Management Practices Affecting Alfalfa Yield and Quality

  • Harvesting alfalfa at mid-vegetative growth stages generally produces a higher quality product but usually results in lower yields.
  • 13;10;
  • Alfalfa stands need a break from harvest during the 6 to 8 weeks prior to the first killing frost in the fall.
  • 13;10;
  • Each ton of alfalfa dry matter removes about 14 pounds of phosphate (P2O5) and 58 pounds of potash (K2O).
13;10;

Yield versus Quality Decision

13;10;

Alfalfa yield and quality are inversely related in the plant’s growth cycle (Figure 1).1 Cutting alfalfa at mid-vegetative growth stages typically produces a higher quality forage, but usually results in lower yield. Conversely, harvesting alfalfa at later plant maturities can increase yield potential, but results in lower overall quality due to the increase in stem yield relative to leaf yield.

13;10;
13;10;
Figure 1. Relative forage yield and quality at different alfalfa growth stages. Orloff, S. and Putnam, D. 2004. Balancing yield, quality, and persistence. Proceedings 2004 National Alfalfa Symposium. University of California Cooperative Extension.
13;10;
 
13;10;
 
13;10;

Determining a priority of quality or tonnage may vary based on individual needs. Depending on your intent to use this crop for a high quality cash crop or an on the farm quality feed, deciding when to harvest can be a difficult decision and no single cutting schedule will fit all situations.

13;10;

Harvest Schedules

13;10;

In order to maximize yield of high quality forage, the first two cuttings are critical as forage quality changes rapidly during this time period and delayed cutting can reduce quality. For high yield and high quality, the first cutting should be taken at bud stage; generally mid- to late-May in northern areas and earlier farther south (figure 2).2 The second cutting should be taken 28-33 days after the first cut, or at mid-bud stage, whichever is earlier. After that, a subsequent cutting should take place 38-55 days later or at 10-25% bloom.2 Letting the stand mature a bit longer before the third cutting can build up root reserves and boost stand persistence. The forage quality of alfalfa does not change as rapidly in later cuttings compared to earlier cuttings: therefore, later cuttings maintain quality to later maturity changes.2


stinkbug

Figure 2. Cutting schedule example for different management goals.

Adapted from Alfalfa Management Guide, American Society of Agronomy.
 
 
 
 
13;10;

In the fall, alfalfa stands need a break from harvest during the 6 to 8 weeks prior to the first killing frost. In northern areas, this timeframe is roughly the first of September through mid-October and later in more southern regions.2 Having this rest period allows plants to build up adequate reserves of carbohydrates in the roots before winter begins. If plants are cut during this rest period, it will not only reduce the speed of regrowth the next season, but can reduce yield potential of the first cutting. Also, the practice can cause the stand to thin. Waiting and making a final cutting after the first hard freeze (24 °F or lower) may not hurt alfalfa and may help reduce pest problems.3 For example, Minnesota researchers found that the highest yields came from three cuttings during the growing season with a late-fall cutting.2

13;10;

Farmers may be tempted to harvest alfalfa during the rest period if significant growth has occurred, but doing this would initiate regrowth and reduce root reserves during a critical time. If it became necessary to cut during the fall rest period, there are a few things to consider. The risk of stand damage is somewhat reduced under the following conditions: in areas with less severe winters,2 if the stand is in bloom at the time of the fall cutting, if it has been at least 45 days since the last harvest, and if the stand is old and at the end of its longevity.3 Conditions where a harvest during the fall rest period are especially risky include: stands less than a year old, stressed fields, fields with inadequate fertility, and where the alfalfa product does not carry multi-pest resistance.3 In general, it is better to cut an older stand as compared to a newer stand because an older stand has already had time to recover establishment costs. The decision to cut during the fall rest period is an individual one and should be made after careful consideration of the risk factors as compared with the need for additional forage.

13;10;

Predictive Equations for Standing Alfalfa Quality (PEAQ)

13;10;

Variation in spring weather from year-to-year make it difficult to use a calendar date to best determine when to harvest the first crop of alfalfa. However, University of Wisconsin developed a simple procedure to estimate relative feed value (RFV) of standing alfalfa which aids in determining when to harvest the first crop. RFV, a calculated value from lab analysis of forages, is being replaced with relative forage quality (RFQ) indexes. RFQ indexes have an average and range similar to RFV.8

13;10;

The procedure is called PEAQ (Predictive Equations for Alfalfa Quality) and uses alfalfa stand height and maturity stage to estimate RFQ. After measuring the tallest and most mature plant in a 2 ft2 area, producers can use a specially designed PEAQ “measuring stick�? available from some seed companies or a PEAQ RFQ table to determine standing alfalfa RFQ levels. The PEAQ procedure is most appropriate for good stands of pure alfalfa with healthy growth.

13;10;

PEAQ tables providing RFQ estimates may be available at your local county extension office. In addition, the PEAQ sampling procedure and RFQ tables for standing forage is available on-line from the University of Wisconsin at

13;10;

 

13;10;

http://www.uwex.edu/ces/forage/pubs/rfv-peaq.html

13;10;

 

13;10;
In general, it is recommended to harvest alfalfa at about 150 RFQ for milking dairy herds and 125 RFQ for heifers, stocker cattle, and lactating beef cattle.4 First crop alfalfa standing in the field can drop 3 to 5 points of RFQ per day.4 Therefore, a one-week delay of first crop harvest could cost at least 20 RFQ points in feed quality.
13;10;

While PEAQ provides an estimate of standing crop quality in the field, adjustments should be made for harvest loss. Under the best conditions, 10 to 20% of the forage dry matter will be lost at harvest.4 This loss equals about 15 RFQ units for haylage, and about 25 RFQ units for hay. Therefore, to end up with 150 RFQ alfalfa, it is recommended to harvest when PEAQ measurements predict 165 to 175 RFQ for standing alfalfa.

13;10;

Nutrient Needs

13;10;

Each ton of alfalfa dry matter removes about 14 pounds of phosphate (P2O5), 58 pounds of potash (K20), 30 pounds of calcium, 6 pounds of magnesium, and 6 pounds of sulfur.2 A current soil test should be used to determine existing soil nutrient levels, especially pH, phosphorus (P), and potassium (K) to avoid future over or under fertilizer applications. Soil tests are the most reliable method to prevent future nutrient deficiencies which can decrease alfalfa yield potential and quality.

13;10;

Visual plant symptoms may indicate nutrient deficiencies; however, by that time, significant yield losses have already occurred. Symptoms may also be caused by other factors such as environmental conditions, restricted root growth, diseases, or other problems not related to nutrient deficiencies. Plant tissue analysis may be needed to confirm symptoms are nutrient related.

13;10;

Reduce Storage Losses

13;10;

During storage, hay is subject to dry matter and quality losses. Losses are minimal for hay stored inside a building at proper moisture content. However, losses can rise sharply if moisture content exceeds 20% for inside-stored hay and losses may be much larger from uncovered bales stored outside under adverse conditions.6

13;10;

When storing round bales outside consider the following practices to reduce dry matter losses and decline in quality.6

13;10;
  • Hay/soil contact is a primary source of spoilage and if possible should be eliminated. Consider placing bales on crushed rock, a concrete pad, or some other object such as wooden pallets.
  • 13;10;
  • If stored on the ground, water should drain away from bales. Storing bales near the top of a slope reduces the amount of water flowing around them. Bale rows should run up and down a slope with a north/south orientation; a southern exposure is desired.
  • 13;10;
  • Flat ends of bales should be butted tightly together but the rounded areas should not touch. At least 3 feet of space should be left between rows to allow for air circulation, unless rows are placed together to facilitate covering with plastic or other material.
  • 13;10;
  • As bale density increases, outside storage losses generally decrease. A minimum density of 10 lbs/cubic foot is recommended for round bales stored outside.
  • 13;10;
  • Store hay in a sunny location, preferably in an area where frequent breezes occur. Hay should not be stored under trees or other areas where drying may be slow.