218 



THE IRRIGATION AGE. 



fits is the improved physical condition of 

 the soil, due to the decaying of the green 

 manure turned under. It causes the soil 

 to bake less and hold irrigation moisture 

 longer. 



The chief benefit to the trees comes from 

 the addition of nitrogen to the soil. This 

 importont plant food is derived from the 

 air mixed with the soil. Most plants are 

 powerless to use nitrogen from the sur- 

 rounding air, notwithstanding the fact 

 that the latter contains about 80 per cent, 

 of the element. Members of the pea fam- 

 ily (peas, beans, clovers, alfalfa, etc.) are 

 an exception. They harbor upon their 

 roots colonies of microscopic plant bacteria 

 which have the ability to absorb nitrogen 

 and pass it along to the plants to which 

 they are attached. The irritation pro- 

 duced by these colonies of bacteria causes 

 the formation of the small nodules or 

 knots by which nitrogen using plants can 

 always be distinguished. 



The plowing under of plants that have 

 secured their nitrogen elsewhere than from 

 the soil, adds to the latter the nitrogen se- 

 cured, and is a great benefit. 



M. W. Ward, a large orange orchardist 

 of Phenix, has used yellow clover in his 

 grove for several years, and with material 

 benefit. His experience was that after one 

 or two sowings enough seed matured under 

 the trees and in other places not reached 

 by the plow to seed the orchard from year 

 to year, the only work necessary being to 

 furrow and irrigate early in October. Bul- 

 letin Arizona Exp. Station. 



TO PREVENT FLOODS. 

 "The famous Johnstown flood of May 

 31, 1889, will probably soon be recalled to 

 the public by an attempt to reforest a 

 large portion of the Conemaugh watershed 

 to prevent further damage from freshets," 

 says the United States Department of 

 Agriculture. "The Johnstown Water 

 Company, which controls 5,000 acres of 

 mountain land, has asked the Division of 



Forestry to devise a plan by which the 

 area can be re-covered with timber and 

 the too rapid run-off of the rainfall pre- 

 vented. 



The region is peculiarly liable to fresh- 

 ets, owing to its geological character and 

 the removal of its timber. The now his- 

 toric catastrophe, which swept away $10,- 

 000,000 in property and half as many lives 

 as the battle of Gettysburg, was but an 

 exaggerated instance of many similar 

 floods. This tendency has been increased 

 by logging off the timber and clearing nu- 

 merous farms, so that the rainfall flows 

 quickly from the surface, causing high 

 water at one time and the drying up of 

 springs later. 



The Johnstown Water Company has 

 bought up many of these farms and torn 

 down their buildings, and now wishes to 

 expedite their return to the forest. The 

 tract is in a sandstone region, much 

 broken, with valleys averaging 350 feet in 

 depth. The timber consists of hemlock, 

 oak, locust and ash, with some beech and 

 poplar. The openings are from twenty to 

 fifty acres. , 



As soon as the weather permits, J. W. 

 Tourney, Superintendent of Tree Planting, 

 and another working plan expert of the 

 Division of Forestry, will examine the re- 

 gion and decide on a plan of reforestation. 

 In the clearings, tree planting will be 

 required. An attempt will probably be 

 made to increase the stand over the whole 

 area by skillfully assisting natural repro- 

 duction. Protection from fire and cattle 

 will also by required. The expense will 

 be shared by the Government and the 

 Water Company, the former furnishing 

 the expert work and, possibly, some of the 

 material for planting." 



PLANT TREES. 



It is on the treeless plains that the set- 

 tler appreciates at its true value the pres 

 enee of tree growth and realizes the neces- 

 sity for some general policy to preserve 

 not only a priceless investment, but a 

 vast source of water supply. 



