0 55 9,142 291 26
50 60 84 13,061
The soil was a typical arid soil of great depth and had been so
cultivated as to contain a large quantity of the natural
precipitation. The first five inches of water added to the
precipitation already stored in the soil produced forty bushels of
wheat. Doubling this amount of irrigation water produced only
forty-one bushels of wheat. Even with an irrigation of fifty inches,
or ten times that which produced forty bushels, only sixty bushels
of wheat, or an increase of one half, were produced. A similar
variation may be observed in the case of the other crops. The first
lesson to be drawn from this important principle of irrigation is
that if the soil be so treated as to contain at planting time the
largest proportion of the natural precipitation,--that is, if the
ordinary methods of dry-farming be employed,--crops will be produced
with a very small amount of irrigation water. Secondly, it follows
that it would be a great deal better for the farmer who raises
wheat, for instance, to cover ten acres of land with water to a
depth of five inches than to cover one acre to a depth of fifty
inches, for in the former case four hundred bushels and in the
second sixty bushels of wheat would be produced.
Pages:
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327