Improving the Performance of Winter Wheat Planted without Tillage After Grain Sorghum.

Over the past two decades no-till management systems have increased in acres throughout Kansas.  No-till has improved soil water conservation while helping reduce soil erosion.  The increased amount of available soil water associated with no-till has allowed growers to intensify and diversify their crop rotations.  This has resulted in more acres of winter wheat planted following summer row crops.  Grain Sorghum (Sorghum bicolor) and winter wheat (Triticum aestivum) are two common crops in Kansas and are adapted to similar growing environments.  Previous rotation research has revealed that wheat often performs worse following grain sorghum compared to other summer row crops.  The objective of this study was to evaluate various residue and harvest management strategies in no-till systems to improve winter wheat yields following grain sorghum.  Three management factors were: glyphosate (preharvest application, postharvest application, and no application), residue (residue removal, residue chopped, and residue left standing), and nitrogen (additional 14 kg ha^-1 applied to residue and no additional nitrogen applied).  Treatment structure was a 3-way factorial with treatment combinations arranged in a randomized complete block design with four replications. The study was conducted at three locations in Kansas that have environments conducive for planting winter wheat following a summer row crop.  Response of wheat grain yields to the management factors varied with environment.  At two of the three locations grain yields were significantly greater where glyphosate was applied to the sorghum crop preharvest.  One location showed higher wheat yields when additional nitrogen was applied to the sorghum biomass.  Response of grain yields were significantly influenced by residue treatments at two of the three locations.  These results support the conclusion that residue management and early applications of glyphosate can improve grain yields of winter wheat depending on environment.