Effect of continuous compost application on water-stable soil macroaggregation in a field subjected to double cropping

The influence of continuous application of compost and fertilizer on soil m acroaggregation in a field subjected to long-term (ca. 20 years) double cro pping (rice and barley) was investigated. Soil samples were collected from 4 different plots: a) No-NF, fertilizer containing P and K but no N; b) F, fertilizer containing N, P, and K; c) F+LC, fertilizer plus low rate of com post; and d) FS HC, fertilizer plus high rate of compost. The application o f compost and fertilizer increased the degree of macroaggregation (>0.25 mm ), the contents of organic C, total N, hydrolyzable carbohydrates, and dith ionite-citrate-bicarbonate (DCB) soluble Al, and the hyphal length in the o rder of No-NF<F<F+LC<F+HC plots. The degree of macroaggregation showed high correlation coefficients (r greater than or equal to 0.95) with the conten ts of organic and inorganic components or the hyphal length. Most of these properties were strongly intercorrelated among themselves. The results obta ined in this study suggest that organic matter including polysaccharides, a ctive Al, and hyphae play an important role together in soil macroaggregati on in the field subjected to double cropping under study.