Virtually everyone who has applied their trade as an alfalfa researcher has done a seeding rate study at some point in their career. The scientific literature is full of such studies and most come to the same conclusion: very little of what we dump in the drill ends up as a productive alfalfa plant that lives to see the next presidential election. It’s not anyone’s fault, but rather that inefficiency is a part of the deal. However, there should be some consideration given to cutting losses simply because input costs, including seed, are not getting any cheaper.
To take a closer look at the issue of alfalfa seeding rates, let’s start at the beginning with the seed itself. There are about 199,000 alfalfa seeds per pound. If that one pound was evenly spread over one acre (43,560 ft2), there would be in the neighborhood of five seeds per square foot. So pick your seeding rate, multiply by five, and that’s how many seeds per square foot are sitting a fraction of an inch below the soil surface waiting to become productive plants when you pull out of the field with your seeder or drill.
So let’s begin with a 15 pound per acre seeding rate (Figure 1). That equates to 75 seeds per square foot. Research suggests that only about 50 to 70 percent of those seeds will be accounted for as seedlings after emergence is complete in three to four weeks. Using a 60 percent average, that leaves us with 45 seedlings per square foot. At this point, it’s a survival of the fittest game. As plants become bigger and compete for available resources, another 40 to 50 percent will be gone by the next spring. This leaves us with about 25 plants per square foot as our stand heads into the first production year. During the next 12 months, expect another 30 to 40 percent loss of plants, leaving us with 8 or 9 productive plants per square foot, a batting average of .120 from our original 75 seeds.
As depressing as all of this may sound (after all, we paid for 75 seeds per square foot), our example stand counts for the spring following seeding and a year later are on the high end of what research suggests are fully productive stands. Generally speaking, we like to see 15 to 25 plants per square foot at the beginning of the first production year and at least 3 healthy plants per square foot in older stands. As stands age, evaluation based solely on plant counts becomes problematic because variables such as stem number, stem size, plant health, weed encroachment, and crop rotation restrictions must be considered (Reference UW-Extension publication “Alfalfa Stand Assessment: Is this stand good enough to keep?”)
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Alfalfa is a versatile forage crop that can be grown in various sizes to suit different needs Choosing the right size alfalfa plant is crucial for success In this article, we’ll explore alfalfa plant sizes and factors to consider when selecting the ideal size for your needs.
Understanding Alfalfa Plant Size
Alfalfa plants come in different sizes depending on variety, age, and growing conditions Here’s an overview of common alfalfa plant sizes
Small Alfalfa Plants
- Best for container gardening or small garden plots
- Typically young, immature plants
- Ideal for sprouts or personal use
- Offer flexibility for indoor growing
Medium Alfalfa Plants
- More mature than small plants
- Good for larger gardens
- Provide balance of yield and ease of care
- Useful as cover crops in agriculture
Large Alfalfa Plants
- Fully mature, full-grown plants
- Best for large fields and commercial production
- Highest yield potential but need more maintenance
- Commonly grown for hay or animal feed
Factors For Choosing Alfalfa Plant Size
Consider these key factors when selecting the ideal alfalfa plant size:
Available Space
- Smaller alfalfa plants suit limited space
- Large plants need ample room for roots and growth
- Choose size based on space constraints or availability
Purpose of Planting
- Small plants work for personal use
- Larger plants better for commercial harvests
- Select size aligned with intended use of alfalfa
Maintenance Requirements
- Small plants need less care
- Larger plants require more time and work
- Match size to maintenance you can provide
Climate and Conditions
- Some alfalfa varieties suit certain climates or soils
- Choose size optimized for your growing environment
- This ensures the best success
Growing Healthy Alfalfa Plants
Follow these tips for healthy alfalfa plants, regardless of size:
- Provide at least 6-8 hours of direct sunlight daily
- Water regularly, keeping soil moist but not soaked
- Fertilize with phosphorus-rich balanced fertilizer
- Monitor and treat pests and diseases promptly
- Harvest at early bloom stage for optimal quality
Properly preparing soil, planting at the right time, and selecting suitable varieties can also promote vigorous alfalfa growth.
Choosing the Right Alfalfa Plant Size
When starting your alfalfa crop, carefully weigh your space, purpose, maintenance ability, and conditions to pick the ideal plant size.
For small-scale home gardens, opt for small or medium plants suited to containers or small plots. They offer flexibility and require less work.
For larger gardens, medium plants provide a robust yield with moderate effort. Or go bigger with large plants for max harvests from extensive plots.
Regardless of size, give your alfalfa the site, soil, sun, and care it needs to thrive. With the right plant size choice and growing conditions, you’ll reap an abundant nutritious alfalfa crop.
What impact does seeding rate have on final stands?
It seems intuitive that more seeds dropped per square foot should result in more seedlings and plants per square foot. Seeding studies show that higher seeding rates do result in more seedlings through the end of the seeding year. Further, very low seeding rates (below 8 pounds per acre) often have fewer seedlings and lower total-season yields in the seeding year. However, as seeding rates increase, the percentage of plants that die during the first year also increases. Research from Missouri and Pennsylvania recently showed a 45 percent first-year plant mortality for a 10 pound per acre seeding rate and a 60 to 70 percent mortality for seeding rates over 20 pounds per acre. It’s been an almost universal research finding throughout the Midwest and Eastern U.S. that plant densities and yield are nearly equal for seeding rates of 10 pounds per acre or more in the year following seeding.
How can doubling the seeding rate, say from 10 to 20 pounds per acre, possibly result in the same forage yield and near the same plant density in the years after seeding? It’s all explained by the alfalfa plant’s ability to compensate based on neighboring plant competition. Forage yield is not just a function of the number of plants per unit area, but also the number of stems per plant and weight per stem. As stands thin, plants initiate more stems and in some cases larger stems as a response to less plant to plant competition.
So what’s the optimum alfalfa seeding rate?
Recommended seeding rates vary with region and can be obtained at your local extension office. Research strongly suggests that there is little benefit to seeding over 10 pounds of pure live seed per acre in the Midwest and Eastern U.S. regions. In Wisconsin, 12 pounds of pure live seed per acre is recommended in most situations. This equates to dropping 60 seeds per square foot. As alfalfa seed becomes more expensive and transgenic traits come with a technology fee, reducing seeding rates to the agronomic and economic optimum is more easily justified. Further, it’s always better to invest in good alfalfa genetics and seed at an optimum rate than to buy the cheap stuff and seed at a higher rate.
Alfalfa Seeding Year Considerations
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