THE ORANGE. 67 



To the soil, therefore, must we look for our supply of plant food, by rendering 

 available the inert material, and when that quantity is too feeble to supply arti- 

 ficially what it may be deficient in. 



The soils of Southern California are generally deficient in phosphates, a most 

 necessary constituent of plant food, and generally the first to become exhausted. 

 They are, as a general thing, rich in potash, and nitric acid, the conveyor of 

 nitrogen to the plant, depends greatly on ourselves, nitrates being formed by the 

 oxidation of ammonia in the soil, derived from the slow decay of organic matter in 

 the soil, and proceeds most rapidly at a temperature of 70 to 80 F., which 

 accounts for an abundance of acid in the summer, and a lack of same in early 

 spring. The formation of nitrate of potash is a most interesting study to the 

 farmer. Only within the past few years has it been discovered that the nitrate is 

 formed through a fermentation produced by bacteria in the presence of humus, 

 lime, and potash. 



The carbon of the plant is derived through the leaf from the carbonic acid of the 

 atmosphere; therefore mayweeds become beneficial to the soil. By being matured 

 and plowed under they keep the soil in a fine mechanical condition, retentive of 

 moisture. They supply nitrogenous material for oxidation into nitric acid. They 

 supply the water of the soil with carbonic acid, which has a "high solvent power 

 on the carbonates of lime, magnesia, protoxide of iron, and protoxide of manganese. 

 When carbonated water comes into contact with siliceous minerals they are decom- 

 posed much more rapidly than by pure water." 



The general mode of fertilizing in this country seems to be principally tillage, 

 with an occasional dressing of some manure once every two or three years, and 

 copious irrigation. Now, it would seem that this constant irrigation with pure 

 water, as it is in the San Gabriel Valley, would wash from the soil its soluble salts, 

 not only depriving it of them, but to an extent leaching and making the soil less 

 subject to hydroscopic water. And again, when thorough tillage is resorted to, to 

 the exclusion of manure, it stimulates the soil beyond the powers of endurance, the 

 vegetable mold is rapidly used up, the available phosphoric acid reverts to an insolu- 

 ble condition, and the soil thus left in its primary condition is subject to bake and 

 form hardpan. And again, where heavy manuring is resorted to, say once in 

 three years, as is sometimes done here, then do parts of the plant food revert to an 

 inert form, and the great quantity of organic matter becomes acid, and sours the 

 soil unless it be an exceedingly calcareous one. 



On my father's place, at San Gabriel, we choose to manure lightly and often, by 

 shoveling sheep manure into the irrigating ditches, allowing each tree to receive 

 about twenty-five pounds at each separate irrigation. Our basins cover the entire 

 surface of the ground. We make no effort to choke such weeds as clover, alfilerilla, 

 and the like ; but the irrigator with his hoe destroys the obnoxious nightshade, 

 hoarhound, and nettle. 



In the fall of the year we follow with a copious liming about three barrels of 

 unslacked lime to the acre applied in the following manner at the head of our 

 irrigating ditch : We plant a box about three feet wide, six feet long, two feet 

 deep, and six inches under the surface of the running water. In it we place a 

 barrel of the lime. It slacks and swells to twice its original bulk. A man stands on 

 this with his hoe, and sees that the water carries it oft" evenly. With an irrigating 

 head such as we use a man will run into the ditch four barrels a day, or about 

 three barrels to the acre. We now leave the orange orchard till spring, when we 



