Page 228 - Nutrient Management Planning Guide

220

Calculating Manure Application Rates and Fertilizer Requirements

Scenario 3: P-based; One Time, Three-Year Application Rate

Since residual manure P will be mineralized in the years following application, the same procedure as in the previous scenario is followed to correct the estimated crop available P content: Crop Available P (years 1, 2 and 3) = Total P × (0.7 + 0.2 + 0.06) Crop Available P

2

O

5

(years 1, 2 and 3) = Crop Available P × 2.29

Liquid manure:

Crop Available P; years 1, 2 and 3 (g/L) = 1.0 g/L × (0.7 + 0.2 + 0.06) = 0.96 g/L

Crop Available P

2

O

5

, years 1, 2 and 3 (g/L) = 0.96 g/L Available P × 2.29 = 2.20 g/L

The target application rate to supply 3 years worth of P would be:

Application rate (metric units) = 3 × 40 kg/ha ÷ 2.20 kg/1,000 L * × 1,000

= 54,545 L/ha

Application rate (imperial units) = 54,545 L/ha × 0.089 (Table 4.3.3)

= 4,854 gal/ac

*Nutrient concentrations in g/L are equivalent to kg/1000 L

Solid manure:

Adjusted Crop Available P (kg/t) = 2.3 g/kg × (0.7 + 0.2 + 0.06) = 2.21 kg/t

Crop Available P

2

O

5

, years 1,2 and 3 (kg/t) = 2.21 kg/t Available P × 2.29 = 5.06 kg/t

The target application rate to supply 3 years worth of P would be:

Application rate (metric units) = 3 × 40 kg/ha ÷ 5.06 kg/t

= 23.7 t/ha

Application rate (imperial units) = 23.7 t/ha × 0.4461(Table 4.3.3)

= 10.6 tn/ac