Soil and Plant Responses to VAMA and HPAN Soil Conditioners in the Presence of High Exchangeable Sodium1
- L. E. Allison2
This paper summarizes two experiments with polyelectrolyte soil conditioners to determine their effect on an irrigated soil—Pachappa loam—having a high content of exchangeable sodium. The conditioners were applied, at the 0.1% rate to a depth of 6 inches, with sufficient mixing to insure thorough incorporation of conditioner with soil. Sweet corn was used as the test crop.
The initial study was started in 1951 and continued for 4 cropping seasons. Treatment of high-sodium plots with VAMA in solution gave a large increase of aggregates larger than 0.10 mm. diameter, gave up to 10-fold increases in infiltration rate, and greatly reduced modulus of rupture values, resulting in increased emergence and stand of crops. Large increases in yield of sweet corn were obtained as a result of soil physical improvement. For the 4 annual crops, the average yield increases due to treatment were 75, 200, and 260% on 3 plots having initial exchangeable-sodium-percentages of 29, 40, and 47, respectively.
In a second and larger experiment begun in 1952, the VAMA and HPAN type of polyelectrolytes (100% active) and their respective clay formulations (25% active) were thoroughly incorporated as a dry treatment into moist soil. For high-sodium Pachappa loam soil and at the rates of application used, there appeared to be little or no difference in performance between the two types of conditioners or between formulations for a given type. Soil and crop responses due to treatment were similar to those obtained in the first experiment.
Sodium removal from the top 6 inches of soil, as a result of irrigation, was approximately twice as rapid on plots treated with conditioner as for plots not so treated. In the second experiment, the effect of the conditioner treatment in facilitating sodium removal was equivalent to a 2-ton application of gypsum.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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