Written collaboratively by Tong Wang and Oladipo Obembe.
An increasing number of farmers across the state of South Dakota have adopted different soil conservation practices such as no-till, conservation tillage and cover crops. Over time, these practices play significant roles in improving soil health and increasing soil resilience towards extreme weather conditions. In addition, soil conservation practices provide environmental benefits, which include reduction in nitrogen leaching, improvement of water quality and increased soil carbon storage (Clay et al., 2012; Delgado et al., 2007).
Geographic location frequently affects the adoption decision of conservation practices (Wang et al., 2019). For example, DeFelice et al. (2006) found no-till generated higher yield in regions with high temperature and/or unfavorable rainfall, but lower yields in areas where soils are poorly drained. Using the United States Department of Agricultural Census data of 2012 and 2017 (USDA, 2017), this article illustrates the spatial and temporal variation in soil conservation practices in South Dakota at the county level.
According to the 2017 Census data, 52.4% of the cropland in South Dakota are under no-till practice (USDA, 2017). As of 2017, the share of no-till has exceeded 60% for the majority of counties located in the central part of the state. Counties such as Buffalo, Campbell, and Walworth had over 90% of their cropland under no-till practice (Figure 1).
Between 2012 and 2017, the proportion of cropland under no-till has increased by 7.1% across the state. Most of the increase in no-till acres between 2012 and 2017 occurred in eastern counties, where the no-till share was relatively low in 2012 (Figure 2). For example, no-till share in McCook, Moody, Lincoln, and Union had increased by over 85% between 2012 and 2017.
Conservation tillage, also referred to as reduced tillage, was practiced on 29.4% of the cropland acres in South Dakota (USDA, 2017). Between 2012 and 2017, conservation tillage acres increased by 24.4% and the majority of the increase came from both eastern and western counties of South Dakota. In the East River counties, both conservation tillage and no-till acres increased, accompanied by a decline in conventional tillage acres. For example, counties such as Clay, Union, and Hamlin have experienced more than a 65% increase in the share of conservation tillage. In most of the West River counties, however, conservation tillage share often increased at the expense of no-till practice (Figure 2).
Between 2012 and 2017, cropland acres under conventional tillage practice was reduced by 33.8%. According to the 2017 Census, only 18.2% of the croplands remained under conventional tillage. However, there were a couple of counties in the state, mostly in the West River where farmers switched from no-till/conservation tillage to conventional tillage or used conventional tillage on newly converted cropland acres. For example, in Custer, Jerauld and Todd, and Stanley, conventional tillage acres increased by over 35% during the 2012-2017 period (Figure 2). Reasons underlying the reversion to conventional tillage at the expense of no-till and conventional tillage in these counties may warrant closer scrutiny.
Cover crop, as a relatively new practice in South Dakota, had maintained a greater growing momentum between 2012 and 2017. As of 2012, cover crop share for most of the counties in South Dakota were less than 1%, while by 2017, the share in most counties have increased to between 1 and 3% of total crop acres (Figure 3). The number of farms using cover crops had increased by 60% from 2012 to 2017. Figure 4 illustrates the changes in cover crop share by county. A major increase in cover crop acres occurred in the central and eastern parts of South Dakota. For example, counties such as Day and Lake increased their cover crops acres by over 300% during the 2012-2017 period. As farmers are recognizing more benefits of using cover crops, usage of cover crops will continue to grow and we expect to see more farm acreage planted with cover crops in the near future (Wang 2018).
This article illustrates the spatial distribution of conservation practice adoption, which may aid future efforts and policies targeted at improving SD soil health. Our findings indicate that many counties in East River SD have seen the greatest increase in no-till and conservation tillage acres, which has largely contributed to the overall increase in cropland under these conservative practices in the state. Conventional tillage acres, however, has also seen an increase in few counties located in the central and western part of SD. Even though its usage remains low compared to other conservation practices, cover crop acres have doubled or even tripled in many central and eastern SD counties. Overall, the increase of cropland acres under conservation practice in South Dakota between 2012 and 2017 are good indicators of continual efforts made by SD farmers, educators and policy makers on soil health improvement.
- Clay, D.E., J. Chang, S.A. Clay, J.J. Stone, R.H. Gelderman, C.G. Carlson, K. Reitsma, M. Jones, L. Janssen, and T. Schumacher. 2012. Corn yields and no-tillage affects carbon sequestration and carbon footprint. Agronomy Journal 104: 763-77.
- DeFelice, M. S., Carter, P. R., & Mitchell, S. B. (2006). Influence of tillage on corn and soybean yield in the United States and Canada. Crop Management, 5(1).
- Delgado, J.A., M.A. Dillon, R.T. Sparks, and S.Y.C. Essah. 2007. A decade of advances in cover crops: Cover crops with limited irrigation can increase yields, crop quality, and nutrient and water use efficiencies while protecting the environment. Journal of Soil and Water Conservation 62(5):110A-117A.
- USDA (2017). Census of Agriculture: Washington, DC: National Agricultural Statistics Service. US Department of Agriculture.
- Wang, T., Jin, H., Kasu, B., J. Jacquet, and S. Kumar. 2019. Soil conservation practices adoption in Northern Great Plains: Economic vs. stewardship motivations. Journal of Agricultural and Resource Economics 44: 404-421.
- Wang, T. Cover Crop Usage in South Dakota is on the Rise. March 11, 2019. SDSU extension article.