Structure Improvement Following Legume Growth on Unfertilized Subsoil

T HE planting of trees is commonly recommended for -*• the rehabilitation of eroded and abandoned lands which are no longer profitable for agriculture. Frequent planting failures or poor growth on such lands indicate that a preliminary period of site preparation is essential to the success of the tree rotation. Certain legumes may be the best solution to this problem, particularly when the more exacting species of hardwoods are to be planted. This paper is a progress report of a continuing study, comparing the physical character of an eroded soil profile under Lespedeza sericea Benth. with that of an adjacent bare area. The legume was seeded without fertilizer in 1941 by Harris and Drew (2) directly on the B horizon of a Weldon silt loam (Fig. 1), exposed by road construction equipment in 1939. Despite an initial 95% mortality, due largely to winter frost heaving, the Lespedeza sericea stand was dense and spreading in 1949 after 8 growing seasons and no intervening attention. The standing Lespedeza sericea vegetation of 4.33 tons dry weight per acre in August had a rainfall interception capacity of about 0.15 inches. The litter accumulated at the soil surface was equivalent to 7.28 tons dry weight per acre, and had a water-holding capacity of about 0.15 'inches. Soil moisture samples were taken at irregular intervals throughout the summer to a depth of 3 feet on both study plots. During the period from June 20 to July 29, when 5.95 inches of rain fell in 12 showers, soil moisture within the bare area profile remained almost unchanged below the 15-inch depth, or approximately at •field capacity (Fig. 3A). The Lespedeza sericea plants SOIL PROFILE DESCRIPTION