【作者】 艾应伟；

【导师】 毛达如；

【作者基本信息】 中国农业大学 ， 植物营养学， 2003， 博士

【摘要】 随着全球水资源危机的日益严重，长期以来农业节水栽培一直是人们关注的问题。20世纪80年代以来，水稻地表覆盖旱作作为一种全新的节水措施引起了国内外广泛关注。稻麦轮作是我国南方地区一种主要的耕作制度，水分和养分（尤其是氮素）是限制这一体系生产力和可持续性的关键。但目前缺乏地表覆盖旱作条件下稻麦轮作体系中作物产量与氮素去向的系统、定量研究。本文通过不同田间小区试验与¹⁵N微区试验，从稻麦轮作的角度系统研究了地表覆盖方式与施氮量对稻麦产量、氮素吸收利用与氮肥去向的影响。其主要结果如下： 连续三年定位试验结果表明，在常规施氮(水稻季150kg hm^-2、小麦季120kg hm^-2，下同)水平下覆膜旱作处理比传统淹水处理显著提高了水稻的吸氮量，而覆秸旱作处理则降低了水稻的产量。在小麦季，稻季覆膜处理与传统淹水处理之间小麦产量和吸氮量之间无显著差异，但水稻季覆秸旱作处理小麦产量和吸氮量有增加的趋势，表明覆秸旱作对小麦季的生长和氮素利用有一定的后效。 连续两年的定位试验结果表明，在不施氮和施低氮(水稻季75kg hm^-2、小麦季60kg hm^-2)水平下，地表覆盖旱作处理（与常规淹水处理相比）对稻麦产量和吸氮量的影响与试验一相似。但在常规施氮和高量施氮(水稻季225kg hm^-2、小麦季180kg hm^-2)水平下覆膜旱作、覆秸旱作和传统淹水三个处理稻麦产量和吸氮量之间的差异明显缩小或未达到显著水平。这说明随着施氮水平的提高，地膜覆盖和麦秸覆盖旱作与传统淹水处理稻麦体系生产力与氮素利用之间的差异趋于消失。 一年的定位试验结果表明，常规施氮水平下覆膜处理获得与传统淹水处理相当的水稻产量，裸地旱作处理产量则低于传统淹水处理。而秸秆地膜双覆盖（覆秸膜）处理水稻产量显著提高，达到传统淹水与覆膜处理类似的水平。这说明覆秸旱作引起的水稻产量下降可以通过覆膜加以克服。在小麦季作物产量仍以传统淹水处理最高，覆秸和覆秸膜处理次之，覆膜和裸地旱作最低。稻、麦吸氮量的结果与产量类似，但各旱作与传统淹水处理之间差异比产量小。 ¹⁵N微区结果进一步表明，在水稻季，覆盖旱作与裸地旱作处理作物的氮肥利用率（18.41％～23.56％）明显高于传统淹水处理（15.30％），肥料氮的土壤残留率却以传统淹水（22.10％）高于各旱作处理（19.57％～20.90％），而氮肥的总损失率各处理之间没有显著差异（55.54％～62.60％）。在小麦季，作物氮肥利用率的情况刚好与水稻季相反，以传统淹水（20.60％）高于麦秸覆盖和秸膜双覆盖（17.65％～18.33％）又高于覆膜旱作和裸地旱作（15.93％～15.99％），而氮肥的土壤残留率（23.06％～26.86％）和损失率（55.49％～60.04％）各处理间差异不显著。 由此可见，覆盖旱作稻麦体系可以获得与传统稻麦体系相当或略高的产量和氮肥利用率，但仍有通过养分综合管理进一步提高的较大潜力。更多还原

【Abstract】 With the increasing global water crisis, water-saving cultivation in agricultural production has been regarded as a serious issue for a long term. Nonflooded mulching rice cultivation systems (NMRCS), as brand new water saving techniques, have aroused special and wide attention nationally and internationally since 1980s. Rice-wheat (R-W) rotation systems are the main cropping systems in south China. Water and nutrient (especially nitrogen) are the two critical factors that restrict the productivity and sustainability in the R-W systems. However, there are lack of the systemic studies on crop yield and fate of nitrogen in R-W systems particularly under the condition of NMRCS. The paper investigated the effects of NMRCS and N applied rate on grain yield, N uptake and fate of fertilizer N in R-W systems through different field plot experiments and one 1SN micro-plot experiment in southwest China Sichuan Province. The main results are summarized as follows:A continuous 3-year located experiment showed that nonflooded plastic film mulching (PM) led to significantly higher N uptake by rice but nonflooded wheat straw mulching (SM) caused relatively lower rice yield compared with traditional flooding under conventional N application level (150 kg hm"2 in rice season and 120 kg hm"2 in wheat season, the same below). In subsequent wheat season, however, grain yield and N uptake of wheat ranked the contrary sequence: SM > TF and PM, indicating the residual effects of SM on the growth and N utilization of wheat following rice.A continuous 2-year located experiment showed that under control (no N applied to both rice and wheat) and low N. (75 kg hm"2 in rice season and 60 kg hm"2 in wheat season) levels PM and SM treatments produced the similar effects on grain yield and N uptake of rice and wheat crops like the first experiment. While under conventional N and high N (225 kg hm"2 in rice season and 180 kg hm"2 in wheat season) levels, the differences of crop yields and N uptake among PM, SM and TF treatments obviously became smaller or were not significant, suggesting that the differences of productivity and N utilization in R-W rotation between NMRCS and traditional flooding cultivation system tended to disappear.The third located experiment further confirmed mat PM and TF could obtain similar grain yield of rice while nonflooded no mulching (NM) led to lower grain yield compared with TF, which was similar to the above two located experiments. However, SPM (wheat straw and plastic film mulching) got the same yield as TF and PM, suggesting that the negative effect of SM on rice be illuminated by measures of plastic film mulching. Grain yield of subsequent wheat followed the sequence of TF > SM and SPM > PM and NM, which was a little different with the first and second experiments. The effect of NMRCS on N uptake by rice and wheat followed the similar trend like grain yield whereas the differences between NMRCS and TF system were lower than those of yields.The results from 15N micro-plots further discovered the fate of fertilizer N in the R-W systems. In rice season, nitrogen use efficiency (NUE) was improved by various nonflooded mulching cultivation treatments (18.41-23.56%) compared with TF (15.30%). The rate of fertilizer N remained in soil (0-100cm depth), however, followed by TF (22.10%) > NM (20.90%) > PM, SPM and SM (19.57-19.91%). While the total N loss rates (55.54-62.60%) were not significantly different with NMRCS and TF cultivation system. In wheat season, NUE by wheat ranked by the sequence of TF (20.60%) > SM and SPM (17.65-18.33%) > PM and NM (15.93-15.99%). The rates of fertilizer N remained in soil (23.06-26.86%) and lost from soil-crop system (55.49-60.04%) did not showed any significant differences among all nonflooded mulching and traditional flooding cultivation treatments.In general, compared with traditional R-W system, nonflooded mulching R-W systems especially PM system can obtain the comparable or a little higher grain yield and NUE under water-saving condition. However, there is a更多还原