干旱绿洲灌区玉米氮素吸收利用对绿肥还田利用方式的响应

Effect of green manure retention practices on nitrogen absorption and utilization by maize crops in the arid oasis irrigation area

针对干旱绿洲灌区小麦与玉米长期连作、麦后休闲期长、氮肥利用效率不高等问题,研究麦后复种绿肥对轮作玉米氮素吸收利用的影响具有重要意义。在石羊河流域,通过田间试验研究麦后复种绿肥不同还田利用方式(全量翻压、地表覆盖免耕、地上部收获后根茬翻压、地上部收获后免耕和不复种绿肥并采用传统翻耕)对后茬玉米氮素利用特征的影响。结果表明,与不复种绿肥相比,绿肥全量翻压和地表覆盖免耕还田处理下玉米播前0~30 cm土层矿质氮含量显著增加11.7%、10.0%,微生物量氮含量增加14.3%、16.2%;抽雄吐丝期,0~30 cm土层土壤矿质氮含量增加17.0%、13.7%,微生物量氮含量增加8.7%、10.7%,为玉米氮素高效利用奠定了基础。绿肥全量翻压和地表覆盖免耕还田处理的玉米地上部植株吸氮量和籽粒吸氮量较不复种绿肥翻耕处理明显增加,其氮素利用率和氮肥偏生产力较不复种绿肥翻耕处理平均提高20.1%、25.8%和17.3%、22.2%,且该条件下玉米氮素利用率和氮肥利用率显著高于绿肥根茬还田处理。因此,在干旱绿洲灌区,麦后复种绿肥全量翻压或地表覆盖免耕在提高土壤氮素含量的同时,实现了玉米氮素的高效利用。

Nowadays,the major issues facing crop husbandry in the arid oasis irrigation region are the sustainability of long-term continuous cropping of wheat and maize,the long period of fallow after the wheat harvest,and a comparatively low nitrogen(N)fertilizer use efficiency.Therefore,investigation of the effects of different green manure retention practices on nitrogen absorption and utilization of subsequent maize crops is of significant importance,and a field experiment was conducted in the Shiyang river basin to determine the effects of different green manure retention practices on nitrogen use characteristics of subsequent maize crops in a wheat-green manure-maize rotation system.Green manure retention practices evaluated were:i)Tillage with the total green manure crop incorporated into the soil,ii)No-tillage with the total green manure crop mulched on the soil surface,iii)Tillage with green manure crop roots incorporated in the soil and with above ground herbage removed;iv)No-tillage with above ground green manure crop herbage removed,and vi)Conventional tillage without green manure.It was found that before maize sowing,the treatments with the total green manure crop incorporated into the soil or mulched on the soil surface increased the soil mineral nitrogen content by 11.7%and 10.0%,respectively,and improved the microbial biomass nitrogen content by 14.3%and 16.2%,respectively,compared with conventional tillage without green manure.At the tasseling and silking stages,the two treatments increased soil mineral nitrogen content by 17.0%and 13.7%,respectively,and improved microbial biomass nitrogen content by 8.7%and 10.7%,respectively,in the 0-30 cm soil layer,which allowed efficient use of nitrogen by the maize.These two treatments also significantly increased above-ground nitrogen accumulation both in leaves and stems,and in the grain.As a result,the N use efficiency of these two treatments increased by 20.1%and 25.8%,respectively,and the N partial productivity by 17.3%and 22.2%,respectively,compared to conventional tillage without green manure.Furthermore,the N fertilizer use efficiency and nitrogen use efficiency of the two treatments were significantly higher than those for the treatment with green manure roots retuned only.In summary,in the arid oasis irrigation area,the practices of incorporating the total green manure crop into the soil or mulching the total crop on the soil surface using no-tillage,can increase soil nitrogen content while at the same time facilitating increased nitrogen use efficiency in maize.