| Under the wheat corn rotation, this paper studies the effects of different organic materials on homestead reclaimed soil organic carbon and labile organic carbon, aiming at the large number and uneconomical use of agricultural organic materials, shortage of cultivated land quantity and the low quantity and quality of the reclaimed land in China. The aim was to provide data support for the work of land reclamation in Chengdu plain. Eight treatments were designed including control ?no fertilizer and organic material, CK?, chemical fertilizer only ?CF?, straw with chemical fertilizer for the total amount of CF ?SCF?,150% total amount of CF that is equivalent to 150% quantity of straw returning with chemical fertilize ?SCF+?, fungal residue with chemical fertilizer for the total amount of CF ?FCF?,150% total amount of CF that is equivalent to 150% quantity of fungal returning with chemical fertilize ?FCF+?, pig manure with chemical fertilizer for the total amount of CF ?MCF? and 150% total amount of CF that is equivalent to 150% quantity of pig manure returning with chemical fertilize ?MCF+?. We mainly study the concentrations dynamics of soil total organic carbon ?TOC?, permanganate oxidizable soil organic carbon ?POXC?, dissolved soil organic carbon ?DOC? and soil microbial biomass carbon ?MBC?. The main research results were as follow:?1? In comparison with CK and CF, organic material treatments can significantly increase the content of soil POXC in 0-40cm soil horizon ?P<0.05?. However, there was no significant difference between the different proportions of the same material returned to the field. In the first year of reclamation, organic material treatments were -5.28%-40.93% higher than CK. In the second year of reclamation, the content of POXC had slowly showed significant difference under different organic material treatments. Returning treatments of straw, fungal residue and pig manure were 18.13%-52.95%,26.75%-58.51% and 18.02%-43.34% higher than before fertilizing when reclamation had completed, respectively. However, there was no significant difference in the reclamation period between the different proportions of the same material returned to the field ?P>0.05?. The effect of organic material treatments on soil POXC in TOC percentage ?POXC/TOC? percentage varies as soil depth varies. In the first year of reclamation, the value of POXC/TOC under FCF+ was highest among the 8 treatments in 0-20 cm; and there was no significant difference in the value of POXC/TOC under organic material treatments in 20-40 cm. In the second year of reclamation, the increase of POXC/TOC under FCF+ was 24.56%?0-20 cm? and 45.30%?20-40 cm? compared to the soil before the experiment.?2? The content of DOC showed a decreasing trend during whole growing period in surface soil and a decrease before rising in 20-40 cm, generally. Compared with surface soil, the content of DOC decreased by 17.06% and 31.68% in first and second year respectively. In second year, the variation range of soil DOC was -17.60%-11.12% in surface soil and -19.19%-47.30% in 20-40 cm. Treatment of organic materials was significantly higher than that of CK and CF treatment. Organic material treatments can significantly increase the content of soil DOC in 0-40cm soil horizon ?P<0.05?. FCF+ treatment showed the greatest increase in the two soil layers. It was higher than the treatment of straw and pig manure by 12.45%-49.21%.The effect of organic material with chemical fertilizer on the percentage of DOC/TOC in different soil layers was different. The percentage of DOC/TOC increased at first, followed by a decrease before another increase in surface soil. Its range of variation was 0.52%-0.90%. Besides, the percentage of DOC/TOC decreased and a decrease before rising to achieve stability in 20-40 cm and the range of variation was 0.47%-1.14%. The FCF+ showed the greatest increase in both two soil layers.?3? The accumulation of soil MBC content in 0-40cm soil horizon is beneficial to the organic material treatment. FCF+ had the largest increase in two soil horizon. Compared with surface soil, the content of MBC decreased by 54.80% and 53.19% in first and second year respectively. In second year, the rate of increase of MBC was 20.23%-95.41% in 0-20 cm and 59.91%-149.93% in 20-40 cm. The FCF+ has the highest growth rate.The effect of organic material on microbial quotient ?MBC/TOC? in different soil layers was different. Microbial quotient showed a gradual upward trend under all of the 8 treatments in first year. Compared with CK, soil microbial quotient of 6 organic material treatments increased by 23.58%-74.70%. In second year, all treatments microbial quotient showed a gradual increase followed by a slight decline on surface soil and slow decline in 20-40 cm. Compared with the soil before the experiment, six organic materials increased by 59.68%-85.88%?surface layer? and 100.56%-129.88%?20-40 cm?, which FCF+?surface layer? and FCF treatment ?20-40 cm soil layer? have the greatest increase.?4? The content of TOC in soil of different soil layers showed a rising trend with different treatments. However, the TOC concentrations in different treatments showed no significant ?P>0.05? difference. TOC incremental is 0.24-0.28g kg-1 ?surface layer? and 0.23-0.29 g kg-1 ?20-40 cm? for six organic materials. POXC, MBC, DOC and TOC have a significant positive correlation while MBC and other carbon-related components have a better correlation. |
PDF Full Text Request