Wheat (Triticum aestivumL.) Cultivar Selection Affects Double-Crop and Relay-Intercrop Soybean (Glycine maxL.) Response on Claypan Soils

Kelly A Nelson,Randall L Smoot,Clinton G Meinhardt

doi:10.1155/2010/543261

Abstract

Field research (2003–2005) evaluated the effect of wheat row spacing (19 and 38 cm) and cultivar on double-cropped (DC) soybean response, 38-cm wheat on relay-intercrop (RI) response, and wheat cultivar selection on gross margins of these cropping systems. Narrow-row wheat increased grain yield 460 kg , light interception (LI) 7%, and leaf area index (LAI) 0.5 compared to wide rows, but did not affect DC soybean yield. High yielding wheat (P25R37) with greater LI and LAI produced lower (330 kg ) soybean yields in an RI system than a low yielding cultivar (Ernie). Gross margins were 267 greater when P25R37 was RI with H431 Intellicoat (ITC) soybean compared to Ernie. Gross margins were similar for monocrop H431 non-coated (NC) or ITC soybean, P25R37 in 19- or 38-cm rows with DC H431 NC soybean, and P25R37 in 38-cm rows with RI H431 ITC soybean in the absence of an early fall frost.

Highlights

Claypan soils cover approximately 4 million hectares in the Midwestern U.S These soils are poorly drained partially because of an argillic claypan layer 15 to 24 cm below the soil surface, and they are highly erodible due to slopes up to 20% and surface water runoff [1, 2]
Since AgriPro 502CL was a new imidazolinone-tolerant cultivar with limited seed supply at the initiation of this experiment, we evaluated light interception only in the P25R37 and Ernie cultivars
Ernie and AgriPro 502CL shoot density was 22% to 26% greater in narrow- (19 cm) than a wide-row (38 cm) spacing in lateMay (Table 3). This did not cause an interaction in light interception (LI) or leaf area index (LAI) between row spacing and cultivar (Table 4)

Summary

Introduction

Claypan soils cover approximately 4 million hectares in the Midwestern U.S These soils are poorly drained partially because of an argillic claypan layer 15 to 24 cm below the soil surface, and they are highly erodible due to slopes up to 20% and surface water runoff [1, 2]. Due to economic considerations and relatively strong corn and soybean prices, cropping systems have shifted from a rotation of corn (Zea mays L.) soybeans [Glycine max (L.) Merr.] and wheat (Triticum aestivum L.) to a rotation of corn and soybeans. Small grains such as wheat are important crops to increase water infiltration, organic matter, soil structure, and to reduce soil erosion from surface water runoff [4,5,6]. No-till soybeans, double-cropped after wheat, had 75% of the runoff of monoculture, conventional tilled soybeans in upland silty soils [5]. Doublecropping soybeans after wheat is risky above 38◦ latitude due to low rainfall and dry soils at planting, and to a relatively short growing season that can be limited by early frost which reduces grain quality and yield [11, 12]

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Conclusion