Dynamic soil tests for rice
1995
Dobermann, A. | Cassman, K.G. | Sta Cruz, P.C. | Neue, H.U. | Skogley, E.O. | Pampolino, M.F. | Adviento, M.A.
The PST method is one approach to replace conventional, static soil tests with dynamic, process-oriented measures of SNSC. Its multi-element character and the environmental conditions used during the resin extraction of soil nutrients (30 deg. C. temperature, anaerobic conditions) overcome many of the shortcomings associated with traditional soil tests used for rice. Other dynamic approaches may provide more specific information for single nutrients. They are all based on similar principles and they are prototypes of a new generation of soil tests which we may call "dynamic soil tests". Results obtained so far with the PST method are promising, particularly for P and K. The PST method is not restricted to particular soil types. The use of kinetic constants is a more flexible approach in soil testing, because it can better quantify actual nutrient supply which helps to specify fertilizer input rates. Knowledge of short- and long-term release characteristics allows the assessment of the nutrient fixing and buffering characteristics of a soil, helping to make decisions about splitting and timing of fertilizer application. A routine soil test developed from the PST procedure could involve a determination of the full nutrient release kinetics (2-wk incubation) the first time a field is tested (and every 5-10 years thereafter) and subsequent annual tests with short incubation times (perhaps 2-7 days). The PST method may contribute to an improved understanding of the processes governing nutrient supply to a growing rice root. It can also indicate other soil related constraints to nutrient uptake and rice growth
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