Improving Exposed Subsoils with Fertilizers and Crop Rotations
- C. W. Robbins ,
- L. L. Freeborn and
- B. E. Mackey
Irrigation-induced erosion and land leveling have decreased crop yields on approximately 800 000 ha of south-central Idaho silt loam soils. Previous attempts to increase subsoil productivity to that of the topsoil have not been successful on these soils. This study was conducted to find a method(s) for increasing the productivity of freshly exposed subsoil to that of the topsoil and to determine the factor(s) limiting subsoil production. A 4-yr study was initiated by removing the surface 0.3 m of topsoil from strips between undisturbed topsoil strips of a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic Calciorthid). Different crop rotations were established within the strips and fertility treatments were applied across the strips. The fertilizer treatments were conventional fertilizer application according to soil test, dairy manure, and two cottage cheese (acid) whey rates. During the fourth year, dry edible bean (Phaseolus vulgaris L., cv. Viva) were grown on the entire plot area as a test crop. The application of 44 Mg manure ha−1 in the spring and 93 Mg manure ha−1 in the fall of 1991 (first year of study) was the only treatment that restored subsoil bean production to that of the topsoil plots. Plant Zn and soil organic C concentrations were the only measured factors that correlated with bean yield increases on the subsoil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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