Severe cutting or pasturing of a crop reduces the amount and depth of roots. Dry weather slows top growth and tends to increase the ratio of roots to tops. Root Weight per Acre and Nitrogen Content. Sweetclover July, yr. The soybean has a low weight of roots when compared with the red clover-sweetclover or the perennial following several years of hay production.
Similar variation exists in the amount of nitrogen produced per acre.
A summation of 14 years of Ohio data indicates corn yields following alfalfa and sweetclover were equal when both crops were plowed down one year following seeding. Mammoth and medium red clover were not as productive. Table 2 shows how the nitrogen and dry matter in legume roots and tops vary with the stage of growth. Leguminous green manure crops ordinarily are plowed under sometime between April 15 and May 15 the year following seeding. At this time, the total nitrogen content per acre is highest for sweetclover, slightly less for alfalfa, and considerably less for red clover.