Written collaboratively by Tong Wang and Michael Wimberly.
In recent years, the Western Corn Belt has been highlighted as an area where cropland acres have expanded at the expense of grassland cover loss (Wright and Wimberly, 2013). To better understand land use change from a producer’s perspective, a survey on land operators’ views was carried out in Eastern South Dakota and North Dakota in spring 2015 (Wang et al., 2017; Wimberly et al., 2017).
The farms that were surveyed were mainly located in the Eastern Dakotas, with Figure 1 depicting survey counties with number of respondents. Note that yellow represents counties with 85-100% of average operator acres under cultivated crops. Light green represents intermediate levels of operator acres under cultivated crops, while dark green represents less than 40% of operator acres under cultivated crops, or more that 60% of farm area under grassland. Towards the drier Western part of the study area, farms were generally larger with more grassland acres.
Figure 1. Cropland as a share of respondent acres, with county names and survey respondent numbers included. Source: Wang et al. (2017)
Cropland Expansion Patterns
Survey results indicated that farms located in the western part of the study area were more likely to report increased cropland acres. As indicated by Figure 2, most of the increase in cropland acres from 2004 to 2014 was concentrated on the western portion of the survey area, where more than one third of producers reported a more than 10% increase in cropland acres.
Figure 2. Percentage of producers who reported more than 10% increase in cropland acres from 2004 to 2014. Source: Wimberly et al. (2017)
Distinguishing 3 Conversion Types
Three different types of grassland conversions were covered in the survey, including:
- Native grasslands that were uncultivated.
- Tame grasslands that had been cultivated and re-planted to non-native grass.
- CRP land that had been cultivated and replanted to grass.
From the survey responses, a comparison of multiple types of grassland to cropland conversion was possible. In addition, survey data provided insights into the percentages of major crop types grown on the acres recently converted from grassland to cropland (Table 1).
Table 1 provides the reported average conversion rates by close to 1000 survey respondents. Among three types of conversion, conversion from CRP land to cropland occurred most frequently among survey respondents. For those farms that made the conversion, the converted cropland acres were most likely to be from CRP land. On average, the acres of converted CRP land were more than the sum of the acres from native and tame grassland conversions combined. On recently converted cropland, the majority of farms reported growing corn and soybeans, whereas fewer reported growing wheat.
For all three types of grassland to cropland conversions, the majority of acres were converted by a small percentage of producers. For conversion of native grassland to cropland, the 5% of producers with the highest converted acres accounted for 81% of total converted acres. For conversion of tame grassland to cropland, the 5% with the highest converted acres accounted for 76% of total converted acres. For conversion of CRP to cropland, the 5% of producers with the highest converted acres accounted for 67% of total converted acres.
Table 1. Land use conversion rate from 2004 to 2014, as reported by surveyed farm operators.
|Variables||# of Operators||Avg.
Conversion Rate (%)
to major crops (%)
|Native grass to crop||989||14.2||118.2||85.7||75.2||21.0|
|Tame grass to crop||991||15.8||102.6||95.3||78.3||25.5|
|CRP grass to crop||994||24.2||239.1||89.6||79.2||28.3|
Data Source: Wimberly et al. (2017)
To sum up, research results suggested that farms located in the Western portion of the survey area were more likely to report an increase in cropland acres by 10% and above. Among three types of grassland conversions, conversion from CRP grassland to cropland occurred most frequently. For all three types of grassland to cropland conversions, the majority of conversions were all made by a small percentage of farm operators.
This article is based upon research work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2014-67003-21772.
- Wang, T., M. Luri, L. Janssen, D. Hennessy, H. Feng, M. Wimberly and G. Arora. 2017. “Determinants of Motives for Land Use Decisions at the Margins of the Corn Belt” Ecological Economics. 134: 227-237.
- Wimberly, M., L. Janssen, D. Hennessy, M. Luri, N. Chowdhury and H. Feng. 2017. “Cropland Expansion and grassland loss in the eastern Dakotas: New insights from a farm-level survey” Land Use Policy. 134: 160-173.
- Wright, C.K., Wimberly, M.C., 2013. Recent land use change in the Western Corn Belt threatens grasslands and wetlands. Proceedings of the National Academies of Sciences USA 110(10), 4134-4139.