【作者】 郑华平；

【导师】 胡恒觉； 黄高宝；

【作者基本信息】 甘肃农业大学 ， 作物栽培学与耕作学， 2004， 博士

【摘要】 本文采用综合试验的研究方法，研究了保护性耕作对土壤水分变化规律及水分利用效率、对土壤养分及地温、对作物生长发育和产量构成的影响，并从防止土壤水蚀、风蚀的角度评价了保护性耕作的生态效应。取得了如下主要结论： 1．旱作农田土壤水分变化动态可分为雨季增墒期、缓慢失墒期和作物生长耗水期3个时期。作物收获前至8月中旬为土壤增墒期，其长短和土壤贮水量的多少与降水特征、地表状况(覆盖材料的有无及其种类)、土壤耕作等有关，免耕秸秆覆盖有利于增加此期土壤的贮水量；雨季增墒期结束至来年作物播种季节为表层土壤缓慢失墒期，此期失墒多少受地表状况的影响较大，免耕秸秆覆盖有很好的抑蒸保墒作用。作物生长期土壤水分状况主要受自然降水、地表蒸发和作物蒸腾耗水3个因素控制，作物生长苗期因受降水和地表蒸发的影响，贮水量呈波动式变化；作物快速生长期，贮水量迅速下降，开花末期达谷值；贮水量下降的幅度主要受作物长势的影响。小麦-豌豆序列比豌豆-小麦序列有利于土壤表层水分的蓄积。 旱作农田整个土壤剖面(0～200cm)贮水量的变化规律总体与表层0～30cm贮水量的变化动态相似，但就整个土壤剖面上贮水量而言，免耕秸秆覆盖并无明显优势，其抑蒸保墒作用仅表现在耕层0～30cm；序列间在作物生长期0～200cm土壤剖面的贮水量变化幅度差异较大，豌豆一生的耗水量要小于春小麦。 2．河西灌区水浇地土壤水分状况变化及节水效应研究表明，采用秸秆覆盖是充分利用麦秸资源节水改土、保护生态环境的非工程性的高效生态节水措施。储水定额在900m~3／hm~2较适宜，储水灌溉时期在9月中旬到11月上旬为好。秸秆还田配合适当灌溉量具有很好的节水、保墒作用，以灌溉量600m~3／hm~2+秸秆还田的节水保墒作用最好。 3．不同保护性措施提高了土壤中氮的含量。试验期间各处理土壤不同层次铵态氮含量均显著增加，特别是表层0～30cm，平均增加至试验初期的6.69倍。耕作处理铵态氮含量增长幅度大于相应的免耕处理，小麦-豌豆轮作模式下T、TP、TS各处理0～30cm铵态氮含量分别增至试验初期的9.78、7.19、8.14倍，而NT、NTP、NTS在0～30cm铵态氮含量则分别增至试验初期的5.00、4.01、6.52倍。轮作模式对铵态氮的变化影响不大。不同轮作模式硝态氮的变化迥然不同，小麦～豌豆轮作中各处理0～30cm硝态氮的平均减少至试验初期的0.97倍，而豌豆-小麦轮作各处理0～30cm硝态氮含量平均增至试验初期的1.42倍。保护性耕作措施可以增加土壤速效磷含量。轮作方式对O一30cm土壤速效磷的变化影响较大，豌豆一小麦轮作各处理平均速效磷含量在试验期间平均增加了193.59%，而小麦一豌豆轮作各处理平均增长幅度仅153.66%。在0~200cm土壤速效磷的变化无明显差异。在不同耕作方式中，以NTP和NTS表层O一30cm有效磷含量增长较快，特别是在表层O一30cm，NTP和NTS处理的绝对增长量和相对增长量都较高。 不同耕作制度、不同轮作方式降低了土壤速效钾的含量。表层O~30cm速效钾减少的幅度大于深层，各处理0一30cm速效钾含量平均减少了巧.24%，0一ZO0cm剖面土壤速效钾含量平均减少了2.32%。轮作方式对表层土壤速效钾的变化有明显的作用，豌豆一小麦轮作方式使得O一30cm速效钾损失严重，各处理速效钾平均含量减少了18.98%;小麦一豌豆轮作各处理O~30cm速效钾含量减少了12.04%。 4.在播种出苗期间降雨较多的情况下，未覆盖处理及秸秆覆盖处理，水分入渗较好，有利于小麦保苗率的提高。但传统耕作结合秸秆还田(Ts)和免耕秸秆覆盖(NTs)处理保苗效果较好，有利于总穗数的增加。免耕地膜覆盖处理有利于旱地作物春小麦根系发育，叶面积增加和干物质积累强度加大，穗粒数和穗粒重增加，产量提高。与传统耕作处理(T)比较，产量提高51.12%(p<0.01)，与免耕秸秆覆盖处理(NTs)比较，产量提高17.22%(p<0.01);免耕秸秆覆盖处理有利于豌豆每株英数和每株粒数的增加，使豌豆最高产量达1269.47~1789.72kg小mZ，比免耕不覆盖处理产量提高26.37%(加02年，p<0 .05)和58.06%(2003年，p<0.01)。 在早作雨养条件下，NTP虽然有利于作物产量的增加，但由于种植成本的增加使纯收益下降。NTS有利于提高种植作物的纯收益。NTS和N仰比较，春小麦产值降低344.4元小mZ(14.64%)，纯收益增加60.15元爪mZ(22.71%);豌豆产值增加651.00元小mZ(57.87%)，纯收益增加1056.00元小mZ(l .64倍);NT和T也有利于提高旱地作物的纯收益和产投比。在荒漠绿洲水地条件下，常规耕作、秸秆还田及免耕秸杆覆盖3种耕作方式的产值、纯收益和产投比表现出较大差异。秸秆还田方式下产值最高，比常规耕作高3.40%，比免耕覆盖高13.02%;免耕覆盖的纯收益和产投比最高，比秸秆还田处理分别高74.43%和41 .98%，比常规耕作处理分别高102.71%和46.46%。免耕覆盖还具有良好的节水效益。 5.甘肃中部人工降雨模拟试验和大田实际观测数据分析结果表明:径流量和侵蚀量的大小与降雨强度及降雨量的关系非常密切。在较低覆盖度条件下(裸地)，降雨强度对土壤侵蚀的影响是主因。不同用地的径流和侵蚀速率随雨强的增加而迅速增加，坡耕?更多还原

【Abstract】 With the integrated methods the experiment was conducted to explore the regularity of soil water consumption and water use efficiency, contribution to the change of soil temperature, soil nutrients and moisture , efficiency for growth and development of crops and the yield output in different conservation tillage measure at Dingxi County, a typical semi-arid area of the Loess Plateau and Hexi corridor, and to evaluate the ecological function of conversation tillage by protecting water erosion and wind erosion in these area. The main results showed as follows:1. The dynamic change of soil water in the arid land can be divided into 3 periods: Water-conservation period, water-retaining period and water-consumption period. The water-conservation period begins from beginning of crop harvesting time, ends in mid-August, how lang of water conservation period and how much water can increase depends on rainfall character, covered or naked land and tillage situation. NT could increase the water storage during this period. From the end of water conservation period to sowing time next year is water-retaining and water loss period. In this period how much water loss depends on cover situation of farming land, NTS was suitable for water storage. Soil water situation depends on three factors e.g. natural rainfall, consumption of crops and water loss amount during the growth stage of crops, at seedling stage water storage varied with rainfall and water loss like undulation, at fast growth stage of crops the soil water storage was decreased, and at anthesis stage the water storage retained at the lowest level. The decrease of water storage depends on situation of crop growth. Crop rotation wheat-pea had more effective water storage ability than crop rotation pea-wheat.The variety of water storage in total section (0-200cm) was similar as in upper layer (0-30 cm), however, it was not obvious dominance in NTS at total horizon, it was very important to protect the water in upper layer(0-30cm). Different crop consumes different water amount, the consumption of water by spring wheat was much more than that by pea during the whole growth stage.2, The study on water situation and water-saving under irrigation condition in Hexi Corridor released that straw mulch on spring wheat field is a very important measure for water-saving. The optimum irrigation ration is 900m3 /hm2, conservational irrigation period is from mid- Sep. to the beginning of Nov. Effects of water -storage and water-conservation caused by straw incorporated were apparent. It was suggested that an amount of 600 m3 /hm2 +straw incorporated treatment is the best measure for water-saving and water-storage.3. The content of total N was increased by different conservation tillage measures during the experiment, especially in the top 0-30 cm soil layer, the average content of ammoniacal-N is 6.69 times as much as that before the experiment began. The increaseunder plough condition is more than that under no-tillage, the content of ammoniacal-N in soil layer of 0-30 cm in treatment T, TP and TS increased to 9.78, 7.19 and 8.14 times in comparison of the normal respectively. 5.00, 4.01 and 6.52 times in treatment NT, NTP and NTS. The change of ammoniacal-N was not obvious under rotation model, but increase of ammoniacal-N was very apparent in NTS treatment. The change of nitrate-N in rotation of wheat-pea was decreased (-0.97 times) and increased in rotation of pea-wheat (+1.42 times).Conservation tillage improved the content of available P. in the top of soil layer (0-30cm) the content of available P increase up by 193.59% in rotation pea-wheat, while 153.66% in rotation wheat-pea. In different conservation tillage the increase of available P was more in treatment NTP, NTS than that in other treatments. The change of available P in different section layers from 0 to 200 cm had no significantly different.Different tillage and crop rotation systems decreased the content of available K. the content of available K in upper layer (0-3 0cm), decrease more than deep horizon, and the averag更多还原