Effect of straw mulching and fertilization on soil respiration from summer-maize farmland during later growth period in Guanzhong irrigation district

Soil respiration is one of the key factors of affecting global scale carbon cycle at farmland levels,and the impact can not be ignored to global atmospheric carbon dioxide concentration.Previous studies showed that soil respiration was closely related with tillage and fertilization of farmland,but the research was less about straw mulching and fertilization effects on soil respiration under no-till conditions.In this study,GXH-3010E1 type portable infrared analyzer was used to measure the soil CO2 emission rate and field experiment was taken to explore the impact of straw mulching and nitrogen fertilizer on soil respiration and the sensitivity of soil respiration to heat and water factors under no-tillage conditions in Guanzhong irrigation area.The result showed that under summer maize(Zea mays L.) no straw mulching no fertilization,nitrogen fertilizer,straw mulching,straw mulching + nitrogen fertilizer and summer fallow treatments soil respiration rate had obvious laws and was downward on the whole from August 9th to September 25th,and soil respiration rate peak appeared in the heading period.Average soil respiration rate was nitrogen fertilizer(7.78 μmol.m-2.s-1) straw mulching + nitrogen fertilizer(6.06 μmol.m-2.s-1) no straw mulching no fertilization(4.81 μmol.m-2.s-1) straw mulching(4.68 μmol.m-2.s-1) summer fallow(2.46 μmol.m-2.s-1).Nitrogen fertilizer significantly increased soil respiration rate.Processing of nitrogen fertilizer than without fertilization and no straw mulching processing increased by 61.75%,and straw mulching + nitrogen fertilizer treatment compared to straw mulch treatment increased 29.49%.Straw mulching could reduce soil respiration.Straw mulching + nitrogen fertilizer treatment than the nitrogen fertilizer treatment decreased 22.11%,and straw mulching processing than less coverage and no fertilization treatment decreased 2.70%.Soil respiration rate had the maximum correlation with 5 cm soil temperature under no straw mulching no fertilization,straw mulching + nitrogen fertilizer and summer fallow,and with 10 cm and 15 cm soil temperature under straw mulching and nitrogen fertilizer,respectively.Soil moisture had significant effects on soil respiration rate(P 0.05) under straw mulching at all tillage layers.The study showed that straw mulching and nitrogen fertilization had important effects on soil respiration,and nitrogen fertilization could increase the greenhouse effect,but straw mulching could alleviate the greenhouse effect.