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.