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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, 2005
Better forage fertility management may improve dryland forage hay production, quality, and tolerance to diseases without compromising environmental quality. Field studies (2004 through 2006) are being conducted at three Florida locations using three forage species (bermudagrass, bahiagrass, and perennial peanut) to compare potassium (K) as potassium chloride (KCl) with and without supplemental potassium magnesium sulfate (K2SO4 · 2MgSO4 , K-Mag®) on forage yield, quality, and tissue mineral content. Soil cores are being taken to determine fertilization effects on nutrient movement over time. The five treatments consist of: a control using 60 lb nitrogen (N) per ton of harvested biomass per acre, plus phosphorus (P) fertilizer applied per soil test recommendation; "low K" using 24 lb K2O per ton harvested biomass per acre following each clipping; "high K" using 48 lb K2O per ton harvested biomass per acre following each clipping; low K with 25% provided as K2SO4 · 2MgSO4 ; and high K with 25% provided as K2SO4 · 2MgSO4. Check plots with no fertilizer were also included.
In 2004, fertilizer treatments resulted in sporadic minor yield improvements with K2SO4 · 2MgSO4 fertilization for bermudagrass and bahiagrass. However, perennial peanut showed no fertilization response in 2004 or 2005. In 2005, bermudagrass plots in south Florida became sulfur (S) deficient, which was expressed visually as leaf chlorosis and a 50% drop in forage yield. Sulfur was the only nutrient consistently deficient in the affected bermudagrass tissue in 2004 and 2005, and in 2004 soil samples. The 2005 soil samples are being processed. Helminthosporiumleaf spot was observed in all bermudagrass plots, but severity was greatest in the plots receiving only N fertilization. Bahiagrass plots in south and north-central Florida became infected with dollar spot Sclerotinia homoeocarpaand fertilization aggravated the symptoms. In mixed Pensacola/Argentine bahiagrass plots, the Pensacola variety appeared more susceptible. In 2006, the effects of K2SO4 · 2MgSO4 fertilization on yields and disease susceptibility will continue to be monitored and root biomass among treatments will be compared. FL-22F
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