摘要：
To reveal the advantage role of corn intercropped with Medicago sativa L.in the improvement of Albic soil fertility and enhancement of corn yield,four different N levels (140,175,200,225 kg/ha) were set,the effects of corn monoculture and intercropped with Medicago sativa L.based on the form of 2-0 culture on the corn yield and the contents of total N,organic matter and available nutrients in Albic soil were studied.The results showed that under the same cultivation mode,the corn yield was enhanced with the increase of N level.Under the same N level,the corn intercropped with Medicago sativa L.had an advantage over the corn monoculture in terms of increasing corn yield.Based on the corn monoculture, with the increase of N level,the peak of total N content was advanced to the tassel stage from the mature stage,the organic matter content was shifted from consumption to accumulation;undert the maximum N level (225 kg/ha),the loss of alkaline N reached the most.Based on intercropped with Medicago sativa L.,the alkaline N content could be enhanced to the peak value in the tassel period;compared with the jointing period,the N application could increase the organic matter content of Albic soil except the treat-ment with N of 200 kg/ha could make the organic matter content decreased by 12.0%;175 kg/ha N was more beneficial to reduce the loss of alkaline N after the corn harvest;when the application level of N (140 kg/ha) was minimum,the corn intercropped with Medicago sativa L.could increase the loss of total N,and with the increase of amount of N,the corn intercropped with Medicago sativa L.could relieve the loss of total N content of Albic soil.When the N levels were 140,175,200 kg/ha,the corn intercropped with Medicago sativa L.could alleviate the loss of organic matter content of Albic soil from the jointing pe-riod to the tassel stage;when the N level was 225 kg/ha,the corn intercropped with Medicago sativa L. could make the organic matter content increased by 13.9% compared with corn monoculture treatment. No matter corn monoculture or intercropped with Medicago sativa L.could increase the loss of available P and K contents of Albic soil in every growth period,among which the available K content was decreased first and then increased with the growth period of corn;the applied N level of 175 kg/ha or 200 kg/ha could make the available P content accumulated under the corn monoculture and intercropped with Medi-cago sativa L.respectively;affected by the corn intercropped with Medicago sativa L.,the applied N of 175 kg/ha could greatly promote the loss of available K,and when the applied N level being decreased to 140 kg/ha,the available K content could be accumulated to the greatest extent.To sum up,under the same N level,the corn intercropped with Medicago sativa L.was more advantageous than corn monoculture in raising corn yield;the high N level could effectively alleviate the loss of total N content of Albic soil from the corn intercropped with Medicago sativa L.,and simultaneously increase the contents of organic matter and available P.In this mode,the applied N amount of 175 kg/ha could minimize the loss of avail-able N and promote the loss of available K furthest.%为了揭示玉米间作紫花苜蓿对白浆土培肥及玉米增产的优势作用,设置4个不同施氮水平(140、175、200、225 kg/hm2),研究了玉米"二比空"单作及间作紫花苜蓿对玉米产量及白浆土全氮、有机质及速效养分含量的动态影响.结果表明:在同一栽培模式下,随施氮水平增加,玉米产量逐渐增加.在相同施氮水平下,玉米间作紫花苜蓿在提升玉米产量方面比玉米单作更有优势.在玉米单作条件下,随施氮量增加,白浆土全氮含量峰值出现的时期由成熟期提早至抽雄期,有机质含量由消耗转为积累,在供试最大施氮量(225 kg/hm2)条件下,白浆土碱解氮含量的损失程度也最大.玉米间作紫花苜蓿条件下,白浆土全氮含量的峰值则出现在抽雄期;与拔节期相比,玉米收获后,除施氮量为200 kg/hm2时白浆土有机质含量降低12.0%外,其余施氮量均可使白浆土有机质含量增加;施氮量为175 kg/hm2时更有利于降低碱解氮的损失;施氮量较低时(140 kg/hm2),玉米间作紫花苜蓿能促进白浆土全氮含量的消耗,而施氮量提高后,玉米间作紫花苜蓿能相应地降低白浆土全氮含量的损失.在施氮量为140、175、200 kg/hm2时,与玉米单作相比,玉米间作紫花苜蓿能够减小玉米拔节期至抽雄期白浆土有机质含量的降幅,而在更高施氮量(225 kg/hm2)下,玉米间作紫花苜蓿能使抽雄期白浆土有机质含量较拔节期提升13.9%.与玉米单作相比,玉米在各个生育时期,无论单作还是间作紫花苜蓿处理白浆土中有效磷及速效钾含量均显著降低,其中,速效钾含量随玉米生育进程的推进表现为先降低后增高的规律;在玉米单作及间作紫花苜蓿模式下,施氮200、225 kg/hm2可使白浆土有效磷含量得以累积;在玉米间作紫花苜蓿模式下,施氮175 kg/hm2可极大地促进白浆土速效钾含量的消耗,施氮量降至140 kg/hm2则可使速效钾含量得到最大程度累积.综上,相同施氮水平,玉米间作紫花苜蓿在提升玉米产量方面比玉米单作更有优势;较高施氮水平可有效降低玉米间作紫花苜蓿下白浆土全氮含量的损失,同时增加有机质和有效磷含量,在此模式下,施氮175 kg/hm2能最大限度地减少碱解氮的损失、促进速效钾的消耗.
