Application of anhydrous ammonia or urea during the fallow period for winter cereals on the Darling Downs, Queensland, 2. The recovery of 15N by wheat and sorghum in soil and plant at harvest
1992
Strong, W.M. | Cooper, J.E. (Queensland Dept. of Primary Industries, Toowoomba (Australia). Queensland Wheat Research Inst.) | Saffigna, P.G. | Cogle, A.L. (Griffith Univ., Nathan (Australia). School of Australian Environmental Studies)
In field experiments, soil fertilized in February generally had a lower mineral-N content at sowing than soil fertilized in May. Deeper application (17 cm) in February did not increase soil mineral-N content to 0.2 m depth in May but addition of nitrification inhibitor (N-serve) did at one site where it appeared to slow the movement of mineral N into the subsoil (0.2-0.4 m). Recovery of 15N by wheat, sown at 2 sites in June, showed that neither fertilizer management practice, application depth nor N-serve affected 15N recovery. Total recovery of 15N in soil and plant after wheat harvest was lower (about 74 percent) for February-application than for May-application (greater than 94 percent). Similarly, total 15N recovery after sorghum was lower the earlier the fertilizer was applied. Use of N-serve with the fertilizer application had no effect in conserving 15N applied for wheat or sorghum. However, deeper (17 cm) placement of N than normal (7 cm) placement of N than normal (7 cm) promoted higher total recoveries, and therefore reduced losses, of applied 15 N at the 3 sites.
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