HORTICULTURE. 237 



that region during the heat of the summer. lie advocates and discusses a 

 system of cultivation which provides for growing a shade crop in the orchard 

 during the hot weather, the hind to be plowed at least every second season. 

 In the case of young orchards when the ground is sufficiently fertile, the intro- 

 duction of some hoed crop is deemed advisable. Although the best shade crop 

 to be used has not yet been determined, red clover appears to be most in favor 

 among those who have used any crop at all. Other crops which have been used 

 to some e.xtent are winter vetch, peas, and alfalfa. 



Orchard fertilization, J. P. Stewart (Pennsylvania Sta. Bui. 91, pp. .3-18, 

 pffs. .'i). — This bulletin discusses the present status of our knowledge of orchard 

 fertilization and gives an outline with the results to date of a series of experi- 

 ments started at the Pennsylvania Station in 1907 with the view of determining 

 the causes affecting yield and quality in apples. In these experiments are 

 being studied the influence of plant food as affected by fertilizers, the influence 

 of moisture as affected by soil management, the influence of cover crops and 

 the influence of htn-edity as shown by propagation from best individuals and 

 by variety. 



The fertilizer work is being conducted in 3 orchards ranging from !) to 19 

 years of age. The fertilizers are applied annually at the rates per acre of 

 nitrogen 50 lbs., phosphoric acid 100 lbs., potash 150 lbs., lime 1,000 lbs., and 

 .stable manure 12 tons. The data secured in 1908 indicate that the nitrogenous 

 manures have materially increased the yield and decreased the color of the 

 fruit. Phosphoric acid showed decidedly beneficial results only when in com- 

 bination with other elements. Potash gave fairly favorable results in both 

 yield and color, and lime appeared to decrease both, although this comparative 

 harmful effect of" lime is not considered permanent. 



The effect of nitrogen ai)plied in the form of nitrate of soda as a top-dressing 

 on July 8, 1907, was plainly evident before the close of August, and during the 

 remainder of the season. In the following spring the trees on the nitrogen 

 plats leafed out much greener than those in the other plats, and continued to 

 show the same marked difTerence previous to the second application of nitrate 

 of soda late in May. These results suggest the possible desirability of delaying 

 soluble applications of nitrogen such as nitrate of soda until the season's 

 growth is well advanced hut not completed, at which time the plant's supply 

 of stored food is about exhausted. 



In the soil management experiments clean tillage, tillage and cover crop, sod 

 mulch and sod are being compared in some young orchards from 6 to 15 years 

 of age, and in a mature orchard about 35 years old. As indicated by the yields 

 for 2 seasons, sod mulch in the young orchards shows 30 per cent better yields 

 than clean tillage and I85 per cent better than the cover crop, while in the 

 mature orchard the cover crop was 40 per cent better than sod mulch. 



Where plant-food is needed the author advocates the general I'ecommendation 

 of about 10 tons of stable manure per acre or leguminous cover crops, alternated 

 with a fertilizer carrying about 30 lbs. of nitrogen, GO lbs. of phosphoric acid, 

 and 100 lbs. of potash per acre. The accompanying soil management suggested 

 for most situations is tillage with a leguminous cover crop while the orchard is 

 young, followed by a mixed grass and leguminous sod or sod mulch when bear- 

 ing age and size is reached, with a return to tillage every second or third year 

 after the i)earing habit is established, increasing the frequency of tillage with 

 the age of the orchard and the demands of the fruit. 



In some related observations it was found that api)Io roots extend much 

 farther laterally than is generally supposed, reaching in some cases more than 

 3 times as far as the spread of the branches. This fact suggests a wider area 

 of distribution for fertilizers and mulches, 



