不同草田轮作模式对土壤养分动态的影响

Effect of Different Alfalfa-Crop Rotation Patterns on Soil Nutrient Dynamic

在宁南旱区10年生苜蓿草地上进行了为期3a的27种不同草田轮作模式试验,研究了土壤有机质、氮、磷的动态变化特征。结果表明,与保持生长的对照苜蓿草地相比,苜蓿草地实行草田轮作后,有机质持续下降,轮作第1,3a的马铃薯,第2a的春小麦对土壤有机质有明显影响,马铃薯连作模式使土壤有机质降幅最大;不同轮作模式的土壤全氮变化有较大差异,谷子和春小麦等禾本科作物单一连作模式对土壤氮素造成偏耗;不同轮作模式碱解氮总体上呈下降趋势,轮作作物产量水平直接影响土壤碱解氮含量的高低。全磷呈先降后升又降趋势。作物轮作能够提高苜蓿草地土壤氮、磷有效性。为了高效、协调和可持续地利用水肥,应选择合理的草田轮作模式。

Three year experiment of 27 kinds of alfalfa—crop rotation was conducted on the 10-year-old alfalfa grassland in the arid region of Southern Ningxia Hui Autonomous Region.Dynamic characteristics of soil nitrogen,phosphorus and organic matter during the three years of alfalfa—crop rotation were studied.Results showed that in comparison with continuous alfalfa planting,organic matter continued to decline during 3 years of alfalfa—crop rotation.Potato in the first and third year planting and spring wheat in the second year planting influenced soil matter content obviously The pattern of potato succession cropping made soil matter content to decline most seriously.Change in soil total nitrogen under different alfalfa—crop rotations was obvious,comparatively.The sole rotation patterns of cereal grain planting,such as millet or spring wheat pattern,was in preference to consume soil total nitrogen.As a whole,soil alkali-hydrolyzed nitrogen content under different rotation patterns tended to decline and was directly influenced by the level of rotation crop yield.Soil total phosphorus presented declining at first,then rising,and again declining.The alfalfa—crop rotation pattern can improve soil nitrogen and phosphorus effectiveness.So,the reasonable alfalfa—crop rotation pattern should be adopted for a highly efficient,harmonious and sustainable utilization of soil water and nutrient.