Penn State has been fine-tuning their Interseeder equipment for years now, testing cover crop seedings in replicated plots of standing corn throughout the Northeast, and they’re now offering it for sale. As cover cropping and no-tilling increasingly become priorities for all types of operations, farmers learn the benefits of year-round, diverse, living soil cover, and want to hear about new ways to make this happen. Interseeding is a valuable tool because it creates crop overlap, buying time in the rotation for another cropping window. Especially for northern no-tillers who have difficulty fitting in a second crop, interseeding the cover crop can provide the flexibility they need.
This technology has been most heavily tested on corn grown in 30-inch rows, at V7 stage for corn (after last cultivation). An interseeded cover established during the early summer has the time to put on plenty of growth for winter survival. This gives the cover crop just enough time to germinate and establish before the corn’s canopy closes, after which it stays mostly dormant until the corn is harvested for silage or grain and the canopy opens up again. At this point, the cover crop has been growing for 2 months, but will only be a few inches tall. Timing it this way allows the crop to get established, yet prevents it from competing with the corn.
Planting this early not only ensures that the crop has the reserves to make it through winter, but also provides the option of a fall grazing. The combination of the lush young cover crop growth and the dry corn stalks makes a balanced forage in a pinch.
The seeder is designed to plant three cover crop rows in between every corn row, and it is equipped to apply sidedress nitrogen and targeted herbicide in the same pass. Most testing has been done on small seeded winter annual or perennial cover crops, like annual ryegrass, crimson clover, and red and white clovers, since these are easily and quickly established. Most of these species are shade tolerant as well.
The interseeder doubles as a no-till grain drill, and works well with small grains and soybeans. Packing wheels help with seed to soil contact, accurate planting depth, and adjustment. It also comes with rear mounted spray and sidedress booms for nitrogen and herbicide applications, and double-disk openers for a uniform seed trench. The planter is available in 4 or 6 row capacity.
With the opportunity to “relay-plant” the cover crop, it can get established in time to provide ample soil cover during winter and all the benefits that go along with that – reduced erosion, added nitrogen (if clover is used), moisture infiltration, nutrient capture, and soil-building organic matter. It can of course double as a forage crop as well. In a continuous corn field, it helps break up the rotation.
Although the interseeder is a relatively new technology, the practice of interseeding has been used for generations, contributing a living mulch, diversity and additional crops to a rotation. Frost-seeding, for example, lets farmers thicken a pasture or add a clover hay crop to an existing wheat stand by broadcasting seed, taking advantage of frozen ground and an existing crop that is dormant. Produce growers sometimes overseed cover crops as their vegetable crops reach maturity.
One of the most important things to remember about interseeding is timing. The interseeded cover has to be established after the “critical weed free period”, which for corn is the V7 stage. Before this time, the cover crop will be too competitive with the corn. Wait too long, and the corn is too tall to drive through or to let enough sunlight through to get the cover crop established.
The emergence of this technology suggests that fitting a cover crop into the rotation has become more a widespread priority than ever before. Farmers understand the importance of building soil, breaking up the rotation, and keeping ground covered. They may also find additional immediate benefit if the cover can be used as a forage in the fall or spring.