Evolution Characteristics Of Soil Organic Carbon And Total Nitrogen And Components In Yellow Paddy Soil Under Long-term Fertilizations

To discover the evolution characteristics of yellow paddy soil organic carbon( SOC) and total nitrogen(TN) and Components under different long-term fertilization treatments, and reveal the relationship between soil fertilization and carbon sequestration and nitrogen supply, to provide the theoretical basis for rational fertilization. This study is based on the long-term experiment in guizhou yellow ecosystem in the 1990 s established, The treatments included: no fertilizer control(CK), organic manure(M), chemical fertilizer(NPK), low application rate of manure combined with chemical fertilizer(0.5MNPK) and high application rate of manure combined with chemical fertilizer(MNPK), used soil physico-chemical fractionation procedure, explore the evolution characteristics of soil organic carbon and nitrogen and Components in yellow paddy field with long-term fertilization. The main results and conclusions were as follows:(1)Compared with no fertilizer treatments(CK), the treatments of high application rate of manure combined with chemical fertilizer(MNPK) ?organic manure(M) and low application rate of manure combined with chemical fertilizer(0.5MNPK) could significantly increased soil organic carbon. Applying organic fertilizer soil organic carbon content was significantly higher than chemical fertilizer. The yellow paddy soil SOC contents showed significant linear increasing trends from 2006 to 2014. M and MNPK processing organic carbon With an average annual 0.71 g / kg and 0.63 g / kg of rate increases, And reached the significant level. Under long-term different fertilization treatments, unprotected organic carbon accounted for the largest proportion of total organic carbon, 54% to 66%. For each Fraction content, Except CK treatment of soil unprotected organic carbon content was significantly decreased, All the other treatments Fractions in everywhere on the rise, Which MNPK and M processing Unprotected organic carbon content increased most significantly. For the content of hysically-protected and chemically-protected organic carbon fractions under long-term fertilization, all treatments were tested significant overall upward trend. But CK and NPK treatment effect on the fraction content is relatively slow, Only 0.5MNPK and MNPK treatment of soil biochemically-protected organic carbon fraction increased significantly. On the relationship of soil organic carbon, Different fractions of organic carbon and total organic carbon was significantly positive correlation.(2)Compared with(CK), except the NPK treatment under different fertilizer treatments other soil total organic nitrogen content has increased significantly, The rate of increase between 0.5% to 41%.Compared With the test at the beginning of the initial soil organic nitrogen containing amount(1.76 g/kg), Soil organic nitrogen content of each processing also have increased. Except(CK) treatment, each other treatment of yellow paddy soil organic nitrogen contents showed significant linear increasing trends from 2006 to 2014. Overall effect on organic nitrogen content, MNPK(0.80g/kg)>M(0.74g/kg)>0.5MNPK(0.45g/kg). The largest fraction of the total organic nitrogen ratio is Unprotected organic nitrogen. Compared with CK, after nine years of long-term fertilization treatment, the all Unprotected organic nitrogen fractions of fertilizer processing have increased significantly, And the other fractions content changed little,Although some fractions have a small increase, but not significant.Overall seen MNPK processing fractions of organic nitrogen average annual rate of increase was significantly higher than other treatments, illustrate that the treatments of high application rate of manure combined with chemical fertilizer can increase soil organic nitrogen content of fractions than each other fertilization treatments. On the relationship of soil organic nitrogen, different fractions of organic nitrogen and total organic nitrogen was significantly positive correlation. This shows that the fractions of organic nitrogen and total organic nitrogen are closely related, and will change with the content of soil total organic nitrogen.Generally, the data indicated that the high application rate of manure combined with chemical fertilizer is the most effective practice for increasing the soil organic carbon and organic nitrogen content?...