Corn and Sorghum for Silage

Corn is generally the standard by which we compare other silage crops. Pound for pound, corn silage has more total digestible nutrients and is higher in net energy than any other silage. Sorghum silage of comparable quality has about 85 to 90 percent the feed value of corn silage.

Silage type sorghums will produce more tons of forage per acre than corn. Under Mississippi conditions without irrigation, corn will produce 10 to 16 tons of silage per acre. You may make higher yields on highly fertile, good corn soils. From intermediate or tall growing rain-type sorghums you can expect 12 to 18 tons per acre and from grain or combine-type sorghums, 6 to 9 tons per acre. Sorghum-sudan crosses may also be ensiled but should be considered more like a grass silage than grain crop silage.

Soil Capacity and Planting Time

Sorghum is adapted to a wider range of soil types than corn. Soils that are deep, well-drained, not subject to drouth stress, and can be planted in March or early April will produce more high quality feed planted in corn. Shallow soils and heavier clay loam or clay soils are subject to some drouth stress. Other soils that are not well-drained cannot be planted until late April, early May, or later. These soils will produce more feed of a slightly lower quality if planted in sorghum.

Silage Uses

Corn silage will be superior to sorghum silage in a feeding program for high producing dairy herds or for finishing steers. For wintering dry cattle or heifers, feeding growing steers, or for medium producing dairy herds, the additional tonnage from sorghum may offset the slight loss in feed quality.

Variety Selection

Corn. Any hybrid recommended for grain is suitable for silage. Taller growing varieties will produce more tonnage, while shorter growing varieties will give a higher grain ratio.

Sorghum. Intermediate sorghum, tall growing, high grain yielding types, will produce the greatest tonnage. Combine-type sorghum will produce considerably less tonnage but give a higher grain ratio. If you use a combine-type for silage, select a taller growing non-bird resistant grain sorghum. Ask your county agent for results of corn and sorghum variety trials.

Planting Dates

Plant corn as early as possible, late February to March 15 in extreme south Mississippi, mid March to early April in central Mississippi, or April 1 to 25 in extreme north Mississippi. You may plant sorghum anytime after the soil temperature reaches 65 degrees F. This will allow planting of sorghum in south Mississippi in mid-April and in north Mississippi in early May.

Seeding Rates

Seed corn at the rate of 23 to 25,000 seed per acre in 30- to 40-inch rows. This rate will give a plant population of 20 to 22,000 plants per acre, assuming 85 percent emergence. Sorghum should be seeded at the rate of 6 to 8 pounds of seed per acre in 30- to 40-inch rows. This rate will give a plant population of 110 to 135,000 plants per acre, assuming 75 percent emergence. Irrigated corn plant population should be increased to 26 to 28,000 plants per acre.

Fertilization

Fertilize and lime corn and sorghum according to soil test. These tables will serve as guides based on soils that test low in phosphate and potash.

CORN
Yield Goal (bu. grain per acre)
	60	80	100	120	140
Nitrogen	90	130	170	210	250
P2O5	30	40	60	60	70
K2O	60	80	100	120	140
Yields more than 80 to 100 bu/A should not be attempted without irrigation.
SORGHUM
Yield Goal (pound grain per acre)
		3,000	4,000	5,000	6,000
Nitrogen		60	85	110	135
P2O5		30	36	42	48
K2O		60	72	84	96

Harvesting

Harvest corn when grain is well dented, when grain moisture content is about 35 percent or about 7 weeks after silks emerge. Harvest sorghum when grain is in the medium dough to hard dough stage, or when grain is about 35 percent moisture. If plants are harvested when moisture content is too high, losses will be excessive; if harvested too dry, silage will not pack properly and may spoil.

You can obtain higher grain ratios by cutting plants so that 1/3 of the stalk is left in the field. However, this practice will reduce total feed production. Reduced tonnage may not be offset by the increased feed value.

You should adjust harvest equipment so that the length of cut is approximately 3/8 to 1/2 inch.

Insect Control

Southern corn root worm can be a serious problem in the southern part of the state as can black cutworm on early planted corn. An in-furrow insecticide or hopper box insecticide seed treatment is recommended for control of these insects. Chinch bug can be a problem regardless of planting time. Early planting will reduce most other insect problems.

Sorghum - Sorghum planted early will have less insect problems than sorghum planted in late May or early June. Sorghum midge will lay eggs in the head when it is blooming, and the resulting larva will destroy the grain. Sorghum planted in late April to mid-May escape midge damage. It is difficult to scout intermediate sorghums for midge because of plant height, but it can be done. Sorghum web worm, corn ear worm, and army worm may also attack grain heads. Corn ear worm and army worm may attack the bud of sorghum plants before they head. Occasionally, when sorghum is planted late, lesser corn stalk borers damage the stand of young sorghum. As with corn, chinchbug can be a problem regardless of planting date. For detailed information on sorghum insect control see Extension Information Sheet 1160, "Grain Sorghum."

Intermediate (silage)sorghums are of two types: the dry stalk, high starch type and the juicy stalk, high sugar type. The dry stalk, high starch type is preferred because the silage produced is of higher quality. Sweet or syrup-type sorghums are not recommended for silage because the quality is poor.

Weed Control

A number of herbicides are available for use in corn and sorghum. Base your herbicide program on your weed problem. Specific herbicides for corn are discussed in Extension Publication 475, "Corn Weed Control Recommendations" and for sorghum in Extension Information Sheet 803, "Grain and Forage Sorghum Weed Control." County Extension agents are also supplied with current "Weed Control Guidelines for Mississippi."

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Information Sheet 485
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director

Copyright by Mississippi State University. All rights reserved.

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