低山丘陵坡耕地秸秆覆盖轮耕对土壤水热及碳氮库的影响

Effects of Soil Hydrothermal Response and Pools of Carbon and Nitrogen Under Straw Cover Rotation on Slope Farmland of Low Mountains and Hills

为了提高坡耕地的秸秆还田效率,探索一种适于坡耕地的基于种植和养地基础上的耕作方式。利用田间小区试验,研究了秸秆覆盖轮耕技术(包括当季秸秆覆盖+休闲、上季秸秆覆盖+旋耕)与常规耕作(秸秆移除后旋耕)对土壤水热变化及碳、氮积累的影响。结果表明:秸秆覆盖可显著提高播种前期20~40 cm土壤含水量,覆盖休闲与覆盖旋耕处理较常规耕作分别提高26.02%和37.49%,同时覆盖旋耕处理降低了20~40 cm土壤容重,较常规耕作和覆盖休闲分别降低6.52%和13.04%;与覆盖旋耕相比,覆盖休闲可降低作物生育前期0~20 cm和20~40 cm土层温度1.57~1.63℃,而土壤含水量提高15.25%~24.41%,为覆盖旋耕区作物出苗和前期生长提供了水分条件;通过秸秆覆盖休闲与覆盖旋耕组合的轮耕技术可提高0~20 cm土层碳氮含量,有机碳和全氮储量较常规耕作平均提高11.36%和20.51%,为今后低山丘陵区坡耕地实施保护性耕作提供了科学依据。

【Objective】The main forms of soil erosion are water,wind and freeze-thaw erosion in the black soil area of Northeast China,and slope farmland is the main source of soil erosion.Human factors such as long-term plowing and straw burning or leaving the field untended and heavy use of light farming or other factors have led to the loss of surface soil,shallow cultivated layer,soil infiltration and erosion resistance of sloping farmland.This would aggravate surface runoff and soil water erosion in summer during severe rainfall.To improve the straw return rate in sloping farmland,a suitable farming method based on planting and cultivating land was proposed.【Method】Field experiments were used to study the effects of straw mulching and rotation tillage technology(including this season straw mulching and fallow,last season straw mulching and rotary tillage)and conventional farming(straw removal and rotary tillage)on soil water and heat changes and carbon and nitrogen accumulation.【Result】The results showed that:water content in the 20–40 cm soil layer in the early stage of planting could significantly be increased with straw mulching,and the mulching fallow and mulching rotary tillage treatments increased by 26.02%and 37.49%,respectively,compared with conventional tillage.At the same time,the 20–40 cm soil bulk density in mulching rotary tillage treatment was higher than that of conventional tillage and mulching fallow,which were reduced by 6.52%and 13.04%,respectively.Compared with mulching and rotary tillage,mulching and fallow could reduce the soil temperature of 0–20 cm and 20–40 cm in the early stage of crop growth by 1.57–1.63℃,while the soil moisture content increased by 15.25%–24.41%,which provided conditions for crop emergence and early growth.Combining straw mulching fallow tillage and mulching rotary tillage technologies increased the carbon and nitrogen content of 0–20 cm soil layer,and the organic carbon and total nitrogen reserves were increased by 11.36%and 20.51%compared with conventional tillage.【Conclusion】All of this provide a scientific basis for the implementation of protective farming techniques on slope farmland in the low mountain and hilly areas.In the future,the optimized combination of crop varieties and dwarfing and maturity promotion would promote the increase of productivity in slope farmland when implementing conservation tillage technology.