黄土高原区多年生苜蓿地土壤干层恢复的适宜后茬筛选

Suitable Succession Crop Screening After Perennial Alfalfa for Soil Dedication Restoration in Loess Plateau

采用大田试验方法研究换茬种植、休闲对9年生苜蓿地土壤水分的恢复作用及产量效应。结果表明:连续种植9年的苜蓿地0-300cm土层整体出现干燥化现象,随着苜蓿生长季的延长和土层加深,干燥化现象加剧,连续2个丰水年,降雨对连续生长11年苜蓿地30-50cm表现出恢复作用,对80-140cm表现出加剧作用,0-30cm和140-300cm缓解作用。在雨养条件下换茬种植玉米、谷子、休闲3种处理的水分恢复效果最好,马铃薯与春小麦次之,要使0-300cm土层土壤水分得到完全恢复,换茬种植玉米、谷子、马铃薯、春小麦分别需要净恢复土壤水分3.85,13.55,16.50,20.40mm,休闲需16.17mm;生长9年苜蓿地挖除苜蓿休闲1年后采用全膜双垄沟播技术种植玉米既能恢复土壤水分又能提高毫米水产能。从土壤水分恢复和提高生产力两方面综合分析,玉米是试验区多年生苜蓿地土壤水分恢复适宜后茬。

Effect of soil water restoration after 9years alfalfa was removed from field by crops rotation and fallow was studied.The results showed that soil desiccation was found on whole 0-300 cm profile,degree of soil desiccation increased with alfalfa growing time and soil depth deeper.For two consecutive wet year,rainfall had recovery effect to 30-50 cm,aggravation effect to 80-140 cm and relaxation effect to 0-30 cm and 140-300 cm for continuous growth for 11 years.Soil water of maize,millet and fallow field after alfalfa removed was restored better,followed by potato and spring wheat field.More soil water restored with time after alfalfa removed,but less soil water restored compared with commence of alfalfa removed.To make the0-300 cm profile soil moisture to get fully recover,plant maize,millet,potatoes and spring wheat respectively need net restoring soil moisture 3.85,13.55,16.50,20.40 mm,fallow field need 16.17 mm.The comprehensive analysis from water restoration and increasing productivity indicated that maize crop,sown with completely mulched alternating narrow and wide ridges with furrow planting technique in fallow field after alfalfa removed for one year,was beneficial for more soil water restore and higher water use efficiency compared with other crop,and maize was the best suitable succession crop in 9years alfalfa field.