Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Gyles W. Randall, Professor, Southern Research and Outreach
Center
John A. Lamb, Associate Professor, Department of Soil, Water and
Climate
James H. Orf, Professor, Department of Agronomy and Plant
Genetics
John P. Schmidt
Hero T. Gollany, Post Doctoral Associate, Department of Soil, Water
and Climate
Completed, 1998
Manure application for soybean production is being considered by livestock producers, but the manure's influence on dry matter (DM), nitrogen (N), and phosphorus (P) accumulation is not well documented. The objectives of this study were to measure N, P, and DM accumulation patterns and quantities by three genetically-different soybean varieties. Two preplant, sweep-injected manure application rates and a control were main plot treatments and three soybean varieties were subplots at seven experimental sites in 1996 and 1997. Starting in mid-June and continuing on a 15-d schedule until maturity, whole-plant samples were collected, dried, weighed, and analyzed for N and P. Plant DM increased with increasing manure rates at each sampling after mid-June. Nitrogen concentration differences among manure rates were greatest early in the season and diminished with time whereas P concentration differences were consistent throughout the sampling period. Compared to the control treatment, the application of manure resulted in an average of 25% more N accumulation at the first sampling date, 35% more at the second sampling, 42% at the third sampling, and then steadily decreased to a 10% increase at the final sampling date. Similar to N accumulation, mean P accumulation mean differences between the control and the manure treatments increased to 27% at the third sampling and then gradually decreased to 14% by the final sampling date. The overall effect of variety was minimal, yet statistically significant, and interactions between manure rate and variety were not measured. Applying manure for soybean increased end of season accumulation of DM, N, and P by 9, 10, and 14%, respectively compared to the non-manure treatment.
National Research Initiative's Water Resources Assessment and
Protection Grants Program
Minnesota Soybean Research and Promotion Council
Minnesota Pork Producers Association
Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Gyles W. Randall, Professor, Southern Research and Outreach
Center
John A. Lamb, Associate Professor, Department of Soil, Water and
Climate
James H. Orf, Professor, Department of Agronomy and Plant
Genetics
John P. Schmidt
Hero T. Gollany, Post Doctoral Associate, Department of Soil, Water
and Climate
Completed, 1998
Manure has traditionally been applied to corn, but as livestock operations expand in the Upper Midwest there are not always sufficient corn acres to minimize the environmental impact of the manure load. Our objective was to evaluate soybean as a reasonable alternative crop to receive manure applications by evaluating grain yield, N accumulation, and soil NO3-N as measures of agronomic potential and environmental impact of this practice. Nodulating and non-nodulating isolines of the same soybean variety were grown at six locations in southern Minnesota in 1996 and 1997. Whole-plot treatments included a control, five liquid swine manure rates, and four NH4NO3 rates. Split-plot treatments were two soybean isolines, one nodulating and one non-nodulating isoline. Above-ground plant samples were collected at the R6 growth stage. Grain yield was collected from the center two rows after maturity. Soil cores to a depth of 4 ft were collected to determine post-harvest soil NO3-N content. Maximum grain yield (average 34.2 bu/a) was obtained for the nodulating isoline regardless of manure or fertilizer treatment. Average N accumulation in the nodulating isoline with manure treatment was about 180 lb/a. This was about 10 lb/a greater than the nodulating isoline with fertilizer treatment. There were no adverse agronomic effects of applying manure to soybean, regardless of the rate. At N applications (as manure or fertilizer) greater than plant N accumulation, post-harvest soil NO3-N (0-4 ft) ranged from 71 to 141 lb/a. Manure applied to soybean at available N rates equal to or less than the amount of N accumulated in the crop appeared to be agronomically and environmentally sound.
National Research Initiative's Water Resources Assessment and
Protection Grants Program
Minnesota Soybean Research and Promotion Council
Minnesota Pork Producers Association
Michael A. Schmitt, Professor, Department of Soil, Water and Climate mschmitt@soils.umn.edu
Gyles W. Randall, Professor, Southern Research and Outreach
Center
John A. Lamb, Associate Professor, Department of Soil, Water and
Climate
James H. Orf, Professor, Department of Agronomy and Plant
Genetics
John P. Schmidt
Hero T. Gollany, Post Doctoral Associate, Department of Soil, Water
and Climate
Completed, 1998
Applying manure to soybean as a routine management practice, especially in regions such as the Upper Midwest in which corn&endash;soybean is a common cropping rotation, will require additional information about cultivar-dependent responses to manure application. This information will help producers make sound agronomic and environmental decisions. Our objective was to determine seed yield, dry matter accumulation, N accumulation, and lodging responses for a cross-section of adapted public and private soybean cultivars when liquid swine manure was applied as a N source. Field studies were conducted at seven locations in southern Minnesota during 1996 and 1997. Whole-plot treatments included three swine manure rates (zero, medium, and high) injected with sweeps to a soil depth of 5 in. prior to planting. Split-plot treatments consisted of twelve public and private soybean cultivars. Average seed yield at six of seven locations increased from 41.8 to 45.8 bu/a with increasing manure rates. Biomass and N accumulation also increased with increasing manure rates at these same locations, increasing from 2.9 to 3.1 t/a and 175 to 193 lb/a, respectively. A significant manure rate by cultivar interaction was observed for lodging scores, but increased lodging was not related to any change in yield. At a seventh location, at which there was a history of white mold incidence, seed yield decreased with increasing manure rates. Seed yield for the control was 3.0 bu/a greater than seed yield from either manure rate, and response to manure application was not the same for every cultivar. Except for the one site in which there was a history of white mold incidence, twelve soybean cultivars responded favorably to manure application with increased yield, despite increased lodging. Manure application to soybean was an acceptable management practice regardless of cultivar, except when the application exacerbated an already-present disease pressure.
National Research Initiative's Water Resources Assessment and
Protection Grants Program
Minnesota Soybean Research and Promotion Council
Minnesota Pork Producers Association