Assessment of farm nutrient management and phosphorus supplementation practices of beef cattle producers in Virginia's Chesapeake Bay watershed

Abstract Text: Concerns over the environmental impact and resource usage of agricultural operations have pressured producers to explore nutrient management as an option to improve sustainability and profitability on the farm. The objective of this study was to determine the level of phosphorus supplementation and nutrient management practices among cow/calf producers in Virginia’s Chesapeake Bay watershed. Surveys were collected from sixty-seven producers in 10 counties. Total cattle populations (unweaned calves excluded) of sampled farms ranged from 6 to 2810 with a mean of 162 (SD = 359). Seventeen percent of producers had no defined calving season, while 21% practiced fall calving, 31% practiced spring calving, and 31% calved in both spring and fall seasons. Nutrient management plans (NMP) are one of the more prevalent strategies currently employed in the Chesapeake Bay watershed in an attempt to minimize whole farm environmental impact and enhance nutrient conservation on the farm by limiting soil erosion and runoff. Fifty-five percent of participants had implemented NMP at the time of survey completion. In relation, twenty-five percent of all producers sampled forage to determine nutrient content.  The majority of producers that sampled forage (94 %; χ² = 17.1; P < 0.0001) currently utilized nutrient management plans. Participants ranked criteria for mineral supplement selection. Responses were weighted based upon participant designated ordinal ranking of criteria (3 for primary, 2 for secondary and 1 for tertiary criteria). Interpretation of response distribution suggests that the primary criterion for mineral supplement selection was price (20.6 %), followed by local availability (17.8 %) and trace mineral content (17.5 %). Sixty-nine percent of producers supplemented a commercial complete mineral mix and 22% used a trace mineral salt block. Eighty percent of producers provided a high magnesium (Mg) mineral (>10% Mg) at some point during the year for an average of 9.5 months (SD = 3.5). Eighty two percent of participants indicated willingness to reduce mineral phosphorus supplementation levels if forage analyses revealed that feed and forage resources were capable of meeting phosphorus requirements, while 15 % indicated uncertainty, and 3 % indicated unwillingness. Survey results suggest that producers are willing to monitor and reduce farm nutrient losses if research shows that over-supplementation is a problem. A concurrent study is underway to assess the extent of nutrient over-supplementation on beef operations in Virginia’s Chesapeake Bay watershed.

Keywords: phosphorus, beef cattle, Chesapeake Bay