It’s early May, and the scenarios aren’t looking good. You’re looking at a rather marginal alfalfa stand, the haylage silo is nearly empty and you generally use some corn silage in the dairy ration.
Here are your options:
- Kill (plow or spray) the alfalfa stand now and plant a full-season corn hybrid, control perennial grassesand broadleaves with a post-emergence herbicide, and harvest the corn for grain or silage.
- Wait and harvest the first cutting of alfalfa, plow and plant a short-season corn hybrid, figure on controlling perennial grasses and broadleaves with a post-emergence herbicide, and harvest the corn for silage.
- Keep the alfalfa stand for one more year.
What are the advantages and disadvantages of each option?
Option 1 gives up all alfalfa production on the field for the current year but ensures maximum yields of corn silage from early planting and using a full-season hybrid. This still may not look too appealing if you REALLY need the alfalfa in the short run or if it’s a relatively new alfalfa stand and you want to capture more return on the establishment investment. Chances are good that you will be taking another field planned for corn and seed it down to alfalfa. Hence, at least some establishment-year yield will be recovered.
Option 2 offers some alfalfa production to fill short-term needs at the expense of reduced corn silage yields. Even with this option, you may be seeding another field to alfalfa that wasn’t originally planned (unless your other alfalfa fields are in good condition).
With Option 3, you forego the additional corn silage production but increase the amount of total-season alfalfa harvested. The amount, however, will be reduced compared to a full, productive stand.
What is the yield and quality penalty for planting silage corn after first-cut alfalfa?
Studies have been conducted in Arlington, Wis., to assess the yield and quality penalty for late-planted corn harvested as silage. In corn silage, a key quality component is the ratio of grain to stover in the forage. Less grain yield usually lowers silage quality. Corn forage yield decreases with a later planting date (Figure 1).
Forage yield of corn planted on June 1 is lower than earlier planting dates in May and April. By the end of June, yield levels are about 50% of the maximum yields observed around May 1. NDFD content is not affected; however, starch content by the end of June is about 50% of the maximum observed around May 1 (Figure 2).
Later planting dates do not affect corn stover yield as much as grain yield, so the grain:stover ratio decreases with a later planting date primarily due to lower grain yield. Lower grain:stover ratio results in less milk per ton (milk/T) for June planting dates than earlier planting dates in April and May (Figure 3). Milk/T ranged from 3,200 lb. to 3,600 lb. milk/T for most planting dates in most years; however, the last planting dates in 1997 and 2001 had significantly lower milk/T values.
Finally, when faced with late planting dates, choose appropriate short-season hybrids to increase the probability that the crop will reach harvest maturity before the first fall frost.
Double-cropping corn for silage after a first cutting of alfalfa is a management option when forage is needed early in the growing season. However, the success of this management strategy is highly dependent on spring growing conditions (primarily heat units) along with early summer rainfall and must be done with the realization that corn silage yield and quality will often be significantly less than that of early-planted corn.
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