Residual Effects of Fall Deep Tillage on Soybean Yields and Net Returns on Tunica Clay Soil

Abstract

Seed yield of monocrop soybean [Glycine max (L.) Merr.] grown on nonirrigated clay soils in the Mississippi River alluvial flood plain has been consistently low and marginally profitable. Deep tillage (subsoiling) of certain clayey soils in the fall when the soil profile is dry significantly increases yields and net returns from this production system. Yields and net returns were evaluated for seven deep‐till treatments and a conventional‐till treatment that was disked annually (C). The deep‐till treatments included subsoiling annually and once every second, third, fourth, and fifth year (DT1, DT2, DT3, DT4, and DT5, respectively), Paratill annually (PT1), and profile modification every fifth year (MP). Over the 5‐yr study, DT1 produced the greatest yield (3452 kg ha−1), which was 1016 kg ha−1 (42%) above the average yield from C (2436 kg ha−1). Yields from DT2, DT3, and PT1 were virtually identical and averaged only 198 kg ha−1 (5–6%) less than the average yield from DT1, whereas yields from DT4 and DT5 averaged 291 kg ha−1 (9%) and 613 kg ha−1 (18%) less. Net returns from DT1 ($436 ha−1) averaged the highest, whereas returns from C ($220 ha−1) were the lowest. Net returns from DT2 and DT3 were within 5% of the net returns from DT1, whereas net returns from the DT4, DT5, PT1, and MP treatments respectively averaged 9, 26, 9, and 31% less than returns from DT1. Thus, fall deep tillage should be performed at least once every 3 yr to maximize and sustain higher yields and net returns from soybean grown on nonirrigated Tunica clay (clayey over loamy, smectitic, nonacid, thermic Vertic Haplaquept).

Soybean Seed Composition Is Influenced by Within-field Variability in Soil Nutrients

“…Soil moisture could have affected the compaction due to higher clay fraction content in some areas of the field, reducing nutrient uptake and plant growth. It was reported that, when maximum water‐holding capacity is approached, the clay fraction swells and severely restricts water movement into and through the soil profile (24). As water is removed from these soils, the clay fraction shrinks and vertical cracks often form within the profile.…”

Comparison of Tillage Types and Frequencies for Cotton on Southern Piedmont Soil

“…Results for PT were surprising because this tool creates deeper soil profile disturbance compared with the other tillage treatments, which should increase water infiltration in the winter and improve soil exploration by cotton roots. Several authors have reported reduced soil density with paratillage (Tollner et al, 1987; Clark et al, 1993; Radcliffe et al, 1989; Wesley et al, 2000). Wesley et al (2000) found that soybean yields on a nonirrigated clay soil in the Mississippi River flood plain were identical following annual fall paratillage or annual subsoil treatment but were significantly reduced with disk tillage.…”

“…Several authors have reported reduced soil density with paratillage (Tollner et al, 1987; Clark et al, 1993; Radcliffe et al, 1989; Wesley et al, 2000). Wesley et al (2000) found that soybean yields on a nonirrigated clay soil in the Mississippi River flood plain were identical following annual fall paratillage or annual subsoil treatment but were significantly reduced with disk tillage. Several factors may have contributed to the reduced response to PT.…”

“…In Mississippi, soybean [ Glycine max (L.) Merr.] production with fall deep tillage had 9% greater net returns than fall paratillage on a Tunica clay (clayey over loamy, smectitic, nonacid, thermic Vertic Haplaquept) (Wesley et al, 2000). Yields and returns were within 5% of annual deep tillage when deep tillage was performed every second or third year.…”

Deep and Shallow Fall Tillage for Irrigated Soybean Grown with Different Weed Management Systems in the Midsouthern USA

“…Wesley and Smith (1991) measured significant yield increases from nonirrigated May plantings following fall DT of a dry Tunica silty clay soil (clayey over loamy, smectitic, nonacid, thermic, Vertic Haplaquept) in Mississippi in years when drought occurred during the growing season. Wesley et al (2000) determined that net return was greatly increased from this practice. The increased production was associated with increased moisture content in the soil, presumably because of greater infiltration and storage of winter rain resulting from fall DT.…”