Estimating Soil Nitrogen Availability in Cropping Systems With and Without Cover Crops

Commodities

Practices

Nitrogen (N) stands out as the primary macronutrient for plant growth and development. Crops such as sorghum, corn, and wheat have substantial N needs, with 120 to 180 lbs/ac of N per growing season. The low N use efficiency (~33%) and the excessive N application annually contribute to Nitrous Oxide (N₂O) emissions, a potent greenhouse gas (300 times more powerful than CO₂) responsible for global warming, as well as nitrate (NO₃^-) leaching, which are major drivers of environmental issues due to N overuse. Additionally, cover crops, particularly leguminous species, have been shown to enhance N availability in agricultural systems. Moreover, cover crops can improve soil properties and reduce leaching losses, further contributing to sustainable agriculture. Therefore, there is a need to improve N fertilizer recommendations, but these improved recommendations are hindered by uncertainty in the N cycle associated with potential nitrogen mineralization rates. The proposed project aims to engage with farmers across Kansas to conduct a comprehensive study on N mineralization rates at different farms focusing on understanding the potential of N mineralization and collaborating closely with farmers to implement appropriate N management practices. By accurately assessing N mineralization potential, it is possible to reduce N application, thereby cutting costs and mitigating environmental impacts. To evaluate this, undisturbed soil sampling will be collected across eight farms in Kansas followed by laboratory incubation of 120 days to access mineralizable N. A model will be developed to estimate the nitrogen mineralization potential across all farms. Data on temperature and moisture on farms will be incorporated into the model to apply to field conditions.  These findings will greatly benefit Kansas farms by improving their N management practices, improving N recommendations for Kansas, reducing N losses to groundwater or the atmosphere, enhancing overall profitability, and contributing to the well-being of both farmer operations and the community. The long-term objectives of this project are to understand the potential N mineralization across the state of Kansas and mitigate N fertilization by adopting cover crops as an agricultural practice. This study is underexplored due to its labor-intensive nature and complexity. However, the potential for impactful outcomes is significant, it could help make farming more sustainable by reducing losses of N to groundwater or the atmosphere and improving finances by reducing the amount of N fertilizer. We believe these findings can impact N fertilization management not only in Kansas but nationwide due to its complexity and uniqueness. 

The proposed project will provide several learning and action outcomes that revolve around profitability, sustainability, and quality of life. Learning outcomes: (1) farmers will gain insight into a crucial aspect of their land that is often overlooked, nonetheless extremely significant; ii) farmers will be able to improve their N management and cropping system with the use of cover crops, reducing fertilizer costs and increasing their diversity iii) provide farmers with the knowledge and practical skills needed to sustain and enhance soil health and sustainability on their farms; (iv) farmers will improve environmental quality by optimizing nitrogen application through a cover crop system and reducing losses of nitrate into their drinking water sources; v) an indirect effect is a decrease of the emission of greenhouse gases (N₂O) into the atmosphere, responsible for the global warming; vi) offer networking opportunities and technical support to assist farmers and their advisors in making decisions that will lead to increased profitability and sustainability. After the project farmers will be able to improve their systems with data-informed recommendations; and improve farmers’ financial prosperity, quality of life, and engagement in matters of environmental stewardship and long-term sustainability.

 Outcomes will be measured by surveying how likely a farmer who attends the field day demonstrations with the study’s findings will be to consider and adopt the recommendations provided. Additionally, extension specialists and educators will be surveyed to determine if producers in their district will be likely to adapt to recommendations and data provided to them.