Effects of Grazing Management and Buffer Strips on Metal Runoff from Pastures Fertilized with Poultry Litter

Abstract

Metal runoff from fields fertilized with poultry litter may pose a threat to aquatic systems. Buffer strips located adjacent to fields may reduce nutrients and solids in runoff. However, scant information exists on the long-term effects of buffer strips combined with grazing management on metal runoff from pastures. The objective of this study was to assess the 12-yr impact of grazing management and buffer strips on metal runoff from pastures receiving poultry litter. The research was conducted using 15 watersheds (25 m wide and 57 m long) with five treatments: hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer strip (RBR). Poultry litter was applied annually in spring at 5.6 Mg ha. Runoff samples were collected after every rainfall event. Aluminum (Al) and iron (Fe) concentrations were strongly and positively correlated with total suspended solids, indicating soil erosion was the primary source. Soluble Al and Fe were not related to total Al and Fe. However, there was a strong positive correlation between soluble and total copper (Cu) concentrations. The majority of total Cu and zinc was in water-soluble form. The CG treatment had the highest metal concentrations and loads of all treatments. The RBR and H treatments resulted in lower concentrations of total Al, Cu, Fe, potassium, manganese, and total organic carbon in the runoff. Rotational grazing with a fenced riparian buffer and converting pastures to hayfields appear to be effective management systems for decreasing concentrations and loads of metals in surface runoff from pastures fertilized with poultry litter.

Long‐term effects of grazing management and buffer strips on phosphorus runoff from pastures fertilized with poultry litter

“…Therefore, the main objective of this paper was to evaluate the long‐term effects of grazing management strategies and buffer strips on P loads and concentrations in runoff from pastures fertilized with poultry litter. Earlier research on the watersheds in this study showed that grazing management practices in combination with buffer strips can significantly reduce soil erosion (Pilon, Moore, Pote, Pennington, et al., ), metal runoff (Pilon, Moore, Pote, Martin, & DeLaune, 2017a), and N runoff (Pilon et al., ).…”

“…Pilon, Moore, Pote, Pennington, et al (2017) observed lower bulk density in hayed pastures compared with continuously grazed pastures. Moreover, results from the same research showed higher runoff volumes and sediment loads in pastures that were continuously grazed over 12 yr compared with hayed pastures (Pilon, Moore, Pote, Martin, & DeLaune, 2017). A grazing study conducted by Hann et al (2003) showed greater concentrations and loads of TP in runoff from pastures that were grazed compared with ungrazed or hay systems.…”

“…A factor that has an effect on surface erosion and nutrient movement is the presence of livestock. Cattle can create pasture conditions that are more susceptible to sediment and P runoff by reducing ground cover and decreasing infiltration by soil compaction (Iglesias, Galantini, Kruger, & Venanzi, 2014;Pilon, Moore, Pote, Martin, & DeLaune, 2017;Pilon, Moore, Pote, Pennington, et al, 2017;Pilon et al, 2018;Tanner & Mamaril, 1959). Duda and Finan (1983) discovered that total P (TP) concentrations in agricultural watersheds with low livestock populations were 5-to 10-fold greater than mostly forested watersheds, whereas TP concentrations in watersheds with high livestock density were closer to 50-fold greater.…”

“…In order to reduce the potential for sediment and nutrient losses, management practices that improve pasture conditions to favor infiltration and reduce runoff need to be considered (Pilon, Moore, Pote, Martin, & DeLaune, 2017;Pilon, Moore, Pote, Pennington, et al, 2017;Pilon et al, 2018). Grazing management practices such as rotational grazing reduce the negative impact of grazing cattle on pastures by strategically rotating livestock in and out of pastures.…”

“…that ground cover was a key driver in reducing sediment and nutrient loss. Research has shown that rotational grazing reduces the amount of bare ground resulting in greater protection of the soil against erosion, as well as increased infiltration through reduced compaction, which prevents surface sediment and nutrient loss to waterbodies (Gilley, Patton, Nyren, & Simanton, 1996;Pilon, Moore, Pote, Martin, & DeLaune, 2017;Pilon, Moore, Pote, Pennington, et al, 2017;Sanjari et al, 2009;Warren, Thurow, Blackburn, & Garza, 1986). Pilon, Moore, Pote, Pennington, et al (2017) observed lower bulk density in hayed pastures compared with continuously grazed pastures.…”