By James Hoorman, Hoorman Soil Health Services
Planting small seeded clovers and legumes can be challenging, be that for forages or as a cover crop. Soil types, surface residue, weather especially moisture, seeding depth and getting the right rate on can all either cause a failure or a reduced stand. Here are a couple planting tips.
Small seeded clovers and legumes can grow well in sandy loam soils to clay soils with some modifications. Sandy soils tend to dry out and the seed may move too deep in the soil at planting. On clay soils, the soil may be more compacted but they tend to hold more moisture. If the seed stays to close to the surface, without adequate rain, the seed may dry out or get tied up in a thick crust. Often a nurse crop (oats) may help small seeded crops emerge and also initiate critical microbes that can assist a small seedling in germination and growth.
Most clovers and legumes need a good pH and lime (calcium carbonate) or gypsum (calcium sulfate) to have good germination. Adequate calcium is needed to initiate germination and good root growth. The ideal pH for clovers and legumes is between 6.0-7.0 with 7.0 being neutral.
For most soils, microbes, plants, and even animals and humans; 6.7 (slightly acid) is the best pH. If the pH is low, lime should be applied 6-12 months before seeding to correct soil pH. If the soil pH is adequate but calcium base saturation is low, gypsum can be used to increase both calcium and sulfur soil levels. All clovers and legumes require the proper seed inoculation with their own specific Rhizobia bacteria. Keep inoculate refrigerated and out of sunlight.
Ideally, before planting, perennial weeds should be controlled. The soil should be level, and there needs to be adequate moisture at planting time. Most clovers used in Ohio can be frost seeded. Spring to early summer and late summer are generally when most clovers and legumes (alfalfa) are seeded. The smaller the seed, the shallower the seeding depth but for most clovers and small seeded legumes, ¼ inch should be the maximum depth. Seeding a little shallower and then culti-packing seed in dry soils improves seed-to-soil contact. Ideally avoid airspace which may cause the seed to dry out. Keeping seed moist aids in germination.
There are many ways to seed clovers and small seeded legumes, each has advantages and disadvantages. Broadcast spinners are not as accurate on seeding rate and the seed placement can be influenced by wind. Also, the seed tends to dry out if not followed by a cultipacker or firming equipment. Broadcast spinners tend to work well with frost seeding, when the soil cracks, frost heaving occurs, and wet soil allows the seed to get incorporated. On drills, small seeder boxes attached to the rear of the drill improve small seed soil placement. Some drills are harder to adjust, to get and keep small seed at a consistent shallow depth. Planting depth is harder to control when the soil is too wet, too rough, or there is too much surface vegetation. In pasture or sod, chain drags or a spiked tooth harrow can scratch the soil to allow seed to get good seed-to-soil contact. Brillion seeders work well in lightly tilled soils.
The hardest part of seeding mixtures of small clovers, legumes and grasses is getting the right seeding rate. Experimenting or guessing can be expensive. Putting on a rate too high results in not having enough seed. Too low, and the stand will be thin or requires extra trips over the field. Calibrating a drill to seed small seeded clover or legumes is the best way to get good results. Calibration requires a calculator, measuring tape (100 foot), a small scales, and trays or bottles to collect seed.
First measure off 100 feet. Then attach bottles to the two outside seed hoses and put in seed on the ends. Run the equipment in gear over the 100-foot measured area. Collect the seed separately and weigh it. For 7.5-inch drills in 100 foot, 10 pounds of seed is equal to 0.23 ounces or 6.5 grams seed. For 7-inch drills, 10# of seed equals 0.21 oz or 6.1 grams and for 5.5-inch drills, 0.17 oz or 4.8 grams seed, respectively. A quick example. For a 7.5-inch drill, if .75 oz or 22 grams of seed is collected, that equals 32.6 pounds of seed per acre (.75/.23 oz seed or 21.2 grams/6.5 grams seed per 10# ). Following these tips on planting small seeded clovers and legumes should improve your stands and growth, of course, weather permitting.