Using drought-stressed corn      

[JULY 21, 2005]  URBANA -- Livestock producers should consider several guidelines when making decisions in the next few weeks when and if to harvest their drought-stressed corn silage and consider purchasing barren corn from grain farmers, said Mike Hutjens, University of Illinois Extension dairy specialist.

"Several areas in the Midwest are under moderate to severe moisture stress," he said. "Some corn has not pollinated, some corn is fired, and other corn has not reached the critical stages that will impact corn yield and quality."

Hutjens' recommendations include:

--When deciding to cut the corn crop for silage, determine ear development and stage of maturity. If the corn plant has green tissue remaining, allow it to grow and mature, adding nutrients. Once the crop is down to 30 percent to 40 percent dry matter, successful ensiling can be achieved (be sure to add an inoculant). If a sample of chopped corn silage is squeezed tightly in a grip and water runs out between fingers, the silage is over 70 percent moisture and too wet. Running a dry-matter test using a Koster tester, microwave or commercial lab will be more accurate.

--The yield of corn silage will depend if cob formation has started. Purdue University suggests one ton of wet corn silage (70 percent moisture) per foot of barren or immature corn plant excluding the tassel.

--Nitrate levels can be a concern. The level nitrates in the lower one-third of the corn stalk can contain over 5,000 parts per million nitrate-nitrogen, while the top one-third of the stalk and leaves contain less than 160 parts per million.

--The feed value of the corn silage is reduced 80 percent to 90 percent depending on the amount of corn grain in the drought-stressed corn silage. Barren stalks will feed similar to high-quality grass silage or hay.

--Making corn forage as hay will be difficult as the corn stalk will be wet (over 70 percent moisture) and difficult to dry down. Hay curing also does not reduce nitrate levels, while corn silage does reduce nitrate levels due to fermentation by 35 percent to 50 percent. Testing for nitrates by a commercial lab is highly recommended after fermentation has been completed.

--Grain managers may sell drought-stressed and barren corn to livestock producers. Based on the quality and tonnage in the field and adjusting for harvesting costs, a price can be calculated. Using a guideline of one ton (wet basis) per linear foot, one acre of corn silage standing at 5 feet (excluding the tassel) could provide five tons of wet corn silage times 30 percent dry matter, or 1.5 tons of forage dry matter. Subtracting harvesting costs (higher than normal for corn silage due to lower yields) of $8 per ton of wet corn silage, or $40 an acre, if the corn forage is worth $80 a ton of dry matter, the value per acre could be $120 per acre minus harvest costs of $40. Values should be adjusted based on individual situations. The recommended approach is to weigh actual chopper boxes of silage and test the silage for quality to determine a price per ton and per acre.

--Some grain producers may consider plowing down the corn stalks for fertility. The nutrients in the corn stalks are estimated to be worth $25 per acre.

--Drought-stressed corn silage is an alternative for livestock producers. But producers should be sure to balance rations for lower levels of starch and reduced dry-matter intake potential.

[News release from the University of Illinois College of Agricultural, Consumer and Environmental Sciences]