78 MINNESOTA STATE HORTICULTURAL SOCIETY. 



CAPILLARY WATER OF THE SOIL. 



H. H. HARRINGTON, COLLEGE STATION, TEXAS. 



If we take a small glass rod and dip it into a goblet of water it 

 will be observed that the water rises a little way along- the surface 

 of the rod. Or if we use a small glass tube instead of a rod, the 

 water will rise a greater distance, or if we take a rock and place it in 

 a pan of water, say, half immersed, the water will rise in a thin film 

 along the surface of the rock. This movement of water illustrates 

 what we call capillary attraction. The vertical distance to which 

 this water can rise in these tubes is inversely proportional to the 

 size of the tube. That is to say, the smaller the tube, the higher the 

 water will go; while on a surface, as illustrated in the case of the 

 rock, the vertical rise of the water will be very small. In a soil, 

 therefore, we do not want rocks of clods because the capillary water 

 which feeds the plant can not rise to the plant roots and replace the 

 moisture carried off by evaporation. But if the soil is pulverized 

 and of an even mechanical condition, with a certain degree of com- 

 pactness, then the capillarity takes place more readily and moisture 

 passes to the surface. In cultivation, then, our first object is to 

 pulverize the soil and carry this mechanical condition as deep 

 beneath the surface as our time and means will allow. By this we 

 create a large amount of surface within the soil to hold winter and 

 early spring moisture. According to King, a cubic foot of marbles 

 one inch in diameter possesses an aggregate surface of twenty- 

 seven and seven-tenths square feet, but if the marbles were pulver- 

 ized until their diameter was only one-thousandth part of an inch, 

 then the total area per cubic foot would be increased to twenty- 

 seven thousand and seven hundred square feet. The great differ- 

 ence of water-holding power between the two can be readily appre- 

 ciated, and with it the necessity of having the soil in proper 

 mechanical condition. But, as we have said, there must be a certain 

 degree of compactness to the soil in order that the water may reach 

 from below to the surface by capillary movement. If the soil is too 

 loose or open, the water can not be drawn through it by capillary 

 attraction. Therefore, in times of drouth, and especially after a 

 shower of rain, shallow plowing should be done in order to retain a 

 soft mulch of dust or dry earth over the pores or capillary channels 

 of the moist soil beneath, breaking the avenue of escape of soil 

 moisture to the surface. On the other hand, this shallow cultiva- 

 tion should be frequent enough to keep the surface thoroughly 

 open and so loose that water cannot rise through it, thus forcing it 

 to go through the tissues of the plant. On the other hand, the time 

 and labor, as well as the stage of growth of the plant, must have a 

 controlling influence on the frequency of cultivation. In a heavy 

 clay soil, fall or winter plowing may be a disadvantage, or at least 

 a waste of time, because of tamping or puddling the soil, causing 

 it to run together. — Texas Farm and Ranch. 



