1020] SOILS — FERTILIZERS. 517 



the eft'wt will be favorable or unfavorable will depend ui)on Uie nature of 

 the soil and of the substances added. .Moreover, it is probable that this jjhase 

 of the subject has not received sullicieiit atlentidii in connectidn witli our 

 Held exiHM-inieiils. 



"Two soils of sunu'what different texture and orj^anic content were treated 

 witli a saturated solution of culeiuni .sulpluite, a n/10 solution of calcium 

 phosphate, and a combination of t!Te two. The soils were waslied and the 

 rate of fonnatiou of soluble salts was determined. The calcium sulphate 

 markedly increased the solubility in each soil, while the calcium pliosphate 

 decreased the rate of formation of soluble substances. When calcium plios- 

 jihate was used in conjunction with calcium sulphaffe it counteracted the 

 effects of the latter to some extent. 



■• If the carbon dioxid produced, as deternnned by the methods used, is taken 

 as a measurement of the biological activities, the increase in the rate of forma- 

 tion of .soluble substances brought about by the calcium-sulpliate treatment 

 is due mainly to other causes." 



Sulphur in relation to soil fertility, R. Stkwart (Illinois Sta. Bui. 221 

 \1920), pp. 99-108). — The available data on the value of sulphur as a fertilizer 

 are summarized, leading to the conclusion that there is no basis for the 

 belief that it is necessary to add sulphur to soil in a permanent system of soil 

 fertility. 



Experiments extending over a period of years are reviewed, showing that 

 uniler Illinois conditions sulphur is not a factor on brown silt loam soil in 

 the production of such couunon farm crops as corn, oats, wheat, clover, and 

 alfalfa. It is further shown that the sulphur supply of the soil is automatically 

 reitleiushed from the atmosphere, and it is concluded that the relation of 

 sulphur to soil fertility is not in any sense similar to that of phosphorus, Imt 

 is more sinnlar to that of carbon on the basis that both suli)hur and carbon are 

 supplied to crops from the atmosphere. 



Kflect of nianur(*-sul|>hur composts upon the availability of the potas- 

 sium of ji'rt't''»'^an<l, A. ii. .Mc(l\Lr, and A. IVI. Smith {./our. Ayr. Research 

 [r. S.], 19 (1920). .\(). 6, pp. 2.39-256, fig. i).— Studies conducted at the Mary- 

 land Experiment Station on the effect of composting gret^nsand with sulphur, 

 manure, and other materials, with a view to making the potas.sium in the 

 greensand available through sulfotication, are reported. 



Two greensands, one containing 5.88 per cent and the other 1.42 per cent 

 of potassium, were used. It was found that in composts consisting of green- 

 sand, manure, and soil in different proportions an appreciable amount of the 

 potassium of the greensand was made water soluble through sulfotication. 

 The composts containing the largest proportion of manure developed the highest 

 degree of acidity, oxidized the greatest amount of suli)hur, and produced the 

 largest quantity of water-soluble potassium, while those in which soil was sub- 

 stituted for a part of the manure developed less acidity, oxidized less sulphur, 

 and produced a smaller amount of soluble potassium. When all the manure 

 was reitlaced by soil the rate of sulfotication was so slow that at the end of 

 ' 23 weeks only a vory small amount of acidity had developed and very little 

 potassium had been made soluble. When no organic matter was added, the 

 amounts of acidit>' and soluble sulphates were no greater than might be ac- 

 counted for by the natural oxidation of the suli)hur. 



The addition of small amovmts of ferrous and aluminum sulphates failed to 

 stinmlate sulfoflcation. Calcium carbonate added to the suliJhur-manure-soil 

 compost produced a stimulating effect during the early part of the period, but 

 failed to increase the acidity, soluble sulphates, or potassium above the uiaxi- 

 mutuj-eached by the corresponding compost in which no calcium carbonate was 



