Nitrogen Loss in Gaseous Form from Soils as Influenced by Fertilizers and Management

Abstract

AbstractThe experiments reported here were aimed to ascertain the magnitude of gaseous loss of nitrogen in Spencer silt loam under greenhouse conditions, as affected by pH, form of nitrogenous fertilizer, energy material, and cropping. Four additions of 150 ppm. nitrogen each were made to both cropped and uncropped soils; four successive oat crops were grown on the former.At field moisture levels large volatile losses of nitrogen occurred from the uncropped soil regardless of treatment. Over an 11‐month period these losses ranged from 35% in the soil at pH 5.5 amended with straw and nitrogen as (NH4)2SO4 to 72% in the soil at pH 6.5 with (NH4)2SO4 but no straw. In soils similarly treated and subsequently cropped with oats, the losses were between 7 to 8%.In other experiments the levels of NO3, NH4, and total N in the uncropped Spencer silt loam at pH 6.5 were measured 8 times during a 1‐year period. Irrespective of the form of nitrogen added, presence or absence of straw, and whether liming occurred at the time of fertilization or 12 weeks earlier, the greatest decrease in total nitrogen occurred during the first 6 weeks after fertilization and thereafter remained more or less constant over the year. Approximately one‐half of the 300 ppm. nitrogen added was volatilized from the soil under each treatment. Concurrent increases in nitrate nitrogen levels occurred without exception.