Effect of Anaerobic Digestion Temperature and Manure Type on N and S Mineralization

Abstract

ABSTRACT Digested, undigested and green organic amendments were used to improve soil fertility and minimize any harmful effects. To understand the events in soil, we evaluated the nitrogen (N) and sulfur (S) mineralization in soil after adding with cattle manure and green manure. Eleven organic amendments were fresh dairy cattle manure, digested cattle manure with different temperature, green manure digested and undigested. The organic matter mixed soil was 200 mg total N kg−1 soil on dry weight basis, and this rate was equivalent to about 180 kg N/ha. Water was added to each soil sample and was incubated at temperatures 20 ± 2 °C under anaerobic condition. Soil sampling was done at 7-day intervals up to 84 days of the experiment for analysis of available N and S contents. The availability of N and S in all amended soils increased with incubation time showing a maximum mineralization occurring within 84 days for N and 49 days for S then decreased. Soils amended with digested green manure released 169.8 mg N kg−1 during the 84-day incubation. At the end of the incubation, net N mineralization was observed from alfalfa digested treatment as 71.3% of the applied total N. At the end of the incubation (84 days), net S mineralization ranged from 1.75% in Alfalfa digested (T11) to 26.0% in wheat straw (T3) treatment. Significantly lower amounts of S mineralization was observed for the soil treated with different digested cattle slurry and straw condition as compared to undigested cattle manure.