■2i-2 



THE AGRICULTURAL NEWS. 



August 5, 19n. 



of grain; while in the case of cotton seed and the 

 soy bean, the total suljihnr trioxide recovered by the 

 method emplo3ed is about ten limes as great as that 

 in the ash. The disparity is usually largest in plants 

 like the cabbage and the ouion, which contain a fair 

 proportion of volatile sulphur oils. 



The matter of practical importance brought forward 

 by these considerations is that cultivated cnjps probably 

 remove much more sulphur from the soil than has been 

 supposed. Thus, basing the computation on an ash 

 analysis, a crop of corn of 100 bushels per acre would 

 appear to remove about J-lb. of sulphur trio.xide; while 

 the total actual amount consumed by the same crop, 

 employing the method of determination u.sed by the 

 investigators, would be more than 20 lb. These facts 

 are sufficient to show that careful attention is required 

 to the subject of the supply of sulphur from the soil to 

 growing plants. 



It is commonly realized that a certain amount of 

 sulphur must be available for the u.-e of plant.s, particu- 

 larly in view of the fact that all the proteids which are 

 found in plants ci>ntain sulphur. The r-ason why so 

 little attention has been given to this element in devis- 

 ing schemes of manuring would aj)pear to be that the 

 amount of sulphur required by crops is usually consid- 

 ered to be small, so that little is removed from the soil 

 and the ordinary supply is sufficient for the growth from 

 season to season. There are added to this circumstance 

 the difficulties that arise in estimating the total sul- 

 phur in soils; the most reliable methods that have given 

 the best figures are tedious, but are much more accurate 

 than that of ash analysis or extraction with acids because 

 they give results which take account of all the sulphur 

 in the soil, in whatever form it may e.xist. It may be 

 stated shortly that the effect of the more accurate 

 determinations has been to show that the amount of 

 sulphur in all ordinary soils is comparatively low. 



There is not much significance to be attached to 

 this proportionately low sulphur content of soils, if it con- 

 tinues to be maintained that the requirements of plants 

 in this direction are also relatively small. 'J'he matter 

 appears in another aspect, however, when it is con- 

 sidered, as a result of the work to which attention is 

 being given, thatthe amount of sulphur removed by crops 

 from the .soil is, in proportion to the supply, quite as 

 large as that of phosj)hates; while in the case of crops 

 like the cabbage, onions and turnips, it is actually 

 larger. 



The work undertaken included the determination 

 of the change in the sulphur content of soils that is 



caused when plants are being grown continually on 

 them, and for the purpose a number of anal3ses oi 

 cropped, virgin and manured soils were made, the soils 

 of the different kinds being as nearlj' .alike as possible 

 in relation to such matters as drainage and ti))jography. 

 The unmanured soils employed in the invostigation 

 had received little or no manure for periods varying 

 between fifty and sixty-three years. The manured 

 soils had been chiefiy given applications of stable 

 manure. 



It was shown, first of all, that about 40 per cent, 

 of the sulphur trioxide had been lost by thn growing of 

 crops on the unmanured soils; in every case they gave 

 a smaller percentage of sulphur trioxide than was 

 found in the virgin soil. The matter of practical 

 importance which may be deduced is tiiat, the con- 

 tinuous raising of crops on land, without adequate 

 manuring, causes a large decrease in its sulphur content. 

 With the manured soils, it was demonstrated that their 

 sulphur content was maintained, and even inoreased to 

 some extent, by liberal applications of stable manure. 



The amount of suljjhur in the soil and the (|uan- 

 tity supplied in manure cannoo be considered alone, in 

 in such investigations. Rain-water is responsible for 

 the addition of a certain amount of sulphur to the soil, 

 more particularly in parts of the world whore soft coal 

 is burned. It is pointed out in the Bulletin which 

 describes the work under review that it has been 

 found at Rothamsted that the annual rainfall adds 

 about IcSJlb. of sulphur trioxide per acre. This quantity 

 naturally varies, from season to season, and with the con- 

 ditions of the cotmtry which may be under considera- 

 tion. (Correlated with this gain of su^jhur there is 

 its loss in drainage water. At Rothamsted, Voelcker 

 and Frankland have found that the quantity of sulphur 

 trioxide lost aniuially from the unmanured and manured 

 plots are respectively 247 and 410 to 10(J I pt-r million. 

 In discussing such losses, Hall assumes that the 

 mean annual drainage is equal to 10 inches of rainfall 

 and, employing the above figures, each acre of the 

 unmanured land would lose annually about .")0 lb. of 

 sulphur trioxide, while the similar loss in the case of 

 nianured land would be from 8.5 to 220 lb. Thus the 

 loss of sulphur trioxide by drainage is large, and. in the 

 case of unmanured lands, it is nearly three times as 

 great as the amount contributed in the rainfall. These 

 figures are not, of course, universal in their application; 

 they will be modified considerably, particularly by 

 matters connected with climate. 



These considerations would appear to indicate that 



