苜蓿轮作玉米后土壤养分时空变化特征分析

Analysis of the Spatial-temporal Variation of Soil Nutrient of Alfalfa-maize Rotation

以7龄紫花苜蓿地为前茬,连续3年采用同一高产栽培方案种植玉米,研究其土壤养分的时空变化特征。结果表明,苜蓿轮作玉米后,随着玉米种植年限的增加,玉米各生育时期土壤有机质、全氮和全磷含量均有不同程度下降。其中,0-20cm土层降幅高于其他土层,且降幅表现为有机质>全氮>全磷。受玉米高量施氮的影响,碱解氮含量随玉米种植年限的增加而增加,不同生育时期、不同土层年际间碱解氮含量的差异多数达到显著水平。玉米产量随着连作年限的增加而降低,第2,3年产量较第1年产量分别下降了9.7%和13.6%,表明苜蓿对后作的增产效应持续降低。

The spatial-temporal variation of soil nutrient was studied under 3-year high-yielding cultivation maize in preceding of 7-growth-year alfalfa.The result showed that organic matter,total nitrogen,total phosphorus of alfalfa-maize rotation were decreased at each growing stage of maize with tillage years prolonged.The decrement of 0-20 cm soil layers was higher,and decrement ranking from much amount to small was organic matter 〉total nitrogen〉 total phosphorus.Because of the influence of high nitrogen application rate,available nitrogen was increased with tillage years prolonged,and its differences were significant between years in different growth stage and different soil layers.Maize yield was decreased with the increasing of continuous maize years,the yield in the second and third year decreased respectively by 9.7% and 13.6%,which indicated that alfalfa＇s effect on succeeding maize yield-increasing was continuously decreased.