浅埋地下滴灌不同土壤基质势调控对苜蓿生长和产量的影响

Effects of Matric Potential Threhold Used for Control of Shallow Drip Irrigaion on Growth and Yield of Alfalfa

【目的】探明浅埋地下滴灌不同土壤基质势对苜蓿生长和产量的影响,制定呼伦贝尔地区苜蓿浅埋地下滴灌的灌溉制度。【方法】以紫花苜蓿为研究对象,设置5个不同的土壤基质势下限处理,将滴头正下方10cm深度处的土壤基质势分别控制在-10、-20、-30、-40k Pa和-50k Pa,研究不同土壤基质势对土壤水分布、苜蓿生长、产量和灌溉水利用效率的影响。【结果】浅埋地下滴灌条件下,控制滴头正下方10cm深度处的土壤基质势下限可以显著改变土壤含水率的空间分布,该点土壤基质势阈值越高,0~30cm土层的土壤含水率则越高。苜蓿的株高和产量随着土壤基质势的降低呈先增加后降低的变化趋势,土壤基质势下限控制在-20k Pa时的苜蓿株高和产量最高。苜蓿的平均灌溉水利用效率随着土壤基质势的降低而升高,当土壤基质势下限在-50~-40k Pa范围内时最高。【结论】为了保证苜蓿高产,当耕层土壤保水性能较差且土层浅薄时,浅埋地下滴灌条件下滴头正下方10 cm深度处的土壤基质势下限建议控制在-20 kPa。

【Objective】Matric potential measured at a position below the emitter is often used as a threshold to control drip irrigation.In this paper we investigate the effect of the threshold on growth and yield of alfalfa irrigted by shallow drip irrigation.【Method】The field experiment was conducted in Hulunbeier area in Inner Mongolia,with the variety Longmu 806 used as the model plant.We compared five matrix potential thresholds measured at the depth of 10 cm below the emitter:-10,-20,-30,-40 kPa and-50 kPa,to study their effects on soil moisture distribution,growth and fresh grass yield,as well as water use efficiency of the alfalfa.【Result】The matrix potential threhold significantly affected spatial distribution of soil moisture;the higher the soil matrix potential threshold was,the higher the soil water content in the 0~30 cm soil layer was.With the decrease in the matrix potential,the plant height and fresh grass yield of the alfalfa increased first and then declined;the highest plant height and fresh grass yield were achieved when the soil matrix potential was-20 kPa.The average irrigation water use efficiency of the alfalfa increased with the decrease in soil matrix potential,and the highest irrigation water use efficiency was when the soil matrix potential was between-50 kPa and-40 kPa.【Conclusion】In order to maintain high and stable grass yield,for 1~3 year old alfalfa,the soil matrix potential threshold at the depth of 10 cm underneath the emitter of the shallow subsurface drip irrigation should be-20 kPa,when water holding capacity of the soil in the tillage layer is poor and the roots of the alfalfa are shallow.