Timing First-cut Alfalfa is Both an Art and a Science

Mike Rankin
Crops and Soils Agent
University of Wisconsin - Extension

As we look back over the years, there has been no lack of information on when is the optimum time to cut alfalfa.  Some of the proposed methods include: calendar date, visual maturity stage, combination of calendar date and maturity stage, regrowth from crown/axillary buds, sugar content (brix method), and measured forage quality (e.g. scissors cutting information).

With all of the above guidelines as options, it becomes confusing as to what is the best strategy for determining optimum cutting time.  To make matters even more complicated, using any of these guidelines as the sole criteria for making a cutting management decision is probably going to lead to a wrong decision in a significant number of situations.

We have long known that making accurate estimates of harvested forage quality (bales or haylage) is an impossible task.  Why then should we assume that estimating the quality of standing alfalfa is any easier?  It's not, especially for the first cutting.  A primary reason why no single criteria can predict optimum cutting time is that environment plays a key role in both alfalfa growth and forage quality.  Moisture stress and/or cool temperatures result in a slower decline of forage quality and generally slower growth.  Conversely, high temperatures result in a more rapid decline in digestibility and increased growth assuming adequate moisture is present.  Keeping these relationships in mind will help when making forage quality estimates this spring.  This comprises the "art" of haymaking.  However, there is even more to consider.

Until plant breeders develop the perfect alfalfa plant, there will always be tradeoffs between yield, quality, and persistence.  In the case of the initial spring harvest, persistence is easily the least important issue from a timing perspective.  Research studies have repeatedly shown that alfalfa has maximum resilience during the spring growth cycle.  However, first-cut timing may indirectly impact stand persistence from the standpoint that it does set-up the cutting schedule for the remainder of the growing season.

For most dairy producers, forage quality is a non-negotiable item.  In other words, it is typically the driver of harvest timing.  The challenge with first-cut is dodging the rain bullets to obtain an acceptable quality on forage that will comprise 30 to 40 percent of the total-season yield.

       The first cutting of alfalfa offers the most opportunity for economic loss or gain and for this reason gross miscalculations of forage quality simply have to be avoided.  The optimum time to harvest the initial spring cutting is determined by knowing two factors: 1) the number of rain-free days it will take to harvest and 2) the quality of the standing forage.  The first factor will help estimate a baseline starting point to allow for the harvest to be completed before forage quality drops to an unacceptable level.  In many situations, this means starting to cut when standing alfalfa relative feed value (RFV) is in the 170 to 180 range.  For all practical purposes, forget about visual stage of maturity and calendar date.  Neither factor, in and of itself, makes milk.  The tools are now available through local scissors cutting results and by using Predictive Equations for Alfalfa Quality (PEAQ) to make standing forage quality estimates that will eliminate major misjudgments in harvest timing (assuming the weather cooperates).