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Appendix 6B

Calculating Expected Nutrient Uptake and Removal

Tables 6A-1 and 6A-2 (Appendix 6A) provide coefficient ranges to estimate crop nutrient uptake and removal based on expected or measured crop yields.

For a barley yield of 70 bu/ac, the expected range of nutrients taken up by the barley is

Crop Nitrogen Uptake (lb N/ac) = Yield (bu/ac) X Uptake Coefficient (lb N/bu) (Table 6A-2) Using lower coefficient Crop N Update = 87.5 lb N /ac = 70 bu/ac x 1.2500 lb N/bu Using upper coefficient Crop N Update = 106.8 lb N/ac = 70 bu/ac X 1.5250 lb N/bu

A 70 bu/ac barley would be expected to take up between 87.5 to 106.8 lb N/ac in the total biomass (grain and straw).

For the barley yield of 70 bu/ac, the expected range of nutrients removed in the grain is

Crop Nitrogen Removal (lb N/ac) = Yield (bu/ac) X Removal Coefficient (lb N/bu) (Table 6A-2) Lower61.3 lb N/ac = 70 bu/ac X 0.8750 lb N/bu Upper 74.4 lb N/ac = 70 bu/ac X 1.0625 lb N/bu

A 70 bu/ac barley would be expected to remove between 61.3 to 74.4 lb N/ac in the grain removed from the field.

A barley silage crop with a yield of 6 tons/ac at 50% moisture is equivalent to 3 tons/ac dry matter Yield

Dry Matter

= Yield

50% Moisture

/ (100/(100-% Moisture)) = 6 tons/ac / (100/(100-50)) = 3 tons/ac

For the barley silage yield of 3 tons/ac of dry matter, the expected range of nutrients removed in the grain is

Nutrient Uptake (lb N/ac) = Yield

Dry Matter

(tons/ac) x Uptake Coefficient (lb N/ton) (Table 6A-2) Nitrogen: Lower 86.7 lb N/ac = 3 tons/ac X 28.8889 lb/ton Upper 120 lb N/ac = 3 tons/ac X 40.0000 lb/ton

A 6 ton/ac barley silage crop at 50% moisture would be expected to take up between 86.7 and 120.0 lb N/ac in the total silage biomass (grain and straw).

Appendix 6B