Intensified dryland crop rotations support greater grain production with fewer inputs

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

“…Crop footprint maps were developed for each three year rotation window by including pixels if they grew a particular crop at any point in the three year period. Soil carbon sequestration, herbicide use, grain production, and net income analyses Recent studies measured the differences in SOC, annualized grain yield, and input use between the different cropping system intensities in the High Plains across 96 farm fields representing the geographic extent of the study area examined here [12,15]. Data used for the spatial and regional analysis in this study include least-squared means and standard errors generated by statistical models of cropping system intensity and significant soil, management, and climate covariates (table 2).…”

“…For example, the observed doubling in global agricultural production from the 1960s to the 1990s coincided with almost a seven fold increase in nitrogen (N) inputs and a three fold increase in pesticide use, with cascading effects for the environment and human health [8][9][10][11]. In contrast, data from on-farm and research station studies have shown that semi-arid cropping intensification can increase crop production and residues returned to the soil while reducing chemical inputs [12,13]. As a result, reducing summer fallow frequency can simultaneously contribute to desirable environmental and economic outcomes.…”

“…wheatcorn-fallow), and some have even eliminated summer fallow completely through diverse crop rotations, a practice called continuous cropping. Continuous cropping likely provides a greater environmental and economic benefit relative to mid-intensity and wheatfallow [12,15], but previous estimates of intensification have only been derived from changes in individual crop or fallow acreages, and thus we lack an estimate of cropping systems-level changes. For example, Hansen et al [14] report a reduction in summer fallow acres by 70% in the US Northern Great Plains since 1990, and Maaz et al [2] report similar reductions in several Canadian provinces, suggesting that millions of hectares are being intensified.…”

“…However, by increasing precipitation use efficiency, total grain production can be enhanced by 60%-75% in intensified systems relative to wheat-fallow [13], and substantial herbicide reductions can be achieved through increased plant competition with weeds and the ability to rotate different herbicides in intensified systems [7,19]. Additionally, Rosenzweig et al [12] found that, despite achieving greater crop production, continuous farmers in the High Plains apply similar amounts of nitrogen fertilizer as traditional wheat-fallow farmers while cutting herbicide use in half, leading to 80% greater net operating income (i.e. gross profit minus operating expenses, not including fixed costs).…”

“…gross profit minus operating expenses, not including fixed costs). Intensification, and especially continuous cropping, can enable greater crop production without increases in fertilizer because the added plant diversity and carbon inputs enhance soil fertility and beneficial soil microbial populations [12]. Thus, the intensification of cropping systems may provide an opportunity to act on both sides of the double squeeze-to reduce inputs while enhancing crop production.…”