Improving the Condition of the Soil 



and in England in Derbyshire, only containing 

 calcium and sulphur, which are not necessary to the 

 soil in the form of sulphate of calcium [CaSOJ, 

 because they are given in sufficient quantities in 

 lime or phosphates, and especially in the sulphates 

 of the potash salts. Different explanations of its 

 action on plant life have been given. The right one 

 has not yet been found, though its discovery seems 

 to be imminent. Formerly the results were attri- 

 buted to the reactions of anhydrite on the salts of 

 the soil ; then to the promotion of nitrification after 

 the double decomposition which created favourable 

 conditions for this process. In some alkaline soils 

 (NagCOs) in America, where formerly young plants 

 were completely destroyed, the neutralisation of 

 the alkali by means of gypsum has rendered the land 

 cultivatable, although only 2| to 3 cwt. per acre 

 were employed. 



Recent experience tends to show that gypsum 

 acts beneficially in driving the alkali from the soil 

 into the subsoil, and these alkalis, combining with 

 the humic acids of the subsoil, render the humates 

 assimilable. 



Deep-rooted plants profit best by gypsum. Its 

 use is recommended for leguminosae in general, 

 and above all for clovers, lucerne, and sainfoin, 

 on which in some cases it doubles the crops. The 

 instance of Franklin, writing in big characters in a 

 field of lucerne, " This has been gypsum," is now a 

 classic. It is frequently used on carrots: 



The increase of weight obtained by the use of 

 gypsum is very noticeable, but it is partially due, 

 probably, to the absorption of additional water caused 



142 



