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| 半干旱农田生态系统地膜覆盖模式和施氮对小麦产量和氮效率的效应 |
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沈新磊1, 黄思光1, 王 俊2
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1.西北农林科技大学 资源环境学院;2.兰州大学 干旱农业生态国农重点实验室
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| 摘要: |
| 在年降水量415 mm的黄土高原中部黄绵土和年降水量632 mm的黄土高原南部红油土上，分别以春小麦和冬小麦为供试作物进行大田试验，研究了地膜覆盖（春小麦设不覆膜、播后覆膜30 d、覆膜60 d和全程覆膜；冬小麦设不覆膜、播后覆膜75 d、覆膜150 d和全程覆膜等4个水平）和施氮（春小麦设不施氮和每公顷施氮75 kg，冬小麦设不施氮和每公顷施氮225 kg 2个水平）对小麦产量和氮效率的影响。试验结果表明，覆膜对春小麦产量和吸氮量的效应因底墒、施氮、覆膜进程和生育期降雨量而异。在湿润年份（1999年），无论施氮与否，在低底墒时，各种覆膜处理的籽粒、茎叶和干物质产量较不覆膜处理虽有增加，但二者之间的差异并不显著；在高底墒时，不管是籽粒，还是干物质，以覆膜60 d最大，以不覆膜最低，但不覆膜与覆膜30 d、覆膜60 d和全程覆膜间差异并不显著。氮肥肥效也因底墒和覆膜进程而异：低底墒不覆膜和覆膜30 d的氮肥增产效果最显著，但随着覆膜进程的进一步延长，氮肥效果下降；高底地以覆膜30 d氮肥增产效果最高，不覆膜最低。在极端干旱年份（2000年），地膜覆盖显著影响地上部分生物量；在低底墒不施氮条件下，以覆膜30 d效果最明显，覆膜60 d和全程覆膜效果依次递减，不覆膜者最低，而施氮后，覆膜30 d与不覆膜、覆膜60 d和全程覆膜间的差异均不显著；在高底墒下，不施氮时各覆膜处理籽粒产量为1 430～1 482kg/hm2，没有任何差异；施氮后，以全程覆膜籽粒产量最高，与覆膜30 d和60 d间的差异达显著水平，但从2个施氮水平平均看，不同覆膜处理间无任何差异；由于不同覆膜处理对作物体含氮量基本没有影响，因此不同覆膜处理对作物吸氮量的与对产量的影响基本相同，但在春小麦生长前期覆膜（如播种后覆膜30d)能够促进后期茎叶中氮素向穗部（主要是籽粒）转移。对2年春小麦试验中各种产量构成因子分析后发现，小穗数和有效小穗数是影响地膜覆盖产量的主要因素。覆膜进程对氮肥利用效率的影响与作物生育期降水量有关：在降水丰富年份，低底墒处理在不覆膜和覆膜30 d时，氮肥利用率最高，分别为30.4%和30.3%，而覆膜60 d和全程覆膜的烃利用率下降，分别为19.0%和19.6%；在高底墒处理中以不覆膜最低，为10.1%，并随覆膜持续时间的延长而显著增加，覆膜30 d，60 d和全程覆膜时分别为32.7%,34.2%和38.9%；在极端干旱年份，地膜覆盖对氮肥利用效率的影响与湿润年份截然不同，在低底墒和高底墒处理中均以不覆膜最高，分别为18.3%和19.7%，而覆膜处理或者为零，或者为负值，说明在极其干旱年份覆膜条件下，施用氮肥的效果并不突出，甚至产生一定的负效应。在冬小麦试验中，无论是干物质，还是籽粒，覆膜75d,150 d和全程覆膜处理之间差异均不显著，籽粒最大和最小产量之间仅相差42 kg/hm2，这一差值远远小于试验误差；地膜覆盖进程和施氮对作物吸氮量的影响，与对干物质和籽粒产量的影响基本相同。从2个施氮水平平均看，覆膜75 d,150 d和全程覆膜处理吸氮量之间的差异也没有达到显著水平，在这3个处理中，最大和最小吸氮量仅相差12.0kg/hm2；以覆膜75 d氮肥利用率最高，之后，随着覆膜进程的进一步延长，氮肥利用率下降。可见，尽管春小麦和冬小麦生育期不同，生长期间经历的气候变化不同，但地膜覆盖进程对作物产量和氮素效率的影响规律基本相同。覆膜的作用主要表现在作物生长前期和中期，后期基本没有效果。从总体上看，全程地膜覆盖并没有使春小麦和冬小麦产量、吸氮量和氮效率大幅度提高，从维持土壤肥力和土壤生态条件以及保持农业生产持续发展出发，不应提倡全程和长期地膜覆盖，春小麦以播种后覆膜30～60 d为宜；对冬小麦，虽然覆膜75 d和150 d 相差不显著，但为了减少冬季和春季土壤水分的蒸发损失，在覆膜150 d左右（拔节初期）时揭膜比较合适。 |
| 关键词: 半干旱农田生态系统 地膜覆盖麦产量 氮效率 |
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| 基金项目:国家自然科学基金资助项目(30230230,39970151和 39970459);2002年度教育部全国优秀青年教师资助项目;国家重点基础研究专项项目(G200001803);国家基础研究重大项目前期研究专项 “半干旱黄土植被景观覆盖格局与生态系统功能调控”;黄土高原土壤侵蚀与旱地农业国家重点实验室基金项目(10501285);农业部科技跨越计划项目“面条专用小麦品种生产技术与产业化”(农跨200026) |
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| Effects of plastic film mulching models and nitrogen fertilizer on wheat yield and nitrogen efficiency |
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| Abstract: |
| Field experiment shave been carried out on loess plateau in middle part with 415 mm average precipitation andin south part with 632 mm precipitationper year.In these experiments,springwheat (Triticum aestivum) and winter wheat (Triticum aestivum) have been used as indicating crops to study the effects of plastic film mulching (for spring wheat,including non-mulching,mulching for 30 days and 60 days after sowing,and mulching for the whole growing period;and for winter wheat,including non-mulching,mulching for 75 days and for 150 days after sowing,and mulching for the whole growth period) and nitrogen fertilizer application (for spring wheat,including no nitrogen application and nitrogen app lication 75 kg N ·hm2,and for winter wheat,including no nitrogen application and nitrogen application 225 kg·hm2)on wheat yield and N efficiency.There sults showed that the effects of plastic film mulching on the yield and N efficiency differed according to the soil water storage amount before sowing,the application of N fertilizer,the course of plastic film mulching and rainfallin the growth periods.In 1999 with rich rainfall,no matter whether nitrogen fertilizer was applied or not,under the condition of low soil water storage before sowing,although the grain,straw and biomass yield under all the film mulching treatments increased,there was no significant difference compared with non-mulching treatment (control);under the condition of high soil water storage be fore sowing,both grain and dry matter had the highest yield after film mulching for 60 days,and non-film mulching had the lowest one.But,there was no significant difference between the non-mulching treatment and film mulching for 30 days,and between film mulching for 60 days and film mulching for the whole growth period.In 2000 with the extreme drought,film mulching affected significantly the biomassyield.Under the conditions of low soil water storage before sowingand no application of nitrogen fertilizer,biomass yield increased markedly in the treatment of film mulching for 30 days,then was thet reat ment of film mulching for 60 days,and the last was the treatment of film mulching for the whole growth period.After applying nitrogen fertilize,the biomass yieldps difference betw een the non-film mulching and the film mulching for 30 days,and between film mulching for 60 days and film mulching for the whole growth period did not reach significant level.Indealing with the plotofhigh soil water storage before sowing,if nitrogen fertilizerwas not applied,there was not any difference,nomatter how plastic film was mulched.The grain yield ranged from 1 430 kg·hm2 to 1 482 kg·hm2.When nitrogen fertilizer applied,the grain yield in the treatment of film mulching for the whole growth period was the highest the earlier growth stage (e.g.film mulching for 30 days after sowing)straws to spikes (mainly in grain),and there was no significant difference between the film mulching for 30 days and for 60 days.According to the average of two rates of nitrogen fertilizer application,therewasno significant difference among various film mulching treatments.Because there were npt notable difference of crop nitrogen content between different mulching treatments,the effect of film mulching treatment on crop up take of nitrogen was the same as the effect on crop yield.But,it was obvious that film mulching during could improve the nitrogen to transferfrom in later growth stage.According to the analysis of the factors affecting the yield in two year psex periments,the effects of film mulching on the number of spiklet and the valid number of spiklet were mainly factor saffecting the grain yield.At the same time,the effects offilm mulching course on then it rogen fertilizer efficiency were related to precipitation in crop growth stage.In the year with richrainfall,under low soil water storage before sowing,nitrogenfer tilizerefficiency was the highest in the treatments of non-filmmulching and film mulchingfor 30 days,they were 30.4% and 30.3% respe ctively,while nitrogen fertilizer efficiency decreased in the treatments of film mulching for 60 days and film mulching for the whole growth period,they were 19.0% and 19.6% respectively;under high soil waters to rage before sowing,nitrogenfer tilizerefficiency was the lowes twith 10.1% for no film mulching treatment (control),and it increased markedly with the lasting of film mulching period,and they were 32.7%,34.2%,and 38.9% in the treatments of film mulching for 30 days,60 days and the whole growth period,respectively.In the extreme drought year,nitrogen fertilizer efficiency was obviously different com pared with the year with richrainfall,under the low soil water storageand the high soil water storage before sowing,then it rogen fertilizerefficiency in the plot of no film mulching was the highest,they were 18.3% and 19.75%,respectively,the nitrogen fertilizer efficiency in the plot of film mulching treatment was zero or minus,which implied that there was no significant effect of applying nitrogen fertilizeron thecrop yield under the conditions of plastic film mulching in the year with extreme drought.In the experiment of the winter wheat,for dry matter and grain,there wasn’ to bvious difference among the treatments of film mulching for 75 days,film mulching for 150 days and film mulching for the whole growth period,and the difference between the highest and the lowestgrain yield was only 42 kg·hm2,which was farless than the experiment alerror.The effect of plastic film mulching course and application of nitrogen fertilizeron the crop nitrogenup take was almost the same as the effects on the dry matter and grain yield.However,according to the average of the two levels of nitrogen fertilizer application,the difference among the treatments of film mulching for 75 days,for 150 days and for the whole growth period did not reach a significant level statistically.In the three film mulching treatments,the highest nitrogen uptake was only 12.0 kg·hm2 more than the lowest one,and the nitrogen fertilizer efficiency was the highest in the film mulching for 75 days treatment,with the prolonging of the film mulching course,the nitrogen fertilizer efficiency was dropping.Ingeneral,although the growth period of the spring wheat and the winter wheat was different,and the climate conditions during growth stage were also different,the plastic film mulching processes for two kinds of wheat had the same tendency on yield and nitrogen fertilizerefficiency,and the filmmulching appeared in thee arlier growth stage,and the mid-growth stage,almosthad no effectduring the latergrowth stage.As forthe whole,film mulching for the whole growth period didnpt make the yield,nitrogen uptake and nitrogen efficiency increase markedly.To maintain soil fertility and good soile cological conditions,and tomaintain the sustain able develop ment of agriculture,it should beadvocate dfilm mulchingfor 30-60 day safter spring wheat sowing,and it is more suit able to winter wheat to uncover plastic film which has been covered for 150 days after sowing inorder to lessen soil moisturee vaporation in winter and spring. |
| Key words: agro-ecosystem in semiarid area plastic film mulching wheat yield nitrogen efficiency |
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