秸秆还田对皖北砂姜黑土团聚体组成及胀缩性的影响OA

To investigate the effects of wheat and maize straw incorporation on the composition and swelling-shrinkage characteristics of lime concretion Shajiang black soil aggregates in the wheat-maize rotation system of northern Anhui province,a long-term field experiment was conducted to provide a scientific basis for improving soil quality and promoting rational utilization of crop residues.Five treatments were conducted:control(CK),chemical fertilizer only(NPK),straw combined with chemical fertilizer(SNPK),straw combined with chemical fertilizer plus 150 kg/hm2 straw decomposer inoculant(SNPK 10),and straw combined with chemical fertilizer plus 300 kg/hm2 straw decomposer inoculant(SNPK20).Undisturbed topsoil samples(0-20 cm)were collected during the maturity stages of both wheat and maize crops.Water-stable aggregates of various size fractions were separated using the wet-sieving method,and the coefficient of linear extensibility(COLE)was determined using the needle-extensometer method.The results indicated that long-term application of straw decomposer inoculants enhanced soil organic carbon levels across the rotation cycle.Compared with the SNPK treatment,SNPK20 treatment increased soil organic carbon by 18.02％in the wheat season and by 55.64％in the maize season.Soil pH showed an increasing trend following straw incorporation.With increasing rates of straw and decomposer inoculant,soil porosity and field capacity increased,while soil bulk density decreased.In SNPK20 treatment,the maximum increases in porosity and field capacity relative to NPK treatment reached 23.35％and 36.09％,respectively,averaged across both cropping seasons.Soil aggregates were primarily composed of the 0.25-2 mm and＞2 mm size fractions.Following straw incorporation,the proportion of 0.25-2 mm aggregates increased by 11.09％-41.25％and 18.02％-24.32％compared to CK in the wheat and maize seasons,respectively.In terms of aggregate stability,SNPK20 treatment increased mean weight diameter(MWD)and geometric mean diameter(GMD)by 15.28％and 30.17％on average,respectively,and reduced fractal dimension by 7.36％on average compared to CK.Furthermore,all straw incorporation treatments reduced soil COLE values.Relative to CK,COLE was reduced by 28.26％-65.22％in SNPK20,SNPK10,and SNPK treatments.COLE exhibited negative correlations with the proportion of＞0.25 mm aggregates,MWD,GMD,soil organic carbon,and porosity,but positive correlations with bulk density and fractal dimension.These findings suggested that integrated application of wheat and maize straws,chemical fertilizers,and straw decomposer inoculants could improve the size distribution and stability of water-stable aggregates,reduce soil swelling-shrinkage potential,enhance effective water retention,and increase soil organic carbon content in Shajiang black soil,demonstrating its potential for sustainable soil management in northern Anhui province.