Monitor first-cut forage for quality

Keeping close tabs on the initial spring growth of alfalfa will pay big quality dividends. "Alfalfa Scissor Cut Projects" are helping producers do just that!

by Mike Rankin

The author is a crops and soils extension agent in Fond du Lac County, Wisconsin.

Monitor first-cut forage for quality

Okay, you don't have enough dry cows and heifers to feed all of your low quality first-cut forage. Two obvious solutions are to get more heifers and dry cows or try to harvest higher quality forage in the spring. The latter may be the more practical approach. Several strategies can be implemented to enhance overall first-cut forage quality. Obviously, taking control of the weather is not one of them and will always be a barrier to a timely harvest in some years. However, when the weather is "right", there are no field operations that will match the economic return of harvesting high quality alfalfa. This return comes in the form of greater animal intake potential and lower feed costs.

Calendar date vs. maturity...

Both calendar date and maturity stage have been discussed as methods to determine optimum cutting time. No single factor impacts forage quality more than plant maturity and if improvements in first-cut forage quality are to be made, manipulation of cutting date is the key. However, both research and experience have proven that annual variations in forage quality can exist at a similar calendar date or stage of plant maturity. These variations can be primarily attributed to weather fluctuations from year to year. Previous fall cutting management and soil type can also impact plant maturity on a given date.

Perhaps the best approach, especially for first-cut, is to use both calendar date and maturity stage. For example, the rally cry of some upper Midwest producers is "Done by June One", regardless of maturity stage. This strategy helps avoid delays caused by early June rains and opens more scheduling options for subsequent harvests. These same producers realize that plant forage quality, as indicated by maturity stage, may dictate harvest be completed before this date in some years.

How early to cut?...

Spring offers a unique growing environment for the plant. Day and night temperatures are relatively cool and plant respiration rates are low. Also, if plants were not stressed during the fall, root carbohydrate levels are generally high. Research from a number of states consistently shows that the alfalfa plant is very tolerant of cutting or grazing almost anytime in the spring. It's ironic that some producers who are hesitant to harvest an early first-cut for fear of low yields and reduced stand longevity, think nothing of harvesting that same field in a surplus forage year during the high-risk period of mid-September or October for very little yield.

Many top dairy producers set a goal to harvest and feed, on the average, a given high quality forage product to their lactating dairy cows. Nutritionists tell us that alfalfa with a crude protein of 20% and relative feed value (RFV) of 150 is a good goal from a ration balancing standpoint. To meet the goal, harvest operations must begin before the standing forage reaches this desired average quality. The optimum harvest date on any individual farm, in any year, will depend largely on environmental conditions, desired forage quality, amount of acreage to be harvested, available labor, and method of harvest.

Scissor cuttings help...

Armed with the realization that low first-cut forage quality is a problem on many dairy farms, some local forage councils in Wisconsin are coordinating efforts to hand-harvest alfalfa samples from designated field areas on at least a weekly basis before and through the normal first-cut harvest period. These samples are then immediately analyzed for quality and reported to area producers. Such efforts have been coined "Alfalfa Scissor Cut Projects".

The projects are carried-out with several objectives in mind. They are:

1. Provide producers with an additional management tool for determining the optimum time to initiate alfalfa harvest in the spring.

2. Start the alfalfa harvest "thought process" prior to the optimum harvest period and during a time when other field operations often dominate farm activity.

3. Provide educators with localized data that can be used to demonstrate changes in forage quality both within and between years.

The scissor cut projects have been very successful in accomplishing these objectives. Working with various forage testing labs, extension agents have been able to attain quick results via telephone and computer modem. The primary method of accessing the forage quality information to the producer has been local radio. Alfalfa growers are tuning in the "Forage Quality Report" as their grain producing counterparts would listen to the daily commodity markets. The use of the telephone answering machine as an "Alfalfa Hotline" is also being implemented in some counties.

An obvious concern about using a limited number of alfalfa scissor cut samples to predict actual harvested forage quality for a large number of farms is the accuracy of results. Care must be taken in sampling from the same designated small area of representative fields. Most forage councils sample from at least two different fields. From one to three samples are taken per week. It has been beneficial to analyze pre-bud stage samples with wet chemistry procedures rather than NIR because few machines are properly calibrated for these types of samples.

In Fond du Lac County, we've found a very close correlation between scissor cut quality reports and results from those samples obtained at similar cutting dates "on the farm". Producers are normally told to expect lower quality than what scissor cut results are indicating because the hand-harvested samples represent no respiration or harvest loss and do not include any grass.

One of the more interesting aspects of the alfalfa scissor cut projects is to examine the results after the harvest is complete and compare data between dates and years. The graph represents scissor cut RFV data averaged from ten southern Wisconsin counties for the years 1991 and 1992. In 1991, early season temperatures were far above normal with adequate rainfall. By contrast, 1992 was characterized by far below normal temperatures and rainfall in May and June. Note the wide RFV variation that existed between years at similar sampling dates. Nearly 50 points between May 25 and June 1! It's easy to see the frustration that might occur when only calendar date is used to determine optimum harvest time and when the growing alfalfa crop is not monitored.

Harvesting first-cut alfalfa offers producers an opportunity to provide high quality forage to the dairy herd. Too often the opportunity is missed because of unfavorable weather conditions, a shortage of time and labor, or the misconception that an early harvest will decrease total-season yields and stand longevity. This spring, keep a close watch on your alfalfa crop and the calendar, or start an alfalfa scissor cut project in your area. The dividends can be measured in the bulk tank.