| Recently, global warming is facing mankind being, and agriculture is one of the sourcesof greenhouse gases. Soil CO2emission rate and yield of summer maize were evaluated in afield experiment in the Northwest A&F University, involving tillage: conventional tillage(CT), subsoiling (CP), rotary tillage (RT), and no-tillage (NT) plus straw application: strawreturning (SM) and no-straw returning under a winter wheat/summer corn systems, and theaim was to achieve low power consumption and efficient farming methods. After study, themain conclusions are as follows:1. It showed that soil CO2rate increased first and then decreased during the samplingdays. There are three peaks in soil CO2rate: seedling, jointing, flowering, and grain fillingstage, respectively. And the CO2emission rate was the lowest in maturity stage. It showedthat no-tillage with straw returning, plowing with straw returning, subsoiling tillage withstraw returning and zero tillage can effectively reduce soil CO2rate, especially in no-tillage,the effect is more significant.2. In the summer corn throughout the growing period,0-25cm soil temperature aregrown with maize first and then decreased to minimize harvest maturity, and no-tillagecooling effect is most obvious.The correlation coefficients were in the order of: CP> NT> CP+SM> NT+SM> CT+SM> RT> RT+SM> CT; The moisture content of the soil tillagedecreased first and then increased with the growth of maize, and there was a minimumjointing stage, the highest harvest maturity. Analysis of variance of0-40cm soil moisturecontent showed that under no-tillage, soil moisture had the highest value. There was anegative correlation relationship between soil CO2emission rate and15-20cm soil moisturein CP treatment. The correlation coefficient was-0.944. The correlation coefficient was-0.881in RT+SM treatment; The correlation coefficient was0.811between the soil CO2emission rate and40-60cm of soil organic matter. However, the correlation coefficient was-0.039between the soil CO2emission rate and soil organic matter of0-10cm soil layer. Theorder of correlation coefficient was:40-60>80-100>60-80>10-20>20-40cm; The numbersof soil microbes of were increased by79.36%,53.32%,80.05%and99.48%in CP, CP+SM,RT and RT+SM treatments respectively. However, NT, NT+SM and CT+SM treatments reduced soil microbes by16.39%,13.72%and36.10%, respectively compared with CT. Theorder of correlation coefficient was: total number of microbes> actinomycetes> bacteria.3. CP+SM treatment can significantly improve photosynthetic rate of summer maize,especially in the filling stage. In the filling stage, CP+SM treatment Pn increased by25.53%compared with CT. The ear numbers were increased by4.46%,4.49%,0.42%,8.72%and8.59%in CP, CP+SM, RT, RT+SM and CT+SM respectively, compared with CT. NT, andNT+SM treatments reduced ear numbers by1.06%and0.77%compared with CT. CP andCP+SM treatments significantly increased grains per spike by11.15%and8.14%comparedwith CT, NT+SM, RT, RT+SM and CT+SM treatments reduced grains per spike by0.18%,2.12%,12.21%,1.95%and1.95%, respectively compared with CT. There was nosignificance in100-grain weight among treatments. For the grain yield, RT was lowest, butno significant difference. The CP, CP+SM, NT, NT+SM, RT+SM and CT+SMtreatments increasec yield23.11%,24.35%,7.07%,7.27%,9.01%and9.01%respectively ascompared with CT; There is significant impact on yield-scaled CO2emissions under differenttreatments. Subsoiling tillage and no tillage reduced yield-scaled CO2emissions7.93%and33.54%as compared with moldboard plough tillage. Straw incorporation increasedyield-scaled CO2emissions40.30%as compared with no mulch treatments. |
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