228 FUNDAMENTALS OF FRUIT PRODUCTION 



larger stores of elaborated foods and making possible the formation of 

 stronger, if not more, fruit buds. 



The Relation of Seasonal Conditions to Response from Fertilizers.— 

 Many features of environment may be limiting factors to growth. The 

 supply of nutrients in the soil constitutes only one series or group of 

 these factors. With a change in other factors it is to be expected that a 

 definite balance of nutrients in the soil will limit growth in different ways 

 and a corresponding variation is to be expected from the use of a par- 

 ticular fertilizer on a particular soil and for a particular crop, depending 

 on temperature, humidity, rainfall and other factors. Such differences 

 have been studied in certain grain and forage crops. Thus applications 

 of nitrogenous fertilizers to grass land give much more striking results 

 when the season is comparatively dry than when it is wet.^^^ Little 

 is known regarding the responses of fruit trees to the same fertilizer with 

 varying seasonal conditions. The great differences found in field crops, 

 however, suggest that some variations may be expected. 



Summary. — Potash, phosphoric acid and lime-carrying fertilizers 

 are seldom required by orchard trees, which rarely show a direct response 

 to their application. However, these fertilizers often increase greatly 

 the growth of intercrops or cover crops and when these are used for mulch- 

 ing or green manuring purposes tree growth and production are indirectly 

 increased. This indirect influence is particularly important in case the 

 intercrop is a legume. Nitrate of soda, sulphate of ammonia and dried 

 blood have proved the best of any of the nitrogenous fertilizers tried; 

 the first two are in most common use. Sodium nitrate tends to leave the 

 soil more basic in reaction and sulphate of ammonia has the opposite 

 effect. These different residual effects may be of considerable importance 

 under some conditions. Phosphorus is generally applied as acid phos- 

 phate ; potassium, either as muriate or sulphate. Data as to the best time 

 for fertilizer applications are meager. They indicate, however, that for 

 increasing the setting of fruit, quickly available nitrogenous fertilizers 

 should be used just as the trees are starting growth in the spring. The 

 nature and relative magnitude of the response from similar fertilizer 

 applications may be expected to vary considerably with different growing 

 season conditions. 



Suggested Collateral Readings 



Ewert, A. J. On Bitter-Pit and the Sensitivity of Apples to Poisons. Proc. Roy. 

 Soc. Victoria. 24(N.S.): 367-419. 1912. 



Kraus, E. J., and Kraybill, H. R. Vegetation and Reproduction with Special Refer- 

 ence to the Tomato. Ore. Agr. Exp. Sta. Bui. 149. 1918. 



Gourley, J. H. Studies in Fruit Bud Formation. N. H. Agr. Exp. Sta. Tech. Bui. 9. 

 1915. 



Wiggans, C. C. Factors Favoring and Opposing Fruitfulness in the Apple. Mo. 

 Agr. Exp. Sta. Res. Bui. 31. 1918. 



