134 Appendix. 



pulverizing harrow follows until the middle of July or first of August. By this 

 time or even by the middle of Jiine. tlie surface soil from two to three inches 

 deep is a perfect dust, the so-called "dust mulch" or "earth-blanket" a mrst 

 important factor in the conservation of soil moisture. Where ferns or some 

 other deep rooted perennial plants persist in playing the part of weeds ( See 

 Fig. 19» it is often necessary to go over the grouu'l at intervals of ten days 

 with a tool known as a scarifier. By removing the tops at frequent intervals 

 the roots finally become exhausted, and as there is left no other means for 

 the plant to propogate itself it disappears. It fretiuently requires from tliree 

 to four years to rid a piece of land of a well established crop of ferns. 

 Occasionally one hears that trees should not be planted on a fern ridge he- 

 cause the plant is such a pest in the orchard. In truth fern ridges when 

 once subdued are the very best of sites for orchard purposes. Ferns only grow 

 abundantly on well drained soil. The ramifications of their underground stems 

 and the ultimate death and decay of these very materially aid in oxidizing and 

 aerating the soil, to the depth of two feet, or even more This oxidization and 

 aeration are liighly important processes in the biological functionings of the 

 soil, and most useful factors in rendering the plant food of the soil available for 

 tree growth. 



COVER ("KOrS. 



This is a pliase of orchard management that has received little atteutiim 

 as yet. Speaking more particularly of Western Oregon it may be said : Thus 

 far our orchards that are thoroughly tilled have shown no especial need of 

 service in the directions in wliich a cover crop would aid tliem, but the time 

 is approaching when such conditions will no longer exist. 1'horough tillage 

 increases oxidation in the soil. The liumus burns away as it were and need 

 for material to replace the original supply will Ije manifest, in a dryer, harsher 

 soil, sometimes lieavier : sometimes ligliter : in a soil that will be cloddy and in- 

 tractable, generally throughout Western Oregon. Tliis material can be obtained 

 at least expense by means of cover crops, as oats, wheat, rye, vetch, clover, 

 mustai'd, and the like. 



As to the funcrions of a cover crop altogether, it may be well to quote 

 from bulletin No. <il . of the r)elaware station, which says: 



"Wn.\T DUES A COVER CKOl" DO".'" 



(1.) If sown at the prop r time, about August 1 if weatlier conditions are 

 favorable, it competes with the trees for soil moisture and plant food. The 

 supply of moisture and food to the trees is lessened and their growth is 

 checked. This is desirable, because at that time the trees should stop growing 

 and ripen their wood for the winter.* 



(■-!.) It catches solul)le nitrates late in the fall when root action of the 

 trees has nearly or quite ceased, thus much plant food is saved rather than 

 allowed to escape in drainage. 



(:j.) It prevents erosion of the surface soil by catching the rains as they 

 descend and by conducting them into the soil. This is in contrast to streams 

 of water flowing over the bare surface and cutting channels for the escape 

 of surplus water It also holds the snow of winter which adds to the efficiency 

 of the protection. 



(4.) It protects the ground from frost to a certain extent, that is, actual 

 tests have proven that ground protected by live cover crops during the winter 

 does not freeze so deep as does bare ground. 



(.J.) In the spring it catches soluble nitrates tluit might leach out of the 

 soil before active root action of the tree begins. 



*This statement applies more particularly to young trees. Bearing trees, 

 with us would need no such check and it would be well to sow the cover later, 

 thus not shortening the supply of water for the fruit. 



