BIENNIAL, RETCtRT, 1927 AND 1928 333 



Tlie purpose of the latter treatment was to bring in a white clover sod. 

 No white clover appeared previous to 1927, but during the past two years 

 areas of white clover have been developing. Determination of soil nitrates 

 indicated considerably more under the clover than elsewhere. It is now 

 planned to continue this project to see if the clover will increase and if it 

 is eflFective in promoting growth and fruitfulness of the trees. 



Test of Different Amounts of Nitrate of Soda. (J. K. Shaw). This 

 project involves a number of Baldwin trees now thirty years old, growing 

 in sod. Since 1922 they have received 5, 10 or 15 pounds of nitrate of 

 soda each year in addition to adequate amoimts of phosphorus and potash. 

 The general results seem to be that production increases with the amount 

 of nitrate applied. No injurious effects on the trees or on the color of the 

 fruit have been observed. In the spring of 1928 the amount of nitrate was 

 increased to 10, ITVs and 25 pounds of nitrate of soda per tree. 



Comparison of Cultivation and Heavy Mulching for Apples and Pears. 

 (.i. K. Shaw). This experiment has been continued as started in 1922. 

 Tlie marked difference in foliage color of the trees on the two treatments 

 was less distinct in 1928 than in previous years. Most of the mulched 

 trees continued to yield heavier crops and no injurious effects have been 

 observed. This is remarkable. The amount of nitrates in the soil under 

 the mulch is far in excess of that usually found in cultivated orchards 

 receiving annual ajiplications of nitrate of soda; shoot growth continued 

 no later in the summer; and the apples are similar in every respect on the 

 two plots. The trees on the imfertilized cultivated plots continue to grow 

 rather slowly ;ind ;ire evidently slowly exhatisting the fertility of the soil. 



The Effects of Fertilizer Limitation on Fruit Plants. (J. K. Shaw). 

 This project deals with apple and peach trees and grape vines planted in 

 1922 on an old fertilizer test field which, for nearly forty years, had 

 received fixed fertilizer applications involving nitrogen, phosphoric acid, 

 ;md potash alone and in combination. The remarkable result of this 

 experiment is that the only fertilizer effect seen is on the plots which 

 have received potash and which have been limed. The unlimed i^ortions 

 of the potash jilots show no better growth than the plots which have 

 never received any fertilizer. The same is true of all fertilized plots riot 

 receiving potash. In order to further investigate this condition, a new pro- 

 ject lias been formulated and pursued during the past season. 



Role of Poteish and Lime in Fruit Tree Nutrition. (J. K. Shaw). In 

 order to throw light on the puzzling questions that arose in the preceding 

 project, experiments were carried out in Wagner pots. Soil from two of 

 the plots was placed in pots in the summer of 1927 and" seedling peach 

 trees planted as indicators. The behavior of the trees in the pots was 

 similar to the behavior of the trees in the field j)lots. Also the Wagner 

 pot jiroved to be satisfactory as a container. 



During the summer of 1928, 115 pots were filled with soil from a 

 miniber of these field plots, and seedling peach trees planted. Some of 

 the soils were placed in the pots without treatment, and others received 

 var'ous fertilizers and in some cases certain amounts of lime. Each treat- 

 ment was replicated five times. The general (piestion was whether the 

 results shown in the field plots were really due to the soil treatment; and 

 the answer was, in general, affirmative. Additions of lime to the soils 

 which iiad received potash resulted in increased growth and increased 

 amounts of nitrates in the soil. Determinations of soil nitrates and of 

 the i)H value of tlte soil in the pots were made during the season. It is 



