Agronomic assessment of grazing method of corn residues on cow performance, residue utilization, crop yield, and soil properties

The objectives were to evaluate the effects of beef cows grazing corn residues on cow performance, residue utilization, subsequent crop yield, and soil physical and chemical properties. Two grazing methods (strip grazing, (SG) and continuous grazing, (CG)) and a control (ungrazed, (CT)) were arranged in a randomized complete block design with 3 replications each yr for 3 yr. Within SG, subplots were assigned with a grazing order (1, 2, 3). Thirty-six spring-calving, multiparous, Angus cows were utilized in yr 1 (BW = 648 ± 41 kg) and 2 (BW = 710 ± 71 kg) at a stocking density of 3.0 cows·ha-1, and 42 winter-calving Angus heifers (BW = 566 ± 39 kg) were utilized in yr 3 at a stocking density of 3.6 heifers·ha-1. Cattle grazed for 42 d beginning on 29 Sept. 2012 (yr 1), 2 Nov. 2013 (yr 2), and 4 Oct. 2014 (yr 3). Residue samples were collected on d 14 and d 28 of grazing and after grazing in yr 1, and before and after grazing in yr 2. Soil samples were collected before and after cattle grazing in yr 1 and 2. Paddock dimensions were marked during yr 1 with GPS coordinates so that the same treatment was applied to the same paddock area and location each yr. Cows within the SG treatment were heavier (P = 0.04) after grazing and had an increase (P = 0.04) in body weight change compared to CG. At d 28 in yr 1, SG residue had decreased (P ˂ 0.01) acid detergent fiber and tended (P = 0.08) to have increased organic matter compared to CG. At the conclusion of grazing, SG had decreased (P = 0.02) neutral detergent fiber compared to CG. Within SG in yr 2, strip 3 tended to have increased (P = 0.10) total residue available compared to strips 1 and 2 after grazing. Strip 1 had increased (P = 0.02) acid detergent fiber and tended (P = 0.09) to have decreased crude protein compared to strips 2 and 3. No differences (P = 0.19) were detected between treatments for subsequent corn yield following two grazing seasons. However, within SG, the first strip tended (P = 0.10) to have reduced yields compared to the second strip, with the third strip being intermediate. Soil bulk density was increased (P ˂ 0.01) in both grazing treatments compared to CT, but penetration resistance was not affected (P = 0.56) by treatment. Water aggregate stability was decreased (P = 0.01) in CG and SG compared to CT. Soil nitrate was increased (P = 0.03) in CG compared to SG, with CT being intermediate. Soil ammonium was not affected (P = 0.14) by grazing treatment. Soil pH was increased (P ˂ 0.01) in SG compared to CG and CT. Grazing order in SG did not affect (P ≥ 0.25) soil physical or chemical properties. Strip grazing corn residues increased cow performance. Grazing residue did not affect subsequent crop performance, yet the effects that strip grazing has on crop performance need to be further investigated. Although livestock grazing increased soil compaction, root restricting levels of compaction were not reached. Results indicate that cattle and crops can be integrated with the grazing of corn residue, resulting in minimal effects on soil properties and subsequent crop yield