726 EXPERIMENT STATION RECORD. [Vol.36 



" When . . . superphosphate is employed the author recommends that dung 

 should always be used according to the following rules: (1) The dung should 

 be well decomposed . . ., and (2) it should be well mixed with the super- 

 phosphate shortly before application, according to the phosphate content of the 

 soil and the requirements of the crop, at from 1 to 2 cwt. of superphosphate 

 per ton of well-decomposed dung." 



Electro-potash as a fertilizer, S. Rhodin {K. Landtbr. Akad. Handl. och 

 Tidskr., 54 {1915), No. 8, pp. 710-729; Meddel, Centralanst. ForsokHV. Jordbruk- 

 somrddet, No. 119 {1915), pp. 22; abs. in Chcm. Abs., 10 {1916), No. 7, p. 948).— 

 This is a progress report of field experiments with electrically-treated feldspar. 

 The products of the Lindblad and Yngstrom method are so far the most prom- 

 ising. The fertilizing value of these substances was found to be very largely 

 dependent upon the nature of the humus in the soil, type of plant, and vegetation 

 period. 



Influence of calcium and magnesium compounds on plant growth, F. A. 

 Wyatt {U. S. Dept. Agr. Jour. Agr. Research, 6 {1916), No. 16, pp. 589-620, 

 pis. 6). — Experiments conducted at the Illinois Experiment Station on the effects 

 of calcium and magnesium on wheat, alfalfa, soy beans, cowpeas, oats, timothy, 

 and sweet clover when applied in different natural and in artificially prepared 

 forms, and to determine the amount of calcium and magnesium which the 

 plants could tolerate, together with the relation between the ratios of these two 

 elements in the plants, in the soils, and in the materials applied, are reported. 



" Dolomite, limestone, magnesite, calcareous soils, and brown silt loam were 

 used as souces of the natural forms, while prepared materials, such as the car- 

 bonates, chlorids, and sulphates served as sources of the artificial forms. . . , 

 The earlier applications varied from 0.1 to 0.6 per cent of magnesium added in 

 magnesium carbonate and in magnesite. Later the following amounts were 

 employed : 2, 6, and 10 per cent of magnesium in magnesite ; 10 and 12.7 per 

 cent of magnesium in dolomite; 0.1, 0.01, and 0.001 per cent of magnesium in 

 the carbonates, chlorids, and sulphates. In each series sand or soil was used as 

 a control." 



The following conclusions are drawn : 



" Wheat, soy beans, alfalfa, and cowpeas grew normally either in 96 per cent 

 of dolomite and 4 per cent sand, 100 per cent of magnesian limestone, or in 

 sand containing 8 per cent of magnesite. Dolomite up to 40 per cent proved 

 beneficial to plant growth. These results indicate that dolomite and magnesian 

 limestone will not be detrimental as applied in agi'icultural practices. Appli- 

 cations of prepared magnesium carbonate up to 0.7 per cent caused no injury 

 in brown silt loam, but 0.35 per cent prevented the growth of all plants tested 

 in sand. 



"The crop yields and the ratio of calcium to magnesium in the plants bear 

 no direct relation to the ratio in the natural carbonates applied. Different 

 ratios of calcium to magnesium within rather wide limits produced no marked 

 differences in yields. Increasing the size of applications increased the calcium 

 and magnesium content of plants. 



"A tolerance of calcium and magnesium occurred in all varieties of plants 

 grown. With approximately identical yields, wheat straw grown in sand, 

 brown silt loam, dolomite, and soil containing 35 per cent of magnesite showed 

 calcium contents varying between 0.165 and 0.547 per cent and magnesium con- 

 tents varying between 0.132 and 0.955 per cent. 



"Acid extractions failed to remove all the calcium and magnesium from the 

 sand. There remained after the various extractions from 7GS to 852 mg. of 

 calcium and from 540 to 960 mg. of magnesium per 6,000 gm. of sand. The 



