Manure management: AgriLife Research studies to answer questions

Organic sources of fertilizer subject of on-farm and small-plot research


Fertilizer prices spiked over the past few years amid supply and demand issues, and that’s when Katie Lewis, Ph.D., Texas A&M AgriLife Research soil scientist in Lubbock, took on several projects to examine manure-based fertilizers and their management in cropping systems.

Producers are looking for environmentally and economically sustainable management strategies for their cropping systems, Lewis said, and they want to determine how manure fits in as a possible fertilizer source.

In the five-year “Sustainable Agricultural Intensification and Enhancement Through the Utilization of Regenerative Agricultural Management Practices” project funded by a U.S. Department of Agriculture National Institute of Food and Agriculture grant, Lewis is determining the value of manure in relation to carbon sequestration, greenhouse gas emissions and cover crops with on-farm testing.

In a separate industry-funded study, during the 2023 and 2024 growing seasons, she will be examining small-plot nutrient sources at the Texas A&M AgriLife Research and Extension Center at Lubbock. This project is a thesis project for her master’s degree student, Tessa Bennett.

“With fertilizer prices still high, producers are looking to alternative forms of nitrogen, phosphorus and potassium,” Lewis said. “And that’s where the manure sources come into play. This research also focuses on climate-smart practices, including incorporating organic sources of nutrients into your production systems. And so, we’ll be collecting data that will either support the use of manure from a greenhouse gas perspective, or possibly determine if there are negatives to the use of manures.”

She said one of the big concerns when applying manure — which stimulates lots of microbial activity — is the potential for large losses of carbon dioxide, ammonia and nitrous oxide from the soil. Those losses need to be evaluated.

The USDA- and industry-sponsored projects support research studies; the information collected from each will benefit the other, Lewis said.

“Because we aren’t able to dive as deep when we’re doing on-farm studies to really get a better idea of what’s contributing to greater carbon sequestration on this farm versus that farm, the study that we’re doing with the different manure sources amongst cropping systems will allow us to hopefully pinpoint different management strategies that are causing certain effects in the large farm study.”