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Experiments with Phosphates and Slags. [Oct., 



FIELD EXPERIMENTS WITH ROCK 

 PHOSPHATES AND BASIC SLAGS, 



II.— EFFECT ON THE QUATJTY OF HAY AND PASTURE. 



G. S. EOBERTSON, D.Sc, F.I.C. 



For the first fart of this article see the Journal for 

 September, v. 519. 



The most imporfcant indirect effect of the application of basic 

 slag to pasture is the great improvement v^^hich is brought about 

 in the quality of the hay crop and the feeding value of the 

 pasture. In other words one ton of hay from a slagged plot has 

 a higher feeding value than one ton of hay from an untreated 

 plot, and the feeding value of the herbage on a slagged pasture 

 plot has a considerably higher value than the same weight from 

 a corresponding untreated plot. The Cockle Park experiments 

 have put the increased feeding value in the case of hay from 

 the basic slag plot at 13s. per ton — a figure based on actual 

 feeding trials and on pre-war values. 



It is of considerable importance, therefore, when considering 

 the value of the various substitutes for the rapidly disappearing 

 high grade slag to v/hich the Cockle Park results apply, to take 

 into consideration their effect upon the quality of the hay crop 

 and the pasture herbage. In other words, is the increased crop 

 produced from rock phosphates and the new types of slag accom- 

 panied by a corresponding improvement in the quality and 

 feeding value? 



With this object in view samples of hay were taken for two 

 seasons at each of the Essex Experimental Stations and a 

 botanical analysis of the crop made. The results from two of 

 the experimental centres which are typical of the results obtained 

 at the other centres are dealt with below. 



Martins Hearne. — During the two seasons (1917 and 1918) 

 following the application of the various phosphates the growth 

 of red and white clover rapidly spread over the treated plots until 

 in 1918 it was to the eye the dominant constituent of the herbage. 

 As far as the eye could judge the advantage in this respect was 

 with the high soluble slag in 1917 and with the rock phosphates, 

 and particularly Gafsa rock phosphate, during the 1918 season 

 (see Fig. 3). During the dry season of 1919 the clover on the 

 phosphate plots as well as on the untreated failed to make an 

 appearance. The phosphate plots were nevertheless always dis- 



