不同耕作方式下长期秸秆还田对旱作春玉米田土壤碳、氮、水含量及产量的影响

为了探索渭北旱塬春玉米田保护性轮耕模式的土壤培肥效果和增产增收效应,于2007—2014年在陕西合阳实施了秸秆覆盖或还田条件下免耕/深松(NT/ST)、深松/翻耕(ST/CT)、翻耕/免耕(CT/NT)、连续免耕(NT)、连续深松(ST)和连续翻耕(CT)等6种耕作处理田间定位试验,测定并分析了2010—2014年玉米收获期各耕作处理下0～60 cm土壤有机碳、氮储量,0～200 cm土层土壤含水量变化及春玉米产量差异.结果表明: 6种耕作处理中以NT/ST处理增加土壤有机碳和全氮储量最为明显.与2007年试验前相比,6种耕作处理均增加了0～60 cm土层土壤有机碳储量,5年平均值增幅为12.3%～28.3%,5种保护性耕作处理土壤有机碳储量5年平均值较CT对照处理显著增加7.1%～13.2%.NT/ST、ST/CT、CT/NT等3种轮耕处理和NT处理0～60 cm土层土壤氮储量5年平均值较试验前增加2.5%～7.3%.NT/ST、ST/CT、CT/NT、NT和ST处理土壤氮储量5年平均值比连续翻耕增加3.6%～11.1%.5种保护性耕作处理土壤含水量较CT处理依次增加5.7%、2.3%、2.0%、5.5%和4.4%,以NT/ST处理土壤含水量最高.6种耕作处理春玉米平均产量表现为NT/ST>ST/CT>ST >NT>CT/NT>CT,以NT/ST处理最高,分别较其他5种处理显著增产4.2%、13.0%、11.3%、4.7%和13.8%;经济效益平均表现为NT/ST>ST/CT>ST>NT>CT/NT>CT.在6种耕作处理中,免耕/深松轮耕处理在改善土壤环境质量、提升土壤肥力和增产增收方面都表现出优越性,为旱作春玉米田较适宜的土壤轮耕模式.

Effects of long-term straw mulching on soil organic carbon,nitrogen and moisture and spring maize yield on rain-fed croplands under different patterns of soil tillage practice.

In 2007-2014, a position experiment was conducted in the Weibei Highlands Region to study effects of long-term straw mulching on spring maize planted on rain fed farmlands with diffe-rent conservative tillage practice patterns, no tillage plus sub-soiling (NT/ST), sub-soiling plus deep plowing (ST/CT), deep plowing plus no tillage (CT/NT), only no tillage (NT), only sub-soiling (ST) and only deep plowing (CT), by measuring and analyzing organic carbon and nitrogen storage in 0-60 cm soil and dynamic moistures in 0-200 cm soil at the maize harvesting time as well as the yields of maize. The results showed that the soil organic carbon storage and soil nitrogen storage increased most with the NT/ST among the six conservative tillage practice patterns. Compared with the experiment results before 2007, the organic carbon storage in 0-60 cm soil increased under the six conservative tillage practice patterns and their five-year averagely increase reached 12.3%-28.3%. Compared with the organic carbon and nitrogen storage with the CT, the five-year soil organic carbon storage under the other conservative tillage practice patterns increased by 7.1%-13.2%. The five-year nitrogen storage in 0-60 cm soil under NT/ST, ST/CT and CT/NT as well as NT increased by 2.5%-7.3% compared with the corresponding soil nitrogen storage before the start of experiment. The five-year average nitrogen storage under NT/ST, ST/CT, CT/NT, NT and ST increased by 3.6%-11.1% compared with that under CT. Compared with the soil moisture under CT, the soil moistures under the other five conservative tillage patterns separately increased by 5.7%, 2.3%, 2.0%, 5.5% and 4.4%, and the soil moisture under NT/ST was the highest. The average yields of spring maize ranked in order of NT/ST>ST/CT>ST>NT>CT/NT>CT and the yield of spring maize under NT/ST was the highest and separately increased by 4.2%,13.0%,11.3%,4.7% and 13.8% compared with those under the other five conservative tillage patterns, and the average economic returns were in order of NT/ST>ST/CT>ST>NT>CT/NT>CT. Among the six conservative tillage patterns, NT/ST performed better in improving soil environment quality, soil fertility and increasing maize yield and return, so it was a conservative tillage pattern more suitable for croplands for spring maize.