Effect of combined applications of ^<15>N-labeled ammonium sulfate and cattle composts on nitrogen dynamics in upland soil conditions

KATOH Masahiko, HAYASHI Yasuhito, TANAKA Fukuyo, MORIKUMI Hiromasa

doi:10.20710/dojo.79.2_163

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畑条件下での重窒素ラベル硫安と各種牛糞堆肥の併用下における由来別無機態窒素の増減要因の解析
ハタケジョウケンカデノジュウチッソラベルリュウアントカクシュギュウフンタイヒノヘイヨウカニオケルユライベツムキタイチッソノゾウゲンヨウインノカイセキ

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Abstract

We examined the effects of combined applications of ^<15>N-labeled ammonium sulfate and cattle composts on nitrogen dynamics under upland soil conditions in comparison with a single application of compost or of ^<15>N-labeled ammonium sulfate in incubation experiments. The amount of inorganic nitrogen (N) derived from the ammonium sulfate was smaller in the combined application than in the single application, indicating that some N derived from the ammonium sulfate was immobilized. The degree of immobilization was correlated with the amount of easily decomposable carbon (C) in the compost. Immobilized N tended to be re-mineralized during the incubation. The 1-month N mineralization rates of the composts increased by 5% to 10% after the application of ammonium sulfate. This increase was negatively correlated with the C/(N+fAN) ratio, where C and N represent the C and N contents derived from the compost, and fAN represents the amount of N derived from the ammonium sulfate. These results suggest that the pattern of N mineralization from compost was changed by the application of N fertilizer. Appropriate application rates can thus be calculated from the C/(N+fAN) ratio. In addition, it will be necessary to select composts that induce little immobilization of applied fertilizer N.

Journal

Japanese Journal of Soil Science and Plant Nutrition

Japanese Journal of Soil Science and Plant Nutrition 79 (2), 163-171, 2008

Japanese Society of Soil Science and Plant Nutrition

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