显著提高土壤酶活性1)在0～5 cm和5～10 cm土层,无论是在W-P-W轮作序列,还是P-W-P轮作序列,总体上蔗糖酶、磷酸酶、脲酶和过氧化氢酶活性均表现为NTS处理最高,其次是NT和TS处理,T处理的则最低。2)总体上来讲,4种土壤酶活性具有一定的垂直分布特征,各种酶活性均随着土层的加深而呈现出减小的趋势,但不同处理其下降幅度不一致,NTS处理降幅度最大。4土壤微生物特性间的相关性在两种轮作次序下,土壤微生物量碳、微生物量氮与基础呼吸及土壤酶活性均呈正相关关系;而与代谢熵呈负相关关系。更多还原

【Abstract】 With intending to explore tillage practices that increase soil structure property, reduce its losses and maintain sustainable productivity, effects of different tillage practices on soil microbial properities and phyical and chemical characteristics in soil plough layer were investigated. The experiment was conducted at a located experimental station for seven years in Loess Plateau of central Gansu province where the area represents semiarid.The experiment contain four treatments, namely conventional tillage (T), no-tillage no straw cover (NT), conventional tillage with straw incorporated (TS) and no-tillage with straw cover (NTS). Two sequence rotation systems with spring wheat and pea at the Gansu Agricultural University′s farm in Dingxi .In the article“the spring field”and“the pea field”represented the order of rotation spring wheat and pea had been planted in 2008. The main results obtained were listed as follows:1 Conservation tillage has impoved the content of soil microbial biomass carbon and nitrogen1) In the 0~30 cm soil layer of the spring wheat field the contents of SMBC and SMBN followed the order in the treatments: NTS>TS>NT>T while NTS>TS>NT>T、NTS>TS>NT>T in the pea field.2)With the soil layer being deepened,the content of SMBC and SMBN followed the order: 0～5 cm > 5～10 cm > 10～30 cm.2 The differences in the four treatments of soil basal respiration potential were similar to the laws of SMBC and SMBN. No-tillage with straw cover (NTS) did improve soil basal respiration potential significantly.3 Conservation tillage has significantly impoved soil enzymatic activities1)The enzyme activities of the invertase, phosphatase, urease and catalase were shown as that NTS had the highest enzyme activity than NT and TS, and T was lowest in the depth of 0～5 cm and 5～10 cm.2)The enzyme activities decreased as the increase of the soil depth, especially under NTS.3) Long-term conservation tillage so that soil microbial biomass C, N compared to traditional farming increased in varying degrees, possession increases in the proportion of TN and organic C, and has a good parallel relationship between the level of correlation significant.4 The correlation coefficient among the soil microbial propertiesThe positive correlation amony the SMBC,SMBN,soil basal respiration potential and activities of 4 soil enzymes;soil microbial metabolic quotient has a negative correlation with the other soil microbial properties.更多还原