Fallow replacement cover crops in a semi‐arid High Plains cropping system

Abstract

Replacing portions of fallow between sorghum [Sorghum bicolor (L.) Moench] harvest and wheat (Triticum aestivum) planting with cover crops provides opportunity to increase productivity and profitability in dryland winter wheat-sorghumfallow (WSF) cropping systems. The objective of this study was to identify potential spring fallow replacement cover crops and management to optimize productivity and resource use efficiency of a WSF system. The study was conducted 2013-2018 at Garden City, KS. Three crop rotation phases (WSF, SFW, and FWS) were the main plot, and fallow replacement cover crops were the sub plot. Cover crop treatments were further split into hayed and cover crop left standing groups to estimate forage potential. Results showed precipitation utilization and storage efficiency (PUtSE) increased by 146% for grain cover crop, 50% for cover crop hayed, and 38% for cover crop left standing compared with fallow. Available soil water at wheat planting (ASWP ww ) was not different between cover crop left standing and fallow. Spring triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)] had up to 182% more forage accumulation over other forage cover crops and a 108% grain yield advantage over other grain cover crops. Our findings showed fallow replacement, foragehayed, and grain cover crops have a greater PUtSE than fallow which may increase economic returns if subsequent crop yields are not reduced. Cover crops left standing had a moderate PUtSE advantage and similar ASWP ww compared to fallow, and cover crop left standing, or fallow would be the best choice if the production goal is to maximize ASWP ww and subsequent crop yields.

Productivity and profitability with fallow replacement forage, grain, and cover crops in W‐S‐F rotation

“…Due to possible reduction in soil water content at planting and reductions in main crop yield after cover crop, a soil water based flexible fallow cover crop management system, "flex-fallow" for short, was proposed. Flexible-fallow cover crop management is the practice of planting cover crops only in wet years, leaving the field fallow when conditions are dry, with the intention of storing soil water and limiting the negative effects of growing a cover crop ahead of wheat or grain sorghum main crop (Holman et al, 2021).…”

Can cover crops improve soil ecosystem services in water‐limited environments? A review

“…Ensuring timely termination of the CC and growing CCs for only a portion of the fallow period could be strategies to allow water recharge and reduce the chances of subsequent crop yield reductions (Holman et al, 2021a;Nielsen et al, 2016). Cover crop impacts on crop yields did not generally differ with differences in precipitation, temperature, soil texture, tillage and cropping systems, years under CCs, and CC functional groups in water-limited regions (Figure 8).…”

“…Besides the benefit of weed control and potentially less herbicide expense, haying or grazing CCs for forage was suggested as a method of offsetting the cost of growing a CC (Holman et al, 2018;Nielsen, Lyon, Hergert, Higgins, & Holman, 2015), and this practice was thought to be easily adapted across the U.S. Great Plains and Canadian Prairie (Carr et al, 2021). However, few studies have compared CCs grown for hay (Holman et al, 2018(Holman et al, , 2021aHolman, Schlege, et al, 2020) or grazing (Kelly et al, 2021) compared with those left standing, and there are no studies published on the long-term >10-yr effect of haying or grazing a CC. One of the primary agronomic concerns with livestock grazing among growers is the potential for soil compaction (Baumhardt et al, 2011), degradation of soil structure and reductions in subsequent crop yields.…”

“…Cover crops that have low seed cost and high biomass tend to be monoculture grass species such as oat, triticale, or forage sorghum. There is a tendency for CCs with high forage yield to have the least amount of soil water available for subsequent grain crops and reduce subsequent grain crop yields (Holman et al, 2018(Holman et al, , 2021a. In situations where CC biomass yield is low, grazing or leaving the CC standing might be more economical and beneficial than haying.…”

“…In arid and semiarid regions, growing a CC for forage rather than a short-season grain crop to replace the fallow period can be less water use intensive, have lower risk for crop failure, and less likely to reduce subsequent crop yields (Holman et al, 2018(Holman et al, , 2021a. Managing a CC for both forage and soil benefits requires more management than only growing a forage crop, yet forage CCs might provide an economic solution to adopting CCs in arid and semiarid regions.…”