How can I use cover crops to quickly build soil organic matter and fertility in order to grow a cash crop?
I would recommend growing cover crops on the plot for at least a full year before planting your cash crops. Alternatively, you could plant half the plot in cover crops and half the plot in cash crops. If you plow down strips of the cover crop for your crop rows right after it comes up, you’re not going to get much benefit from the cover crop at all. Most of the benefit comes from returning the cover crop biomass (above-ground growth) to the soil to add back organic matter and nutrients.
I recommend the Kerr Center publication Market Farming with Rotations and Cover Crops: An Organic Bio-Extensive System for some ideas about how you could create a cover-crop rotation in your plot to build up fertility and suppress weeds. Once you have built up your fertility with cover crops, then you could look into strip-tilling your rows. I would recommend getting started with a winter cover crop planted this fall. A potential mix would be rye, crimson clover, and winter peas. You can use this seeding calculator to figure out seeding rates for your blend.
In the spring, you can mow and plow in your cover crop and then get started with your rotation, planting half the plot in a cash crop and the other half in summer cover crops. The winter cover crop would need to be mowed down in the spring when the clover is just starting to flower and before the rye sets hard seed, preferably when it is in the “soft dough” stage.
Allow at least three weeks between plowing in the cover crop and planting. This will allow that cover crop biomass to break down in the soil and for any allelopathic effects to be minimized. The same principal would apply to strip-tilling your cover crop – you will want to wait a few weeks after strip-tilling before you plant. Winter rye would make a good winter cover crop for strip tillage and sorghum-sudangrass would make a good summer cover crop for that method. Just be sure to leave the strips wide enough that you can mow down the cover crops occasionally during the season to keep them from shading out your vegetable crops.