Effects of Long-term Fertilization and Plastic-mulching on the Stability and Organic Carbon Contents of Brown Soil Aggregates
In this study,we examined the effects of fertilization and plastic-film mulching on aggregate stability and organic C in aggregates of a brown soil based on a long-term (29 years) field experiment.Fertilization treatments included application of manure (M4),application of nitrogen (N4),combined application of manure and nitrogen (M2N2),combined application of nitrogen and phosphorus (N4P2),combined application of manure,nitrogen and phosphorus(M4N2P1),and no fertilization(CK).Each treatment was either carried out alone or combined with plastic-film mulching.Results showed that long-term fertilization significantly increased the percentage of ＞2 mm aggregates while significantly decreased that of 0.25～2 mm aggregates when there was no film mulching,especially under application of manure as well as under application of nitrogen and phosphorus.Manure treatments(M4,M2N2,M4N2P1) significantly increased soil organic C in all aggregates without film mulching.Application of manure alone also significantly increased the mean weight diameter of soil aggregates without film mulching.These results suggested that long-term manure application increased organic C sequestration in soil aggregates as well as aggregate stability.The fertilization treatment also significantly affected the stability of soil aggregates and the contents of organic C when there was film mulching,and compared with the control,only the high amount of manure(M4 and M4N2P1) treatment could significantly increase the average weight diameter of soil aggregates and the organic C contents of aggregates at all levels.These results suggested that in the film mulching,the need to put more organic matter in order to maintain the stability of soil aggregates and higher organic C contents.The effects of nitrogen and phosphorus fertilizers could significantly improve the average weight diameter of soil aggregates in differentfertilizations and film treatments,but the effects on the organic carbon contents of aggregates were significantly decreased or not significant.Water-stable large aggregates are the main carriers of soil organic C in soil treatments,the application of manure,organic and inorganic combination is beneficial to promote the formation of water-stable aggregates and increase the organic C contents and it is an effective measure to improve the soil aggregate structure and maintain and improve the soil fertility of brown soil.
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维普
