Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Paul R. Bloom, Professor, Department of Soil, Water and
Climate
Hero T. Gollany, Post Doctoral Associate, Department of Soil, Water
and Climate
Gyles W. Randall, Professor, Southern Research and Outreach
Center
Paul R. Carter
Completed, 1999
Soil P build-up is occurring because manure applications have been based almost exclusively on nitrogen (N) considerations, which inevitably over-applied P. To decrease manure-P quantity, low-phytate (LP) corn has been introduced that can decrease the amount of P in excreted manure. The primary objective of this study is to compare manure-P availability from different manure sources in soils using soil P availability indices with a series of manure application rates. A laboratory incubation study was conducted using two soils (silt loam or sandy loam) and three sources (fertilizer, standard manure, LP manure) of phosphorus. Soil P availability was determined on all collected samples using three standard soil P availability indices--Bray P1, Olsen, and Mehlich-III. Using fertilizer P as the baseline index of 1.0, the LP corn manure would have an index of 0.386 and the standard corn manure has an index of 0.479. This accounts for almost a 20% reduction in manure-P availability when LP corn is used in a swine ration based on this research using soil P test changes. Although the three soil P tests did extract different quantities of P, the correlation between the soil test P extracted by each of the tests and the rate of P applied was not different among the three tests. Soil type/texture had a significant effect on the amount the available soil P measured after addition of P, regardless of sources. Future manure management planning tools may need to consider dietary P sources if guidelines stipulate P-based rates.
Pioneer Hi-Bred International, Inc.
Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Gyles W. Randall, Professor, Southern Research and Outreach Center
On-going, started in 1998
The threat of P movement into lakes, streams, and rivers is a major environmental issue. Recently, a scientific discovery was made in the selection of corn that contains low amounts of phytic acid (phytate), the primary P storage compound in traditional corn, which is unavailable for non-ruminant animals. With the selection for and development of low-phytate (LP) corn, swine and poultry diets can rely more on corn grain P rather than supplemental additives for their dietary P needs. Yield performance of LP corn at six site years has shown a yield depression of only 5% for the LP hybrids. Initial yield data indicated a 7% yield depression with LP corn whereas 1999 field trials only measured an average yield depression of 3%. It is expected that this differential will decrease when improved conversions of these hybrids are released. Other P parameters, such stover P and grain P concentrations and quantities were not significantly affected by the LP characteristic, indicating that plants were not compensating for a change in P form with a change in P quantity. There also was not an interaction between soil test P levels/fertilizer P rates and the LP/normal P trait for any of the parameters. The environmental benefits of LP corn are significant. Low-phytate corn may also be a benefit in consideration of current and/or potential regulations and may not be a significant economic liability. The ultimate benefit of LP corn may allow producers to stay in business as it can greatly aid manure utilization and provide flexibility in manure management decisions.
Pioneer Hi-Bred International, Inc.
Minnesota Pork Producers Association
National Pork Producers Council
Minnesota Corn Growers Association
Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Gyles W. Randall, Professor, Southern Research and Outreach
Center
Samual D. Evans
Completed, 1994
As manure injection methods vary with modifications in application equipment, the availability of manure-N is probably altered. This study was conducted to quantify differences in the concentrations of inorganic (nitrate and ammonium) soil N and corn yield as affected by vertical knife (VK) and horizontal sweep (HS) injection systems, and broadcast (BCST) applications. These manure application methods, plus a VK injection with nitrapyrin, were compared at a single manure rate at seven locations in Minnesota in 1992 and 1993. Soil inorganic N was measured at growth stages V1 and V4 and after grain harvest. At the V1 growth stage, inorganic-N from 0 to 2 ft depth averaged 24% higher in the manured treatments than in the nonmanured, unfertilized control. The average of VK and HS treatments had 10% more inorganic-N than the BCST treatment and the HS resulted in 7% more inorganic-N than the VK. At the V4 growth state, similar results were measured with the HS treatment having 8% more inorganic-N than the VK treatment. The impact of manure application methods on nitrate-N was greater than on ammonium-N for both in-season samplings. The use of HS resulted in significantly greater nitrate-N early in the growing season than did VK injection. Grain yields paralleled soil nitrate-N levels; average yields for the N responsive sites were 85, 107, 115, and 123 bu/acre for the control, BCST, VK, and HS treatments, respectively. While the use of nitrapyrin with VK injection delayed nitrification, the effect on yield was inconsistent.
Cannon River Watershed Partnership
Minnesota Department of Agriculture Grand Program
Minnesota Extension Service Initiative Grant Program
Gyles W. Randall, Professor, Southern Research and Outreach Center grandall@soils.umn.edu
Michael A. Schmitt, Professor, Department of Soil, Water and
Climate
Bruce D. Montgomery
Completed, 1994
Information regarding the effects of time and manure application and use of a nitrification inhibitor on manure mineralization and corn yield is needed for producers to make sound manure management decisions. Studies were conducted at seven southern Minnesota sites in 3 yr to determine the effects of three manure application times (mid-September, mid-October, and late April), two manure rates, and a nitrification inhibitor, (nitrapyrin [NP] 1.0 lb a.i/acre), on corn yield and soil nitrate N concentration (0 to 12 in.) at the V4 growth stage. Application rates ranged from 3000 to 4000 gal/acre for the low rate and from 6000 to 8000 gal/acre for the high rate. For the four sites receiving liquid dairy manure, soil nitrate N was greatest when manure was applied in April and lowest when applied the previous September. The addition of NP increased soil nitrate N at three sites but affected grain yields at only one site when averaged across time and rate of manure application. Grain yields for the April, October, and September applications averaged 146, 142, and 139 bu/acre, respectively, across manure rates and NP treatments, with April exceeding the September application time. When liquid swine manure was used, the effects of application time and NP on soil nitrate N concentration and grain yield depended on climatic conditions. Results from the seven site-yr support about a 5% yield increase with April application compared with fall applications. However, it is unlikely that many farmers will consider this an economic advantage because of logistical challenges often faced with spring application of manure in the Northern Corn Belt.
State of Minnesota Legislative Commission on Minnesota Resources
Gyles W. Randall, Professor, Southern Research and Outreach Center grandall@soils.umn.edu
Michael A. Schmitt, Professor, Department of Soil, Water and Climate
Completed, 1999
Many livestock producers have inadequate capacity to store manure for either an annual application or application at ideal times when the manure can be incorporated immediately. Under these scenarios liquid manure is often applied to frozen ground in the late winter or early spring and is not incorporated until just prior to planting corn. This study was conducted to determine the amount of "available" N from winter and early spring applications that had not been incorporated in a timely fashion. The purpose of this study is to determine the N availability to corn from early- and late-winter applied manure compared to spring-applied manure. Two field experiments were conducted to meet the objectives of the project. Liquid dairy and hog manure and turkey litter were broadcast-applied in late February, late March, and late April. All treatments were disked in at the end of April. Corn yield and soil nitrate data will be collected to evaluate the treatments. Corn yields ranged from 185 to 202 bu/A for the optimum, preplant treatments. Winter application of swine manure reduced corn yields from 15 to 30 bu/A.
Minnesota Farm Bureau
American Farm Bureau Foundation
Minnesota Pork Producers Association
Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Craig C. Sheaffer, Professor, Department of Agronomy and Plant
Genetics
Gyles W. Randall, Professor, Southern Research and Outreach
Center
Completed, 1994
Overapplication of N from various sources can be partially attributed to the lack of proper N crediting when organic N sources, such as alfalfa and manure, are part of a farm's cropping system. The objectives of this study were to evaluate: (i) the effect of manure applied prior to alfalfa establishment on subsequent corn grain yield and soil nitrate-N concentrations; and (ii) grain yield response to alfalfa cutting management preceding plowdown. Prior to alfalfa establishment, three preplant manure rates (3 000, 6 000, and 12 000 gal/acre) were applied at Rosemount MN, on a Waukegan silt loam and at Waseca MN, on a Nicollet clay loam. Fall alfalfa cutting management treatment consisted of either leaving or removing the fourth-cutting herbage before plowdown. First-year corn grain yields following alfalfa plowdown were similar for all manure treatments applied prior to alfalfa establishment. By the second and third year after alfalfa, corn yields declined and yield responses to the original manure treatments were less than those observed with 30 lb/acre of fertilizer N. Not harvesting the fourth-cutting herbage before moldboard plowing significantly increased yields by an average of 4.2 bu/acre. In the first year after alfalfa plowdown, the N contribution of alfalfa overshadowed the contribution of the manure in the first year after plowdown. By the third year of corn following alfalfa, the manure-N and alfalfa-N contributions to the mineralizable N pool are exhausted based on soil nitrate-N concentrations and corn grain yield response. Good stands of alfalfa can supply optimal N for corn in the year after plowing, regardless of whether preplant manure was applied prior to alfalfa seeding.
Potash and Phosphate Industry-Foundation for Agronomic Research