Herbage Mass, Nutritive Value, and Grain Yield of four Wheat Varieties Managed as a Dual-Purpose Crop

Micayla H West, William B Smith, Adam Rabinowitz, Kim K Mullenix, Leanne L Dillard

Dual-purpose wheat (Triticum aestivum L.) systems increase farm sustainability by diversifying on-farm income. While these systems are common in the Southern Great Plains of the U.S., they are not often utilized in the Southeast. This study aimed to evaluate pre- and post-grazing herbage mass (HM) of four winter wheat varieties managed under a dual-purpose grazing and grain production system. The wheat varieties evaluated were generic feed-type wheat (unknown variety blend, Feed), seed-type wheat ‘GA Gore’ (Seed) and two forage-type varieties, ‘AGS 2024’ (AGS) and ‘Pioneer 26R41’ (Pioneer). The experiment was a randomized complete block design (n = 4) conducted during the winter of 2021 and 2022. Three grazing frequencies were utilized: an ungrazed control (NG), low frequency (LF) and high frequency (HF) grazing schedule. Low frequency plots received monthly grazing in January and February while HF treatments received a third grazing in March. Plots were grazed with 20 cow-calf pairs (Bos taurus) until an even defoliation height of 10 cm was achieved. Herbage mass was determined using three 0.1m²-quadrats per plot and clipped to a 10 cm stubble height before (PreG) and after (PostG) each grazing event. Forage samples were then dried at 45°C for 72 h. Data were analyzed using PROC GLIMMIX of SAS (SAS Inst., Cary, NC) with forage sample date as a repeated measure. Differences were declared at P < 0.05. Final biomass, including stems, chaff, and grain, was greatest for Pioneer but was not different from AGS or Feed (4,112 kg/ha and 4,003 kg/ha; P ≤ 0.94). Before grazing, AGS herbage mass (2,646 kg/ha) was greater (P ≤ 0.03) than all other varieties. There was an interaction (P ≤ 0.01) of variety and grazing frequency for Pre-G herbage mass. Compared with all other varieties, AGS had greater ADF (24.93%; P < 0.01) and least TDN (72.49%: P < 0.01). Forage nitrate-nitrogen was not different (P ≥ 0.49) among all varieties or grazing frequencies (157.73 ppm). Across grazing frequencies, Pioneer had greater final grain yield (3,619.43 kg/ha; P < 0.01) with Seed having the least (1,272.12 kg/ha; P < 0.01). These results indicate that common Southeastern wheat varieties can be successfully utilized in a dual-purpose management system; however, grazing frequency should be monitored to prevent grain yield losses.