Reducing peanut seeding rates can save you in seed costs, but at what point does it become detrimental rather than beneficial? That’s the question Georgia researchers have been attempting to answer with field trials during the past several years.
“It won’t be beneficial in every case,” says Scott Tubbs, University of Georgia cropping systems agronomist. “It’ll depend on a number of different factors.”
Tubbs reminded growers at the recent Georgia Peanut Farm Show in Albany that maximizing yield and maximizing profit are not always synonymous in row crop production. “There are multiple scenarios I can think of where I would encourage a grower to purposely sacrifice a chance at a higher yield simply because the cost to achieve the additional yield outweighs the possible gain,” he says.
A reduction in seeding rate, adds Tubbs, can be an opportunity to save money on input costs as long as yield and grade of peanuts are not drastically reduced.
“We’ve been looking at the seeding rate of some of the larger-seed size cultivars that have been coming out in recent years to try and help you reduce your costs at planting, and we now have several years of research under our belts,” he says.
Plant stand is the key, says Tubbs. “The seeding rate itself is not the most important factor. What you want is to get a good, optimal plant stand. Unfortunately, you can’t know what your plant stand will be at planting. Therefore, we adjust the seeding rate in an attempt to get our optimal plant stand. To get an optimal plant stand, you also need to plant quality seed. Planting good quality seed is going to give you the opportunity to know what your seeding rate is going to give you potentially in terms of plant stand,” he says.
It’s also important to plant in optimal conditions, with good soil moisture, he says.
Another consideration is that diseases respond differently to varying plant stands, says Tubbs. In the case of white mold, an increased plant stand could potentially be harmful because if the plants are closer together, the disease will spread down the row.
“So it could potentially benefit you to have a reduced seeding rate or plant stand with white mold. But tomato spotted wilt virus has the opposite effect. With a reduced plant stand, you could have an increased incidence of TSWV,” he says.
When quality seed are planted and good planting practices are used, the seeding rate usually will directly affect final plant stands, with higher seeding rates resulting in denser plant stands and lower seeding rates ending with sparser plant stands.
There is optimum plant stand
“Yet, research has demonstrated there is an optimum plant stand to shoot for, and that a denser stand will not always result in greater yields. This is often due to plant competition for space, light, water, nutrients and other beneficial resources that are needed to maximize yield potential,” says Tubbs.
Since peanuts are bought on a weight basis and not by seed quantity like some other commodities, the seed size becomes a very important variable in determining the cost per acre to plant.
“Thus, adjusting seeding rates can mean greater savings with some varieties than it will with others, as larger seeded varieties will cost more than smaller seeded varieties on a per seed basis. So, an equivalent reduction in seeding rate results in a greater savings with larger-seeded varieties than with smaller seeded varieties.”
Of course, he adds, the higher the cost of the seed, the more pronounced these values become, and in recent years, the cost on a per-acre basis has exceeded $20 per acre simply by altering the seeding rate by only one seed per foot of row.
“If similar yields can be achieved at lower seeding rates, this can constitute a fairly significant improvement to the bottom line by year’s end,” says Tubbs.
When compared to single rows, twin rows result in each individual plant being more spread out with extra room to grow and less intra-row competition with adjacent plants for necessary resources, he explains.
Using Extension’s recommended seeding rate of six seed per foot of row, the total plant population in a given area remains the same whether grown in a single or twin-row pattern, says Tubbs.
“But in twin rows, half the seed are planted in a row 7 inches away, which moves the most adjacent seed within the same drill row to 4 inches apart instead of just 2 inches away. This creates less intra-row competition and often results in less mortality of slightly weaker plants from a more aggressive neighboring plant.”
In single rows, he says, there is a greater occurrence of the “survival of the fittest” scenario, as the plants mature, expand and compete for resources.
Data from UGA research over the last few years tend to defend previous reports that a final plant stand between three and four plants per foot will suffice in a single row pattern. However, a slightly higher final stand (at least four and a half plants per foot or more) may be necessary in twin rows to achieve maximum yield, yet this usually can still be achieved when planting six seed per foot of row, according to Tubbs.
“But in single row patterns, a reduced seeding rate as low as five seed per foot of row at planting should achieve three to four plants per foot of row when good planting practices are followed. Thus, a reduced seeding rate in single row pattern can increase profits by lowering seed cost at planting while still maximizing yield.”
Knowing that increasing plant stand does not automatically mean increased yields, especially at very dense populations, it becomes critical to plant only the amount of seed necessary to optimize plant stand.
“Anything above that level is a waste of seed since it will not result in improved yields, and will only end up reducing net profit. This is true regardless of whether planting in single or twin row patterns.”