覆膜对滴灌棉田土壤水分时空运移的影响

Effects of Plastic Film Mulching on Temporal-spatial Migration of Soil Moisture in Drip Irrigation Cotton Fiel

【目的】对比分析覆膜与无膜滴灌棉田土壤水分在时间维度上以及空间维度上的运移规律,为棉花精准灌溉、无膜棉栽培技术提供理论依据与技术支撑。【方法】以膜下滴灌和无膜滴灌作为试验处理,采用5TE土壤水分温度传感器实时采集棉花全生育期土壤水分数据,采用Voxler和Surfer等软件对土壤水分网格数据进行时空插值、3D可视化以及切片。【结果】膜下滴灌土壤水分含量整体高于无膜滴灌处理;垂直方向上,膜下滴灌各不同深度土层间的运移加快,土壤水分含量随着深度增加而增加,在底层土壤(80~100 cm)水分含量最多,而无膜滴灌各土层间的土壤水分交流不活跃,水分主要集中表层土壤(0~20 cm);水平方向上,2种处理的近根系和远根系土层的土壤水分含量无显著差异;时间维度上,随着棉花生育进程的推进,膜下滴灌处理的土壤水分含量总体呈现上升的趋势,土壤水分消退速率在滴灌前(6月20日)为3×10^(-4) m^(3)/(m^(3)·d),6月20日至8月11日(滴灌后)维持在30×10^(-4) m^(3)/(m^(3)·d),8月11日至8月26日增至30×10^(-4) m^(3)/(m^(3)·d),8月26日(最后1次滴灌)后降低至30×10^(-4) m^(3)/(m^(3)·d),而无膜滴灌处理的土壤水分变化较为平稳,滴灌前水分消退速率在0.7×10^(-4) m^(3)/(m^(3)·d),滴灌后为10×10^(-4) m^(3)/(m^(3)·d)。【结论】覆膜处理能使土壤水分从表层向下运移,底层(80~100 cm)水分最多;而水平方向上,2种处理的近根系和远根系土壤水分无明显差异;时间维度上,覆膜处理提高了滴灌棉田的土壤水分的变化波动,使其水分消退速率增加,无膜处理的水分消退速率却保持稳定。

【Objective】To compare and analyze the law of soil moisture movement in time and space dimension in the film-mulching and non-film drip irrigation cotton fields.【Method】Film-mulching drip irrigation and non-film drip irrigation were used as experimental treatments.The 5TE soil moisture temperature sensors were used to collect soil moisture data during the whole growth period of cotton in real time,and software such as Voxler and Surfer were used to perform temporal-spatial interpolation,3D visualization and slicing of the soil moisture grid data.【Result】The overall soil moisture content of drip irrigation under film-mulching was higher than that of drip irrigation without mulch;In the vertical direction,the migration between the different depths of the drip irrigation under the mulch accelerated,and the soil moisture content increased with the increase of depth.The water content in the bottom soil(80-100 cm)was the largest,while the drip irrigation without mulching the soil moisture exchange was not active,and the moisture was mainly concentrated in the surface soil(0-20 cm);In the horizontal direction,there was no significant difference in the soil moisture content of the near root system and the far root system soil layer between the two treatments;In the time dimension,as the growth process of cotton advanced,the soil moisture content of drip irrigation under the mulch showed an overall upward trend.The rate of soil moisture loss before drip irrigation(June 20)was 3×10^(-4) m^(3)/(m^(3)·d),and maintained 30×10^(-4)m^(3)/(m^(3)·d)from June 20 to August 11(after drip irrigation),then increased to 30×10^(-4)m^(3)/(m^(3)·d)from August 11 to August 26(the last drip irrigation).After that,it was reduced to 30×10^(-4)m^(3)/(m^(3)·d).For the soil moisture of the non-film drip irrigation treatment,it was relatively stable,and the water loss rate before drip irrigation was 0.7×10^(-4)m^(3)/(m^(3)·d),and 10×10^(-4)m^(3)/(m^(3)·d)after drip irrigation.【Conclusion】The film-mulching treatment can make the soil moisture move down from the surface layer,and the bottom layer(80-100 cm)has the highest volume of water;while in the horizontal direction,there is no significant difference in soil moisture between the near-root side and the far-root side of the two treatments;in the time dimension,the film-mulching treatment increases the fluctuation of soil moisture in drip irrigation cotton fields,which increases the water extinction rate,while the non-film drip irrigation treatment keeps the water extinction rate stable.The results of this study provide the theoretical basis and technical support for the cotton precision irrigation and the filmless cotton cultivation technology.