872 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Potato Crop, Influence of Tree Shade on. By E. Oven {Nat. 

 Zeit. Land-Forst. n. pp. 469-484 ; 1904). — Potatos, Turnips, and Cereals 

 grown under the shade of trees give reduced crops. The author has 

 experimented with Potatos, and gives numerous examples which prove that 

 shade is injurious to the crop-yield. The chief factors which bring this 

 about are temperature, moisture-content of the soil, and light. Tem- 

 perature is shown to be lower in shade than in the open ; statistics given 

 show that the average temperature under a large Cherry tree during ten 

 days was about 3° C. lower. This in itself is not considered enough to 

 account for the reduction of the crop in shade. In regard to soil moisture, 

 it is shown that Potatos grow best in a soil containing 80 per cent, of the 

 water capacity cf the soil, while Barley is best with 50 per cent. The 

 author's experiments indicate that the soil moisture under shade of trees 

 is slightly less than in the open, chiefly because the tree-roots use it ; this 

 was also found to be the case where many weeds were allowed to grow. 

 The author considers the loss of light under trees to be the most 

 important factor. His results and others cited indicate that shaded 

 Potatos give a smaller weight of tubers, which contain less starch and 

 other dry material, but more water. For example, plants grown in the 

 open gave four times the weight of tubers given by those under trees : this 

 was tested under trees, and confirmed by artificial shading. Testing the 

 loss of light under trees, he found that if the intensity of the light in the 

 open be put as- 1, then under Apple and Pear it is 0-233, and under 

 Cherry 0-345. These results apply with greater force in Northern 

 countries than in Southern Europe, where sunlight is much stronger and 

 more constant. — W. G. S. 



Potato Culture. By F. W. Bane and H. F. Hall (U.S.A. Exp. 

 Stn. New Hampshire, Bull. Ill ; 4/1904; 8 figs.).— The results of a 

 series of ten experiments on Potato culture with various manures and 

 varieties are given here. It was found that it was much more economical 

 to mix manures at home than to buy them ready mixed. A comparison 

 was made between the manures used in New Hampshire and those in New 

 York, slightly in favour of the latter as regards yield, the New Hamp- 

 shire mixture being 150 lb. nitrate of soda, 112^ lb. sulphate of 

 ammonia (=3 per cent, nitrogen), 565| lb. bone black (=6 per cent, 

 phosphoric acid), and 300 lb. muriate of potash (=10 per cent, potash) 

 per acre, while the New York mixture cost $5.33 more per acre, and 

 yielded 8^ bushels per acre more ; it was 150 lb. nitrate of soda, 180 lb. 

 sulphate of ammonia (=3*9 per cent, nitrogen), 750 lb. bone black 

 (=8 per cent, phosphoric acid), and 300 lb. muriate of potash (=10 per 

 cent, potash). The addition of potash gave increased yields according to 

 the amount of potash used, while the addition of farmyard manure in- 

 variably gave a greater yield whatever other applications were made in 

 addition. The method of sowing the manure, either all in the "hills " or 

 broadcast, seems to have very little influence on the yield. Much better 

 results were obtained when the farmyard manure was ploughed in than 

 when it was harrowed in, the yield being about 15 bushels per acre of 

 marketable Potatos better in the former case ; while when the artificial 

 manures were sown above the seed instead of below, as is usually done, 



