Effects of varying static and changing moisture contents during incubation on ammonia and nitrate levels in soil

Abstract

The effects of varying static and changing moisture contents on mineralization of nitrogen after incubation (28° C.) for 3, 6 and 12 weeks were studied.Mineral-nitrogen, accounted for entirely by nitrate, increased with increasing static moisture content up to 40-50% water-holding capacity (W.H.C). With further increasing moisture up to waterlogging, both mineral-nitrogen and nitrate decreased, the latter to negative values, indicating disappearance of nitrate originally present in the soil. Ammonia accumulated only at moisture contents above 50 % W.H.C. and its extent of accumulation increased with moisture content.When soils with moisture contents of 10-50% W.H.C. during an initial 6-week period were changed to waterlogging for a second 6-week period, mineralnitrogen and nitrate accumulation decreased with increasing initial moisture in comparison with soils left at initial moisture contents for the second period.