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.

Abstract

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.