Plant Recovery of Immobilized Nitrogen in Greenhouse Experiments

Abstract
A series of greenhouse pot experiments was conducted to measure plant uptake of fertilizer N in the presence and absence of straw. Soils were incubated with straw for periods up to 12 weeks to overcome the depressing effect of straw and then cropped. Two or more crops were evaluated for each treatment. In spite of preincubation, plant recovery of N was invariably lower where straw had been added, even when the level of fertilizer N added was equivalent to 2.5% of the weight of straw.The presence of growing plants on the soil during the period immediately following application of fertilizer N resulted in more efficient utilization of fertilizer than where planting was delayed several weeks after fertilizer application. This was true whether straw was added or not.A tracer experiment lasting nearly 2 years indicated progressive stabilization of fertilizer N after incorporation into the soil organic fraction.
Funding Information
  • National Science Foundation

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