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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #397771

Research Project: Enhancing Sustainability of Mid-Atlantic Agricultural Systems Using Agroecological Principles and Practices

Location: Sustainable Agricultural Systems Laboratory

Title: Managing cover crop C:N ratio and subsurface-banded poultry litter rate for optimal corn yields

item Mirsky, Steven
item DAVIS, BRIAN - North Carolina State University
item POFFENBARGER, HANNA - University Of Kentucky
item Cavigelli, Michel
item Maul, Jude
item Schomberg, Harry
item SPARGO, JOHN - Pennsylvania State University
item THAPA, RESHAM - North Carolina State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2023
Publication Date: 3/2/2023
Citation: Mirsky, S.B., Davis, B.W., Poffenbarger, H., Cavigelli, M.A., Maul, J.E., Schomberg, H.H., Spargo, J.T., Thapa, R. 2023. Managing cover crop C:N ratio and subsurface-banded poultry litter rate for optimal corn yields . Agronomy Journal.

Interpretive Summary: Corn production heavily relies on nitrogen (N) inputs. Farmers typically apply 150-200 kg N ha-1 before or during corn growth to optimize yields and maximize economic returns. In cover crop-based cropping systems, cover crops with low carbon-to-nitrogen (C:N) ratios (e.g., legumes) can provide some of the corn N requirements , thereby providing the opportunity to lower manure application rates and hence fertilizer costs. Whereas cover crops with high C:N ratios (e.g., grasses) can immobilize soil N during its decomposition that needs to be properly accounted for--to avoid corn N stress--by increasing manure application rates. Therefore, to balance economic and environmental objectives in cover crop-based cropping systems, farmers need to adjust poultry litter application rates based on cover crop C:N ratios. ARS scientists conducted field studies at the Beltsville Agricultural Research Center during 2012-2014 to model corn yield response across gradients of cover crop C:N ratios as well as gradients of subsurface banded poultry litter application rates. At sub-optimal poultry litter application rates, corn yields decreased linearly as cover crop C:N ratios increased. Moreover, the optimal poultry litter application rate for maximizing corn yields increased with increasing cover crop C:N ratios. The response surface model developed here will be of interest to farmers, land managers, environmentalists, policy experts, and others aimed for adaptive N management in cover crop-based cropping systems for economic and environmental stewardships.

Technical Abstract: Cover crops can be used to provide some of the nitrogen (N) needs of a cash crop to complement mineral fertilizers or manure, but there has been limited work to describe corn (Zea mays L.) yield as a function of cover crop stoichiometry and N inputs. We investigated the response of corn yield to gradients of both cover crop stoichiometry and poultry litter (PL) application rates in Beltsville, MD during 2012-2014. To achieve a gradient of cover crop stoichiometry, we seeded hairy vetch (Vicia villosa Roth. ‘Groff’) and cereal rye (Secale cereale L. ‘Aroostook’) in a replacement series of six seeding rate proportions, resulting in shoot C:N ratios of 9.2:1 to 152:1 across years. For each hairy vetch:cereal rye sown proportions, we side-dressed PL in subsurface bands (SSB) at four targeted rates: Zero, P-based (67 kg plant available nitrogen (PAN) ha-1), N-based (135 kg PAN ha-1), and excess N and P (269 kg PAN ha-1). We found that corn yield followed a linear-plateau relationship across these two dimensions. Within the linear region, each unit increase in log-scaled cover crop C:N ratio resulted in a yield decrease of 2.56±0.26 Mg ha-1 at a given rate of SSB PL. To achieve maximum yield potential, we describe a model where each unit increase in log-scaled cover crop C:N ratio required an additional 45.9±6.22 kg plant-available N from SSB PL. Yields following winter fallow were typically intermediate to the range of yields observed following the gradient of cover crop C:N ratios. We did not find significant differences in corn yields when comparing SSB PL to at-planting incorporated or broadcast PL; we also found no significant differences between SSB PL and surface banded UAN. Taken together, our approach of modeling yield response across two dimensions can be widely used to guide adaptive N management in subsequent cash crops following winter cover crops, thereby balancing both economic and environmental objectives in cover crop-based cropping systems.