Effects Of Different Depth Of Returning Fields In Different Areas On Decomposition Characteristics Of Maize Straw

Straw decomposition is one of the important factors affecting the effect of returning maize straw to the field.The experiment was carried out in the central and western regions of Jilin Province,each area has two straw burying depths(20cm and 35cm).Studied on the changes of the decomposition rate,decomposition speed,lignin,cellulose and hemicellulose content and release rate of maize straw returned to the field at the same buried depth in different areas and at different buried depths in the same area within 120 days.Clarified the changes of the decomposition rate and decomposition speed with the returning time in the process of maize straw decomposition and the interaction mechanism of lignin,cellulose and hemicellulose on maize straw decomposition.The results were as follow:(1)The four treatments of maize straw showed a tendency to decomposition from fast to slow and then to stagnation.Under different buried depths in the same area,the decomposition rate of maize straw treatment with a depth of 20 cm was always higher than that with a depth of35 cm.The straw decomposition speed at the early stage of returning straw to the depth of 20 cm was much higher than that of the treatment at the depth of 35 cm,the straw decomposition speed at the depth of 35 cm in the middle and later stages of returning straw was slightly higher than that at the depth of 20 cm.The effects of different straw buried depths on the decomposition of maize straw were significant in a short time,but the impact was not significant in a long time.Under the same buried depth in different area,there was no significant difference between the Songyuan area and the Changchun area when treatment at a depth of 20cm;in the 35 cm buried depth treatment,the straw decomposition rate in Songyuan area was generally higher than that in Changchun treatment.(2)The changes of lignin,cellulose and hemicellulose contents and release rate in the maize straw returned from the four treatments were almost the same.After the straw was returned to the farmland,the lignin content first increased,then decreased,and then slightly increased;lignin began to release after the straw was returned to the farmland for 40 days,the release speed increased sharply,and then slowed down to stagnation.The content of cellulose continuously decreased;the release of cellulose was fast,then slow,and then tended to stagnation.The hemicellulose content decreased and then increased,and the final cellulose content in the straw was slightly lower than the initial straw cellulose content;the release of hemicellulose was fast,then slow,and then tended to stagnation.(3)The lignin content in the straw was more than the cellulose content about 30 days after the straw was returned to the farmland,and the lignin content in the straw was more than the hemicellulose content about 20 days after the straw was returned to the farmland.Hemicellulose content was more than cellulose content about 70 days after straw returned to the field.Lingin,cellulose and hemicellulose in maize straw accounted for about 70%of the weight.When the straw was returned to the farmland for 50 days,its content ratio exceeded 90%,and then fell to about 80%.The decomposition constant k,lignin release rate,cellulose release rate,and hemicellulose release rate of two different deepth treatments in Songyuan and Changchun areas were significantly correlated with each other at p <0.01 level.