Soybean Relative Maturity, Not Row Spacing, Affected Interseeded Cover Crops Biomass

Hans J Kandel,Kory L Johnson,Marisol T Berti,Dulan P Samarappuli

doi:10.3390/agriculture11050441

Abstract

Adoption of cover crop interseeding in the northwestern Corn Belt in the USA is limited due to inadequate fall moisture for establishment, short growing season, additional costs, and need for adapted winter-hardy species. This study evaluated three cover crop treatments—no cover crop, winter rye (Secale cereale L.), and winter camelina (Camelina sativa (L.) Crantz)—which were interseeded at the R6 soybean growth stage, using two different soybean (Glycine max (L.) Merr.) maturity groups (0.5 vs. 0.9) and two row spacings (30.5 vs. 61 cm). The objective was to evaluate these treatments on cover crop biomass, soil cover, plant density, and soybean yield. Spring wheat (Triticum aestivum L.) grain yield was also measured the following year. The early-maturing soybean cultivar (0.5 maturity) resulted in increased cover crop biomass and soil cover, with winter rye outperforming winter camelina. However, the early-maturing soybean yielded 2308 kg·ha−1, significantly less compared with the later maturing cultivar (2445 kg·ha−1). Narrow row spacing had higher soybean yield, but row spacing did not affect cover crop growth. Spring wheat should not follow winter rye if rye is terminated right before seeding the wheat. However, wheat planted after winter camelina was no different than when no cover crop was interseeded in soybean. Interseeding cover crops into established soybean is possible, however, cover crop biomass accumulation and soil cover are limited.

Highlights

In the northern crop growing areas in the USA, crop rotations were simplified, and corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) became dominant crops
Winter rye or camelina interseeded in an early-maturing soybean (0.5) had higher biomass yield and soil green cover compared with the same crops interseeded in a later maturing (0.9) soybean
The yield penalty of planting an early-maturity soybean cultivar was higher in value than the value of increased cover crop growth and cover

Summary

Introduction

In the northern crop growing areas in the USA, crop rotations were simplified, and corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) became dominant crops. After harvest, a soybean field has limited cover [2] and may result in soil erosion, mainly by wind. Including cover crops in the cropping system provides soil cover, increases biodiversity and soil organic matter, utilizes available nutrients by preventing leaching, and may increase growth and yield of the following crop [3]. Overwintering cover crops that resume growth in the spring in the northwestern Corn Belt (NWCB) were proven to provide many ecological beneficial attributes. Depend on cover crops growth to cover the soil [4,5,6]. Cover crop adoption is steadily increasing in farming operations across the United States, especially in the eastern Corn Belt [7]

Methods

Results

Conclusion