136 Appendix. 



gen material as Is obtainable In the soil during its period of growth, and, as 

 this is at a time when the dormant tree could make no use of such nitrogen 

 material, which, if not used, soon escapes as a waste by leaching from the soil, 

 it is seen that the cover crop thus becomes a saver of nitrogen as well as 

 other substances and thus performs a work as important as that of a nitrogen 

 gatherer under the circumstances. 



In Western Oregon orchards in particular, not a foot of soil should remain 

 uncovered or bare of plant growth from the time the crop is fully grown to 

 the time when the fruit begins to form the folowing spring. The warm winter 

 temperature, together with the rainfall, results in a set of conditions quite suita- 

 ble for the growth of many hardy plants. Under the same conditions biological 

 and chemical changes in the soil are setting free much soluble plant food 

 material. This material, if not used by active plants on the ground, will be 

 wasted very largely by surface washing or leaching through the drainage system. 

 An active crop saves this waste ; puts it in such form as can be more readily 

 used by the trees when they become active in the spring. And thus, while 

 saving that would otherwise be lost to the soil tiller, the cover crop performs 

 a preliminary or preparatory work for the trees, getting ready for their use 

 early in the spring a quantity of predigested breakfast food as it were. And, 

 as with the human, the more substantial the breakfast the better the start in 

 the season's work. 



While the list of plants that may be grown for cover purposes is quite long, 

 each locality, and each grower, will lind that local conditions and personal re- 

 quirements will render some more suitable than others for his purpose. So 

 far as reports .lave been made the vetch — Vicia sativa — appears to give the best 

 results in Western Oregon. L. T. Reynolds says :* "Our first test of cover crops 

 was in 181)0, when we sowed crimson clover. It did not prove suitable for 

 our climate. The common vetch lias been found to meet all requirements. It 

 can be sown later than crimso clover: is nearly always a good stand; makes a 

 good growth auring the wirter, and pushes forward rapidly in the spring, so that 

 one can have a growth of two to three feet in lieight to turn under by May 

 the first. As such luxuriant growth renders it somewhat diflScult to plow in, 

 we have found it convenient to sow the seed only one way between the trees, 

 leaving about tliree feet in the tree row unsown. Sown in this way it requires 

 about fifty pounds of seed per acre, and it can be readily plowed under."** 



"In an orchard of young trees making vigorous growtli the vetch can be 

 sown in February and plowed imder in June, but under such conditions I should 

 hardly consider a cover crop necessary." 



In 'bulletin Ko. 40 (1896) of this Station the following statements are 

 found : Speaking of a twenty-five acre tract, in a large prune orchard, that 

 had become covered with a rank growth of wild mustard, the author said : "The 

 soil of this mustard strip remained moist and friable all summer tlirough, 

 and with one-third the tillage it presented a more favorable condition for 

 tree growtli. as shown by the vigor of the trees, than any other part of the 

 orchard imder otlierwise similar treatment." 



If the supply of nitrogen in the soil is quite sufficient there are some ad- 

 vantages in a mustard crop not found in otliers. The crop may be pastured 

 in the winter, and if not plowed under too early in the spring, ample seed 



♦Oregon report 1903. 



**In a letter to the writer dated December 24, 1903, Mr. Reynolds speaks 

 further of the vetch as a cover crop. "In ordinary years, I would say the 

 vetch should not be sown later than December 1st. I prefer to sow it in Sep- 

 tember and October as it then gets a good start and makes a rapid growth 

 as soon as warm weather comes in the spring and enables one to turn under a good 

 crop by the early part of May. It then rots ((uickly and assists in preserving osil 

 moisture together with its other functions. If a heavy growth is turned under 

 in .Tune, the soil moisture is usually too low to permit of ready decay and 

 thus the vetch not only does not yield plant food, but it renders tlie soil dryer 

 and In this way works an injury to tlie orchard crop." 



