Virginia will collaborate with researchers from OH, IN, MN, NC, AR, LA, GA, KS, and WI on a multi-state project to evaluate the response of soybean to sulfur (S) and nitrogen fertilization. Individual states will request funding from their State Qualified Soybean Boards (QSSB). The Extension network lacks information related to utility of N and S application in soybean.

Research plots will be established across the Coastal Plain region of Virginia where N and S responses are more likely to occur. The S objective will be completed at 4 locations, using 3 S rates and 4 S sources. To account for N applied using ammonium sulfate and ammonium thiosulfate, we will have a comparable N treatment that will also demonstrate utility of N fertilization to soybean. The N objective will focus on N and S applied at 2 plant growth stages and 3 S rates. Plant tissue will be sampled to assist with establishment of leaf tissue concentrations in each state along with yield and oilseed quality. All data will be analyzed on a state basis and agglomerated together within all participating states.

SULFUR: Sulfur recommendations need to be established for Virginia soybean production systems if soils do not supply adequate sulfur. A 70 bu./acre soybean yield requires 22 lbs. S/ac. Likewise, significant S may be removed from double cropped systems if small grain straw is removed (32 lbs. S/acre for barley and 25 lbs. S/acre for wheat). Soybean S sources and rates need to be investigated in sandy textured and S deficient Virginia soils as farmers’ questions are increasing yearly regarding this nutrient.

NITROGEN: Nitrogen is typically fed to soybean plants via symbiotic relationships with soil bacteria that allow the plant to effectively capture atmospheric nitrogen. Overall, a 70 bu./acre soybean crop will need to obtain 364 lbs. N/acre from the atmosphere or soil nitrogen to meet plant needs. Will nitrogen fertility hamper this symbiotic relationship and cause yield reduction or extra fertility expense that is not necessary?

The overall objective of this research project is to assist producers with management decisions regarding S and N yield responses as they relate to soybeans. More specifically, objectives include:
1) Identify yield and economic response in soybean to N and S fertilizer applications.
2) Characterize biological nitrogen fixation in soybean and create nitrogen production budgets.
3) Extend results to soybean growers through Extension networks.

Updated fertility information will be included in the Virginia Cooperative Extension fertilizer recommendations that is used by the VT Soil Testing Laboratory (Maguire and Heckendorn, 2019), Extension Agents, the Virginia Department of Conservation and Recreation, and industry for designing nutrient management plans for optimal production. Data will also be utilized on a regional basis for other states participating in this project.

Data will be showcased at farmer meetings and events, such as the Virginia Ag Expo, the Tri-County Grain production meeting, the Eastern Shore Ag Conference and Trade Show, the Five-County Ag Conference, and others on the “Extension Circuit” throughout the year.

Data will ultimately be written into a scientific peer reviewed publication and then summarized into shorter Fact Sheets that will be permanently housed on Virginia Cooperative Extension website.

The overall objective of this research project is to assist producers with management decisions regarding S deficiencies, understanding S-N interactions, and yield responses as they relate to soybeans.