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Nitrogen Cycling in a Wheat Crop: Soil, Plant, and Aerial Nitrogen Transport 1
Author(s) -
Harper L. A.,
Sharpe> R. R.,
Langdale G. W.,
Giddens J. E.
Publication year - 1987
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1987.00021962007900060004x
Subject(s) - agronomy , cycling , loam , nitrogen , anthesis , fertilizer , chemistry , growing season , environmental science , soil water , biology , soil science , cultivar , archaeology , organic chemistry , history
An understanding of N cycling in the soil‐plant‐atmosphere components of wheat ( Triticum aestivum L.) production systems is necessary to maximize yield and quality. The objectives of this study were to examine N cycling and observe the effects of N surplus and deficit on N absorption/desorption in the soil and atmosphere and to evaluate translocation within the plant. Soil, plant, and microclimate measurements were taken concurrently, and soil, plant, and atmospheric ammonia (NH 3 ) transport determined. During the early vegetative phase, plant N concentration reached a maximum; however, during the remaining growth periods, N concentration decreased even though N uptake from the soil continued until plant maturity. More total N was translocated to grain from leaves than stems, and translocation from the leaves began earlier than that from stems. Isotope and total N studies showed that after anthesis about half of the grain N came from remobilization from leaves and stems and the other half directly from the soil. A progressively larger percentage of N came from mineralized organic matter as the season progressed. Nitrogen was lost as volatile NH 3 from the plant after fertilizer application and during the senescence period. Prior to anthesis, atmospheric NH 3 absorption was observed during a period when soil N was temporarily unavailable. About 21% equivalent of the applied fertilizer was lost as volatilized NH 3 . During the period of soil unavailability an amount equivalent to about 1% equivalent of the applied fertilizer was gained from atmospheric NH 3 by plant absorption.