32 FUNDAMENTALS OF FRUIT PRODUCTION 



if the vegetation were cut and allowed to remain on the ground as a 

 mulch the treatment would be called a sod-mulch system. No attempt 

 is made here to go into any detail regarding some of these systems of 

 soil management that are very much alike or that are intermediate in 

 character between those that stand out clearly as types. However, it 

 is desirable to recognize how certain of the typical systems of soil manage- 

 ment may be expected to influence the water content of the soil and, 

 through it, the growth and behavior of the tree. With this information 

 at hand, it will not be difficult, as a rule, to predict more or less accurately 

 the results that may be expected from one of the intermediate or combi- 

 nation treatments. 



Orchard -soil Management Methods and Surface Run-off. — A 

 word may be said first regarding the influence of these several methods 

 of soil treatment upon surface run-off. Much of course depends upon 

 the lay of the land, the character of the soil itself and the way in which 

 precipitation occurs. Most soils cannot take up the water that falls 

 in a torrential rain lasting but an hour so completely as they can the same 

 amount of rainfall distributed over a 12- or 24-hour period. Exact 

 figures are not available, but it has been observed many times that there 

 is much less run-off from sodded areas than from equal areas of similarly 

 lying bare land. The covering of vegetation or of mulching material 

 checks the flow of the water over the surface of the ground and gives 

 it a greater opportunity to soak in. Furthermore, if there is any con- 

 siderable amount of mulching on the ground it acts as a sponge, first 

 absorbing the water as it falls and then permitting it slowly to seep into 

 the soil. In this connection, mention should be made of the influence 

 of mulching material or vegetation of any kind upon erosion. There 

 are many orchards and parts of many others, planted on slopes so steep 

 that there would be much loss of soil from washing, were the land to be 

 cultivated and left bare any considerable portion of the year. Orchards 

 of this type should be left in sod or artificially mulched, regardless of 

 how these treatments may influence the water or nutrient supply avail- 

 able to the trees. 



Moisture Under Tillage and Sod-mulch Systems of Management. — 

 There is Httle reason to beheve that there is much difference between 

 the methods of soil management in the amounts of seepage into the lower 

 layers of the soil. However, it is obvious that these several treatments 

 would have very different influences upon surface evaporation from the 

 soil and the evaporation that takes place through the plant itself. Fortu- 

 nately, considerable data are available upon certain phases of this 

 question. 



Some New York and Pennsylvania Records. — The New York data 

 presented in Table 18 show nearly 5 per cent, difference in soil moisture 

 between the surface soils of the tilled and of the sodded orchards and 



