Effects of Preceding Crop On No-till Winter Wheat Yield and Quality.

Crop diversity is an essential component of no-till cropping systems that helps reduce pest pressure and has the potential to impact crop yields. Winter wheat (Triticum aestirum), corn (Zea mays), soybeans (Glycine max), grain sorghum (Sorghum bicolor), and sunflowers (Helianthus annuus) are five primary grain and oilseed crops grown in Kansas.  Canola (Brassica napus) has increased in popularity in portions of South Central Kansas where continuous wheat systems have been practiced historically.  The objective of this study was to quantify the influence of several crops on yield and quality of a following wheat crop.  Six crops were grown preceding wheat: wheat, corn, soybeans, grain sorghum, sunflowers, and canola.  Wheat was planted without tillage on October 4 following the harvest of these crops.  Treatments were arranged in a randomized complete block design with four replications.  The experiment was conducted on a Chase silty clay loam soil south of Manhattan, KS.  Plot sizes were approximately 9m x 15m for each treatment.  Plant populations, fall tillers, spring tillers, head number, spikelet number, kernel weight, and yield were determined for the winter wheat crop.  Preceding crop influenced both plant growth and yield.  Wheat populations in soybean residue were significantly greater compared to other crops, and fall tiller production was favored following both soybean and canola.  Final population and fall tiller numbers were least in wheat planted in wheat and sunflower residues.  Both spring tiller and head numbers were greater following corn and soybeans, while kernel weight was significantly higher following soybeans.  Wheat grain yields were significantly greater following corn and sunflowers, and wheat following wheat yielded the least.  These data support the conclusion that growth and productivity of winter wheat is influenced by the preceding crop.