This was very strikingly shown by the investigations of Ototzky in the South-Russian steppes, in comparing both the moisture contents and the depth of bottom water as between forest land and the open plains. On the steppe near Chipoff, Government of Voronej, he found the ground water at from 3 to 5 meters (10-16 feet) depth; under the forest in the same region and in identical underground formations, the water level stood at 15 meters. In the Black Forest near Cherson, the water is found at about 15 feet beneath the surface; under the steppe and in cultivated ground it stood at 10 feet. At the same time the forest soil was moister in the upper two feet than the soil of the steppe, where surface evaporation (partly through shallow plant-roots, partly direct) was greater than under the shadow of the forest; under which, moreover, there were few shallow rooted plants to draw upon the moisture of the surface soil. The great evaporation from forests is a matter demonstrated by actual measurement; hence it is not surprising that certain shallow-rooted trees should serve for the reclamation of wet ground, as has been demonstrated on the large scale, _e. g._, in the use of the eucalyptus in the Pontine Marshes of Italy, and of the maritime pine in the Landes of western France. Thus the sanitation of swampy districts through tree-planting has become one of the established measures in their settlement. But this refers only to the evaporation from the trees themselves; for in the shade of the forest, a free water-surface is found to evaporate on the average only one-third as much as in open ground. Of course there must be a correspondingly great difference in the amounts of evaporation from the soil-surfaces in the respective areas. The great draft made by the _Eucalyptus globulus_ upon soil-moisture has been also abundantly shown in California, where on account of its rapid growth this tree has been largely used for windbreaks. It was found that the trees deplete the fields of moisture for from twenty to thirty feet on either side, so as to materially reduce crops within that limit. For this reason the pine and cypress has of late found greater acceptance for this purpose. _Mulching._—Covering the soil with straw or similar loose materials to prevent waste of moisture is a common garden practice everywhere, although not usually applicable on the large scale. It may readily however, be carried to excess, in preventing not only evaporation but also the warming of the soil which is so needful to the thrifty growth of plants. It must not therefore be done too early in the season; and after cold rains it sometimes becomes necessary to remove the mulch in order to allow the ground to become properly warmed. Mulching in early spring is often used to retard blooming of trees where spring frosts are feared.