| Autor: |
Grimes, Donald W., Dickens, W. L., Yamada, H., Miller, R. J. |
| Zdroj: |
Agronomy Journal; January 1973, Vol. 65 Issue: 1 p37-41, 5p |
| Abstrakt: |
Field studies were conducted on two widely different soils over a 3‐year period in a semiarid irrigated region to establish functional relations between responses of cotton (Gossypium hirsutumL.) plants and the major production input factors: water, nitrogen, and plant density. The nitrate‐nitrogen concentrations of petioles from the most recently matured leaves were influenced by N‐fertilization level, time of sampling in the season, and water management. Plant population did not alter the nitrate‐N levels of petioles. High concentrations were associated with large amounts of N applied in side‐dress soil applications. On a fine‐textured soil with a high water‐retention capacity N side‐dressed after emergence was not taken up by the plant until the first irrigation was added. Concentrations of nitrate‐N in petioles at critical times in the season were characterized by a 2nd‐degree polynomial model having water and nitrogen quantities as independent variables (0.54≤2R≤0.94). A second model was subsequently developed that incorporated time as an independent variable in addition to water and nitrogen quantities. Using a yield equation and model 2, a procedure was developed that enables time‐dependent “desired” levels of plant nutrient concentrations to be established that are dependent on commodity price and production factor costs. This model is sensitive to changing price levels for commodity and/or production factors. |
| Databáze: |
Supplemental Index |
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