24 BITTER PIT INVESTIGATION. 



VII. EXPERIMENTS CONDUCTED UNDER NATURAL CONDITIONS 

 WITH A VIEW TO CONTROLLING THE DISEASE. 



A. MANURIAL EXPERIMENTS. 



The experiments with manures have been conducted for five years, under varying conditions of 

 soil and climate, and the results are necessarily of a mixed character. But a few general conclusions 

 may be drawn with regard to the yield and the amount of Pit in relation to the kind of manure. 



The highest yield was obtained in each State from the use of a complete manure, such as super- 

 phosphate, sulphate of potash, and sulphate of ammonia. When potash was omitted from this 

 manure the yield was lowest, and when nitrogen only was omitted the yield was intermediate. 



As regards the Pit, the unmanured plots were least affected, so that manure by itself does not 

 tend to reduce the amount of Pit. 



There is one substance which merits further trial in this connection, and which has been found 

 in some instances both to increase the yield and reduce the Pit, viz., sulphate of iron. 



A number of fertilizers were tested, and their influence upon the crop would be affected by the 

 nature of the soil and the amount of rainfall. A chemical and mechanical analysis of the soil is there- 

 fore given for each experiment station, along with the monthly rainfall. While the results of the 

 experiments are given in detail, in each case the percentage of Pit in relation to yield and manure is 

 clearly shown in a separate table. 



In the strictly technical sense, the term manure is applied to natural products used for increasing 

 the fertility of the soil, such as farmyard manure, while the term fertilizer is applied to artificial 

 products used for the same purpose, such as superphosphate, But it is customary to make a distinction 

 between manures and fertilizers, and to regard a fertilizer as simply supplying plant food, and a 

 manure as, in addition, acting beneficially on those constituents already present in the soil. However, 

 we will use manure as a general term to include both natural and artificial products. 



1. AT H. H. HATFIELD'S ORCHARD, Box HILL, NEAR MELBOURNE. 



This is the fifth year of the manurial experiments. In the previous season (1914-15) there was 

 no crop, so that the manures then applied were not repeated for the past season. The manure was 

 thus applied four years in succession, and in the fifth year it might reasonably be expected to show its 

 full effect upon the crop. 



The trees were about 14 years old at the start, so that they are now 19 years of age, and were 

 treated alike in every respect, with the exception of the manure applied. The yield was far above any 

 previous record, and it will be interesting to compare the rainfall at the critical time when apples show 

 the greatest amount of growth, viz., November, December, and January, together with the yield, 

 from the beginning of the experiment. 



1910-11. 1911-12. 1912-13. 1913-14. 1914-15. 1915-16. 



Inches. Inches. Inches. Inches. Inches. Inches. 



November .. 3-26 -49 2-96 2-96 1-72 -49 



December .. 3'23 3-54 4-15 1-25 3- 18 -36 



January -64 1-57 -40 1-57 2-13 -24 (up to 27th) 



7-13 5-60 7-51 5-78 7-03 1-09 



Lbs. Lbs. Lbs. Lbs. 



Yield of 9 plots .. 6835 2359 5954 11,695 



Taking the rainfall for these three months in each season for five successive years, and comparing 

 it with the past season, it is found that six times as much rain fell, on an average, during the five 

 preceding seasons as during the past season. 



