稻草不同途径还田对土壤结构及有机质特征的影响

通过3年的田间定位试验,系统的研究了稻草不同途径还田对稻田土壤容重、孔隙度、团聚体、有机碳总量、腐殖质组成及腐殖质结合形态的影响。结果表明,与无肥(CK)及纯施化肥(NPK)对照相比,稻草直接深埋还田(NPK+S)及利用后的菌渣、牛粪、沼渣深埋还田(NPK+FD、NPK+CD、NPK+BD)均能一定程度的降低土壤容重、增加孔隙度、增加>0.25 mm水稳性团聚体的数量和提高土壤团聚体的稳定性,有利于形成和保持良好的土壤结构;同时能提高土壤腐殖质中胡敏酸含量和HA/FA比值,增加松结态腐殖质含量和提高松/紧腐殖质比值,能一定程度的改善土壤腐殖质的组成、性质及结合形态,提高腐殖质品质,不过这4个处理间的差异不明显。稻草焚烧还田(NPK+S′)在以上方面效果均不显著,且带来严重的大气污染,并不可取。

Effects of Different Modes of Straw Returning on Soil Structure and Character of Soil Organic Matter

A three-year field experiment was carried out to study the effects of different modes of straw returning on soil structure and character of soil organic matter in Hunan Province,China.The experiment included seven treatments:zero fertilization(CK),chemical fertilizers alone(NPK),combined application of straw and chemical fertilizer(NPK+S),combined application of fungus dregs and chemical fertilizer(NPK+FD),combined application of cattle dejecta and chemical fertilizer(NPK+CD),combined application of biogas dregs and chemical fertilizer(NPK+BD),combined application of straw ash and chemical fertilizer(NPK+S′).The main results were as follows.Compared with CK and NPK treatment,the soil porosity and >0.25 mm water-stable aggregate content and stability of soil aggregate were increased while the soil bulk density were decreased,and the contents of the humic acid and loosely combined humus were increased,and the ratios of HA/FA and loosely combined humus/tightly combined humus were also increased in the four organic matter application treatments.It meant that the four modes of straw returning were beneficial to the maintenance of good soil structure and the improvement of the composition and properties and combined forms of humus of phaeozem,but the differences among the four organic matter application treatments were not significant.But the effects of combined application of straw ash and chemical fertilizer were much worse than other returning modes,and burning straw produces serious environmental potential threat,so it was suggested that the mode of straw burning should not be adopted in the crop planting.