基于长期定位试验的松嫩平原还田玉米秸秆腐解特征研究

为了研究松嫩平原还田玉米秸秆的腐解特征和养分释放规律,该试验采用尼龙网袋法,设置埋土和覆盖地表2种玉米秸秆还田方式,进行连续4 a的定位观测。结果表明:1)还田玉米秸秆的腐解速率和养分释放率都表现为埋土处理大于覆盖地表。秸秆腐解主要集中在还田的前3年,3 a累计腐解率达到91.70%和81.96%,其中第1年腐解率分别为60.63%和45.53%。2)还田玉米秸秆中养分释放的快慢顺序为KPCN。埋土和覆盖处理秸秆中钾的释放主要在还田第1年,释放率达到了96.26%和84.04%;而磷、碳和氮的释放则主要集中在还田前3年,其中磷释放率为92.03%和83.29%;碳释放率为90.96%和82.06%;氮释放率为91.70%和81.96%。3)还田玉米秸秆中半纤维素的腐解速度快于纤维素,木质素最慢。其中埋土和覆盖处理秸秆半纤维素2 a腐解率为88.78%和86.30%;纤维素2 a腐解率为80.42%和70.86%;而木质素3 a累计腐解率为78.63%和66.48%。

Decomposing characteristics of maize straw returning in Songnen Plain in long-time located experiment

Abstract: The Songnen Plain is located in the provinces of Heilongjiang and Jilin, and which is an important spring maize producing area in China. Excess maize straw resource causes large amounts of straw to be burned in the open air, which causes serious environmental pollution. Straw returning can not only solve the problem of environmental pollution caused by incineration of straw, but also return various nutrient elements contained in straw to the soil and increase the supply of soil nutrients. The straw returning is the development direction of maize production. It has great significance to study the characteristics of maize straw decomposition and nutrient release. The nylon bag method was used, the size of the nylon mesh bag was 34 cm×36 cm and the aperture was 80 mesh. The maize straw was crushed and cut into 5 to 10 cm segments after drying, 80 g of the maize straw were put into a nylon net bag and sealed with a nylon thread. The experiment set up two maize straw returning methods: buried and covered ground, with located observation for four years, both treatment fields were planted with maize in no-tillage manner. In the buried soil treatment, the nylon mesh bag was buried vertically in the ridge body, and the upper end of the mesh bag was level with the ground surface, which was basically the same as the depth of the mixed straw in the production field. The covered treatment was to lay the nylon mesh bag in the ditch, fixed with iron wire. The results showed that: 1) The maize straw decomposition rate and nutrient release rate in buried treatment were higher than that of covered treatment. The decomposition of straw was mainly concentrated in the first three years of returning to the soil, with the fastest decomposition rate in the first year, the total decomposition rate of buried and covered straw reached 60.63% and 45.53%, and the three-year decomposition rate was 91.70% and 81.96%. 2) The order of nutrient release in maize straw was K>P>C>N. For buried and covered treatment, in the first year of returning to the soil, the K release rate reached 96.26% and 84.04%, respectively; In the first year, the release rate of P was 61.63% and 54.30%, and the release rate of P of three-year was 92.03% and 83.29%; In the first year, the release rate of C was 57.58% and 45.32%, and the release rate of C of three-year was 90.96% and 82.06%; In the first year, the release rate of N was 52.65% and 41.33%, and the release rate of N of three-year was 91.70% and 81.96%. 3) The decomposition rate of hemicellulose in maize straws was faster than cellulose, and the lignin was the slowest. Among them, the hemicellulose decomposed rate of buried and covered straw was 73.70% and 54.72% in the first year and 88.78% and 86.30% of two-year, respectively; Cellulose was 59.29% and 45.31% in the first year and 80.42% and 70.86% of two-year, respectively; Lignin was 28.10% and 23.65% in the first year and 46.64% and 40.65% in two-year and 78.63% and 66.48% of three-year, respectively.