2013 Annual Report
1a.Objectives (from AD-416):
To compare factors within and among modern cropping systems that may impact soil microbial communities, plant-microbe interactions, and plant health and productivity.
1b.Approach (from AD-416):
ARS is interested in determining if the root health and soil born organism load is related to the legacy of field management and subsequently impact plant-microbe interactions, plant health (disease and nutrition), and productivity. ARS will conduct a field study at Stoneville, MS, as part of an Area-wide (three growing regions; Mid-Atlantic, Beltsville, Maryland; Mid-South, Stoneville, Mississippi; and Mid-West, Urbana, Illinois) approach to compare several agricultural parameters in reciprocal plantings of glyphosate resistant (GR) of corn and soybean treated with and without glyphosate and non-GR isolines without glyphosate grown in fields with a legacy of glyphosate use and in fields where glyphosate has not been used for the past 12 years. The field design will allow comparisons of the plant genotype in isolation from the legacy of the farming system management and the plant genotype by systems interactions. Plots will be 15’ wide by 30’ long. For those plots receiving glyphosate, the herbicide will be applied at 0.84 kg a.e. ha-1 in a 130 Lha-1 spray volume at a pressure of 138 kPa when soybean and maize are at the V4–V5 and V5–V6 growth stages, respectively. Plots not receiving glyphosate will be hand-weeded periodically during the growing season.
Two separate studies, one each for corn and soybean, were initiated in 2013 at the USDA-ARS, Crop Production Systems Research Unit farm, Stoneville, MS. Soil samples were collected at crop planting. Bulk and rhizosphere soils and leaf samples were collected weeks before glyphosate application and at R2 growth stage of crop. The samples are being processed and complete processing will take at least another 6 months. Crops are doing well and will be harvested for yield in August-September 2013 and seed samples will be collected for chemical analysis. Complete results are not expected until spring of 2014.