Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 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 understood. This study showed that applying 130 metric tons of fresh dairy manure (on a dry weight basis) per hectare 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 decreased crop yields on approximately 800,000 ha of south central Idaho silt loam soils. Previous attempts to restore subsoil productivity to that of the topsoil have not been successful on these soils. This study was conducted to find a method for restoring the productivity of freshly exposed subsoil to that of the topsoil and to determine the factor(s) limiting subsoil production. A four year 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 Calciorthids). Different crop rotations were established along 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 beans (Phaseolus vulgaris L., cv. Viva) were grown on the entire plot area as a test crop. The application of 44 Mg manure/ha in the spring and 93 Mg manure/ha in the fall of 1991 was the only treatment that restored subsoil bean production to that of the topsoil plots. Plant Zn and soil organic carbon concentrations were the only measured factors that correlated with bean yield increases on the subsoil.