Measurement of gaseous emission from denitrification of applied nitrogen-15, 3. Field measurements
1995
Avalakki, U.K. (Griffith Univ., Brisbane (Australia). School of Environmental Studies) | Strong, W.M. (Queensland Wheat Research Inst., Toowoomba (Australia)) | Saffigna, P.G. (Griffith Univ., Brisbane (Australia). Graduate School of Environmental Sciences and Engineering)
Field experiments were conducted during autumn and winter (April-July) at 4 locations on Vertisol or Alfisol soils on the Darling Downs of Queensland in 1988 and 1989 to determine 15N losses when soil was saturated after applications of 15N labelled nitrate-N prior to sowing winter cereal crops. Loss estimates for the 6 field sites by accumulating daily gas emissions averaged about 80 percent of that estimated by mass balance. Loss estimates from peak emission measurements were generally closer to that estimated by mass balance. Loss of applied 15N when soils were saturated in April was several-fold more than that lost when soils were saturated in July. Loss of 15N following saturation during July 1988 was similar in magnitude to the quantity of 15N apparently immobilized into soil organic forms. Sorghum residues returned in March, or wheat straw added in December prior to a long period of dry weather, promoted loss of 15N applied prior to soil saturation in April or July. Alternatively, where residues of a previous winter cereal had decomposed considerably, loss of applied 15N was much lower than where sorghum residues had been added prior to saturations in April or July.
显示更多 [+] 显示较少 [-]