秸秆还田对绿洲棉田土壤CO_2时空分布的影响

基于静态箱法和气井法,测定棉花秸秆还田对绿洲棉田土壤CO_2浓度和通量时空分布的影响。结果表明:棉花秸秆还田后土壤CO_2浓度与通量具有明显的时间变化特征,均表现为7月份出现峰值,10月出现低值;与NS(对照组)相比,秸秆还田处理下的土壤CO_2浓度与通量在5月也出现峰值。土壤CO_2浓度随着土壤深度的增加而增加,但秸秆还田对土壤CO_2浓度的垂直分布影响不大。观测期内,NS、HS(半量)、TS(全量)和DS(加倍)处理下的土壤CO_2浓度均值分别为5 946.2、6 837.3、7 717.3 mg·kg~(-1)和10 437.6 mg·kg~(-1),土壤CO_2通量均值分别为110.22、136.84、140.75 mg·m~(-2)·h~(-1)和169.47 mg·m~(-2)·h~(-1),即棉花秸秆还田增加了土壤CO_2浓度和通量;其中,DS处理下的土壤CO_2浓度和通量均显著高于其他处理(P0.05)。此外,NS、HS、TS和DS处理下土壤CO_2浓度与通量之间的相关系数分别为0.30~0.60、0.68~0.72、0.72~0.77和0.85~0.88,相关系数随秸秆还田量增大而增大,即土壤CO_2通量强烈依赖于土壤CO_2浓度。在当前的农业生产水平下,综合评价不同秸秆量还田的效应,应采用全量秸秆还田。

Effects of Cotton Straw Return to Field on Spatiotemporal Distribution of Soil CO2 in Oasis

The effects of cotton straw returned to field on soil CO2 concentration,flux and spatiotemporal distribution were conducted by using the closed chamber method and diffusion chamber technique in oasis.The results showed that the temporal variation of soil CO2 concentration and flux with the time was significant,their peak values occurred in July,and their minimums in October;compared to NS,the peak values of soil CO2 concentration and flux also occurred in May after cotton straw was returned to field.Vertically,soil CO2 concentration was increased with the increase of soil depth,but the effect of returning cotton straw on the vertical distribution of soil CO2 concentration was not significant.Over the measurement period,the mean values of soil CO2 concentration were 5 946.2,6 837.3,7 717.3 and 10 437.6 mg · kg-1,and those of soil CO2 flux were 110.22,136.84,140.75 and 169.47 mg · m-2 · h-1 under NS,HS,TS and DS,respectively.These indicated that cotton straw returned to field played an important role in soil CO2 concentration and flux,but soil CO2 concentration and flux were significantly higher in DS than in TS and HS (P ＜0.05).In addition,the correlation coefficients between soil CO2 concentration and flux were 0.3-0.6,0.68-0.72,0.72-0.77 and 0.85-0.88 under NS,HS,TS and DS,and they were increased with the increase of amount of cotton straw returned to field,that means soil CO2 flux depended strongly on soil CO2 concentration.Under current level of agricultural production,it was suggested to return total cotton straw to field in comprehensively evaluating the effect of different amounts of cotton straw returned to field.