Replacing Fallow with Continuous Cropping Reduces Crop Water Productivity of Semiarid Wheat

Water supply frequently limits crop yield in semiarid cropping systems; water defi cits can restrict yields in drought-aff ected subhumid regions. In semiarid wheat (Triticum aestivum L.)-based cropping systems, replacing an uncropped fallow period with a crop can increase precipitation use effi ciency but reduce wheat productivity. Our objective was to analyze crop sequence and environmental eff ects on water use, components of water productivity, and net returns of winter wheat (WW) in a semiarid region. A fi eld study was established to evaluate eight 3-yr crop sequences, including a wheat phase followed by a feed grain phase (corn (Zea mays L.) or grain sorghum (Sorghum bicolor (L.) Moench)) and an oilseed phase (OS; spring canola (Brassica napus L.), soybean (Glycine max (L.) Merr.), sunfl ower (Helianthus annuus L.), or none (fallow)). Standard measurements included crop water use (WU), canopy leaf area index at anthesis, biomass, grain yield, and yield components. Net return (NR) was calculated as the diff erence between crop revenue and total operating costs. Replacing an uncropped fallow period with an OS crop reduced water productivity responses of WW (biomass, grain yield, and NR) by 18, 31, and 56%, respectively, relative to that of WW grown aft er fallow. Th ese responses to continuous cropping corresponded to reductions in all components of a water-limiting yield production function. Th e modest water productivity observed (0.28-0.62 kg m -3 ), relative to a reported global range of 0.6 to 1.7 kg m -3 , indicates opportunity to improve wheat water productivity through management and genetic gain.

[1]  M. Madore,et al.  Genotypic Variation for Stem Reserves and Mobilization in Wheat , 2006 .

[2]  C. Norwood.  Profile Water Distribution and Grain Yield as Affected by Cropping System and Tillage , 1994 .

[3]  M. Madore,et al.  Genotypic variation for stem reserves and mobilization in wheat: II. Postanthesis changes in internode water-soluble carbohydrates , 2006 .

[4]  E. Cook,et al.  Drought duration and frequency in the U.S. Corn Belt during the last millennium (AD 992-2004) , 2011 .

[5]  Jürg M. Blumenthal,et al.  Eliminating summer fallow reduces winter wheat yields, but not necessarily system profitability , 2004 .

[6]  Fengmin Li,et al.  The cooperative relation between non-hydraulic root signals and osmotic adjustment under water stress improves grain formation for spring wheat varieties. , 2008, Physiologia plantarum.

[7]  J. Araus,et al.  Plant breeding and drought in C3 cereals: what should we breed for? , 2002, Annals of botany.

[8]  David C. Nielsen,et al.  Efficient Water Use in Dryland Cropping Systems in the Great Plains , 2005 .

[9]  Gary A. Peterson,et al.  Continuous Dryland Cropping in the Great Plains , 2005 .

[10]  Wim G.M. Bastiaanssen,et al.  Review of measured crop water productivity values for irrigated wheat, rice, cotton and maize , 2004 .

[11]  J. Passioura,et al.  Grain yield, harvest index, and water use of wheat. , 1977 .

[12]  J. T. Musick,et al.  Physiological mechanisms contributing to the increased water-use efficiency in winter wheat under deficit irrigation. , 2006, Journal of plant physiology.

[13]  P. Miller,et al.  Cropping sequence effect of pea and pea management on spring wheat in the northern Great Plains , 2006 .

[14]  D. Nielsen,et al.  Legume Green Fallow Effect on Soil Water Content at Wheat Planting and Wheat Yield , 2005 .

[15]  Keith R. Harmoney,et al.  Comparative Morphology of Caucasian Old World Bluestem and Native Grasses , 2004 .

[16]  L. López-Bellido,et al.  Long-Term Tillage, Crop Rotation, and Nitrogen Fertilizer Effects on Wheat Yield under Rainfed Mediterranean Conditions , 1996 .

[17]  L. Ahuja,et al.  Modeling Nitrogen Management Effects on Winter Wheat Production Using RZWQM and CERES‐Wheat , 2004 .

[18]  B. Ehdaie.  Variation in Water-Use Efficiency and Its Components in Wheat: II. Pot and Field Experiments , 1995 .

[19]  Alcalde Rovira Roure.  Plant Breeding and Drought in C 3 Cereals: What Should We Breed For? , 2002 .

[20]  D. Nielsen,et al.  Choice of Summer Fallow Replacement Crops Impacts Subsequent Winter Wheat , 2007 .

[21]  David C. Nielsen,et al.  Nitrogen Fertility Influence on Water Stress and Yield of Winter Wheat , 1991 .

[22]  Gary A. Peterson,et al.  Dryland cropping intensification: a fundamental solution to efficient use of precipitation , 1998 .

[23]  D. Nielsen,et al.  Winter wheat yield depression from legume green fallow , 1998 .

[24]  P. Miller,et al.  Cropping sequence effects of four broadleaf crops on four cereal crops in the northern Great Plains , 2005 .

[25]  Joseph G. Benjamin,et al.  Cropping System Influence on Planting Water Content and Yield of Winter Wheat , 2002, Agronomy Journal.

[26]  D. Young,et al.  Economics of Alternative No-Till Spring Crop Rotations in Washington ’ s Wheat – Fallow Region , 2003 .

[27]  D. Nielsen,et al.  Cropping System Influence on Planting Water Content and Yield of Winter Wheat , 2002, Agronomy Journal.

[28]  K. Dhuyvetter,et al.  Economics of dryland cropping systems in the Great Plains: a review , 1996 .