SOILS, FERTILIZERS AND IRRIGATION 63 



fall rains. If you are pretty sure of good rains in September and Octo- 

 ber and the trees are looking well when the fruit is gathered, the prob- 

 ability is that they do not need irrigation. 



Windbreak on Irrigation Ditch. 



What deciduous tree will make a good erect windbreak along an 

 irrigation ditch in the San Joaquin Valley? How far apart should 

 they be planted? 



If you want it very upright nothing beats the Lombardy poplar and 

 by planting close, say 20 feet, you can get an effective windshield. It 

 does well in your valley. 



Underground Irrigation. 



What is the best way to subirrigate citrus trees and where is there 

 published information on the subject? 



No method has been demonstrated to be of continued value and suc- 

 cess. Since 1870 every kind of subterranean distribution has been tried, 

 including board boxes, cement pipes or tiles, perforated or otherwise, iron 

 pipes with various outlets all these have been tried and abandoned. The 

 literature on the subject consists of descriptions of patented systems in 

 the publications of the U. S. Patent Office and subsequent announcements 

 of their undesirability in the horticultural journals. Often one hears of 

 the success of fruit on "subirrigated land," but the term applies to land 

 moistened by gravity or lateral seepage in the form of natural under- 

 flow, and does not indicate any method of artificial subterranean distri- 

 bution. (For subirrigation in gardens see Part IV, Vol. 1.) 



Irrigating Sorghums. 



/ have planted Egyptian corn. The ground was thoroughly 

 watered before planting and the corn is just now coming up. The soil 

 is getting very dry on the surface. I have been told that Egyptian 

 corn should not be watered at all. Would you advise permitting it to 

 go through the dry hot months without irrigation? If not, when and how 

 often should it have water? 



The sorghums are especially valuable for drouth and heat toleration, 

 and because they will give most growth with least water, but that does 

 not mean that they do not enjoy moisture. They make amount of growth 

 proportional to the moisture available and will grow from six inches to 

 six feet high according to the soil moisture available. Therefore, unless 

 your ground is naturally moist, you will get more green feed or grain 

 by irrigation, the water being run in furrows between the rows, or flooded 

 if sown broadcast. How much and how frequently irrigated depends 

 upon whether the soil is retentive or not. Ordinarily irrigation once a 

 month is desirable. Watch the plants and keep the foliage from yellow- 

 ing until it is natural for it to mature the seed. Whether you will irri- 

 gate or get the most you can without it, good cultivation while the plant 



