宁南旱区苜蓿草地土壤水分消耗规律及粮草轮作土壤水分恢复效应研究

对宁南旱区不同生长年限紫花苜蓿草地土壤水分消耗及粮草轮作水分恢复效应进行了研究。结果表明:(1)随着苜蓿生长年限延长,在1￣6年内苜蓿草地土壤湿度下降迅速,产草量逐年上升,7年后土壤湿度下降趋于平缓,但苜蓿产草量下降迅速,表明苜蓿生长强烈耗水引起深层土壤干燥化,导致苜蓿生长逐渐衰败,苜蓿平均降水生产效率逐年下降;(2)苜蓿草地土壤垂直剖面可分为降水入渗恢复层(0￣200cm)、根系发达枯竭层(200￣500cm)和根系衰老缓耗层(500cm以下)三个层次。随苜蓿生长年限延长,苜蓿剖面的主要土壤干层逐渐上移,并且干层厚度呈现减小趋势;(3)耕翻的苜蓿茬后轮作粮食作物的年份越长,土壤水分恢复越好,实行草粮轮作的苜蓿最迟不超过生长的第10年。

Soil Water Study of Afalfal Grass Water Consume Disciplinarian and Resume Effection while Grain-grass Rotation in the Arid Regions of Southen Ningxia

This paper researches vary growth age alfalfal''s grass water consume disciplinarian and resume effection while grain-grass rotation. Results show: with increasing of alfalfal growth age, grass soil containing moisture is decreasing rapidly during 1~6 year and grass yield is increasing, after 7 years old,decreasing of grass soil containing moisture tend to slow but grass yield rapidly reduce?It indicates that alfalgal intensitily consume soil water, bring deep soil dry, alfalfal growth decline and alfalfla''s average pricipitation production efficiency drop; alfalfla grass soil''s vertical section may think as three depth layer: pricipitation seep and water resume layer(0~200cm), root system up growth drying-up layer (200~500cm)and root system decline and slow consume layer(500cm hereinafter). With increasing of alfalfal growth age, dry layer of soil section is going up to ground gradually and its depth tend to minish; Furrowed alfalfal batch rotates grain, the more rotate years are, the more soil water resume. Growth alfalfal in the grass-grain rotation should be furrowed in its No 10 year.