98 



Campbell's 1902 Soil Culture Manual. 



pend upon replenishing his soil with moisture from the heavens, but this 

 is not the question today with the progressive farmer. It is how can we 

 get the greatest results from our soil, labor and expense considered. In 

 irrigation, water usually means money. There are few irrigation ditches 

 today that carry enough water through the season to irrigate all the land 

 that might be reached with water from the ditch. There are many fields 

 that are made to suffer that are under the ditch and crops made light that 

 if the principles involved in this book were understood and applied pre- 

 cisely as we outlined them to these fields, larger yields might be realized, 

 and more acres covered with the same amount of water when the irrigator 

 better understands the nature of plants and just what physical condition 

 is best for the support of healthy roots and how they gather plant foods. 

 Due consideration must be given to the roots of the plant and their neces- 

 sary supply in proper (|uantities, not only of water, but of air also. Too 

 much water at times is just as detrimental as too little water. A clear 

 conception of how water moves in the soil is just as important to the irri- 

 gator as to the man who depends solely upon the rainfall. 



The ideal condition for the most healthful and successful growth of 

 all cultivated crops is a good depth of root bed made thoroughly fine and 

 firm. There is little danger in getting the average sand loam soils, so 

 common in the arid and semi-arid sections, too firm, while some of our 

 heavy clay soils if not properly handled might become too closely com- 

 pacted, but this kind of soil is not at all common. Previous to the 

 thorough fitting of the seed and root bed see to it that ample moisture is 

 stored below where nature can do her part by bringing it up to the roots 

 of the growing plants by capillary attraction, then keep your surface al- 

 ways cultivated in such a manner as to provide as near as possible a fine, 

 loose mulch of soil (not dust), stirring it often enough to keep the moisture 

 up to the top of the firm soil just beneath the mulch. The moment the top 

 of this firm soil becomes in the least dry there is immediately a process of 

 depositing of salts and other matter between these particles of soil closing the 

 pores and consequently diminishing the quantity of air that should freely 

 pass through this soil to the roots. This condition not only points to the 

 fact that you are allowing the air to be shut out but that you are losing 

 moisture by evaporation from the soil which may be checked by cultiva- 

 tion. In fact, there should be no dry soil abov*^ your moisture except 

 what is loose and fine. See to this point at all times. Note our explana- 

 tion on this subject under Growing Trees. 



Our article on percolation should be of interest to the irrigator as it 

 indicates under what condition he can most economically apply his water. 



The articles on Evaporation and Capillary Attraction should like- 

 wise be studied. Sub-irrigation is being practiced with marvelous results 

 in some instances. It simply illustrates the importance of keeping the soil 

 above the roots simply moist but in condition to admit of a free circulation 



