Submitted to: Western Society of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: June 6, 1997
Publication Date: N/A
Technical Abstract: Irrigation-induced erosion and land leveling have reduced yields on about 800,000 ha in southcentral Idaho. Previous attempts to increase exposed calcareous silt loam subsoil yields to that of the original top soil were not successful. A long-term study was conducted to find a method(s) to restore freshly exposed subsoil productivity and determine the limiting factor(s). The surface 0.30 m topsoil was removed from a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic Calciorthid) for comparison to adjacent topsoil plots. Fertilizer treatments applied to the subsoil the first year were: conventional fertilizer applied according to soil tests; a heavy fresh dairy manure application; and two cottage cheese (acid) whey rates. After the fourth growing season, additional manure, whey, and zinc was applied to topsoil plots and some of the subsoil plots. Barley (Hordeum vulgare L.), a sorghum (Sorghum bicolor (L.) Moench)- sudangrass (Sorghum sudanense (Piper) Staph) hybrid, alfalfa (Medicago sativa L.), wheat (Triticum aestivum L.) and bean (Phaseolus vulgaris L., c.v. Viva) yields were measured for six years. Conventionally, fertilized subsoil plots yielded 60 to 80%; whey treated subsoil plots yielded 40 to 90%; and manure-treated subsoil plots yielded 90 and 110% of the topsoil plots. Soil organic matter and zinc uptake increases were the only measured factors that appeared linked to increased subsoil yields.