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Soil Fertility Considerations

Soil Fertility Considerations. Part of the Ruminant Livestock: Facing New Economic Realities Meetings. Fertilizer Prices. Late January 2008: Nitrogen = $0.65/lb, P 2 O 5 = $0.65/lb, K 2 O = $.0.41/lb Future Projection: Increasing costs! Management Options? Continue as before

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Soil Fertility Considerations

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  1. Soil Fertility Considerations Part of the Ruminant Livestock: Facing New Economic Realities Meetings

  2. Fertilizer Prices • Late January 2008: Nitrogen = $0.65/lb, P2O5 = $0.65/lb, K2O = $.0.41/lb • Future Projection: Increasing costs! • Management Options? • Continue as before • Quit using synthetic fertilizer • Use strategically

  3. pH Effect on Element Availability • When talking about fertilizers and fertility, begin by looking at soil pH. • Soil pH has an effect on fixation and release mechanisms in soil • Lime may be the cheapest “fertilizer”

  4. Soil pH: Legume species Source: Ohio Agronomy Guide, bulletin 472

  5. Soil pH: Grasses Source: Ohio Agronomy Guide, bulletin 472

  6. Soil pH and Lime Application • Apply lime when soil pH is below optimum • It is the buffer pH number that determines the lime application required to get the desired response • Agronomy Guide recommendations are based on tons/acre of ag lime with an ENP of 2000 lbs/ton • Lime is not very soluble, surface applications neutralize acidity slowly (may move downward approximately 1 inch/year) • Implications for nitrogen fertilization (can increase losses)

  7. Nitrogen Fertility • Rate of nitrogen application is directly related to yield potential • Nitrogen sources include synthetic fertilizer, livestock manure, compost, and organic matter release in the soil • Cool season grass response is greatest in spring and in fall • Pasture and hay fields with > 25% evenly distributed legumes do not need nitrogen application

  8. Phosphorus (P) • Needed at critical soil test level to ensure maximum forage production • Rate recommended is not directly related to yield potential • For every 7.5 – 10 lbs/acre of P2O5 added or removed from the soil, soil test P will change by 1ppm Source: Robert Mullen, 3-6-07 presentation to Athens Grazing Council

  9. Potassium (K) • Poor potassium nutrition can result in poor forage production • Application not related to yield potential • For every 2 –6 lbs/acre of K2O added or removed, soil test K will change by 1 ppm • High levels of soil K can be a problem: • Luxury consumption and high forage concentrations • Can suppress magnesium uptake Source: Robert Mullen, 3-6-07 presentation to Athens Grazing Council

  10. Critical Soil Nutrient Levels for Forages: P and K P critical levels based on crop, K critical levels based on CEC Source: Robert Mullen, 3-6-07 presentation to Athens Grazing Council

  11. Role of Soil Organic Matter • O.M. increases the water holding and nutrient storage capacity of the soil • Critical to soil organisms that play a role in nutrient release, decomposition, and breakdown of chemicals • Release nutrients and increase nutrient availability to plants • Buffers the soil system: in high organic matter soils macro nutrients are more available compared to low pH soils (What is a “high” OM soil?)

  12. Pastures: Nutrient Cycling • Removal rates for pasture are lower than for hay crop, but… • Grazing livestock move nutrients and concentrate nutrients into patches • Nutrients are lost from pastures as animal product, through volatilization, leaching, erosion, but… • Purchased feeds and stored feeds fed to livestock on pasture can add nutrients

  13. Pastures: Nitrogen Cycling • 70% of nitrogen returned to pastures is in the form of urine • The nitrogen application rate can be the equivalent of 1000 lbs/acre in a urine patch • Leaching losses can approach 50% and 22% of nitrogen is lost to volatilization • Negligible N-fixation under a urine patch Source: Dave Barker, 2-9-07 OFGC conference presentation

  14. Pasture Nutrient Cycling: Feces/Dung • Phosphorus applications can amount to 220 lbs/acre in dung patches • Soil K in camp areas are commonly 4 to 10 fold higher than the overall pasture average • The nitrogen in dung can approximate urine N levels but is in an organic form and is more stable: volatilization losses about 5% and leaching losses about 4% Source: Dave Barker, 2-9-07 presentation to OFGC conference

  15. Nutrient (manure) Management in Pastures • Higher stock density = better distribution • Shorter occupation periods = better distribution • Shade, water and minerals can concentrate manure • Use water and minerals to spread distribution • More intensive management can reduce fertilizer costs

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