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Interpretive Summaries:
2006 - Soil Fertilization of Perennial Pasture Systems
2005 - Soil Fertilization of Perennial Pasture Systems
2004 - Soil Fertilization of Perennial Pasture Systems
Soil Fertilization of Perennial Pasture Systems, 2006
Adoption of comprehensive forage fertilization practices can improve dryland forage hay production, quality, and tolerance to diseases without compromising environmental quality. Field studies are being conducted at three Florida locations, using three forage species (i.e., bermudagrass, bahiagrass, and perennial peanut) to compare K as potassium chloride (KCl) with and without supplemental potassium magnesium sulfate (K2SO4·2MgSO4, as K-Mag®) on forage yield, quality, and tissue mineral content. In addition, soil cores are being collected to determine fertilization effects on soil nutrient status over time. The K is applied at two rates (24 lb or 48 lb K2O/t of hay removed) following each cutting. All plots, excluding the check plots, receive N at 60 lb/t hay removed and P fertilizer based upon Florida IFAS recommendations. Control plots receive N without any K.
Bermudagrass has shown the greatest response to fertilization treatments, where plots not receiving K2SO4·2MgSO4 had declining yields. Low soil S and plant tissue S less than approximately 0.18% resulted in chlorotic plants, with yields nearly 50% lower than yields from plots receiving K2SO4·2MgSO4. Sulfur deficiency in bermudagrass presented itself in the first year on the Spodosol soil and the third year on the Entisol soil. The Ultisol soil contained enough residual S to support bermudagrass growth during the 3 years of this study. Bermudagrass had declining yields on plots excluding K if soil K was low and tissue K fell below approximately 1.5%. Additionally, Helminthosporium infection was much greater on K-deficient bermudagrass. Bahiagrass and perennial peanut have larger root/rhizome nutrient storage capacity than bermudagrass, so treatment differences did not appear as quickly. Low tissue S and K began to result in declining bahiagrass yields at some locations in 2006. Perennial peanut has yet to show a yield response to fertilization practices. However, tissue K and S contents in perennial peanut approached critically low values in 2006, suggesting that nutrient-related yield declines may occur in 2007. FL-22F
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