Can Cover or Forage Crops Replace Fallow in the Semiarid Central Great Plains?

Abstract

Growing a crop in place of fallow may improve soil properties but result in reduced soil water and crop yields in semiarid regions. This study assessed the effect of replacing fallow in no‐till winter wheat (Triticum aestivum L.)–fallow with cover, forage, or grain crops on plant available water (PAW), wheat yield, grain quality, and profitability over 5 yr, from 2007 to 2012. Plant available water at wheat planting was reduced the most when the fallow period was the shortest (i.e., following grain crops) or when biomass production was the greatest. Winter and spring lentil (Lens culinaris Medik.) produced the least biomass, used the least soil water, and had the least negative effect on yield. For every 125 kg ha−1 of cover or forage biomass grown, PAW was reduced by 1 mm, and for every millimeter of PAW, wheat yield was increased by 5.5 kg ha−1. There was no difference in wheat yield whether the preceding crop was harvested for forage or left as standing cover. In years with above‐average precipitation, wheat yield was reduced 0 to 34% by growing a crop in place of fallow. However, in years with below‐average precipitation, wheat yield was reduced 40 to 70% without fallow. There was minimal negative impact on wheat yield growing a cover or forage crop in place of fallow if wheat yield potential was 3500 kg ha−1 or greater. Net returns were reduced 50 to 100% by growing a cover crop. However, net returns were increased 26 to 240% by growing a forage crop. Integrating annual forages into the fallow period in semiarid regions has the greatest potential for adoption.

Winter cover crop production and water use in Southern Great Plains cotton

“…Whereas biomass production for pea and vetch were comparable to cover crop production in the Central Great Plains (Holman et al., 2018; Nielsen et al., 2015a), seeding rates used in this study were at least 65% lower for pea and 20% lower for vetch. Mirsky et al.…”

“…They also found crimson clover to generally produce less biomass than peas and vetch. Biomass production in the Central Great Plains of Kansas was 0–1052 kg ha −1 for vetch and 0–982 kg ha −1 for pea (Holman et al., 2018).…”

“…Holman et al. (2018) observed better pea and vetch winter survival when planted with triticale as compared with a monoculture in Kansas no‐till cropping systems. However, we observed no winter kill of vetch and pea and no advantage of a mixture regarding winter survival.…”

Impacts of cover crop planting dates on soils after four years

“…Due to the differences in CC functional groups within a mixture, the enhanced resource efficiency could lead to greater CC biomass production, which may then differently impact soil ecosystem services (Smith et al., 2014; Wortman, Francis, & Lindquist, 2012). Published studies comparing CC biomass production between single species and mixes found no differences in biomass production (Holman et al., 2018; Hunter et al., 2019; Murrell et al., 2017; Wortman et al., 2012), increased biomass production with mixes compared to some single species (Murrell et al., 2017; Smith et al., 2014), or decreased biomass production (Appelgate, Lenssen, Wiedenhoeft, & Kaspar, 2017; Finney, White, & Kaye, 2016; Hunter et al., 2019). Several studies evaluated CC mix biomass production and its effects on weed suppression and effects on main crop yields (Finney et al., 2016; Noland et al., 2018; Smith et al., 2014; Wortman et al., 2012), but those investigating the effects of CC mixes on soil properties are fewer.…”

Green and animal manure use in organic field crop systems

“…Preliminary results indicated that yield reductions as high as 50% can occur when summer fallow was replaced by a CGM in Utah (unpublished data). Recent work showed that CGMs in Kansas could replace summer fallow successfully where grain yield potential exceeded 3.5 Mg ha −1 (Holman et al., 2018). This is considerably higher than yields typically achieved by farmers in semi‐arid and arid regions (Reeve et al., 2012).…”