施肥对红壤性水稻土颗粒有机物形成及团聚体稳定性的影响

土壤颗粒有机物 (POM)是土壤有机碳库中活动性较大的碳库。POM的形成对提高土壤碳库和缓解大气CO2 的升高具有重要意义。POM的形成与土壤团聚体的形成和性质密切相关 ,且深受土地利用和土壤管理的影响。实验土壤采自江西省红壤研究所无机肥长期定位试验地 ,各施肥处理为 :CK(不施肥 )、NPK(施氮磷钾肥 )、NPK(=) (施双倍氮磷钾肥 )和NPK OM(施氮磷钾肥和猪粪处理 )。研究发现 :施肥显著地增加了水稻土POM的含量 ;随着化肥施肥量和有机肥的增加 ,POM含量增加 ,NPK、NPK(=)和NPK OM处理的POM含量比CK分别增加了 1 1～ 1 3倍、1 2～ 1 4倍和 1 5～ 1 9倍 ;施肥也提高了土壤团聚体稳定性 ,表现为NPK OM >NPK(=) >NPK >CK ;各处理POM含量随土壤团聚体粒级的减小而增加 ,其C/N比为降低趋势 ;团聚体稳定性与POM含量呈极显著关系 (r=0 98,p <0 0 1)。研究结果说明施肥导致POM碳库的增加是因为有机物投入的增加以及水稻土大团聚体的形成

EFFECTS OF FERTILIZATION ON PARTICULATE ORGANIC MATTER FORMATION AND AGGREGATE STABILITY IN PADDY SOIL

Particulate organic matter (POM), as an active pool of soil organic carbon, play an important role in C sequestration in cultivated soil.Formation of POM is related to aggregate format ion and sensitive to land use and soil management.The objectives of this study are (1) to determine effects of fertilization on POM content in paddy soil;(2) to determine effect of fertilization on formation and stability of aggregates;and (3) to clarify relationship between POM and aggregate stability.Soil samples were collected from the experiment fields of the long-term fertilization experiment station treated separately with CK (without fertilization), NPK (chemical N, P, K fert ilizers), NPK(=) (double the dose in Treatment NPK) and NPK + OM (NPK plus farmyard organic manure).The results showed that fertilization increased significantly the content of POM in the soil.In Treatments NPK, NPK(=) and NPK+ OM, it increased by 1.1~1.3, 1.2~1.4 and 1.5~1.9 t imes over that in CK and in Treatment NPK+ OM it was 37%~71% higher than that in Treatments NPK and NPK(=).The C/N ratio decreased with the increase in aggregate size, suggesting that the POM in smaller aggregates was older than in larger ones.In terms of aggregate stability, the treatments were in a decreasing order of NPK+ OM> NPK(=) > NPK> CK.The aggregate stability had a very significant linear correlation with POM (r = 0.98, p < 0.01).These results suggest that fertilization increased POM level due to increased input of organic materials into soil, thus enhancing soil aggregation.