THE IRRIGATION AGE. 



36] 



ARID AGRICULTURE 



BY 



B. C. BUFFUM, M. S. 



Manager of the Wyoming Plant and Seed Breeding Company, Wor- 



land. Former Professor of Agriculture in the University of 



Wyoming and the Colorado Agricultural College, and 



Director of the Wyoming Agricultural 



Experiment Station. 



PROF. B. C. BUFFUM. 



THE CONSERVATION OF MOISTURE. 



There has been much specula- 

 tion in regard to the possible pro- 

 duction of a crop with a certain 

 amount of moisture. This interest 

 has arisen from experiments car- 

 ried out in France and parts of this 

 country, which show the amount 

 of water taken up by plants and 

 .ranspired from their leaves to pro- 

 .uce their growth. In one of these 

 xperiments, it was shown that it 

 ook an average of three hundred 

 pounds of water taken from the 

 soil to produce one pound of dry 

 matter. On this basis, Headden 

 made a calculation of the approxi- 

 mate amount of water required for the production of a 

 twenty-five-ton crop of sugar beets. Where sugar beets 

 produce a large amount of tops, these tops have been 

 known to equal at least ninety per cent of the weight of the 

 roots. To grow twenty-five tons of beets, then, there 

 would be twenty-two and one-half tons of tops. In the 

 beets there would be five tons of dry matter requiring fif- 

 teen hundred tons of water, and the tops and beets to- 

 gether would require 2,175 tons. This amount of water 

 would cover the land to a depth of over nineteen inches, 

 and on this basis, twelve and one-half tons per acre could 

 be produced with ten inches of moisture, provided it is all 

 saved and made available to the plants. 



Several years ago, the author made the following 

 statement: The amount of .water found to be necessary 

 to produce one pound of dry crop of grains in the humid 

 region is approximately five hundred pounds, which is 

 used by the plant and evaporated from the soil during 

 growth. An annual rainfall of twelve inches would bring 

 to each acre of land 2,722,500 pounds of water. If all this 

 water could be made available for the crop during the 

 growing season, and assuming that 500 pounds of water is 

 sufficient to produce one pound of dry crop, twelve inches 

 of rain would produce 5,445 pounds, or approximately 2^4 

 tons of vegetable matter. If one-half the rainfall of a 

 single year could be saved to the growing plant, it would 

 support more crop than the average native hay production 

 of our irrigated meadows. 



Such speculations are useful as indicating certain pos- 

 sibilities, but it is unquestionably true that some plants 

 require more moisture than others, and there are many 

 things to consider outside of the actual amount of moisture 

 used. There are drouth-resistant crops which will ap- 

 proximately stand still in ding of drouth until more moist- 

 ure renews their growth. Other drouth-resistant crops 

 have so adapted themselves to arid conditions that they 

 produce less top and leaf surface to evaporate the water 

 and put their energies chiefly into the production of seed 

 or fruit rather than into the making of much growth. We 

 find nothing in these scientific speculations which is dis- 

 couraging to the dry fanner or which would indicate that 

 it is impossible to produce profitable crops of suitable 

 plants once in two years where the annual rainfall is as 

 little as eight or ten inches. "The proof of the pudding 

 is in the eating," and such crops having actually been 

 produced under such conditions, is sufficient demonstration 

 of the fact. 



Having the principal rainfall come during the growing 

 season is a great advantage in some ways. Often a crop 

 will have used up the stored soil moisture and be ready 

 to give up the struggle when a rain will revive the plants 

 and make them mature successfully. This enables the 

 farmer to take advantage of that useful semi-dormnnt 

 or waiting- character of certain drouth-resistant plants. 



Soil Mulch. 



Maintaining the soil mulch is one of the most import- 

 ant factors in the success of dry farming. It is by the 

 soil mulch that we are able to make our soils absorb all 

 the moisture that comes to them by precipitation or from 

 dews or other moisture. By it we conserve this moisture 

 and prevent its loss back into the air by evaporation. 

 Summer-tilled land should at all times be covered with this 

 mulch, which should be in granular form of small lumps. 

 Care should be taken not to get it too fine. Dust does 

 not absorb moisture so well and is apt to drift or blow 

 away. Working the ground when dry will tend to make 

 the surface soil too fine. The object of cultivating the 

 summer fallowed soil is to prevent the formation of a 

 crust after heavy rains; to allow proper action of sun and 

 air; to prevent the moisture from rising to the surface 

 where it will evaporate and to destroy the growth of 

 weeds. The film moisture in the soil travels up and down 

 by what is called capillary action. This is merely the 

 flowing of the moisture which surrounds one particle of 

 the soil to, and around, the next soil particle, which is 

 close enough to touch the_ film and so on as long as the 



Some Arid Land Recently Opened for Settlement Shoshone Reservation. 



soil particles are close enough together, until it reaches 

 the surface where it is evaporated. By stirring the soil, 

 we let in air and separate the grains of soil so the capillary 

 movement is stopped, and loss by evaporation is prevented. 

 The soil mulch must be maintained over the whole field, 

 and the drag harrow is the principal tool used for this 

 purpose. Writers have recommended that those who 

 practiced summer-fallowing should get on to the land 

 with the harrow immediately after every rain or snow. 

 This is not always necessary or advisable, for working 

 too soon may cause rapid loss of the moisture which is 

 still in the surface layer. The ground should be worked 

 as soon after every heavy rain or snow as it is dry enough. 

 Do 'not wait too long, for when too dry the soil will 

 dust and drift. Light rains may cause actual loss of soil 

 moisture by forming a connection which lifts the water to 

 the surface, where it is lost into the air. Judgment should 

 be used and the ground cultivated as early and often as 

 the conditions indicate. 



Humus and Vegetable Mold. 



There is much misconception about what humus is. 

 Often when we speak of humus, we do not mean true 

 humus, but refer to the partially decayed plant substances, 

 which were better called vegetable mold. True humus is 

 the final product of the decay of organic matter in the 

 soil. It is a very complex chemical compound, which 

 contains nitrogen, and may act in an important way 

 toward the change and use of soil plant foods. On the 

 other hand, it is the partially decayed vegetable matter 

 which has so much to do with tilth. This substance ab- 

 sorbs water, holds the soil particles apart, aerates the 

 soil, and fosters bacterial and chemical changes which 

 should pay for a do-nothing proposition, with reference to 

 legislation. Since the Reclamation Act was passed eight 

 years ago it has not been remedied in any respect what- 

 ever, and it has been defective from the hour it was 

 passed. The time has come to get relief along as many 

 lines as possible." 



