不同年限全量玉米秸秆还田对玉米生长发育及土壤理化性状的影响

Effects of continuous straw return to soil on maize growth and soil chemical and physical characteristics

试验以未进行秸秆还田（H0,对照）、连续3年秸秆还田（H3,2007—2010年）、连续6年秸秆还田（H6,2005—2010年）及连续9年秸秆还田（H9,2002—2010年）的连作玉米农田为对象,通过测定土壤理化性状及玉米根系发育和地上产量性状的变化,探索不同秸秆还田年限对不同层次土壤改良效应及作物生长响应机理。结果表明：随着玉米全量秸秆连续还田,耕层0~30 cm土层土壤有机质、全氮、全磷含量大幅增加,速效氮、速效钾显著增加,而速效磷养分变化幅度较小,表明秸秆还田能够有效改善土壤养分状况;20~50 cm土层土壤容重随着秸秆还田年限增加较对照显著下降,表现H9〈H6〈H3〈H0趋势。主要生育期玉米根重密度、总根长及根系活力水平等指标,均表现出随着还田年限增加而增加的趋势。特别是生长后期较深土层的根系,表现不同处理间变化幅度差异显著的特点,成熟期40~60 cm土层H9、H6、H3处理根系活力水平分别较对照高54.76%、29.1%和16.3%,H9根重密度、总根长分别较对照高44.3%、79.3%,H6、H3处理根重密度分别较对照增加30.8%、18.8%,根长增加58.9%、47.7%,而对照根系表现迅速衰退现象,说明秸秆还田处理使成熟期玉米根系衰退延迟,有利于后期作物对养分的吸收和产量的形成。随秸秆还田年限增加,玉米地上株高及穗位高相应增加,H9、H6、H3穗位高分别较对照增加11.1 cm、5.3 cm和0.7 cm;百粒重各处理较对照依次增加17.4%、10.2%和7.5%,H9处理产量较对照增产15.4%以上,H6、H3分别较对照增产10.3%和4.5%,表现随还田年限增加显著增产的趋势。

As it significantly improves the physical and chemical characteristics of farmland plow layer soil,straw return is an efficient strategy to enhance soil fertility.To understand the effects of different straw return methods on soil fertility and maize growth,experiments were conducted from 2002 to 2010 in Pingliang Maize Breeding Experimental Station（PMBES） of Gansu Agricultural University.Soil chemical and physical characteristics,and maize plant root growth and yield were determined for three straw return treatments — 3-year straw return（H3,2007—2010）,6-year straw return（H6,2005—2010） and 9-year straw return（H9,2002—2010） — and non-straw return used as the control（0-year straw return,CK）.The results showed that soil contents of organic matter,total nitrogen,total phosphorus,alkali-hydrolysis N and available K in the 0-30 cm soil layer significantly improved with increasing years of straw return.Soil bulk density reduced significantly in the 20-50 cm soil layer with increasing years in the order of 9 〈6 〈3 〈0 years.Root weight density,total length and activity significantly improved with increasing years of maize straw return.Especially during later growth stage,maize root characteristics in deep soil exhibited significant differences among different straw return treatments.Root activity in the 40-60 cm soil layer in H9,H6 and H3 treatments were higher than in CK treatment by 54.8%,29.1% and 16.3%,respectively.Root weight density and total length in H9 treatment increased respectively by 44.3% and 79.3% over CK.The root weight density and total length increased by 30.8% and 58.9% in H6,and by 18.8% and 47.7% in H3 treatments over CK,respectively.Under CK,maize root rapidly recession in the fields.Plant height,ear height of maize increased with increasing years of straw return.Ear height of H9,H6 and H3 was 11.1 cm,5.3 cm and 0.7 cm higher than that of CK respectively.The maize yield improved with increasing years of straw return too.100-seed weigh and yield of H9,H6,H3 increased by 17.4%,10.2%,7.5%,and 15.4%,10.3%,4.5%,respectively,over the CK.The findings suggested that straw return delayed root consenescence,enhanced root nutrient uptake at the later growth stage and increased maize yield.