A Study On Daily Change Of Soil Respiration Rate Under Different Land-use Types At The Middle Hill In Sichuan Basin

We used the soil respiration apparatus of Li-8100 to measure the daily change of soil respiration rate under different land-use types at the middle hill in Sichuan Basin.In the meantime,we measured the 10 cm soil temperature under ground,surface temperature,air temperature,soil moisture of 0-10 cm,relative humidity of atmosphere,organic carbon of 0-10 cm soil,total nitrogen of 0-10 cm soil,C/N,heavy metal and volume-weight.We want to recognize the diurnal variation difference of soil respiration rate under different land-use types.The relation between soil respiration rate and environmental factors was analysed more.The soil respiration rate of three land-use types(garden plot,Arable land and wasteland)present peak valley fiuctuation in the days.The soil respiration rate of three land-use types were very significantly different.The size relationship present the wasteland(4.76±0.800 ?mol/m2·s),the arable land(2.88±0.336?mol/m2·s),the garden plot(1.96±0.300?mol/m2·s),in turn.That the soil respiration rates of three land-use types(garden plot,Arable land and wasteland)reach the peak time were 9:00-11:00,15:00-17:00,13:00-15:00 in local area.That the soil respiration rates of three land-use types(garden plot,Arable land and wasteland)reach the valley time were 5:00-7:00,7:00-9:00,5:00-7:00in local area.The range ability of diurnal courses of soil respiration rate was in the garden plot(67.86%),followed by wasteland(62.39%),and the lowest was in Arable land(42.36%).The soil respiration rate of garden plot,Arable land and wasteland by day was 22 percent,8 percent,24 percent higher than that by night.Among the 10 cm soil temperature and soil respiration rates was the highest correlation at the air temperature 0cm,10 cm soil temperature.The 0-10 cm soil moisture content of Arable land and garden plot with the soil respiration rates was a significant correlation(P<0.05);the0-10 cm soil moisture content of wasteland with the respiration rates was a highly significant correlation(P<0.01).The atmospheric moisture and the respiration rates of soil was a negative correlation.In this study,it chose Exponential model to reflect the changing trend of soil respiration rate by the temperature.Before the rain in garden,Q10 of soil respiration rate were: Arable land> garden plot> wasteland.Compared with single factor model,the water hot composite model can better simulate the relation of temperature,moisture and soil respiration rate.In this study,it selected the binary linear model and interaction model to fit the relationship of soil temperature,moisture and soil respiration rate,compared with the single factor model,both improving their performances.The fitting effect of binary linear model is better.At the three kinds of land-use types,the order of soil organic carbon,total nitrogen,C/N were garden plot> wasteland>arable land.The soil organic carbon,total nitrogen,C/N of arable land and wasteland is the same order of size when compared with the soil respiration rate.In addition to the content of Zn in garden reach Level 2 standard,the other is the Level 1 standard.In experimental area,heavy metal content of soil basically keep in the natural background value level,did not receive the pollution level.The heavy metal content and soil respiration rate are not significant correlation.