Manure Management Plan Form Appendix AS: Crop Nitrogen Usage Rate Factors for Various Crops Corn Zone 1 0.9 lb/bu Orchardgrass Zone 2 1.1 lb/bu Tall fescue Zone 3 1.2 lb/bu Switchgrass Corn silage 7.5 lb/ton Vetch Soybeans 3.8 lb/bu Red clover Oats 0.75 lb/bu Perenial ryegrass Alfalfa 50.0 lb/ton Timothy Wheat 1.3 lb/bu Wheat straw Smooth bromegrass 40.0 lb/ton Oat straw Sorghum-sudan 40.0 lb/ton 38.0 lb/ton 38.0 lb/ton 21.0 lb/ton 56.0 lb/ton 43.0 lb/ton 24.0 lb/ton 25.0 lb/ton 13.0 lb/ton 12.0 lb/ton C. Determine the maximum amount of nitrogen needed based on the yield goal and the crop nitrogen usage rate factor. d. In the yield goal approach we also need to give legume credits if legumes were grown previously in the rotation. Assume soybean were grown the previous year and yield 47 bushel per acre. In lowa, the legume credit for growing soybean is 1 b/N per bushel of soybean yield, with a maximum credit of 50 lb N/acre. What is the soybean credit for this field? e. Nitrogen need is then determined as the yield goal times the crop nitrogen use factor minus the legume credit. What nitrogen need would you estimate for this field? 4. Estimate the nitrogen need for a corn field in lowa (25 points) a. Your corn yield on this field 47 acre field the last 5 times you grew corn were. 176, 155, 211, 207, and 186 bushels per acre. What would you choose as a realistic yield goal? You may choose either the average of the last 5 crops plus 10% or the average of any four of the last five years. b. Now that you have determined a realistic yield you need to select a crop nitrogen usage rate factor. Your farm is in western Sac county. What is the nitrogen use factor? Manure Management Plan Form Appendix AS: Crop Nitrogen Usage Rate Factors for Various Crops Corn Zone 1 0.9 lb/bu Orchardgrass Zone 2 1.1 lb/bu Tall fescue Zone 3 1.2 lb/bu Switchgrass Vetch 7.5 lb/ton Corn silage Red clover 3.8 lb/bu Soybeans Perenial ryegrass 0.75 lb/bu Oats Timothy 50.0 lb/ton Alfalfa Wiveat straw 1.3 lb/bu Wheat Oat straw 40. lb/ton Smooth bromegrass 38.0 lb/ton 38.0 lb/ton 210 lb/ton 56.0 lb/ton 43.0 lb/ton 24.0 lb/ton 25.0 lb/ton 13.0 lb/ton 12.0 lb/ton + 1009 DFocusi- 12:52 PM Manure Management Plan Form Appendix AS: Crop Nitrogen Usage Rate Factors for Various Crops Corn Zone 1 0.9 lb/bu Orchardgrass Zone 2 1.1 lb/bu Tall fescue Zone 3 1.2 lb/bu Switchgrass Corn silage 7.5 lb/ton Vetch Soybeans 3.8 lb/bu Red clover Oats 0.75 lb/bu Perenial ryegrass Alfalfa 50.0 lb/ton Timothy Wheat 1.3 lb/bu Wheat straw Smooth bromegrass 40.0 lb/ton Oat straw Sorghum-sudan 40.0 lb/ton 38.0 lb/ton 38.0 lb/ton 21.0 lb/ton 56.0 lb/ton 43.0 lb/ton 24.0 lb/ton 25.0 lb/ton 13.0 lb/ton 12.0 lb/ton C. Determine the maximum amount of nitrogen needed based on the yield goal and the crop nitrogen usage rate factor. d. In the yield goal approach we also need to give legume credits if legumes were grown previously in the rotation. Assume soybean were grown the previous year and yield 47 bushel per acre. In lowa, the legume credit for growing soybean is 1 b/N per bushel of soybean yield, with a maximum credit of 50 lb N/acre. What is the soybean credit for this field? e. Nitrogen need is then determined as the yield goal times the crop nitrogen use factor minus the legume credit. What nitrogen need would you estimate for this field? 4. Estimate the nitrogen need for a corn field in lowa (25 points) a. Your corn yield on this field 47 acre field the last 5 times you grew corn were. 176, 155, 211, 207, and 186 bushels per acre. What would you choose as a realistic yield goal? You may choose either the average of the last 5 crops plus 10% or the average of any four of the last five years. b. Now that you have determined a realistic yield you need to select a crop nitrogen usage rate factor. Your farm is in western Sac county. What is the nitrogen use factor? Manure Management Plan Form Appendix AS: Crop Nitrogen Usage Rate Factors for Various Crops Corn Zone 1 0.9 lb/bu Orchardgrass Zone 2 1.1 lb/bu Tall fescue Zone 3 1.2 lb/bu Switchgrass Vetch 7.5 lb/ton Corn silage Red clover 3.8 lb/bu Soybeans Perenial ryegrass 0.75 lb/bu Oats Timothy 50.0 lb/ton Alfalfa Wiveat straw 1.3 lb/bu Wheat Oat straw 40. lb/ton Smooth bromegrass 38.0 lb/ton 38.0 lb/ton 210 lb/ton 56.0 lb/ton 43.0 lb/ton 24.0 lb/ton 25.0 lb/ton 13.0 lb/ton 12.0 lb/ton + 1009 DFocusi- 12:52 PM