No. 7. Department of agriculture. b31 



Here we have some very positive results from the application of 

 fertilizers. In growth, the trees of the treated plots show an in- 

 crease of 13 to 40 per cent, over the checks, and in yields, they show 

 benefits of 201 to 415 per cent. The quality of the fruit is also im- 

 proved in all plots except that receiving the stable manure, in which 

 it is poorest. Manure, although most efficient in securing growth 

 and yield, fails so completely on quality that it takes relatively low 

 rank in final value. The most valuable returns clearly have come 

 from plot five, where ground bone and low-grade sulphate were used. 

 This plot also shows a surprising gain over plot four, which differs 

 only in the use of the muriate instead of low-grade sulphate of pot- 

 ash. Whether this superiority is due to the magnesia in the sulphate 

 or to a harmful effect of the chlorine accumulating from the mu- 

 riate, or to a soil difference can not now be stated. It is being further 

 studied by the Massachusetts Station. 



Thus we have before us the results from three experiments in 

 orchard fertilization, running for 14, 12, and 20 years respectively. 

 One shows no results, another partial results, and the third shows 

 very beneficial results. Altogether, they show for a certainty that 

 plant food is a crop limiter, but not in all orchards. 



To obtain additional evidence, the series of experiments now in 

 operation in this State were started, as you konw, by the Pennsyl- 

 vania Experiment Station in April, 1907. The series is without the 

 merit of age as yet, but we trust that it has some of extent and plan. 

 An idea of the extent can be obtained from the fact that the records 

 of the past season required the handling of 82 tons of fruit from 

 2,268 trees. These trees covered nearly 50 acres, and involved ten 

 soil types and twelve varieties. Young orchards to the amount of 

 42 acres in addition were set during the season. 



Before examining the records in detail, we shall outline briefly 

 the work as a whole. The problem placed before us was to deter- 

 mine and study the causes that affect yield and quality in apples. 

 We based our work upon the general proposition that the growth 

 and development of any plant vary with the limiting factor. The 

 possible environmental limiting factors for all plants are moisture, 

 food, heat, light, carbon dioxid and oxygen. Some of these factors 

 are beyond the control of man and, hence, it was decided to study 

 first the influence of those that are more or less within his control. 

 We, therefore, are now studying (1) the influence of plant food as 

 affected by fertilizers; (2) the influence of moisture as affected by 

 soil management; (3) the influence of cover crops; and (4) the in- 

 fluence of heredity as shown by propagation from best individuals, 

 and by variety. 



