Submitted to: Western Nutrient Management Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 4, 1997
Publication Date: N/A
Interpretive Summary: Approximately 800,000 ha of silt loam soils in southcentral Idaho have decreased crop yields due to erosion and land leveling. Up until now the technology to restore this loss of crop production has not been available. This study showed that applying 150 tons of fresh dairy manure (on a dry weight basis) per acre restored dry edible bean production to that of top soil, while application of conventional commercial fertilizer at rates suggested by traditional soil lists produced bean yields at about 64 to 68% of the top-soil yield rates. The zinc plus organic carbon added with the manure appear to be the factors that increased the bean yield.
Technical Abstract: Irrigation induced erosion and land leveling have reduced yields on about 2 million acres in south central Idaho. Previous attempts to restore productivity on eroded silt loam soils to that of the original top soil have not been successful. This long term study was conducted to find a method(s) that would restore the productivity of exposed subsoils to that of topsoils and to determine the factor(s) limiting subsoil productivity. This study was initiated by removing the surface 12 inches of topsoil in strips between undisturbed strips of Portneuf silt loam (coarse-silty, mixed, mesic, Durixerollic Calciorthid) topsoil. Different crop rotations were established along the strips and fertilizer treatments were applied across the strips. Fertilizer treatments were applied the first year and were, conventional fertilizer applied according to soil tests, a heavy fresh dairy manure application and two cottage cheese (acid) whey rates. Dry edible beans (Phaseolus vulgaris L. cv. Viva) were grown on the entire plot area the forth year as the test crop. Crop rotations did not significantly effect overall bean yields the fourth year after topsoil removal. Applying 150 tons of dairy manure/acre (air dry basis) was the only treatment that restored bean production to that of the topsoil. Plant Zn and soil organic carbon were the only factors measured that correlated with bean yield increases on the subsoil plots.