WATER-SUPPLYING POWER OF THE SOIL UNDER DIFFERENT SPECIES OF GRASS AND WITH DIFFERENT RATES OF WATER APPLICATION

Abstract

The water-supplying power of the soil has been investigated by a number of workers during the past 30 years. The soil-point method which is used in this study was described by Livingston and Koketsu (3). This method has since been used to study the seasonal variations in the watersupplying power of the soil with reference to rainfall, evaporation rate and the growth condition of lawn grasses by Livingston and Ohga (4) and by Wilson (5). Other closely related investigations have been made by Livingston, Hemmi and Wilson (2) and by Baldwin (1). An unpublished paper by Wilson and Livingston deals with the relations existing between the decreasing water-supplying power of the soil and the wilting and death of a number of grass species. Some of the observations made in the course of the last mentioned study suggested the experiments reported here. During the past three seasons the senior author has been conducting an experiment on the use of water by various lawn grasses. This includes a series of seven plots, each of which is watered differently. Each plot is divided into three equal parts, one-third of which is planted to Kentucky blue grass, one-third to Chewing 's fescue and the remainder to Washington bent grass. Water is added to five of these plots in measured quantities and at definite times and intervals. The other two plots serve as checks and receive only what water falls as rain. The grass is clipped and weighed at intervals, the length of these in days being determined by the rate of growth. Only four of the seven plots were used in the study reported here. These included one check and three other plots which received 1.5, 2.0, and 3.0 times the normal, respectively. This normal is the average amount of rainfall for the months included in the growing season at Wooster, Ohio, as determined by the Weather Bureau station during the past 40 years. Thus the plot represented by 1.5 N received an amount of water which exceeded that which would normally fall on the plots by 50 per cent., the 2.0 N an excess of 100 per cent., and the 3.0 N exceeded the check by 200 per cent. Since the rainfall was very deficient during the summer of 1930 these relative values did not obtain, as will be shown later.