100 



LIME REQUIREMENT OF THE SOIL 



from the hay crops on all soils with a lime requirement between -13 

 and -45 %, but are present on meadows which contain a small reserve 

 of calcium carbonate, and whose lime requirement is negligible. The 

 absence of clover (which 'fills up the bottom') during a dry season 

 adversely affects the yield of hay, and any factors which tend to 

 produce conditions unfavourable to the clover plant obviously limit 

 the yield. 



The acidity of the soil as measured by its 'lime requirement' does 

 therefore to some extent limit the action of basic slag, and it becomes 

 of importance to ascertain to what extent the application of basic 

 slag affects favourably or unfavourably the acidity of the soil. 



TABLE LI. LIME REQUIREMENT AND PH. VALUE OF THE SOILS 



IN THE BASIC SLAG AND UNTREATED SOILS AT THE VARIOUS 



EXPERIMENTAL CENTRES 



Samples of soil to a depth of nine inches and three inches were 

 removed from the basic slag and untreated plots at several of the 

 experimental centres during October 1919. The lime requirements of 

 all the soils were ascertained and in some cases the Ph. value also. 

 The results are set out in Table LI. 



In every case the lime requirement figures are higher for the soil 

 on the basic slag plots than on the untreated, and although the 

 differences are not great, they suggest that the application of even 

 a heavy dressing of basic slag is not sufficient to counteract the 

 acidity which develops from the decaying organic matter which 

 accumulates on such plots. The Ph. values also show but small 

 differences, and with one exception, namely, the soils from Martin's 

 Hearne, they confirm the lime requirement figures and indicate a 

 tendency towards greater acidity on the basic slag plots. 



As it seemed probable that the continued use of basic slag over a 

 long period of years would accentuate this tendency, samples of 

 soil were secured from Plots 4, 6 and 8 at Tree Field, Cockle Park, 



