264 



FARM DEVELOPMENT 



in canals and field ditches without serious waste till it 

 is evenly spread over the soil and allowed to percolate 

 slowly downward. On these soils leaching is reduced to 

 a minimum and most of the water supplied is conserved 



to be taken up by the 

 roots of plants, or is lost 

 by evaporation from the 

 surface of the soil. These 

 heavy soils require intel- 

 ligent management to 

 make them produce well, 

 whether in a region of 

 heavy rainfall or under 

 irrigation. They are liable 



Figure 163. Ditching "A," used for finish 

 ing small lateral ditches. 



to become baked and in 

 poor mechanical condi- 

 tion for producing good 

 crops. 



Medium textured soils 

 of mixed sand and clay 

 are best for irrigation, 

 and more money can be 

 profitably invested in 

 irrigating these soils 

 than for the very light 

 or the very heavy soils. 

 The water can be spread 

 over them without great 

 loss; they will absorb 

 and retain large quan- 

 tities of water and will 

 supply it gradually to 

 the growing crops; they 

 may be cultivated and 

 kept in good mechanical condition without large expense ; 

 and they are usually productive. 



Figure 164. Canvas dam. 



