Economic Evaluation of Cover Cropping on Farm Profitability from an On-Farm Trial in Southern Texas
Date
2024-08
Authors
Sharma, Anup
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Abstract
This study examines the net economic and environmental benefits of cover cropping in southern Texas. Cover crops, primarily cultivated for their significant benefits in soil health, erosion control, and ecosystem services, often face adoption barriers due to substantial costs in seeds, labor, equipment, and concerns over the negative impact on the yield of subsequent cash crops. The benefits of cover cropping are not uniform as variations in regional climate, soil conditions, and farming practices significantly influence the impact on subsequent cash crop yields and the associated economic and social benefits. Southern Texas has its unique climate, soil, farming practice and rural culture and is among the regions with the lowest adoption rate of cover crop practices. Meanwhile studies focusing on this region is rather limited. This thesis is comprised of two sections. Section one is a meta-analysis using a data compiled from literature of 85 studies to examine the key factors that affect heterogeneity of cover crop effect across region and natural condition. Section two is the use of economic and soil test data from a 3-year (2021-2023) on-farm trial in south Texas to examine the net monetarized benefits of cover crop practices. Utilizing a split-plot experimental design in collaboration with local farmers, the effects of cover cropping treatments on soil health metrics, specifically focusing on soil carbon and nitrogen storage was accessed.
Results from the meta-analysis reveals that legume CCs can boost yields by over 20-25%, while non-legume broadleaf and mixed-species CCs contribute to increases of 8% and 6%, respectively. Incorporating CC residues into the soil elevates yields by about 15%, outperforming the practice of leaving residues on the surface. Fields with grass or legume CCs experience yield increases of 16% and 18% over fields without CCs. Particularly silty loam and clay loam soil and high rainfall conditions, legume CCs surpass no-CC controls by 18%, 9%, and 7% respectively. Moreover, CCs enhance soil organic matter and microbial biomass with carbon storage in soil organic content rising by 14-18% compared to bare-soil controls. Legume cover crops enhance soil nitrogen content by an estimated around 15-25%, showcasing their ability to contribute beneficially to soil fertility and productivity. Despite these positives, some few studies indicate neutral or negative yield impacts, especially when CCs compete with the main crop for moisture or nutrients, or due to poor management such as inadequate termination before planting the cash crop. Nonetheless, CCs positively affect soil carbon levels by adding biomass, enhancing the soil's carbon and nitrogen storage capacity. For the monetized value computation, the pre and the post treatment data of soil carbon and nitrogen were taken, and the difference-indifference economic model was used to find the post and the pre-treatment effect of cover crops and the control. Also, the analysis of variance (ANOVA) was utilized to find out any significant difference between the treatments and control. The findings indicates that, in the first year, Farm 1 experienced significant economic gains from both soil carbon ($776.61), nitrogen ($1047.64) and $244.44 of nitrogen in the second year. However, there was a notable loss in carbon ($286.12) during the second year, likely may be due to the adverse weather conditions. Similarly, Farm 2 reported economic benefits of $706.02 from carbon in the second year, indicating a successful adaptation to improved farming practices. Meanwhile, Farm 3 showed a marked improvement in carbon benefits, rising from a loss of -$245.25 in the first year to a gain of $653.99 in the second year, suggesting effective soil recovery and nutrient management.
Description
Keywords
cover crops, meta-analysis, soil carbon, soil nitrogen, difference-in-difference
Citation
Sharma, A. (2024). Economic evaluation of cover cropping on farm profitability from an on-farm trial in Southern Texas (Unpublished thesis). Texas State University, San Marcos, Texas.