ANNUAL REPORT, 1938 87 



Comparison of Cultivation and Heavy Mulching for Apples. (J. K. Shaw.) 

 The Mcintosh blocks, comprising 18 trees, in this experiment were so badly in- 

 jured by wind that it seems wise to remove them. The block of Wealthy will be 

 continued for a while. The amount of nitrogen supplied to the cultivated plots 

 was reduced this year and a moderate amount of potash added, because our 

 'experience has shown that continued moderate to heavy applications of nitrate 

 of soda bring about an unbalanced condition which may be corrected by supply- 

 ing potash. 



The results from this experiment were reported in Bulletin 328 in 1936. Since 

 then the mulched Mcintosh trees have shown somewhat greater trunk growth 

 and the Wealthy exactly the same as the trees in cultivation. Shoot growth on 

 Mcintosh 1933-1937 inclusive, a five->ear period, was 42.3 inches for the cul- 

 tivated trees and 45.6 inches for the mulched trees. Yields of the mulched trees 

 have continued larger, especially in the lighter bearing year, than those of the 

 cultivated trees. A heavier crop is picked even with a larger percentage of pre- 

 harvest drop from the mulched trees. The practice of heavy mulching is increas- 

 ing among fruit growers. It is a sound practice where it can be carried on at a 

 reasonable cost. 



The extraordinarih' high nitrate content of the soil under the mulch has been 

 previousl}- reported. High potash has been reported from Ohio, and an examina- 

 tion into conditions in this orchard was therefore made. The test for available 

 potash in the soil by the Morgan and the Thornton tests indicated very high 

 potash under the mulch (over 500 pounds per acre by the Morgan test and over 

 400 by the Thornton test), and this was true not only of the surface soil but also 

 through the 32-36 inch level. In the cultivated plots available potash was very 

 low or none. The dates of sampling were in May and July. These plots have been 

 heavily mulched with waste hay for fifteen years. In an orchard with plots mulched 

 for five years and others with moderate applications of hen manure, available 

 potash in the plow slice by the Morgan test was 300 pounds per acre on each 

 plot and very low in the subsoil. In a near-by commercial orchard mulched for 

 about five years, it was very low. This suggests that it may take several years 

 for a high amount of potash to accumulate under a mulch. It seems as though 

 soil conditions under the mulch were such as to maintain the soil potash in a more 

 available form than in a cultivated soil. 



The Effects of Fertilizer Limitation on Fruit Plants. (J. K. Shaw.) No changes 

 were made in this project, but it will soon be necessary to remove the trees as 

 they are crowding. The scattered crop of this year had little relation to fertilizer 

 treatment. There is much variability in the growth of the trees on many of the 

 plots indicating that some condition other than fertilization is greatly influencing 

 tree behavior. 



Effect of Potash and Lime on Apple trees. (J. K. Shaw.) The trees in this 

 orchard, especially those without nitrogen, have lacked vigor for several years. 

 Tearing up the heavy sod with a harrow proved not very effective and so the 

 orchard was plowed diagonally in the spring of 1938. Cultivation was continued 

 a few weeks and then the plowed area allowed to return to grass. The trees were 

 somewhat invigorated. This practice will be continued. The fertilizer program 

 started in 1927 was continued. 



The trees on the nitrogen plots continue to ^ield better than either those 

 receiving potash or those receiving potash and phosphorus, as would be expected. 

 Those receiving potash in addition to nitrogen yield still better, but there is yet 

 no indication that the complete fertilizer plots yield any better than the nitrogen- 

 potash plots. The study of the effect of lime has been discontinued for some time. 



