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How not to destroy your alfalfa yield and quality this year

Carla Hines-Snider for Progressive Forage Published on 29 May 2022
Weeds compete for water and nutrients

The cost of most everything has skyrocketed this year. Before you start eliminating inputs, make sure to fully assess return on investment potential for your farm or operation.

It is easy to pick out which inputs to cut based on purchase cost alone, but be mindful that each input provides some amount of output. Reduction of certain inputs will likely reduce overall forage quality, yield potential and stand persistence, maybe even more than you think. As alfalfa hay prices continue to rise, consider whether the reduction of input cost is worth the potential loss of income or shortage of feed.

Below are some management considerations to ensure you can maximize and protect your yield and quality potential.

Soil fertility

One of the most expensive but also one of the most important is soil fertility. Know your soil test and actual alfalfa yield and replace the nutrients at crop removal rates (Table 1).

Pounds of nutrients removed

Fixed costs like land, equipment and labor are expensive and remain the same regardless of yield. Cutting back on fertility may return yield reductions and loss of income.

Apply fertilizer after first cutting to replace removed nutrients.

  • Potassium (K) and phosphorus (P) are important nutrients required for high-yield alfalfa.

  • Sulfur (S) is important for protein production. Sulfur should be applied annually at a rate of 5 pounds per ton of expected forage.

  • Boron (B) is also needed for alfalfa and can be applied annually with K.

  • Tissue sampling before first cutting helps indicate micronutrient needs for second crop.

  • Neutral soil pH, 6.8 to 7.2, is very important for rhizobium activity to support high-yield alfalfa.

Foliar applications

Foliar treatments applied in-season are a perfect opportunity to protect the yield and quality potential of your alfalfa. Pair fungicide with micronutrients and/or herbicide or insecticide applications.

Fungicide

Foliar-applied fungicide applications made on established alfalfa maximizes yield and quality potential. High humidity and moisture can lead to leaf and stem diseases and significant leaf loss. Applying a foliar fungicide and selecting an alfalfa variety that is highly resistant to multiple races of anthracnose can help protect the plants all season long.

  • Apply fungicide at 6 inches of growth after crop breaks dormancy. On average, first cutting has the largest yield benefit from fungicide application since it is typically the largest biomass.

  • Depending on moisture, humidity and weather conditions, another application may be made on second or third crop and again on fourth crop to provide protection going into winter.

  • The value of fungicide application increases as harvest intervals increase.

Insect management

Scout early and often. Insect feeding can quickly diminish both yield and quality if not managed.

Alfalfa weevil

Leaf defoliation from weevil

Destructive insects that feed on the leaves and growing points.

  • Weevil hatch and begin feeding around 400 growing degree days (GDD). Could be earlier based on amount of crop residue present over winter.

  • Scout and monitor stands prior to first harvest by using sweep net counts and terminal percent feeding to evaluate potential damage.

  • Scout regrowth early on second crop, as weevil may still be present and can cause significant damage to new growth.

Potato leafhopper (PLH)

Can be very destructive to alfalfa in both yield and quality. Generally, control is needed during July and August in the Midwest and eastern U.S.

  • Pay special attention to new seedings and third-crop regrowth.

  • PLH can cause severe damage to alfalfa plants before the yellow “burn” appears on leaves.

  • Use a sweep net to detect PLH before symptoms appear. Once symptoms appear, damage is already done.

Weed control

Control weeds as needed. Use the glyphosate-prepared alfalfa system to provide effective weed control without crop injury. Weeds compete for water and nutrients, reduce palatability and forage quality, and can hinder alfalfa stand density for the life of the stand.

For new seedings established with a companion crop, you may harvest the crop then spray out five to seven days after harvest, or spray out 30 to 45 days after planting. Delaying this can increase insect and disease pressure and companion crop competition to the alfalfa, impacting yield potential long-term.

Harvest management

Cutting alfalfa less than 25-day intervals is detrimental to yield and stand persistence.

  • First-cut harvest goal: Harvest first crop when the tallest alfalfa plants are 28 inches tall to prevent lodging. First crop has the most biomass and yield. Delaying harvest too long increases lodging risks (regardless of variety trait).

  • Some alfalfa varieties allow subsequent harvest to be adjusted to maximize harvestable yield per cutting throughout your growing season. Other alfalfa varieties should be harvested based on the quality of hay needed or approximately 10% bloom.

  • Schedule last cutting in early September. This provides alfalfa with adequate time to rebuild root reserves for improved overwintering ability and increased stand persistence.

Don’t leave your leaves behind

Many factors can cause excessive leaf loss.

  • Mechanical losses, especially when forage is too dry.

  • Leaf loss during cutting, merging and chopping are all additive.

  • Foliar leaf diseases can cause leaf defoliation before the crop is harvested.

  • Insect damage from alfalfa weevil or other defoliators.

  • Standing alfalfa is about 50% leaves and 50% stems by dry matter weight. It is critical to preserve as many leaves as possible. Leaves lost can be a significant yield and quality cost.

o Leaves = 500 relative forage quality (RFQ), stems = 70 RFQ

  • Forage quality lab analysis is now available to measure your harvested alfalfa leaf percent.

Reduce feed costs by growing and feeding more high-quality alfalfa on-farm

As off-farm feed and protein costs continue to rise, feeding high-quality alfalfa is critical in reducing ration costs.

  • Most of the time, it is more cost-effective to grow the necessary feed requirement on-farm than purchasing those inputs. Alfalfa produces the most protein content per acre of any forage crop.

  • Feeding high-quality alfalfa also has high fiber digestibility, allowing for high intake needed to support milk or meat production. This fiber can help provide more efficient rumen function to allow for improved digestion of the smaller grain particles.

Adequately fertilized alfalfa, foliar applications, proper harvest timing and minimized leaf loss can increase alfalfa yield and quality potential. As you plan for the season ahead, keep these points in mind and fully assess the value of inputs versus output potential. Remember, low-yield is the most expensive alfalfa to produce.  end mark

PHOTO 1: Weeds compete for water and nutrients, reduce palatability and forage quality, and can hinder alfalfa stand density for the life of the stand.

PHOTO 2: Weevils hatch and begin feeding around 400 growing degree days. Photos courtesy of Winfield.

Carla Hines-Snider is the senior product development manager with Croplan. Email Carla Hines-Snider.

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