Conservation production systems in the mid‐southern USA: III. Zone tillage for furrow‐irrigated soybean

Abstract

Mid‐southern U.S. soybean [Glycine max (L.) Merr.] producers are frequently encouraged to adopt no‐tillage systems to capture the associated environmental benefits; however, adoption is minimal due to the need for raised seedbeds for irrigation and drainage purposes. This research was conducted to determine if zone tillage systems, with and without a tillage radish (Raphanus sativus L. var. longipinnatus) cover crop, can maintain yield, profitability, and water use efficiency relative to that of a conservation tillage system with subsoiling. The effects of conservation systems on soybean grain yield, net returns above specified costs, and water use efficiency were investigated near Stoneville, MS on a Dubbs silt loam (Fine‐silty, mixed, active, thermic Typic Hapludalfs). Relative to a conservation tillage system with subsoiling, switching to a zone tillage system with or without a cover crop had no effect on soybean grain yield (P = .4986), net returns above specified costs (P = .3724), or water use efficiency (P = .5652). Our data indicate that mid‐southern U.S. soybean productivity and profitability are maintained in zone‐tillage systems.

Furrow‐irrigation application efficiency in mid‐southern U.S. conservation tillage systems

“…These data indicate that tillage can be reduced to only furrow creation on medium‐ to coarse‐textured soils in the mid‐southern United States without negative effects on irrigation application efficiency and irrigation water use efficiency. Zone tillage systems are further validated as viable conservation soybean production systems as they have no negative effects on soybean grain yield and net returns (Bryant et al., 2020c). However, there is anecdotal evidence that planting soybean in a flat, zone tillage configuration increases the risk for replants and subsequent yield loss relative to bedded systems when high‐intensity rainfall events occur during emergence and establishment.…”

“…In 2019, 72 mm of rainfall occurred 7 d after planting which reduced soybean plant populations to 30% of desired stand. Based on the average yields for this study, the estimated costs for replanting zone tillage and the yield drag associated with delayed planting is $233.47 ha −1 , that is, a 54% reduction in net returns relative to reduced tillage/subsoiling (Bryant et al., 2020c). Moreover, climate scientists are predicting that the frequency of high‐intensity rainfall events will increase due to climate change (Dourte, Fraisse, & Bartels, 2015; Easterling et al., 2017).…”

“…Experimental units were 8-m wide by 152-m long with each experimental unit containing eight 1-m wide raised seed-beds. As this research was part of a larger study, details such as treatment description and agronomic parameters have been presented earlier (Bryant et al, 2020a(Bryant et al, , 2020b(Bryant et al, , 2020c. Briefly, treatments are described as follows:…”

“…Moisture was adjusted to 130 g kg −1 for final yield determinations. Soybean grain yield is presented in Bryant et al (2020aBryant et al ( , 2020bBryant et al ( , 2020c).…”

“…Switching to a modified zone tillage system Ground cover and cover crop biomass data for this research were previously reported (Bryant et al, 2020c). Briefly, at soybean planting, ground cover in all treatments was provided by native, cool-season weed species and increased in the order of 44% for reduced tillage/subsoiling = 54% for zone tillage/tillage radish <72% for zone tillage/winter fallow.…”