154. Response of Cotton to Simulated Grazing

Abstract Cotton (Gossypium hirsutum L.) is a staple crop in the southeastern US. In recent years, grazing pressure from wildlife has led to stand losses and decreased yield. However, this has led to interest among researchers in exploring the viability of cotton as a potential source of livestock nutrition. Currently, there is a lack of data regarding cotton as a grazed forage. Thus, our study aimed to determine the nutritive value, regrowth potential, and cotton yield based on level of simulated grazing pressure. This experiment was conducted as a completely randomized block design with defoliation (simulated grazing) being the single treatment factor. During this study, cotton from a standard production field was divided into two, 0.08-ha blocks. These blocks were then divided into five 9 x 18 m strips, and strips were assigned to one of four defoliation treatments (above the 1st, 4th, 8th, or 12th node) or a negative, unharvested control. Cotton was allowed to grow for approximately 75 d before simulating grazing events. Immediately prior to the simulated grazing event, ten plants were selected at random in each plot. Cotton was then harvested according to the assigned treatment. Plant density (count/ha) and pre-harvest height were consistent across treatments (P > 0.77). Post-harvest heights from the 12th node were not different (P > 0.05) from the control but decreased (P < 0.05) with increasing defoliation intensity. Dry matter yield was greatest (P < 0.05) from those harvested at the 1st node (1,921 kg/ha) and decreased through the 12th node (286 kg/ha). Leaf-to-stem ratios, however, were not different (P > 0.05) across treatments. Initial results are interpreted to mean that cotton may be a viable forage crop in a dual-purpose system, but replication across years and subsequent live animal trials will be required to fully assess viability.