1a.Objectives (from AD-416)
The overall objective is to develop soybean cropping systems that reduce disease and nematode incidence, maximizing yield and economic return.
1b.Approach (from AD-416)
The Tennessee Agricultural Experiment Station (TAES) will use existing and new research plot areas to measure the effects of soybean cropping systems variables, such as no-tillage, cultivar selection, seeding rate, planting date and use of animal waste, on diseases and soybean yield. This will be done on cropping systems experiments already in place at University of Tennessee (UT) and on experiments being conducted by USDA, ARS scientists in the Crop Genetics and Production Research Unit. TAES will provide expertise in possible cropping system changes to enhance economically and enviromentally viable soybean production.
The effect of poultry litter application on tilled and no-tilled soybeans has been completed. The objective of this research was to determine if litter affects soybean cyst nematode levels and soybean yield. Two poultry litter rates were compared using surface application in no-tillage, and incorporation and surface application in tilled soybeans. In this study, litter had no significant effects on cyst nematode reproduction but in one year out of three, poultry litter application increase soybean yield. Soybean biomass increased in every year of the study. Reasons for the yield increase are not known. The agronomic part of the study is in revision stages for peer-reviewed manuscript submission. The effects of tilled and no-tilled cropping systems on soil diseases and soybean cyst nematode incidence and severity are being evaluated. Research is underway on a long term soybean experiment comparing single to double-cropped soybeans and winter wheat. The six main plot treatments include tillage (disc only, chisel plow, and moldboard plow) compared to no-tillage (single crop in winter wheat cover, single crop in previous crop residue, and no-tillage after wheat harvest in a double crop system). Each of the six treatments are split with one half being no-tillage soybeans and the other half being tilled. Sampling is underway on all plots to determine nematode populations, and soil bacterial and fungal levels in addition to effects on soybean cyst nematode reproduction. Charcoal rot incidence and severity are also being monitored. Different procedures to determine microbial community structure have been used on these plots to determine relationships between diseases and microbe populations as influenced by tillage, cover crop, wheat grain crop and soybean planting timing. Data collected on the components of the microbial community indicate that this is a bacterial driven environment. New research will involve more precise bacterial population determinations and measure the ratio of gram negative to gram positive bacteria. Undescribed bacteria parasitizing soybean cyst nematode have been found in this plot area. Research by others suggests that the ratio of bacteria may help determine bacterial predation potential. New work is also being planned on the effects of rotation crop and cover crop on charcoal rot levels. This will be conducted at the Milan Experiment Station on a long term study where soybeans are rotated with cotton and corn both grass and legume cover crops established in each rotation each year. Presently the plots are in their second three year cycle of rotations. ADODR used site visit, email and telephone conferences to monitor activities of the project.