Crop diversification, tillage, and management system influences on spring wheat yield and soil water use

Authors: LENSSEN, ANDREW - Iowa State University; Sainju, Upendra; Jabro, Jalal "jay"; Iversen, William - Bill; Allen, Brett; Evans, Robert

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2014
Publication Date: 6/24/2014
Publication URL: http://handle.nal.usda.gov/10113/59068
Citation: Lenssen, A.W., Sainju, U.M., Jabro, J.D., Iversen, W.M., Allen, B.L., Evans, R.G. 2014. Crop diversification, tillage, and management system influences on spring wheat yield and soil water use. Agronomy Journal. 106(4):1445–1454. DOI: 10.2134/agronj14.0119.

Interpretive Summary: Depleted soil quality, decreased water availability, and increased weed competition constrain spring wheat production in the northern Great Plains. Integrated crop management systems are necessary for improved crop productivity. An 8-yr field experiment compared productivity and soil water use of spring wheat (Triticum aestivum L.) under four crop rotations (continuous wheat, wheat-pea [Pisum sativum L.], wheat- forage barley [Hordeum valgaris L.] -pea, and wheat- forage barley -corn [Zea mays L.]-pea), two tillage systems (conventional till and no-till), and two management systems (conventional and ecological). Spring wheat characteristics, yields, and soil water use varied among treatments and years. Spring wheat in diversified rotations had greater preplant soil water content, increased water use and water use efficiency, and greater grain and biomass yields than continuous wheat. Compared to ecological management, conventional management was taller, had fewer heads per acre, more seeds per head, and heavier seed weight, resulting in greater yield. Wheat under ecological management used more water, but water use efficiency was greater under conventional management. Postharvest soil water content was similar among rotations, tillage, and management systems, suggesting that wheat uses most of the available soil water. Spring wheat in diversified rotations planted early in the season is more resilient and should confer greater production stability than continuous wheat systems planted late.

Technical Abstract: Depleted soil quality, decreased water availability, and increased weed competition constrain spring wheat production in the northern Great Plains. Integrated crop management systems are necessary for improved crop productivity. We conducted a field experiment from 2004-2010 comparing productivity and soil water use of spring wheat (Triticum aestivum L.) under four crop rotations (continuous wheat, wheat-pea [Pisum sativum L.], wheat- forage barley [Hordeum valgaris L.] -pea, and wheat- forage barley -corn [Zea mays L.]-pea), two tillage systems (conventional till and no-till), and two management systems (conventional and ecological). Conventional management included recommended seed rates and plant spacing, early planting date, broadcast N fertilization, and reduced stubble height. Ecological management included variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height. Spring wheat characteristics, yields, and soil water use varied among treatments and years. Spring wheat in diversified rotations averaged 35 mm greater preplant soil water content, 37 mm greater water use, 0.8 kg ha-1 mm-1 greater water use efficiency, and 473 kg ha-1 and 817 kg ha-1 greater grain and biomass yields, respectively, than continuous wheat. Wheat in conventional management averaged 9 cm taller height, 28 fewer heads m-2, 4 additional seed head-1, and 2 mg seed-1 heavier seed weight than wheat under ecological management, resulting in 644 kg ha-1 greater yield. Wheat under ecological management used 8 mm more water, but water use efficiency was 2.6 kg ha-1 mm-1 greater under conventional management. Postharvest soil water content was similar among rotations, tillage, and management systems, suggesting that wheat uses most of the available soil water. Spring wheat in diversified rotations planted early in the season is more resilient and should confer greater production stability than continuous wheat systems planted late.