What Is It? Forage maize is a type of corn (Zea mays) grown to provide fresh fodder = green chop for grazing animals like dairy cows and beef cattle. Forage maize is specially adapted for dense plantings and maximum yield of leaves and stalks per acre. Fast growth, dense shade, and high tonnage make forage maize an ideal cover crop for weed control, surface mulch, and green manure.
Crop Height: Forage maize typically grows 12 to 15 feet tall. High growth enables forage maize to kill the most aggressive weed vines.
Growth Rate: Under favorable conditions forage maize grows 2 to 2.5 inches per day = 1.8 to 2 tons of biomass (leaves & stalks) per acre per week. Fast development allows forage maize to out-compete most temperate and tropical weeds.
Plants Per Acre: Unlike silage corn that has ideal populations of 30,000 plants per acre (for milk production) or 40,000 plants per acre (for maximum biomass), forage maize is planted at much higher densities: 80,000 to 100,000 plants per acre. Tall growth and close spacing create deep shade that kills most weeds.
Plant Spacing: 9 inch x 9 inch equidistant spacing = 77,440 plants per acre. 8 inch x 8 inch equidistant spacing = 98,010 plants per acre. If rows are spaced 15 inches apart then plants must be spaced 4 to 5 inches apart within rows. 166 rows per acre (15 inches between rows) x 624 plants per row (4 inches between plants) = 103,584 plants per acre. 166 rows per acre (15 inches between rows) x 499 plants per row (5 inches between plants) = 82,834 plants per acre.
Seeding Rate: Forage maize has an average seed weight of approximately 100 seeds per ounce or 89,600 seeds per bushel = 8 gallons = 56 pounds. At 80% standard field survival, drill or broadcast 1.25 bushels = 10 gallons = 70 pounds of forage maize seed per acre to obtain a final population of 89,600 plants per acre.
Hybrid Seed: There is no advantage to planting hybrid forage maize seed. Open pollinated seed is significantly less expensive and equally effective for animal fodder, weed control, surface mulch, or green manure. Note: Brown mid rib forage maize varieties are preferred for green chop because they are more digestible.
Broadcast Seeding: Most corn is planted with a grain drill or seeder. Forage maize can also be broadcast with a rotary spreader. For best results, mix live seed with feed corn that has been baked in shallow 2-inch deep pans to kill the seed. (2 hours baking at 300 de3grees Fahrenheit is sufficient). Dilution of live seed with non-viable filler provides extra volume for easier and more accurate distribution. Divide seed mixture into 2 equal portions. Seed up and down the length of the field then broadcast from side to side. Seeding from 2 directions gives the most uniform plant spacing. Rototill or harrow seed 2 inches deep then irrigate to firm and moisten seedbed.
Yield: Forage maize reliably produces 18 tons = 36,000 pounds per acre of biomass at 65% moisture content in 70 days = 10 weeks (from seeding to harvest). Yields exceeding 30 tons per acre are commonly obtained from long-season crops of 120 days or more.
Fertilizer: Apply fertilizer according to soil test recommendations for silage corn of equivalent tonnage. To reduce fertilizer cost plant forage maize following a nitrogen-fixing cover crop like Sunn Hemp (Crotalaria juncea) or Red Clover (Trifolium pratense). Either organic or synthetic fertilizers are equally effective; nutrients are most efficiently applied in irrigation water.
Nutrients Required Per Ton Of Biomass:
Fertilizer Element Pounds of Fertilizer Needed Per Ton of Forage Maize Harvested Per Acre.
A 30-ton expected yield of forage maize per acre requires 30 x 10.36 = 310.8 pounds of nitrogen, 30 x 1.6 = 48 pounds of phosphorous, 30 x 9.2 = 276 pounds of potassium, 30 x 0.92 = 27.6 pounds of sulfur, and 30 x 0.02 = 0.60 pound of zinc per acre. Note: Remember to subtract nitrogen fixed by preceding legume cover crop (if any).
Irrigation: Forage maize needs 1 to 2 inches of water weekly for optimum growth rate and yield. Adequate soil moisture is essential for quick germination and rapid crop development. Forage maize seedlings must have sufficient water in order to outgrow weeds.
Weed Control: Spray weeds or cover crop with organic herbicide (10% glacial acetic acid liquid + 5% citric acid powder + 2% wetting agent + 83% pure water = 100% by weight. Wetting agent is necessary so herbicide sticks to leaves). If desired, dead weeds or cover crop can be mowed to facilitate planting. Alternatively, use a roller-crimper to kill vegetation. Seed forage maize with a no-till planter then irrigate promptly to speed germination. Forage maize will outgrow most weeds. Once maize reaches 6 inches high the crop can fend for itself.
Harvest: Forage maize can be harvested whenever convenient; it is not necessary for ears or grain to develop. (Forage maize can even be left standing in the field over winter). Harvest at any season is most efficient with a common forage chopper. If desired, harvester discharge chute can be modified to deposit shredded vegetation into windrows for mulching. Alternatively, green chop can be blown directly into a wagon, truck, or mulch spreader for transport and application in another field. Forage maize can also be flattened with a roller-crimper or cut with a sickle-bar mower to make dense, slowly decomposing mulch ideal for vine crops. (Set transplants immediately then top-seed with a low-growing clover).
Green Manure: Forage maize must be shredded or it will not rot quickly. Do not plow stalks into the soil; whole stalks will take 2 or more years to decompose. For best results, harvest forage maize with a silage chopper. Disperse shredded vegetation evenly, spread fields with phosphate rock or other fertilizers, then incorporate soil amendments by rototilling or disking 8 inches deep. If a rototiller or tandem disk harrow is not available, double plow using a common moldboard plow. (Bury green manure under the soil then plow it back up again).
No-Till Farming: Leave forage maize (shredded, rolled or mown) and broadcast fertilizers on soil surface. Do not plow, harrow, or cultivate as this will stimulate weed germination. Over-seed surface mulch with grain, turnips, or other small seeded crop; seeds will work their way into the soil. Irrigate immediately to speed germination. When cash crop reaches 6 inches high top-seed with Dutch White Clover (Trifolium repens) or other low-growing legume. Note: Winter grains and clover can be seeded at the same time. Alternatively, use a no-till planter to drill seeds through the mulch. (Tip: Always work “with the grain” = in the same direction as the mulch is rolled or mown. Seeding cross-grain will clog seeder with mulch).
Cost per Acre: Forage maize costs about $18 per ton to make a crop in Butler County, Pennsylvania. At 2015 prices, a 30-ton forage maize crop costs approximately $540 per acre for seed, fertilizer, fuel, and other out-of-pocket expenses. This works out to $0.009 = 0.9 cents per pound of harvested vegetation.
Would You Like To Know More? Please contact the Author directly if you have any questions or need additional information about using forage maize for weed control, surface mulch, or green manure.
Eric Koperek = firstname.lastname@example.org
About The Author: Mr. Koperek is a plant breeder who farms in Pennsylvania during the summer and Florida during the winter. (Growing 2 generations per year speeds development of new plant varieties).