144 



spent in watering 5 acres, and when dry the ground is thoroughly^ 

 cultivated. 



The annual charges for water by the acre in southern California, 

 ■where this economy of water is practised, have been es low as $d, and 

 from this rising to $6 or more per acre. In ihe case of the San Diego 

 Flume Company, it is stated that water was sold for $600, per miner's 

 inch, with an annual charge or rental of $60, 1 miner's inch being- 

 considered sufficient for from 10 to 20 acres. The annual charge for 

 water, taking the arid region as a whole, has averaged by States from 

 60 cents to §2.00 per acre, or $1.25 (5s. 2^d.) per acre for the entire 

 country. 



The conditions in southern Cttlifornia, while they may be con- 

 eidered as exceptional, yet indicate the limiting or ideal conditions of 

 eccnomical use of water. For good farming in other parts of the arid 

 region, 12 inches of water in depth during the crop season should be 

 sufficient, except in the case of lucerne and other forms of forage 

 which are cut a number (f limes, when at least from 4 inches to 6- 

 inches should usually be given to a cutting. As previously stated the 

 character of the soil, the temperat^^re, and the wind movement intro- 

 duce so many conditions that breed statements of this kind are merely 

 suggestive and not to be followtd as rules. 



Irrigation is usually carried on during the daytime, and it is un^ 

 usual lor water to be applied during the night, other than to arrange 

 the head gttes and allow the water to flow to certain portions of the 

 field. In times of Ecai city, however, when water can be had only at 

 certain hours, night irrigation must be carried on, and the water care- 

 fully applied, with as much skill as possible in the darkness. Night 

 irrigation, although possessing disadvantages, has many advocates. 

 The air being cooler, excessive evaporation is checked, there is less loss 

 and consequently more economy in use and the plants are not so sud- 

 denly chilled as during the heat of the day when cold water is run 

 upon the fields; and the proportional amount cf water received during 

 the night is often greater than during the daytime, and the charge of 

 cost is correspondingly less; so that, for economy in various directions 

 night irrigation is sometimes preferred. 



LOCAL DEPOSITS OF BAT GUANO. 



By H. H. Cousins, M.A., F.C.S., Government Analytical and 

 i Agricultural Chemist. 



It has long been tnown that there are in Jamaica corsiderable ac- 

 cumulations of Bat Guano in caves and other sheltered places where 

 these animals congregate. A good deal has been used in the past 

 upon various estates in the island, and recently some commercial en- 

 quiry has arisen as to the possibility of an export trade in this mate- 

 rial with the United States. 



Some 35 difi^erent samples of ' Cave Earth' and 'Bat Guano' have 

 been analysed at various times at the Government Laboratory by* 

 Messrs. Bowrey, Watts and the writer. 



