Can biochar provide ammonium and nitrate to poor soils?. Soil column incubation

Abstract

Understanding how nitrogen concentrations respond to biochar amendment in different types of soils is important for agricultural management. Here, we analyzed the effects of amendment with rice hull biochar on sandy soil, red soil, and alkaline soil (coastal solonchak) over 13 months, focusing on factors such as ammonium (NH4+-N) and nitrate (NO3−-N) cumulative leachate losses, pH, cumulative volumes of leachates, NH4+-N and NO3−-N abundance of soils, soil dehydrogenase, and nitrogen-related soil enzyme activities. Our results indicated that biochar amendment increased the pH of red soil but decreased the pH of both sandy and coastal solonchak soils; promoted the retention of NH4+-N in red and sandy soils, but not in coastal solonchak; and reduced the loss of NO3−-N during the early stages of leaching but accelerated losses during subsequent leaching stages. Soil nitrogen supply capacity (NH4+-N + NO3−-N) greatly increased over the short term, with significant differences between treatments. Further, biochar enhanced concentrations of NH4+-N and NO3−-N in soils, and the addition of biochar stimulated the enzymatic and microbial activities in soil, which may increase the abundance of NH4+-N and NO3−-N. Finally, we found that the response of NH4+-N and NO3−-N to biochar addition varied among the different soil types.