Forage Crops

HCS612 Forage Crops
Grasslands and Fertility
(Vol 2 Ch. 5, pg 55-82)

	Soil fertility – the capacity of the soil to provide the nutrients required for plant growth (and animal production)
	Macronutrients are those essential minerals that typically exceed 0.1% of dry weight nitrogen (N, 1-5%) potassium (K, 2-4%) calcium (Ca, 0.4-1%) magnesium (Mg, 0.25%) phosphorus (P, 0.25%) sulfur (S, 0.2%)
	Micronutrients (or trace elements) are those essential minerals that are typically less than 0.05% of dry weight (500 ppm)
	silicon (Si) boron (B) iron (Fe) manganese (Mn) copper (Cu)	zinc (Zn) chlorine (Cl) molybdenum (Mo) nickel (Ni)
	Some elements are not required by plants but are essential for animals that consume forages selenium (Se) chromium (Cr) cobalt (Co) sodium (Na) iodine (I)


	N costs 23c/lb Forage has a nominal value of 5c/lb – and would require a response of at least 23/5= 4.6 lb DM/lb N
	Nitrogen cycle (pg 65)
	Nitrogen balance (pg 65) Can be used at paddock, farm, regional or national scale
	Inputs Fixation (~150 lb N/a/yr) Fertilizer (0-250 lb N/a/yr) Release from soil organic matter (50 lb/a/yr) Purchased feed (0.5 ton/a/yr @ 2.5% N = 25 lb N/a/yr Total (375 lb N/a/yr)
	Outputs Leaching (50 lb N/a/yr) Volatilization (0-250 lb N/a/yr) Denitrification (50 lb N/a/yr) Animal products (500 lb calf/a @ 5% N = 25 lb N/a/yr) Sold feed (0.5 ton/a/yr @ 4% N = 40 lb N/a/yr Total = 185 lb N/a/yr

Phosphorus

control yield at 0 kg P/ha, 1972 = 6870 lb DM/ac/yr, 1973 = 2904 lb DM/ac/yr (Ludwick and Rumberg 1976)

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Soil test website

http://ohioline.osu.edu/software/

fert99A.exe

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