Microbial responses to organic and inorganic amendments in eroded soil

The objectives of this study were to determine the changes in microbial biomass carbon, litter decomposition, microbial abundance and the soil's physical and chemical properties after poultry manure and inorganic fertilizer application in soil‐eroded areas. Four plots measuring 10 m × 10 m, located on approximately the same slope, were established in the study area. Plot 1 (P1) was an eroded plot without any treatment; Plot 2 (P2) was treated with poultry manure (N:P:K ratio of 1:0.8:0·39); Plot 3 (P3) was treated with inorganic mineral fertilizer (NPK 10:10:10); and Plot 4 (P4) was an undisturbed area (no erosion occurred). The one‐time amendments used in this study significantly increased the soil's water‐holding capacity, pH, and the total carbon and nitrogen content, but soil moisture content was not influenced by any amendment. The biomass carbon was increased 3·2‐ and 2·9‐times by the poultry manure and the NPK fertilizer amendments respectively, but the values did not reach the same level as the undisturbed area. The Gram‐positive and Gram‐negative bacteria, fungi, actinomycetes, cellulase‐producers and amylase‐producers responded positively to the additives, which was shown by an abrupt increase in their abundance. Microbial biomass carbon and abundance were shown to be closely correlated with the soil's carbon and nitrogen content. None of the amendments, on the other hand, affected the rate of litter decomposition. Copyright © 2006 John Wiley & Sons, Ltd.