【作者】 张文颖；

【导师】 张恩和；

【作者基本信息】 甘肃农业大学 ， 生态学， 2006， 硕士

【摘要】 本文针对传统耕作方式引起的土壤侵蚀加剧、土壤有机质含量下降、土壤结构的稳定性降低以及水资源浪费严重等问题,研究了春小麦留茬覆盖免耕的防沙尘效应以及翌年免耕春玉米田的土壤水分特征、土壤微生物量C、N、P含量和土壤的部分物理性状,主要研究结果有:1.留茬覆盖免耕保护性耕作的防风蚀效应留茬高度高和立秆留茬能够显著提高风蚀临界风速。高留茬(40cm)可显著提高地表的风蚀临界风速,其防风蚀效果好于低留茬(20cm)。同一留茬量下,高留茬时,立秆留茬的防风蚀效果好于留茬压倒,低留茬时,两种留茬方式的风蚀临界风速相差不大。40cm立秆留茬(NS40)、40cm留茬压倒(NPS40)、20cm留茬压倒(NPS20)、20cm立秆留茬(NS20)和传统耕作(CT)的风蚀临界风速分别为16.0 m·s-1、15.2 m·s-1、14.7 m·s-1、14.5 m·s-1和6.3 m·s-1。高茬立秆处理的防风蚀效果明显好于低茬压倒处理。保护性耕作在吹蚀风速低于20m·s-1时的防风蚀作用显著。NS40的防风蚀效果最好,当吹蚀风速为16m·s-1和22 m·s-1时,其风蚀速率比CT的减少87.84%和80.77%。2.留茬覆盖免耕保护性耕作对土壤容重和硬度的影响留茬覆盖免耕处理有助于休闲期土壤表层疏松。留茬覆盖免耕处理0～5cm层的的平均土壤容重较CT降低2.05%。5～10cm和10～15cm层土壤容重均以CT的最小,与免耕处理差异显著。15～20cm层各处理间差异不显著。留茬覆盖量高能减小土壤容重,增加土壤稳定性。春玉米苗期,各处理0~20cm层的土壤容重自上往下均有增加的趋势。不同耕作方式间,各层次土壤容重均以CT为最小,其0～5cm、5～10cm、10～15cm和15～20cm层容重分别为1.356、1.333、1.426和1.464 g.cm-3。增大灌水量提高了土壤容重,降低了土壤的通透性能。收获期土壤容重,高灌水量(I1)下,除NPS20外,免耕处理0～5cm层土壤容重均高于CT。相同留茬高度下,不同留茬方式0～5cm层土壤容重无显著差异。低灌水量(I2)下,不同耕作方式间土壤容重差异较小。0～40cm土层,随土层的加深土壤硬度呈现“增大→减小→增大”的趋势。免耕处理的土壤硬度均显著高于CT,立秆留茬40cm高灌水量处理(NS40I1)的平均土壤更多还原

【Abstract】 Conventional tillage is widely used in irrigated area, which led to soil erosion aggravates, soil organic matter content drops, the soil structure stability reduces as well as the water resources waste is serious and so on. Using conventional tillage as control to study the effects of no-tillage with straw cover on sandstorm-preventing in irrigated oasis, the soil water character of spring maize field, soil microbial biomass(SOM) and the probability of soil through field experiment in Zhangye, China. , the results are summed up as below:A. The effects of conservation tillage on preventing sand-stormHigher stubble and adopted stubble standing could increase the wind erosion critical wind speed of the surface significantly.Through observed the threshold wind erosion velocity of different height of stubble left and different stubble retaining styles, the result indicated that leaving higher stubble (40cm) could remarkably increase the wind erosion critical wind speed of the surface. At same stubble retaining amount, sandstorm-preventing effect of stubble standing was better than that of stubble pressed, when the stubble amount was higher (40cm), but under the condition of lower stubble amount (20cm), two kinds of stubble retaining style had no differ. The wind erosion critical wind speed of NS40 (leaving 40cm high stubble at harvest) , NPS40 (leaving 40cm high stubble at harvest, then press), NPS20 (leaving 20cm high stubble at harvest, then press) , NS20 (leaving 20cm high stubble at harvest) and conventional tillage (CT) was 16.0 m·s-1、15.2 m·s-1、14.7 m·s-1、14.5 m·s-1 and 6.3 m·s-1 respectively.Higher stubble not only decreased wind speed but reduced wind erosion rate. Conservation tillage had significant effect on prevent wind erosion when the wind speed lower than 20m·s-1.The wind tunnel experiment shows that, the best effect of sandstorm-preventing was gained at leaving 40cm high stubble at harvest. The wind erosion rate of NS40 reduced 87.84% and 80.77% compared to that of CT, when the wind erosion speed were 16 m·s-1 and 22 m·s-1 respectively.B. The effects of conservation tillage on soil bulk and soil hardnessConservation tillage can reduce soil bulk density (BD) in fallow stage. BD in 0~5cm soil layer of different conservation tillage treatments lower than that in CT, the average更多还原