1919] SOILS — FERTILIZERS. 625 



have given better results than organic nitrogenous fertilizers, there being no 

 marked residual effect of the latter. Finely ground rock phosphate was found 

 not to be as economical a carrier of phosphoric acid as acid phosphate, in 

 spite of the high price of the latter. 



"In the study [at the Granville farm] of the value of diiferent sources of 

 nitrogen, phosphoric acid, and potash, and combinations of these for tobacco, 

 results thus far secured indicate that the organic sources of nitrogen are best. 

 Dried blood is probably best, with cottonseed meal next of the more common 

 nitrog^^nous carriers. When mixed with proper proportions of phosphoric acid 

 and potash, sulphate of potash produces a better quality of tobacco than does 

 muriate of potash. Tlie muriate, however, seems to make a larger leaf, or one 

 with a larger spread. Acid phosphate has given better results as a carrier of 

 phosphoric acid for tobacco than has either bone meal or basic slag. . . . 

 The field experiments in the study of the value of tobacco stems and stalks 

 for fertilizing tobacco have indicated that good tobacco can be grown by the 

 use of these, when they are not used at a rate lioavier than 2,500 lbs. per acre, 

 supplemented with a little phosphoric acid and potash, if native or bright 

 tobacco stems are used ; and by phosphoric acid and nitrogen when Burley 

 stem and stalks are applied. . . . 



In the study [at the Reidsville farm] of the residual effect of fertilizers on 

 small grains, generally wheat and then grass following after tobacco with no 

 additional fertilizer, the residual effect of phosphates was dominant and very 

 important. . . . Even when used with phosphate, the residual effect of ma- 

 terials carrying ammonia was not generally important for more than one year. 

 The use of potash alone or combined with ammonia only had almost no residual 

 effect." 



On the persistence of arsenite of soda in the soil, C. W. Mally {So. African 

 Jour. Set., 15 {1919), No. 5, pp. 325-329). — Analyses of samples of stable manure 

 treated with sugar and sodium arsenite as fly killer are reported, together 

 with the results of plat experiments with wheat, oats, rye, barley, maize, peas, 

 beans, potatoes, and cabbage, to determine the direct influence and residual 

 effect of sodium arsenite prepared as fly bait and added at rates of 6.25, 12.5, 

 25, 50, 100, 200, 300, 400, and 500 lbs. per acre, and mixed in the same amounts 

 with stable manure added at the rate of 10 tons per acre. The soil was a deep 

 stiff clay. 



The results showed that in the stronger plats (500, 400, and 300 lbs. per acre) 

 the transplants, as well as the seedlings of all kinds, presented a very sicklj', 

 spindly appearance from the start, being stunted in growth and of a reddish- 

 yellow color, especially at the tips and along the edges of the leaves. On the 

 whole, the sickly appearance was less pronounced from plat to plat as the 

 strength of the arsenite decreased, but there was not much choice between 

 the 500, 400, and 300 lb. plats. In the 200-lb. plat the injury was less severe, 

 and in the 100-lb. plat only noticeable. In the weaker strengths no injury 

 was manifest in comparison with the control and the isolation plats. 



The manured plats were better than the unraanured plats. The manured 

 part of the control plat was better than any of the others, including the isola- 

 tion plats, which received neither manure nor poison. The manure in the 

 poisoned plats clearly counteracted the effect of the poison to some extent. 



" The injurious effect of the arsenic was most noticeable during June and 

 July, while the different plants were young. Of the grain crops, severity of 

 injury was apparent in the order named : Oats, barley, wheat, and rye. Oats 

 were very sensitive, and would make a valuable ' indicator ' of arsenical poison 

 in the soil. Barley followed it very closely. Wheat v-as considerably less 



