Effects of Manure Applications on Crop Growth and Soil Greenhouse Gas Emissions in the Texas High Plains

Nutrient management and availability in agriculture have been an issue throughout time. Some regions encounter issues with nutrient availability more than others. The Texas High Plains (THP) has a unique set of nutrient management challenges, as well as other issues pertaining to the semi-arid climate. Fertilizer, a substance added to soil to increase fertility, is necessary to sustain agricultural production. Alternative fertilizer sources are a viable option to combat the profound issue of nutrient demand and availability in this region, along with other issues. As the price of inorganic chemical fertilizer increases, alternative natural or organic sources are becoming more popular. Along with fertilizer prices increasing, carbon emissions are following the same trend as agricultural production becomes more intense. Organic fertilizers can provide benefits to soil biological, chemical, and physical properties which may be a reason for preference towards organic fertilizers over inorganic fertilizers in addition to its potential advantage in cost, accessibility, and reproducibility. Soil erosion and limited precipitation are well-known problems that farmers in the THP have endured since the Dust Bowl in the 1930s. Conservation management practices in addition to organic soil amendments used as alternative fertilizer sources can be utilized to reduce soil erosion and retain soil moisture. Some conservation strategies include cover cropping, crop rotation, and conservation tillage. Because of the frequency of drought in this region, conservation practices that improve the water holding capacity of soils are necessary. According to the National Weather Service, this region receives an average of 457 mm of precipitation per year (2022). Another imminent issue of concern in THP is the depletion of the Ogallala aquifer. The THP produces 66% of Texas cotton and cottonseed, and with dwindling water resources, conservation management is required to keep agricultural production functioning and sustainable (Plains Cotton Growers, 2024). The objective of this research is to assess the effect of anaerobic digestate and manure soil applications on cotton growth and soil greenhouse gas emissions (GHG) in the THP. The effects of organic amendments were evaluated in two newly established cotton cropping systems (winter cover cropping and a cotton and wheat rotation). Greenhouse gas emissions, soil characterization, cotton and wheat yield, and nutrient cycling were assessed. An imminent topic directly related to agriculture is climate change which is attributed to the increased accumulation of GHGs in the atmosphere. Management practices associated with crop production account for a large quantity of GHG emissions into the atmosphere, contributing to climate change. The accumulation of detrimental GHGs in the atmosphere can lead to the greenhouse gas effect, where heat is trapped by GHGs, in turn contributing to increased temperatures. If the mitigation of excess GHG emissions does not become a priority, climates will become more extreme. Difficult climatic conditions hinder the production of food and fiber needed to sustain the growing population. Between the depleting aquifer and drought-like conditions in this region, global warming mitigation is a requisite for efficient crop production.