Composition of Black Locust Leaf Mold and Leaves and Some Observations on the Effects of the Black Locust 1

D URING April ~934 the writer’s attention was attracted to the organic material on the surface of the soil under a thick stand of black locusts (Robiuia p5eudoacacia L.). These locusts are located in the town of Bath, Mason County, in central Illinois. The soil is mapped as dune sand according to the Illinois soil survey, the soil map of Mason County having been made by a field party under the direct charge of the writer. It was during this work that the author became interested in the growing of the black locust on this dune sand of which 75,443 acres is found in Mason County. This acreage constitutes 2 ~.37% of the area of the county. This particular locust area was started by planting sprouts about ’ 5 years ago for the purpose of controlling the .blowing of the sand. During the intervening years the size of the planting has become enlarged greatly by natural means, mainly sprouting. Fires burn over this sand area all too frequently, the most recent fire having occurred in ~93~The heat from these fires is so intense as to kill most of the locust growth above ground, consequently the present growth consists of sprouts which have come up from the live roots since the latest fire. The surface of the sand under the locusts was covered with the remains of the locust leaves and some small twigs which had accumulated during the pas{ 3 years. In the absence of facilities for collecting samples, a board ~’ inches square was placed on the surface of the soil. It was held down by standing on it and the organic matter cut off b)~ running a knife around the edge of the board. The leaf material was then raked away from the board, the board removed, and the organic material collected from the square foot which the board had covered. The samples were taken to Ithaca, where dry matter, loss on ignition, and total nitrogen were determined. These data are given in Table ~. A number of points are brought out by these data. First, it is little short of crime to permit the destruction by fire of ~o~ pounds of nitrogen and nearly ~ ~ tons of organic matter to the acre, in addition to the killing of the above-ground locust growth. While making the soil map, as well as since then, the writer observed Kentucky bluegrass (Poa pratensis) well established and making good growth under black locust trees even though this bluegrass does not grow on this sand away from groups of locust trees. The growth of bluegrass in association with the black locust appears fully explained by the above data; the locust leaves supplying nitrogen and other nutrients, holding moisture, and probably helping to hold