89 



"Orchard soils are usually plowed in the spring during April or early 

 May. This plowing may be done with a two horse team using a fourteen 

 inch plow. The plowing should be from six to eight inches deep. The soil 

 is turned towards the trees one year alfd away from them the following 

 year. The last one or two furrows near the trees can be plowed with a 

 one horse eight inch plow plowing only from four to six inches deep so as 

 not to interfere with the roots near the trunk. On soils that work easily it 

 is sometimes possible to cultivate the soil deep enough with the disc har- 

 row, thus doing away with the spring plowing. After plowing the land 

 should be smoothed using a smoother or leveler. After smoothing the soil 

 is cultivated with a spring tooth harrow going at least two ways in the 

 orchard. This is followed with a spike tooth or smoothing harrow." 



A deep granular mulch 6 to 8 inches thick is much more effective for 

 deep soils than one only 3 or 4 inches thick. If thorough cultivation is 

 practiced, frequent irrigation is not* necessary. Irrigation water can not 

 take the place of frequent and thorough cultivation. The effects of irri- 

 gation in furrows of different depths and of mulches of different thickness 

 have been determined quantitatively 'by the experiments previously de- 

 scribed (pages 68 to 72). 



VI. IRRIGATION OF POTATOES. 



1. Selection of Soil. 



Potatoes are grown very profitably in many of the irrigated districts. 

 They may be grown separately as a commercial crop on land devoted to 

 this purpose, or they may be planted between tree rows in order to obtain 

 some income from the land while the trees are young and for this pur- 

 pose they are preferable to deep rooted plants which are always more or 

 less detrimental to the proper growth of an orchard. They can also be 

 grown on land which is to be planted in fruit trees, for the purpose of im- 

 proving the texture of the soil. 



Potatoes which are grown on orchard soils either prior to planting the 

 orchard or while the trees are young, can not be expected to give as large 

 yields as obtained on soils which are selected for the purpose of growing 

 potatoes. Orchard soils are not always well suited for large yields of 

 potatoes. This is especially true of a soil which is deficient in organic 

 matter, but the continuous cultivation, the irrigation and the digging up 

 of the soil when harvesting the crop in the fall will very much improve 

 the condition of the soil. 



When potatoes are to be grown separately and for the chief purpose of 

 obtaining maximum production, the soil should be carefully selected and 

 given proper treatment. The best soil is a sandy loam of fairly porous 

 soil, well drained, with sufficient humus or decayed organic matter to put 

 it in good condition and increase its power to retain moisture. 



2. Treatment of Soil. 



To otbain heavy yields sandy soils must usually be prepared by growing 

 a foundation crop which will add humus to the soil. The best crops for 

 this purpose are alfalfa, clover, and peas. To keep the land in good pro- 

 ductive condition the rotation of crops is usually advocated. A common 

 practice in Colorado is to grow either clover or alfalfa for two years, 

 potatoes for two years, and grain or peas for one year; this last crop is 

 sometimes omitted. 



