296 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. " 



The farmer's business, more than any other perhaps, depends for its success upon a true 

 estimate of and careful regard for this interrelation. He adapts his crop to the nature of the soil, 

 the manner of its cultivation to the changes of the seasons, and altogether he shapes conditions 

 and places them in their proper relations to each other and adapts himself to them. 



Soil, moisture, and heat are the three factors which, if properly related and utilized, combine 

 to produce his crops. In some directions he can control these factors more or less readily; in others 

 they are withdrawn from his immediate influence, and he is seemingly helpless. He can maintain 

 the fertility of the soil by manuring, by proper rotation of crops, and by deep culture; he can 

 remove surplus moisture by ditching and draining; he can, by irrigation systems, bring water to 

 his crops, and by timely cultivation prevent excessive evaporation, thereby rendering more water 

 available to the crop; but he can not control the rainfall nor the temperature changes of the sea- 

 sons. Eecent attempts to control the rainfall by direct means exhibit one of the greatest follies 

 and misconceptions of natural forces we have witnessed during this age. Nevertheless, by indirect 

 means the farmer has it in his power to exercise much greater control o\er these forces than he 

 has attempted hitherto. He can prevent or reduce the unfavorable effects of temperature changes ; 

 he can increase the available water supplies, and prevent the evil effects of excessive rainfall; he 

 can so manage the waters which fall as to get the most benefit from theni and avoid the harm 

 which they are able to inflict. 



Before attempting to control the rainfall itself by artifice, we should study how to secure the 

 best use of that which falls as it comes within reach of human agencies and becomes available by 

 natural causes. 



How poorly we understand the use of these water supplies is evidenced yearly by destructive 

 freshets and Hoods, with the accompanying washing of soil, followed by droughts, low waters, and 

 deterioration of agricultural lands. It is claimed that annually in the United States about 200 

 square miles of fertile soil are washed into brooks and rivers, a loss of soil capital which can not 

 be repaired for centuries. At the same time millions of dollars are appropriated yearly in the river 

 and harbor bills to dig out the lost farms from the rivers, and many thousands of dollars' worth of 

 crops and other property are destroyed by iioods and overflows; not to count the large loss from 

 droughts which this country suffers yearly in one part or the other, and which, undoubtedly, could 

 be largely avoided, if we knew how to manage the available water supplies. 



The regulation, proper distribution, and utilization of the rain waters in humid a-, well as in 

 arid regions — water management — is to be the great problem of successful agriculture in the 

 future. 



One of the most powerful means for such water management lies in the proper distribution 

 and maintenance of forest areas. Nay, we can say that the most successful water management is 

 not possible without forest management. 



THE FOREST WATERS THE FARM. 



Whether forests increase the amount of precipitation within or near their limits is still an 

 open question, although there are indications that under certain conditions large, dense forest 

 areas may have such an effect. At any rate, the water transpired by the foliage is certain, in 

 some degree, to increase the relative humidity near the forest, and thereby increase directly or 

 indirectly the water supplies in its neighborhood. This much we can assert, also, that while 

 extended plains and fields, heated by the sun, and hence giving rise to warm currents of air, have 

 the tendency to prevent condensation of the passing moisture-bearing currents, forest areas, with 

 their cooler, moister air strata, do not have such a tendency, and local showers may therefore become 

 more frequent in their neighborhood. But, though no increase in the amount of rainfall may be 

 secured by forest areas, the availability of whatever falls is increased for the locality by a well- 

 kept and properly located forest growth. The foliage, twigs, and branches break the fall of the 

 raindrops, and so does the litter of the forest floor; hence the soil under this cover is not com- 

 pacted as in the open field, but kept loose and granular, so that the water carr readily penetrate 

 and percolate. The water thus reaches the ground more slowly, dripping gradually from the 

 leaves, branches, and trunks, and allowing more time for it to sink into the soil. This percolation 

 is also made easier by the channels along the many roots. Similarly, on account of the open 

 structure of the soil and the slower melting of the snow under a forest cover in spring, where it 



