HY Yu WX Ding JF Luo A Donnison & JB Zhang.Long-term effect of compost and inorganic fertilizer on activities of carbon-cycle enzymes in aggregates of an intensively cultivated sandy loam. Soil Use and Management 2012 28: 347–360.

Abstract

The activities of carbon-cycle enzymes were measured in soil and aggregates to understand compost and inorganic fertilizer amendment effects on soil organic carbon accumulation in an intensively cultivated upland field. Soil samples were collected from a long-term field experiment with seven treatments: compost half-compost N plus half-fertilizer N fertilizer NPK fertilizer NP fertilizer NK fertilizer PK and no fertilizer control. The 18-yr continuous application of compost increased organic C content in soil and three aggregate sizes by 72–124 and 78–234% respectively compared with the control. Fertilization also significantly increased organic C contents in soil macroaggregates and the silt + clay fraction but not in microaggregates. Compost application significantly reduced the specific activities of polyphenol oxidase (activity per unit organic C) in soil and three aggregate sizes compared with control whereas fertilization had a much weaker effect. Compost amendment also significantly lowered the specific activities of invertase in macroaggregates and the silt + clay fraction and this effect was more pronounced than the addition of fertilizer NPK. In contrast inorganic fertilizer and compost application significantly increased the specific activities of cellobiohydrolase in soil macroaggregates and microaggregates (but not in the silt + clay fraction) and xylosidase in microaggregates. The application of fertilizer NPK had a more pronounced effect than compost. We considered that the increase in organic C in compost-amended soil was therefore probably associated with the accumulation of lignocellulose and sucrose in macroaggregates lignocellulose and hemicellulose in microaggregates and lignin (its derivative) and nonstructural carbohydrates in the silt + clay fraction. However the application of fertilizer NPK enhanced organic C probably due to an increase in the content of lignin (its derivative) and sucrose in macroaggregates and the silt + clay fraction. Therefore the application of compost with high lignocellulose should be effective to increase soil organic C in the North China Plain.