Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/18/2018
Publication Date: N/A
Interpretive Summary: Eroded high pH hilltop soils that were damaged during the dustbowl of the 1930’s make up about 15% of the soils in the Central Great Plains region (about 4 million acres). Our objective was to determine how to best use beef manure (a redily available waste-product from large confined animal feedlots in the region) as an amendment to remediate these soils to former productivity. The questions are at what rate, and with what method should we use to apply the manure? Should the manure be incorporated into the soil with tillage or left on the surface of the soil? If so how deep should we bury or mix the manure with the soil? In this on farm research, ARS scientists compared two rates of manure application (low and high) and three methods of manure application timing (annual, once every other year, and a single large applications for 6 years of cropping) with two different depths of manure incorporation by tillage (shallow 4-6 inch incorporation with V-blade sweeps, or deep incorporation with a moldboard plow 10-12 inches deep) with applying the manure on the surface with no tillage. The best crop yields were measured in plots that had manure just shallowly incorporated or no-till managed. We found that the no-till or shallowly incorporated manure at the low rate (2-3 tons/acre per year) was overall the most practical treatment. The manure that was deeply incorporated with a moldboard plow showed excessive nitrate accumulation particularly at the high manure rates and had yields that were less than the shallowly incorporated manure and the no-till managed manure treatments.
Technical Abstract: In the Dust Bowl of the 1930’s, millions of farm acres in the Central Great Plains were damaged by excessive tillage and erosion. Our objective was to determine how to best use manure as an amendment to remediate these soils to former productivity. Specifically, we wanted to determine practical rates of application and wanted to evaluate manure incorporation versus just applying the manure on the surface using no-till practices. A final objective was to evaluate, if incorporated (tilled in), how deep should the organic amendment be incorporated. Two manure rates (low and high) were compared with three check plot treatments that had no fertilizer applied or two rates of chemical urea applied. Three methods of manure incorporation were evaluated in combination with three timings of manure application: manure applied on the surface with no incorporation, manure shallowly incorporated with V-blade sweeps and manure deeply buried with a moldboard plow. The timing of manure application involved annual application (surface applied with no incorporation, and shallowly incorporated with sweeps), once every other year application (incorporated with the moldboard plow) and a single large application were enough manure was added to supply N for six consecutive dryland crops (also moldboard plow incorporated). Yields and soil nitrates were measured each year in the six year study. The single manure application and the other moldboard plow incorporated treatments showed excessive nitrate accumulation particularly at the high manure rates and had yields that were less than the sweep and no incorporated manure treatments. The best yields were found with the shallow and no-till managed manure treatments. We found that the no-till or shallowly incorporated manure at the low rate was overall the most practical treatment.