232 



THE PRINCIPLES OF SOIL MANAGEMENT 



OPENING 6X8" 



with the trunk of trees, or, in general, with the stem of 

 any plant not well shaded. A bright, warm sun in con- 

 junction with the excess of 

 water is usually injurious. 



(5) It is the more convenient 

 method to apply to the class 

 of crops to which it is adapted. 



(6) It more readily permits 

 the avoidance of the injuries 

 due to seepage by avoiding 

 the losses to which that is 

 due. (7) It assists in the con- 

 trol of alkali soils by permit- 

 ting tillage. 



The supply of soil mois- 

 ture by capillarity is most 

 satisfactory to the majority 

 of cultivated crops, and by promoting this the furrow 

 system generally gives better results than flooding. 



The flooding system has some disadvantages: (1) 

 It is not so economical of water as is to be desired. 

 (2) Much attention must be given to forming the furrows, 

 to the construction of head or supply ditches, to the 

 collection of the overflow water at the end of the furrows, 

 and in the general supervision of the flow of the water 

 over the land to repair broken levees, etc. (3) The water 

 is not applied uniformly. The head of the furrow invari- 

 ably becomes more wet than the lower end. (4) Erosion 

 and puddling occur very readily in cultivated furrows. 



105. Overhead sprays. Overhead spray is used only 

 on very limited areas, and almost entirely in humid 



Fig. 74. Canvas dam with 

 opening to divide the water in an 

 irrigating furrow. 



