连续施肥20年后棕壤团聚体分布和碳储量变化

利用两种不同分离方法(干筛法与湿筛法)对耕作施肥20年后棕壤的团聚体组成、团聚体有机碳含量以及有机碳储量进行了研究。结果表明:棕壤团聚体以0.25～1mm团聚体为主。与长期不施肥比较,除0.25～1mm粒级外长期施用氮磷化肥使风干团聚体和水稳性团聚体中较大团聚体和微团聚体数量下降,降低了各级风干团聚体中有机碳积累,增加了水稳性团聚体中有机碳积累;长期施用有机肥较大团聚体和微团聚体数量增加及其相连的有机碳含量和储量均增加;长期有机无机肥配施大团聚体数量下降,微团聚体数量增加,有机碳含量均增加,大团聚体碳库储量下降,微团聚体碳库储量增加。由此可见长期施有机肥土壤结构改善,固C潜力增加。长期高量有机肥与无机肥配施可能有利于土壤固碳,但不利于作物生长。

Soil Aggregation and Carbon Storage in Brown Earth After 20-Years of Fertilization

The objectives of this study were to investigate the impacts of long-term fertilization on soil organic carbon (SOC) sequestration and on distribution within aggregate-size fractions in Brown earth after 20-year of treatment imposition. Soil samples were collected (0 to 20 cm depth) from the field treatments and separated into five aggregate-size classes (>2, 1-2,0.25-1, 0.05-0.25, and <0.05mm) by wet sieving and dry sieving. In all the treatments aggregate size distributions were dominated by 0.25-1mm.Continuous application of mineral fertilizer(N2P1) significantly reduced larger macroaggregate and microaggregate except 0.25-1mm in dry aggregates and water-stable aggregates compared with control(CK). Long-term N2P1 application reduced the C accumulation in dry aggregates and increased the C accumulation in water-stable aggregates.Long-term impacts of application of high manure included a greater proportion of larger macroaggregate, microaggregate and increased SOC concentration associated with aggregates. Long-term application of N2P1 plus high manure caused the loss of macroaggregates and SOC storage associated with microaggregates, but increased macroaggregates and SOC storage associated with microaggregates.Long-term high manure application improved soil structure and enhanced soil C sequestration.