Nov. 8. 191S Relation of Sulphur Compounds to Plant Nutrition 237 



EXPERIMENTAL WORK 

 Beginning in 191 1, experiments have been conducted in the green- 

 house to determine the influence of sulphates and sulphur on the growth 

 of some common farm crops. Seven different crops representing three 

 different orders have been included in the work up to the present time. 

 They were distributed by orders as follows: Cruciferae — radish (Raphanus 

 sativus), rape {Brassica napns); Gramineae — oats {Avcna sativa); barley 

 (Hordeum vidgare); Leguminosae — red clover {Trifolium pratense), bean 

 (Phaseolus vulgaris), pea (Pisum sativum). It should be said of plants 

 grown in this way that they sometimes do not develop so well as under 

 field conditions. The lessened light of winter as compared vs^ith sum- 

 mer, for example, retards growth, and in the early fall and late spring 

 the day temperatures are likely to become excessive. Also, possibly 

 owing to the protection from wind and the absence of insects, the plants 

 rarely seed well. Despite these influences, however, our crops have 

 grown well in most cases and in some cases have developed luxuriantly. 

 It is true, moreover, that in all cases the effect of varying fertilizer 

 treatments is reliable for comparison, since each crop, save the food 

 supply, was grown under conditions as uniform as possible. 



METHOD OF INVESTIGATION 



The soil used in this work was the Miami silt loam which predomi- 

 nates on the University Hill Farm. It was obtained by removing the 

 surface vegetation and selecting the surface soil to a depth of about 4 

 inches. This material was then sifted through a ]4-mch screen and 

 thoroughly mixed. There was practically no loss in the sifting, as 

 hardly a stone was found and the sifted product was smooth and of 

 excellent quality. 



A total analysis of the soil showed the following composition, based 

 on the dry matter: Nitrogen (N), 0.15 per cent; phosphorus pentoxid 

 (P2O5). o-H per cent; sulphur trioxid (SO3), 0.04 per cent; calcium car- 

 bonate (CaCOg), 0.33 per cent; humus, 1.38 per cent. 



The humus was determined by the ofliicial methods of analysis of the 

 Association of Ofiicial Chemists.^ Fifteen kilos (33 pounds) of this soil 

 were placed in rectangular cypress boxes 16 inches long, 14 inches wide, 

 and 5 inches deep. Seven different fertilizer treatments were tried in 

 duplicate boxes of the soil, as follows: 



Boxes Nos. 



1-2. Control (no fertilizer). 



3-4. Complete fertilizer: Gm. 



Tricalcium phosphate (Ca3(P04)2) 12. o 



Potassium chloric! (KCl) 4. 5 



Sodium nitrate (NaNOj) 10. o 



'Wiley, H. W., et. al. Official and provisional methods of analysis, Association of Official Agricul- 

 tural Chemists. U. S. Dept. Agr. Bur. Chem. Bui. 107 (rev.), 272 p., 13 fig. 1908. 



