深耕及秸秆还田对春玉米产量、花后碳氮积累及根系特征的影响

摘要

Continuing rotary tillage and excessive application of fertilizer made the plough layer shallow, plow pan harden, and soil physicoehemical properties deteriorated. To provide a resolution for these problems, a field experiment was conducted to study the effects of different tillage managements, and with maize straw-returning on yield, post-anthesis dry matter and nitrogen accumulation and root characteristics of spring maize. The effects of different cultivation methods like normal plowing (P), subsoiling 30cm without mixing the soil in different layer (S), subsoiling 30cm with mixing the soil in different layer (SM), and effects of maize-straw-returning under the above cultivation methods, on maize yield, the amount of post-anthesis dry matter (PDMA) and nitrogen (PNA)accumulation and root characteristics were studied. The results showed that compared with treatment P, the yield, PDMA and PNA accumulation of treatments S and SM increased significantly, and the proportion of PDMA in total dry matter enhanced as well. It promoted the growth of root under the treatments S and SM, especially in 30-60cm soil layer, and root vigor of the two treatments remained higher than that of treatment P. It decreased dry matter translocation efficiency (DMTE) and nitrogen translocation efficiency (NTE) from plant to grain after anthesis under treatments S and SM. Compared with treatment SM, treatment S improved maize yield remarkably, but it didnot show the same regularity between the two treatments for the other effects on maize. With maize straw returning, the yield of different treatments showed decreasing trend in general, whereas PDMA, the maximum root length and root length in deeper soil layer displayed a significant increase. PNA, post-anthesis nitrogen transfer amount (NT) and post-anthesis dry matter transfer amount (DMT) were restrained with maize straw returning. It was harmful to remain root vigor after anthesis. However, it could relieve bad effects on maize yield while conducting the tillage managements of subsoiling when maize straw is returned.%针对目前农业生产中连年采用旋耕的耕作方式以及过分依赖化肥,使得耕层变浅、犁底层变硬、土壤理化性质恶化的现象,采用田间小区试验,研究旋耕、深松和深翻耕作方式及在此基础上进行的秸秆还田对春玉米产量和花后碳氮积累及根系特征的影响.结果表明:深松和深翻可以显著提高春玉米的产量、花后干物质的积累量及其占总生物量比例和氮素吸收量;促进了根系的发育,尤其有利于30～60cm土层根系的发育,使根系在玉米生育后期保持相对较高的活力;但减少了花后干物质和氮素从营养体向籽粒转移的效率.深松和深翻相比,对产量的促进作用更加显著,但两种耕作方式对春玉米其他方面的影响并没有表现出相同的规律.秸秆还田后当季春玉米产量总体呈下降趋势,花后干物质积累量、最大根长及生育后期深层根系根长显著提高,但秸秆还田对花后氮素吸收、氮素及干物质转移有抑制作用,并且对开花后根系活力的保持不利.在进行秸秆还田的同时,采取适当的深耕措施,可以缓解秸秆还田对当季玉米产量的不利影响.