不同耕作方式下甘蔗地土壤热容量的变化

Study on Changes of Heat Capacity in Sugarcane Soil under Different Tillage Patterns

【目的】研究不同耕作方式下甘蔗地土壤热容量的变化,为改善土壤水热条件提供参考。【方法】以广西农业科学院里建研究基地的甘蔗种植地为研究对象,选定面积为20 m×10 m的试验处理,通过定位监测试验区域的降雨量以及5、20和40 cm 3个深度土层的土壤含水量,计算得到土壤热容量,分析不同耕作方式和不同土壤水分条件下甘蔗地土壤热容量的动态变化过程。【结果】土壤热容量的变化与土壤含水量的变化具有一致性,说明降水是影响本地区土壤热容量的主要因素之一。耕作(T)处理的土壤蓄水上限值更高从而提高了土壤热容量,但水分不易储存;免耕(NT)处理的保水性优于耕作处理,土壤热容量更稳定。T处理中的5、20和40 cm土层的土壤热容量均高于NT处理。5 cm土层中,较高水分时段土壤热容量表现为NT>T,较低和中等水分时段为T>NT,40 cm土层的变化则与5 cm相反;而在20 cm土层,3种不同水分条件的土壤热容量均为T>NT。不同耕作方式下,土壤热容量对降水的响应存在滞后现象:达到峰值前,NT处理响应滞后于T处理;达到峰值后,T处理响应滞后于NT处理,滞后幅度为1 d左右。【结论】土壤热容量主要受到降水等自然因素的直接影响,但不同耕作方式等人为因素将在很大程度上改变土壤热容量。

【Objective】To provide a reference for improving water and heat conditions of soil,the changes of soil heat capacity under different tillage patterns in sugarcane field were studied.【Method】The research plots located at the Lijian research base of Nanning,Guangxi Academy of Agricultural Sciences.The soil moisture content at 5,20 and 40 cm depths in each plot covered an area of 20 m×10 m of the sugarcane plantations was measured to calculate the soil heat capacity,and its dynamic changes under different tillage patterns and different soil moisture conditions were analyzed.Meanwhile the precipitation were recorded.【Result】Results showed that the change of soil heat capacity was consistent with the soil water content,which meant the precipitation was one of the main factors affecting soil heat capacity in this region.Tillage treatment(T)could accumulate more soil water to improve soil heat capacity but moisture was not easy to store.No-tillage(NT)treatment was superior to tillage treatment in water retention,soil heat capacity is more stable.The soil heat capacities of 5,20 and 40 cm soil layer of T treatment were higher than those of NT.At 5 cm depth,the soil heat capacity under the highest water regime was great in NT treatment than that in T treatment,however the lowest and moderate water regimes showed T>NT.It was opposite at 40 cm depth comparing to that of 5 cm depth.Furthermore the soil heat capacity of T treatment was higher than that of NT treatment at 20 cm depth under 3 soil moisture conditions.The response of soil heat capacity to precipitation had a lag phenomenon.Before reaching the peak,NT treatment response laged behind T,and after the peak,T treatment lagged behind NT treatment,and the hysteresis width was about 1 day.【Conclusion】Soil heat capacity was directly affected by natural factors such as precipitation and also constrained to a great extent by human factors like different tillage patterns.