2012 Annual Report
1a.Objectives (from AD-416):
We propose to evaluate FGD gypsum influences on soil properties that determine soil erodibility. The research will help establish proper rates of FGD gypsum to reduce runoff and erosion losses, and improve soil productivity. We will also provide documentation of water quality improvement associated with FGD gypsum needed to help qualify practices for use as a BMP and water quality improvement credits.
1b.Approach (from AD-416):
Two studies will be conducted at the Northeast Mississippi Experiment Station at Verona. In one study, we will evaluate the effects of FGD gypsum on an existing set of no-till cotton plots. The FGD gypsum application rates of 0, 1, 1.5, 2, and 3 tons/acre will be applied on a replicated plot experiment. The other study will evaluate the effects of tillage-gypsum interactions on soybean yields. The three tillage treatments are no-till, fall chisel-harrow, and conventional. Plot sizes, gypsum application rates, and replications are identical to those for no-till cotton. Crop yields will be measured by the experiment station personnel responsible for all agronomic practices. Following harvest each growing season, soil cores will be collected to a depth of 36 inches from each plot and characterized for water dispersible clay as a measure of erodibility, particle size distribution, organic carbon content, pH, exchangeable A1, exchangeable bases, total calcium, sulfur, nitrogen, and phosphorus.
A cotton experiment was begun in 2009 comparing no-tillage and tilled cotton with five gypsum rates, 0, 1, 2, 3 and 5 tons per acre. The experiment is a randomized complete block design with four replications. Initial soil data to a depth of 4 feet in 6 inch increments was taken on each plot prior to gypsum application. Additional soil samples were collected in fall 2011 after three crop years. These samples are being processed and analyzed for various chemical constituents. Chemical measurements have included soil pH; citrate-bicarbonate-dithionite (CBD) extractable iron (Fe), aluminum (Al), and manganese (Mn); oxalate extractable Fe, Al, and Mn; cation and anion exchange capacity (CEC and AEC); and exchangeable cations and anions. Plot yields were measured each year. Soil penetrometer resistance was measured in spring 2012. Monitoring activities were maintained through email, telephone communication, and a meeting in Auburn, AL, with collaborators.