           |
|
-
- Growers are Experimenting
with No-till Vegetables
- By Sieg Snapp
Michigan State University
- Michigan growers are experimenting with no-till vegetables to help improve their soil and reduce some costs. A promising system is no-till planted pumpkins, planted into a herbicide-killed rye cover crop. This produces a clean pumpkin that does not have to be washed.
A cover crop also facilitates walking in a “pick- your-own” pumpkin operation, reducing mud problems. An exciting benefit in vine crops is the potential for effective weed suppression late in the growing season. However, the killed rye must cover the soil effectively for weed control. This requires careful planning to obtain a good cover crop stand that reaches at least one foot in height before it is mowed or a herbicide is applied. The killed rye should be allowed to sit for about 10 days before planting or transplanting a crop into it — rye residues produce toxins that help suppress weeds, but crop suppression must be avoided by allowing decomposition time. Warning: no-till cover systems may not be effective in fields infested by perennial weeds such as quackgrass.
A challenge in a wet, cool spring is the moderately cooler soil temperatures of rye-mulched soil compared to bare soil. On heavy ground the mulch can retard drying out of the soil. On the positive side, in a hot spell, a no-tilled mulched field will remain cooler.
Another potential “good bet” for Michigan is no-till transplanting of tomatoes into a killed cover crop, such as hairy vetch or a rye/hairy vetch mixture. Black plastic can be applied over the cover crop after it is killed through herbicide or close mowing. This system will provide some late season weed suppression, build soil quality and provide nitrogen throughout the season.
Questions frequently asked include: what seeding rates to use and how to calculate the amount of nitrogen contributed by the killed cover crop. Suggested seeding rates are: 1 to 2 bu/acre of rye, 20-40 lb./acre of hairy vetch and 1 bu/acre of rye + 30 lb./acre of hairy vetch for a mixture. Nitrogen contribution of the cover crop depends on the cover crop growth and yield of residues. Residue yield can be estimated as follows. Most cover crops contain about 2,000 lb. per acre of dry matter for the first six inches of growth.
This material will be roughly 4% nitrogen in young legume covers, such as hairy vetch. Thus, incorporating a short (six-inch) hairy vetch cover will add about 80 lb. N/acre. Only about 60% of this nitrogen will be available to a subsequent vegetable crop. Allowing a cover crop to grow an additional six inches will increase the nitrogen contribution by over 40%. Incorporation of the cover enhances the speed at which nitrogen is made available from residue mineralization. If a cover crop is no-till planted, less than half the cover crop nitrogen will be available in the first season. However, soil quality contributions and nitrogen benefits will build over time in a no-till system.
|
|
