Landscape-scale cropping changes in the High Plains: economic and environmental implications

Abstract

A global transformation in semi-arid cropping systems is occurring as dryland (non-irrigated) farmers in semi-arid regions shift from crop rotations reliant on year-long bare fallows, called summer fallow, to more intensively cropped systems. Understanding the rate of cropping system intensification at the landscape scale is critical to estimating the economic and environmental implications of this movement. Here, we use high-resolution satellite data to quantify dryland cropping patterns from 2008 to 2016 in the US High Plains. We use these estimates to scale up our previous field-level research in this region on soil carbon, herbicide use, yields, and profitability. Over the nine year study period, the High Plains witnessed a profound shift in cropping systems, as the historically dominant wheatfallow system was replaced by more intensified rotations as the dominant systems by land area. Out of the 4 million hectares of non-irrigated cropland in the study area, this shift coincided with a 0.5 million-hectare decline in summer fallow and a concurrent increase in alternative (non-wheat) crops. We estimate that, from 2008 to 2016, these patterns resulted in a 0.53 Tg (9%) increase in annual grain production, 80 million USD (10%) increase in annual net farm operating income, substantial reductions in herbicide use, and an increase in C sequestration that corresponds to greenhouse gas reductions of 0.32 million metric tons of CO 2 equivalents per year (MMTCO 2 e yr −1 ). We project each of these implications to a scenario of potential maximum 100% intensification and estimate that, relative to 2016 levels, herbicide use would be reduced by more than half, grain production would increase by 25%, net operating income would increase by 223 million USD (26%), and greenhouse gases would be reduced by an additional 0.8 MMTCO 2 e yr −1 . The scale of cropping intensification in the High Plains and its environmental and economic impacts has important implications for other regions undergoing similar transformations, and for policy that can either support or hinder these shifts toward more sustainable cropping systems.

Genome-Wide Association Study Reveals Candidate Genes for Flowering Time in Cowpea (Vigna unguiculata [L.] Walp.)

“…Considerable gains can be made to increase yield and stability of grain legumes in drought prone environments by shortening crop duration ( Subbarao et al, 1995 ). This would be important in Colorado and other regions of the semi-arid High Plains, where dryland agriculture constitutes a significant proportion of the total cropland and where erratic precipitation patterns due to climate change are threatening the productivity and profitability of such system ( Rosenzweig and Schipanski, 2019 ). Earlier flowering cowpea varieties could also help intensify dryland cropping systems in the High Plains by providing a viable alternative to the summer fallow that precedes winter wheat ( Nielsen and Vigil, 2005 ).…”

Soil and crop management systems that ameliorate damage caused by decades of dryland agroecosystem mismanagement

“…WF, wheat-fallow; WCF, wheat-corn-fallow; CC, continuous crop F I G U R E 12 Relationship of cropping system intensification and surface-soil effective porosity Relationship of cropping system intensification and surface-soil bulk density (0-2.5 cm soil depth) (Shaver et al, 2002) More recent analyses suggest that this transition to more diverse and intensified rotations is underway across the Great Plains. A spatial analysis of cropping patterns showed that as of approximately 2012, wheat-fallow was no longer the most common rotation system in the region for the first time, likely since the fallow system was first introduced (Rosenzweig & Schipanski, 2019). The wheat-fallow system has been largely replaced by 3-to 4-yr rotation systems of wheat-corn-fallow or wheat-corn-millet-fallow.…”

Winter wheat residue impact on soil water storage and subsequent corn yield

“…Also, the use of crop rotations of three or more years has proven to be a beneficial system in semi-arid regions (Schlegel et al, 2002;Schlegel et al, 2019b;Davis et al, 2012;Nielsen & Vigil, 2018) and a 3-year rotation of wheat-corn-fallow is common in the High Plains of the United States (Rosenzweig & Schipanski, 2019). Crop residue remaining on the soil surface can enhance precipitation storage by an estimated 15% to 35% as biomass is increased from 0 to 10 Mg ha -1 (Nielsen et al, 2005).…”

“…Crop residue can be beneficial in limited‐resource environments by conserving water in semi‐arid regions (Nielsen, Unger, & Miller, 2005; Schlegel, Assefa, Haag, Thompson, & Stone, 2019a; Unger, 1992; Unger, Stewart, Parr, & Singh, 1991). Also, the use of crop rotations of ≥3 yr has proven to be a beneficial system in semi‐arid regions (Davis, Hill, Chase, Johanns, & Liebman, 2012; Nielsen & Vigil, 2018; Schlegel, Assefa, Haag, Thompson, & Stone, 2019b; Schlegel, Dumler, & Thompson, 2002), and a 3‐yr rotation of wheat–corn ( Zea mays L.)–fallow is common in the High Plains of the United States (Rosenzweig & Schipanski, 2019). Crop residue remaining on the soil surface can enhance precipitation storage by an estimated 15–35% as biomass is increased from 0 to 10 Mg ha −1 (Nielsen et al., 2005).…”