农田不同肥力条件下玉米秸秆腐解效果

为了探讨农田不同肥力对玉米秸秆腐解转化和能态变化的影响，该文采用砂滤管法在陕西关中高、中等、低3种肥力塿土上进行了480 d的玉米秸秆腐解试验，研究了腐解进程中玉米秸秆的分解率以及有机碳组成和能态变化。结果显示，随着腐解进行，腐解产物中的苯–醇溶性、水溶性组分下降，半纤维素和纤维素含量先上升后下降，而木质素增加；腐解物的能态呈现上下起伏、下降和相对稳定3个阶段的变化，总体是一个放能过程。腐解产物的热值与其有机碳、苯–醇溶性组分、水溶性组分、半纤维素和纤维素呈显著正相关，但与其灰分、木质素、腐殖物质含量呈显著负相关。腐解480 d，3种肥力间比较发现，玉米秸秆在中等肥力田块上矿化率最高，低肥力田块上的最低；中等肥力土壤能够促进玉米秸秆中的水溶性有机组分和木质素的分解，而高肥力土壤能够促进苯–醇溶性组分和半纤维素、纤维素分解，并有利于腐殖物质的形成，而且腐解物的能态最高。

Decomposition of corn stalk in cropland with different fertility

In order to discuss the effect of soil fertility on composition transformation and energy change of corn stalk during decomposition, carborundum tube was used to study the decomposition of corn stalk buried in different soils with high, medium and low fertility for 480 days. The decomposition rate and change of energy states of corn stalk were revealed. The results showed that the fractions of alcohol-benzene soluble and water soluble decreased with the process of decomposition. The concentration of semicellulose and cellulose increased firstly and then decreased. However, the concentration of lignin increased. The change of energy states of corn stalk throughout the whole process could be divided into three stages such as fluctuating stage, decreasing stage and stable stage. Totally, the humification was a process of energy release. For 480 days of decomposition, the decomposition rate was highest in soil with medium fertility and lowest in soil with low fertility among three type of fertility. The decomposition of water soluble factions and lignin were promoted in medium fertility soil. However, alcohol-benzene soluble fraction, and semi-cellulose and cellulose fraction were decayed acceleratedly in soil with high fertility. Furthermore, more humic substance was formed and energy states of decayed corn stalk was highest in soil with high fertility.