Cropping System Influence on Planting Water Content and Yield of Winter Wheat

Abstract

wheat yields were reduced by 79 kg ha Ϫ1 for every centimeter that soil water at wheat planting was reduced by Many dryland producers in the central Great Plains of the USA sunflower (Helianthus annuus L.) ahead of wheat in express concern regarding the effect that elimination of fallow has on soil water content at winter wheat (Triticum aestivum L.) planting rotation. In southwestern Kansas, Norwood (2000) simiand subsequent yields. Our objectives were to quantify cropping sys-larly showed lower winter wheat yields when the previtem effects (fallow weed control method and crop sequence), including ous crop was sunflower or soybean compared with corn corn (Zea mays L.) (C) and proso millet (Panicum miliacium L.) (M), or grain sorghum [Sorghum bicolor (L.) Moench]. These on soil water at winter wheat planting and subsequent grain yield, and reductions in wheat yield were related to lower soil to determine the frequency of environmental conditions which would water at planting. Lyon et al. (1995) showed that soil cause wheat yield to drop below 2500 kg ha Ϫ1 for various cropping water at planting was strongly correlated with yield of systems. Crop rotations evaluated from 1993 through 2001 at Akron, short season summer crops [pinto bean (Phaseolus vul-CO, were W-F, W-C-F, W-M-F, and W-C-M (all no-till), and W-F garis L.), proso millet] but only weakly related to yield (conventional till). Yields were correlated with soil water at planting: of long season summer crops (sunflower, grain sorghum, kg ha Ϫ1 ϭ 373.3 ϩ 141.2 ϫ cm (average and wet years); kg ha Ϫ1 ϭ 897.9 ϩ 39.7 ϫ cm (dry years). Increasing cropping intensity to two corn). They attributed this result in part to shorter seacrops in 3 yr had little effect on water content at wheat planting and son crops having more soil water available at the critical subsequent grain yield, while continuous cropping and elimination of reproductive growth stage than longer season crops, fallow reduced soil water at planting by 11.8 cm and yields by 450which used much of the initial soil water for stover to 1650 kg ha Ϫ1 , depending on growing season precipitation. No-till production and did not have it available for grain develsystems, which included a 12-to 15-mo fallow period before wheat opment.planting nearly always produced at least 2500 kg ha Ϫ1 of yield underIn addition to differences in previous crop water use, normal to wet conditions, but no cropping system produced 2500 kg soil water content at wheat planting can also be affected ha Ϫ1 under extremely dry conditions. by differences in tillage and crop residue effects on precipitation storage efficiency. Precipitation storage efficiency increases as tillage is reduced during the sum-ARS, Central Great Plains Res. Stn., 40335 County Road GG, Akron, quent effects on grain yield, and (ii) determine fre-CO 80720; R.L. Anderson, USDA-ARS, Northern Grain Insects Res. quency of environmental conditions that cause wheat Lab.,

Choice of Summer Fallow Replacement Crops Impacts Subsequent Winter Wheat

“…It is also likely that soil water at wheat seeding would be greater after a forage crop compared with a grain crop as a result of reduced water use during the shorter growing season and subsequent increased time from harvest to wheat seeding. Since increased soil water at winter wheat seeding is usually positively related to winter wheat yield (Musick et al, 1994;Nielsen et al, 2002;Stone and Schlegel, 2006), it would be reasonable, although not always true, that winter wheat yield would be greater after an early planted forage crop like triticale compared with a late planted grain crop like proso millet.…”

“…This would be expected as the amount of soil water at wheat seeding has a strong influence on winter wheat water use (Musick et al, 1994;Nielsen et al, 2002;Stone and Schlegel, 2006). However, despite similar initial starting soil water amounts, wheat grown after triticale and dry pea at Akron in 2004-2005 used an average of 27.9 cm of water compared with 25.5 cm after foxtail and proso millet.…”

“…Elimination of the summer fallow period in eastern Colorado resulted in a significant reduction of available soil water at wheat planting and subsequent wheat yield (Nielsen et al, 2002). When fallow was replaced with proso millet in a wheat-corn-fallow rotation, available soil water content at wheat planting was decreased by 48% (9.8 cm).…”

“…Wheat yield in the wheat-corn-millet system averaged 52% (1530 kg ha 21 ) less than in the wheatcorn-fallow system. Wheat yield has been reported to be strongly correlated with available soil water at wheat planting (Nielsen et al, 1999;Nielsen et al, 2002;Nielsen and Vigil, 2005), with the response ranging from 39.7 to 282.9 kg ha 21 cm…”

Modeling responses of dryland spring triticale, proso millet and foxtail millet to initial soil water in the High Plains

“…Short-season crops such as spring triticale, dry pea (Pisum sativum L.), foxtail millet, and proso millet could be incorporated in crop rotations to replace summer fallow. Impacts of soil water depletion by one crop on the subsequent crop can vary significantly between seasons depending on the seasonal precipitation received (Nielsen et al, , 2002Nielsen and Vigil, 2005). Cropping intensification by replacing summer fallow with a crop can reduce subsequent crop yield (i.e., wheat).…”