MULCHING IN BEARING APPLE ORCHARDS 13 



records shows that there is no relation between tne size of the crop and the 

 percentage of dropped fruit — a light crop may drop as badly as a heavy crop. 

 The amount of drop is plainly greater in certain years, among which 1935 shows 

 the heaviest drop; while 1932 shows the least of any recent year. Despite the 

 heavier drop on the mulched plots the amount of picked fruit has been greater 

 each year than on the cultivated plots. 



Discussion 



The data presented seem to show that the mulched trees have grown and 

 produced better than those under cultivation. On most soils, however, trees 

 will not perform well without fertilization for very many years even under 

 cultivation. If the cultivated plots had been well fertilized for the entire period 

 the trees might have grown and yielded as well as the others. It is reasonable 

 to believe that the differences would have been less than those recorded. The 

 most that can be said is that this experiment indicates that trees heavily 

 mulched so that there is little or no growth of grass and weeds may be expected 

 to give a good account of themselves. 



There are some strong arguments in favor of mulching. 



1. It absolutely prevents erosion of the soil covered; this is extremely im- 

 portant especially when we take a long look ahead. 



2. Soil moisture will be conserved; there will be little or no runoff during 

 heavy rains and less evaporation from the soil. In other words there will be 

 increased absorption and less loss to the atmosphere. 



3. The soil will doubtless be warmer in the winter; this may prevent root 

 killing during severe cold periods and favor root activity during the late fall 

 and winter. 



4. There will be less injury to apples dropping prematurely; they will be 

 cleaner than if they dropped on cultivated soil and less likely to be bruised by 

 stones or stubble. 



The principal argument against mulching is the cost. In most cases, cost 

 is largely that of labor. If one estimates labor at current rates, mulching will 

 cost more than other common systems of soil management, especially in view 

 of the present low prices of nitrogen and potash, the two fertilizer elements 

 drawn upon most heavily by the apple crop. However, the labor involved in 

 mulching can be spread over a long period and may be done when the fruit 

 grower can find no very profitable employment. The cost of mulching will 

 vary greatly under different conditions. 



Another possible objection is the danger of injury from mice and fire. It would 

 seem advisable to place five or six inches of coarse gravel around each tree over 

 a space three or four feet in diameter and to conduct a vigorous campaign for 

 the eradication of mice in the orchard. In several years' experience at this 

 station no tree protected with gravel has been injured by mice, but this is not 

 saying that injury will never occur. The injury to trees from fire in the orchard 

 is seldom as severe as it appears immediately following the burning. The 

 mulch should certainly be kept well away from the tree trunks so that a fire 

 may not kill the bark. If the lower branches only are killed, the tree will soon 

 recover. However, one can hardly escape the fear that if fire ran through such 

 a heavy mulch as is here described the damage would be great. A desirable 



