Early planting for weed suppression: The mechanism of weed suppression is light exclusion by the rapidly growing forage radish. In Maryland radish needs to be established by the last week of August to get adequate canopy closure for weed suppression.
Adequate fall radish growth: The correct seeding rate is important for optimal growth and weed suppression. The suggested seeding rate is 8-10 lbs/acre drilled and 12-14 lbs/acre broadcast. Growth can be hindered if there is not enough residual fertility (radish scavenges nutrients, but if nutrients aren’t there, it can’t scavenge enough for full development), conditions are too wet (radish does not like “wet feet” and will not grow well in poorly drained soils), or there are insufficient crop stands. Insufficient crop stands can occur with seeding that is either too heavy resulting in competition between plants or too light, resulting in bare patches. Radish generally establishes quickly and easily, but some care should always be taken in planting cover crops- just like one would take care to plant cash crops, providing good seed-soil contact.
Weed suppression: If there are visible patches of ground 8 weeks after planting, there will not be adequate weed suppression for no-till planting without herbicides.
The soil in spring is well enough aerated: In low “tilth” soils with few soil aggregates rainfall can quickly compact soil. Soils with a nice crumbly texture which forms pockets to hold air and water and is less easily compacted will more easily support no-till spring planting.
Effective spring planting equipment. Forage radish leaves very little “residue” on the soil surface in spring, which means that under some conditions, it is possible to plant no-till even with simple push seeders. In other soil conditions, however, push seeders such as the Jang and Earthway will skate over a quickly dried out upper crust of the soil surface. Without even penetration and seed to soil contact emergence will be spotty. Heavier duty seeders such as the Mater Mac seeder have no trouble planting into radish “residue.” In some soil conditions, press wheels may need to be adjusted for adequate furrow closing.
The right spring crop. We have had a lot of success with spinach, and farmers have had success with peas and beets. At least one farmer reported that carrots didn’t work very well. There may be delayed maturity of some crops with the no-till planting. We experienced this with some lettuce and kohlrabi trials.
Weeding in no-till planting: Weed suppression only lasts until mid-April (in MD) and then some weeding may be necessary. Hand weeding and using a hoe is relatively easy. The radish carcasses can get in the way. The soil can be hard and form a surface crust. The no-till surface makes mechanical weeding difficult. Basket weeders do not work. Even knives tend to get tangled in the radish carcasses.
(Source – http://extension.psu.edu/plants/vegetable-fruit/research-reports/no-till-no-herbicide-planting-of-spring-vegetables-using-low-residue-winter-killed-cover-crops)