Effect of Fertilizers, Age of Stand, and Decomposition on Weight of Grass Roots and of Grass and Alfalfa on Soil Nitrogen and Carbon1

Synopsis Nitrogen fertilizer increased root weights of three species of grass. Phosphorus increased root weights at the higher rate, while potassium had no effect. Increase in root yield was greatest the first 3 or 4 years after seeding. From 75 to 95% of the roots in the surface 6 inches had decomposed 2½ years after plowing. Changes in soil nitrogen and carbon content during a 5‐year period after seeding to grass and alfalfa and after plowing the sod were small.