【作者】 李文龙；

【导师】 高亚军；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2009， 硕士

【摘要】 秸秆覆盖是我国北方旱地农业的一项重要栽培措施,在提高土壤蓄水、保水和供水能力方面具有显著的作用,同时在许多地区能够显著提高作物产量。然而,一些研究发现,秸秆覆盖条件下作物无法获得与不覆盖时相当的产量,有时甚至显著减产。本研究针对这一问题,通过田间定位试验,研究水氮供应对旱地冬小麦秸秆覆盖效果的影响,以期查明秸秆覆盖时补充灌水时期和施氮量与小麦产量和水肥利用率的关系,从而揭示秸秆覆盖减产的原因,明确覆盖增产的条件,为完善秸秆覆盖技术和旱地水肥管理技术提供科学依据。取得的主要结论有:1.秸秆覆盖条件下冬小麦分蘖数显著降低,单位面积穗数和千粒重同样呈降低趋势,虽然穗粒数有所增加,但最终仍然导致产量下降。无论有无秸秆覆盖,不同生育期灌水处理之间小麦产量没有显著差异。在生育期补充灌水条件下,秸秆覆盖降低了冬小麦的耗水量,但同时也降低了冬小麦水分生产效率。在灌水条件下,秸秆覆盖有降低籽粒吸氮量的趋势;而无论是否灌水,覆盖均有提高小麦茎杆吸氮量的趋势。不覆盖条件下,生育期灌水提高了氮素利用率;覆盖条件下,灌水对氮素利用率影响不明显。无论有无灌水,秸秆覆盖降低了氮素利用率。连续秸秆覆盖并还田4年后,耕层土壤有机质含量有明显提高,灌水对此有不同影响:小麦生育后期灌水不利于覆盖土壤有机质的积累。与此相对应的是,生育后期灌水的处理覆盖土壤全氮含量甚至出现低于无覆盖土壤的趋势。灌水和秸秆覆盖对土壤剖面残留硝态氮累积量和分布均没有显著的影响。2越冬期间,秸秆覆盖土壤10cm和20cm温度均高于不覆盖土壤,而无论覆盖与否,土壤20cm温度均高于10cm温度。返青拔节期间,不覆盖土壤10cm温度高于秸秆覆盖土壤,秸秆覆盖土壤20cm温度最低。抽穗灌浆期间,秸秆覆盖10cm的土壤温度上升最快,高于不覆盖土壤,不覆盖土壤20cm温度最低。秸秆覆盖与不覆盖土壤温度在昼夜24小时内也存在显著差异,具体因生育期和土壤深度而不同。秸秆覆盖显著降低了土壤温度的变幅。无论在返青拔节期还是在抽穗灌浆期,秸秆覆盖10cm的温差(最高温-最低温)仅为不覆盖的三分之二,而20cm的温差仅为不覆盖的四分之一。秸秆覆盖对升温时间和降温时间并没有影响,而仅仅是降低了其变温的速率。3不施氮时,秸秆覆盖小麦有增产的趋势,施氮150kg/ha时,秸秆覆盖小麦显著减产。不论施氮量高低,秸秆覆盖均有降低冬小麦单位面积穗数的趋势,这与覆盖显著降低冬小麦分蘖数有直接关系。在不施氮或低氮量时,秸秆覆盖有降低穗粒数的趋势,高氮量条件下则有相反趋势。无论是否覆盖,随着施氮量增加,冬小麦产量有增加趋势,但当施氮量高于150kg/ha时,产量并不继续增加。虽然冬小麦穗粒数随施氮量增加有增加趋势,但施氮量超过150 kg/ha时,冬小麦单位面积穗数并没有随之增加,而千粒重甚至有降低的趋势,这是产量并没有继续增加的主要原因。施氮量为150kg/ha时小麦籽粒吸氮量最高、氮素利用率较高,同时残留在土壤中的硝态氮累积量不是非常高,在本试验条件下,不论秸秆覆盖还是不覆盖,冬小麦的适宜施氮量应该不高于150kg/ha。无论是否覆盖,施氮量300kg/ha的处理在土壤表层和深层均有显著的硝态氮累积,其他施氮量处理在土壤剖面均没有明显的累积峰。在不同施氮量条件下,秸秆覆盖对残留土壤硝态氮累积量和分布均没有显著影响。更多还原

【Abstract】 Straw mulch is one of the most important cultivation technology in arid zones of Northern China. It can improve capacity of water storage, water retention and water supply in soil, leading to increase of crop yield in many areas. But some researches indicate that crop yield under straw mulch was as same as that of no mulch, or even straw mulching reduced yield significantly. Aiming at the problem, filed experiments were carried out to investigate the effect of irrigation and N fertilizer on wheat growth under straw mulch in dryland in order to find out the relationship between irrigation time, N rate and yield of wheat, water and fertilizer use efficiency. The main results obtained were listed as follow:1. To compare with no mulch, straw mulch decreased the tiller of the wheat significantly, the spike number per acreage and 1000-grain weight showed that they have the same trend, leading to the low grain-yields even though grains per spike increased. No matter straw mulch or not, irrigating time didn’t affect the wheat yield. Irrigation during the growth of the wheat, straw mulch decreased the water consumption and water use efficiency of winter wheat, and had decreased trend in grain N-uptake amount. No matter irrigation or not, straw mulch had the increased trend of the cane N-uptake amount. Under no mulch, irrigation in the growth of winter wheat increased the nitrogen use efficiency. But under the straw mulch, there was no significant effect. No matter irrigate or not, straw mulch decreased the nitrogen use efficiency. Sustained mulching to 4 years, plough layer had larger increased, but irrigation had different effects: irrigation in late growth stage of wheat go against accumulate of organic matter. Related to this, soil total N amount was lower under straw mulch than no mulch during irrigation in the growth of winter wheat. Irrigation and straw mulch had no significantly effect on nitrate accumulation and distribution in depth of 0-2m under the straw mulch.2. During the overwinter growth stage of winter wheat, no matter 10cm or 20cm, soil temperature was higher under straw mulch than no mulch, and no matter straw mulch or not, soil temperature was higher in 20cm than in 10cm. During returning green stage of winter wheat, soil temperature was lower under straw mulch-10cm than no mulch-10cm, and was lowest under no mulch-20cm. During the atheading—filling stage of winter wheat, soil temperature under straw mulch-10cm was rise the fastest of all, and soil temperature was lowest under no mulch-20cm. no matter straw mulch or not, soil temperature had the significantly differences during 24h, related to growth stage and soil depth. Straw mulch significantly decreased the fluctuation of soil temperature. No matter during the returning green stage or the atheading—filling stage of winter wheat, the difference in temperature (maximum-minimum) under straw mulch-10cm was 2/3 lower than no mulch-10cm, under straw mulch-20cm was 1/4 lower than no mulch-20cm. straw mulch didn’t affect the rising time and cooling time of the soil temperature, but decreased the rate of temperature changes.3. Straw mulch had the increased grain yield trend in no N fertilizer, and significantly decreased grain yield in the 150kg/ha N fertilizer. Regardless of the level of nitrogen fertilizer, winter wheat straw mulch to reduce both the trend of ears per unit area, which covers a significant reduction in the number of tillers of winter wheat has a direct relationship. Without nitrogen or low nitrogen, the straw mulch to reduce the number of trends in grain, high-nitrogen conditions, while the opposite trend. No matter straw mulch or not, with the nitrogen application rate increased, the increasing trend of winter wheat yield, but higher than 150kg/ha N, the production does not continue to increase. Although the number of winter wheat grain increased with increasing nitrogen, but nitrogen is more than 150 kg / ha, the winter wheat ears per unit area did not increase, and even reduce the weight of the trend, which is output is not continuing to the main reason for the increase. nitrogen application rate in 150kg/ha for wheat grain N uptake was highest of all, higher nitrogen use efficiency, and residual nitrate in the soil is not very high accumulation. Under the experimental conditions, No matter straw mulch or not, nitrogen fertilizer for winter wheat should be no more than 150kg/ha. Whether or not covered by the deal 300kg/ha nitrogen fertilizer in the soil surface and deep significant accumulation of nitrate and other nitrogen fertilizer in the soil profile to deal with no obvious accumulation peak. Nitrogen application rate in different conditions, the straw mulch on the amount of residual soil nitrate accumulation and distribution were not significantly affected.更多还原