SOILS, FERTILIZERS AND IRRIGATION 75 



Frequently it is possible to drain low places entirely surrounded by 

 higher ground by digging a hole such as you suggest. Go down until 

 you reach sand or gravel through which the water can flow easily. 

 Many large swales have been reclaimed in this way, but to be success- 

 ful the stratum of loose material must be reached, and sometimes it is 

 too far from the surface to make the work profitable. In your case 

 if such gravel stratum occurs it evidently is below the bed of mud and 

 probably separated from it by hardpan which you must get through. 

 The only other way to drain will be by putting in tile drains to take water 

 to lower ground digging deep enough through the sides of the depression 

 to allow the water to run off. If you put in tile to draw the water 

 down to three and one-half feet below the surface, you need not worry 

 about the water below that. 



Uses of Saltpetre. 



What about the use of saltpetre as a fertilizer of crops? I have 

 seen it stated that it has been used with great benefit on garden crops. 



It is Chile saltpetre or sodium nitrate which is used as a stim- 

 ulating nitrogenous fertilizer. When the term saltpetre is used in connec- 

 tion with preservation of meats, etc., it means potassium nitrate which 

 is too expensive for use in fertilizers. Chile saltpetre is largely used in 

 the way you mention and it can be bought from all fertilizer dealers. 

 Great care must be taken, however, not to use too much and not to apply 

 it in quantity near the plants. The usual dose is 200 pounds per acre, 

 well distributed. That is perfectly safe and considerably more may be 

 sometimes used to advantage ; but increasing the dose should be carefully 

 done after some experience has been gained in the use of it. 



What Is Meant by "Nitrate Spraying". 



What is meant by "nitrate spraying" in connection with insecticides 

 to stimulate fruit trees? 



In 1912 W. H. Volck, horticultural commissioner of Santa Cruz 

 County, and Mr. Ballard of the U. S. Department of Agriculture, 

 sprayed apple trees which previously had refused to bear with a solution 

 of nitrate of soda and they bore large crops of fine apples. Unsprayed 

 trees were unproductive, although as much nitrate of soda was applied 

 to the roots as was put on the tops of the first lot, the advantages all 

 coming from the spraying, apparently. Messrs. Volck and Ballard con- 

 tinued the experiments, with favorable results and the practice was taken 

 up by Watsonville growers. The dose is one pound of nitrate to a gallon 

 of water, or sometimes half a pound to the gallon. It can be applied 

 with ordinary lime-sulphur or other sprayings, or by itself with about 

 15 to 20 pounds of caustic soda to the 200 gallon tank added to make it 

 stick to branches. At first it was thought that it should be applied 

 when the buds were swelling, but later it was shown that it can be 

 applied any time to dormant trees. 



