Jeff Stachler, Extension Educator, Auglaize County, The Ohio State University
There were a few fields of alfalfa lost last year due to excessive rains but not like in 2015. We are approaching a good time period to establish alfalfa seedings. Have you thought about what needs to be done to successfully establish alfalfa?
The first task is to obtain a soil sample or samples. If the field is less than 15 acres, then a single soil sample will suffice. If the field is larger than 15 acres, take multiple samples based upon management zones or based upon a grid pattern. It is best to start sampling by a grid method before going to a zone method, so you can more accurately vary the rate of fertilizer and/or lime. Management zones can be based upon soil type, topography, soil organic matter, or a combination of these. If a field has been in no-till and the field will remain untilled, obtain soil samples at two depths, one at a 4” depth for pH and another at an 8” depth for fertilizer recommendations.
For good establishment of alfalfa, soil pH needs to be 6.8 for mineral soils having subsoil pH less than 6.0 and 6.5 for mineral soils having subsoil pH greater than 6.0. Bray P1 soil test phosphorus (P) levels should be between 25 and 50 parts per million (ppm). The Mehlich III soil test P levels should be between 40 and 79 ppm.
The recommended rate of potash is based upon the soil test level in ppm, the cation exchange capacity, and yield goal. If lime is required and the Bray P1 soil test value for phosphorus is below 25 ppm, delay planting until the fall or next spring as stand establishment will likely be poor due to the poor fertility. Fertilizer and lime should be incorporated to maximize nutrient efficiency. If you are surface applying lime and fertilizer, it is even more important to wait a year before establishing alfalfa.
Select varieties having the best disease resistance (the best way to fight diseases), good forage quality, best fit to soil types, and high yields. Have seed inoculated with nitrogen-fixing bacteria to improve nitrogen uptake and treated with fungicides to manage seedling diseases, especially when planting in the spring.
Prepare a proper seedbed. A smooth firm seedbed allows for good soil to seed contact, leading to improved establishment. Control all weeds prior to establishment. Control perennial weeds the year before establishment. For no-tillage seedings, control grass sod with glyphosate at least one month in advance of seeding and manage previous crop residue for good soil to seed contact.
Seed alfalfa as early in the spring as possible. For southern Ohio target March 15th and for northern Ohio target April 1st. For fall seedings, plant as close to August 1st as possible.
Seed alfalfa to a depth of ¼ to ½ inch in clay and loam soils and ½ to ¾ inch in sandy soils.
The seeding rate for alfalfa is 15 lb per acre or 80 seeds per foot of row. If the seedbed is in excellent condition and you are using a brillion packer seeder or something similar to it, the seeding rate can be reduced by 25 to 30%.
It is critical to properly manage leafhoppers in seedling alfalfa to keep it healthy. Successful establishment ensures the healthiest, longest lasting, and highest yielding alfalfa.