Sometimes a planter is on the back of the tractors so that rolling and planting are done in one sweep saving bio fuel and time.
Cereal Rye coming up in October in harvested corn field. Courtesy of the NRCS, cover crops
Cover crop of cereal rye that was killed a few months earlier with soybean planted. This inhibits the growth of weeds, keeps in the moisture and provide nutrients. Farmers have report high yields in drought years using this method when neighboring farmers were loosing crops to the drought. Courtesy of the NRCS, cover crops
See more pictorials of Cover Cropping at DIY Organic Garden and Pinterest NOP Cover Crop