春玉米种植密度对土壤有机碳组分的影响

通过西辽河灌区连续3 a的田间试验,研究春玉米不同种植密度（60 000、75 000和90 000株·hm-2）下土壤有机碳组分的质量分数及空间分布特征,阐明了春玉米种植密度对不同层次土壤有机碳组分的影响机制。结果表明：高、低密度均增加土壤0～40 cm土层有机碳质量分数,中密度下促进土壤微生物生物量碳增加。随着种植密度的加大土壤中活性有机碳增加,轻组有机碳减少。玉米生长主要促进10～20 cm土层有机碳的耗损,高密度下促进犁底层（20～40 cm）土壤有机碳质量分数及其活性,使其轻组有机碳减少,微生物生物量碳增加。低密度下主要增加表层（0～10 cm）土壤有机碳质量分数。种植密度通过影响根系群体生物量及其分布,调节土壤微生物活性、残落物碳输入影响土壤有机碳组分。适当的增加春玉米种植密度有利于春玉米农田高产固碳。

Effect of painting density of spring corn on organic carbon fractions of soil

The changes of contents and spatial distribution characteristics of soil organic carbon fractions under different planting density（60 000、75 000 and 90 000 piant·hm-2） of spring corn were studied by continuous three-year field experiment in Liaohe Irrigation.The influenced mechanism of the painting density of spring corn on organic carbon fractions in different soil layers was clarified.The results showed the contents of organic carbon fractions in 0-40 cm soil layer were increased under high and low planting density,and the contents of MBC（microbial biomass carbon） were increased under medium planting density.With the increase of the planting density of spring corn,the contents of ASOC（soil active organic carbon） were promoted and that of LFOC（light fraction organic carbon） were reduced.The growing corn mainly promoted the depletion of 10-20 cm of soil organic carbon.Under high planting density,to increase the contents and activities of soil organic carbon,to reduce the contents of LFOC,and to increase the contents of MBC in plough ground floor（20-40 cm） soil layer.However,under low planting density,mainly to increase the contents of oil organic carbon in 0-10 cm soil layer.Planting density influenced the weight and distribution of biomass on the root,and then regulated the activity of soil microbial,increased the input of the residual litter carbon,and influenced the contents of organic carbon fractions.So that,appropriately to increase the planting density,it can promoted the yield and fasten carbon in spring corn fields.