Assessment of soil mineralogical and chemical properties and impacts on corn potassium fertilizer recommendations
Leanna Leverich
Potassium (K) is an essential nutrient for corn production in Minnesota and adequate supply is necessary for profitable production. Potassium can be provided to crops from soils, though much of the state’s soils vary in their capacity for K storage and ability to supply K for plants. Soil clay type and mineralogical properties determine much of the soils underlying K cycling and K supply capacity. To better understand K availability in soils, the objectives of this study were to 1) Develop a survey of the state’s mineralogy and determine whether soil clay species influences K critical levels, 2) Determine the impact of soils CEC, pH, and variable charge on K retention and release, and 3) Estimate soil K weathering capacity of soils with varying CEC. Response trials were conducted using a classical latin square design to determine K response at eight sites across the site with various underlying parent material and dominant mineralogy. Archived soil samples from historical K response trials and samples from current trials were gathered to determine soil properties and clay mineral species. Soil properties and soil clay mineral fractions were determined using routine soil tests and X-ray Diffraction (XRD). A deeper understanding of K cycling will allow for recommendations to be tailored to dominant soil mineralogy. Preliminary results from this study indicate potential to provide superior site-specific recommendations for K fertilizer considering soil chemical and mineralogical factors.
A phosphorous index of Minnesota agricultural nutrient management
Heidi Reitmeier
This study explores 20 years of nutrient management data to identify how changing trends in cropping and fertilizer applications have affected phosphorus (P) loss risk across the state of Minnesota. For this study, nutrient management records spanning from 1999 to 2019 were compiled across almost 20 Minnesota counties representing 5 different state regions, including but not limited to data from Discovery Farms Minnesota and others. The compiled Minnesota county data cover two critical watersheds in terms of nutrient management; one leading to Canada’s Lake Winnipeg to the north, the other leading ultimately to the Gulf of Mexico through the Mississippi River to the south. Due to rising concerns about recurrent harmful algal blooms in both watersheds, there is a growing need to identify best management practices (BMPs) for P loss within these watershed basins. This study combines historical data with the Minnesota Phosphorus Index to provide insight into the benefits and the limitations of in-field P management (i.e., the 4 R’s of fertilizer application for the right place, right time, right source, and right rate) as a BMP for water quality improvement in the Red and Mississippi River Basins, respectively.
Irrigation management impact on corn yield and nitrate leaching in Central Minnesota
GP Singh
The Central sands region in Minnesota has coarse-textured soils and low available water holding capacities which makes irrigation essential to obtain ideal yields for corn. Although irrigation is important, excess irrigation in these soils can contaminate ground and surface water sources through nitrate leaching. Some private drinking wells in this region have higher nitrate concentrations than the USEPA standard for drinking water (10 mg/L). The study compares four different irrigation management strategies in terms of their potential to reduce nitrate leaching in coarse-textured soils without significantly impacting corn yield.