20 GARDEN FARMING 



every soil particle is enveloped in a minute film of moisture. The 

 tiny growing roots of the living plant are capable of drinking up 

 this minute supply of moisture and are also benefited by the air 

 which is contained between the soil particles. Too much water in 

 the soil drives out the air, fills the spaces with moisture, and acts, 

 to a certain extent, as a smother to the roots. Roots, like the leaves, 

 must have a certain amount of free oxygen in order to perform 

 their normal functions. The withdrawal of an excessive amount of 

 moisture from the soil, however, leaves it dry, hard, barren, and 

 incapable of supporting productive plant growth. Slight variation 

 or fluctuation in the amount of moisture in the soil is not detri- 

 mental and to a certain extent is desirable, but these fluctuations 

 should not be extreme. It is always desirable to maintain sufficient 

 moisture to prevent the plants from flagging, but it is not desirable 

 to have the soil at all times highly charged with moisture. From 

 studies of seed germination it has been determined that consider- 

 able fluctuation between day and night temperature is needed for 

 the highest germination of certain seeds. The same is true, to 

 a certain extent, with the fluctuation of moisture, although this 

 factor is probably of less importance than temperature. The soil, 

 however, should at all times be maintained as nearly as possible 

 in that condition which gardeners recognize as ideal for the growth 

 of plants a condition which is easily determined by experienced 

 gardeners from the way the soil behaves when handled but which 

 is not easily described. 



Water temperature. The temperature of the water used for 

 irrigation or syringing is of little importance so long as it is below 

 80 F. and above 50 F. The influence of water at a high or low 

 temperature is only temporary, and no decided influence on the 

 plants can be discovered from the use of hot or cold water. A 

 slight change in temperature of the soil is noted where extremely 

 warm or extremely cold water is used ; but this change is only 

 temporary, and careful observations have not been able to detect 

 any decided influence upon either the growth or the yield of potted 

 plants in greenhouses which are watered with water within the 

 above temperatures. 1 The time and manner of applying water is 

 more important than its temperature. 



1 Wisconsin Agricultural Experiment Station Report, 1897, pp. 317-320. 



