稻草易地还土对丘陵红壤团聚体碳氮分布的影响

利用新垦坡地、熟化旱地两个定位试验的典型处理(不施肥、化肥、稻草 NP),研究稻草易地还土对丘陵红壤水稳定性大团聚体(>0.25 mm)内碳、氮分布的影响。结果表明,稻草易地还土提高了土壤大团聚体含量;团聚体粒径越大,有机碳和全氮的含量越高;与对照相比,稻草易地还土提高大团聚体内的有机碳含量10.1%~78.5%、全氮含量9.4%~63.6%(p<0.05),同时也显著提高二者在较大粒径(1~2 mm,2~5 mm)团聚体内的分配比例;与化肥处理相比,稻草易地还土提高>0.5 mm各粒级大团聚体内的有机碳含量6.5%~46.1%,也提高了0.5~1 mm,1~2 mm,2~5 mm团聚体内的全氮含量8.7%~16.1%(p<0.05)。水稳定性大团聚体对土壤碳、氮具有强富集和物理保护作用;稻草易地还土提高水稳定性大团聚体内碳、氮的含量和分配比例,是改良丘陵红壤结构、提高并协调土壤肥力的有效保育措施。

Effects of Ex Situ Incorporation of Straw on Distributions of C and N in Aggregates of Hilly Red Soils

Two experiments in newly-culltivated slope land and upland with three treatments,Nil(CK),NPK(NPK),Straw NP(SNP),were selected to analyze the effects of ex situ rice straw incorporation on the distribution of organic carbon and nitrogen in water-stable macro-aggregates of hilly red soils.Results showed that,ex situ incorporation of straw increased water-stable macro-aggregates and the concentrations of organic carbon and nitrogen increased with increase of water-stable aggregate-size;ex situ incorporation of straw significantly increased the concentrations of organic carbon and nitrogen in water-stable macro-aggregates by 10.1%~78.5% and 9.4%~63.6%(p<0.05),and also increased the ratios of organic carbon and nitrogen in water-stable macro-aggregates(2~5 mm or 1~2 mm) to soil;Compared to inorganic fertilizer,ex situ incorporation of straw significantly increased the concentrations of organic carbon by 6.5%~46.1% in 0.5~1 mm,1~2 mm,2~5 mm,>5 mm water-stable aggregates and nitrogen by 8.7%~16.1% in 0.5~1 mm,1~2 mm,2~5 mm water-stable aggregates.Water-stable macro-aggregates have high potential to accumulate organic C and N,and ex situ incorporation of straw increased the concentrations and distributions of organic C and total N in water-stable macro-aggregates,which increased the ability of regulating soil fertility.Therefore,ex situ incorporation of straw was effective measure to improve soil structure,enhance and regulate soil fertility in hilly red soils.