ON MOISTURE CONTENT OF SOIL 63 



and the climatic conditions of the county, there is much to be said 

 for this practice. 



The botanical analyses from all the centres agree in showing that 

 as far as the quality of the herbage is concerned there is nothing to 

 choose between the effectiveness of rock phosphates and high citric 

 soluble basic slags. There are, however, indications that the open 

 hearth (fluorspar) slags of very low solubility are less efficient in this 

 respect than the high soluble basic slags. 



EFFECT OF PHOSPHATES ON THE MOISTURE CONTENT 

 AND TEMPERATURE OF THE SOIL 



It has already been stated that one of the great difficulties experi- 

 enced on the clay soils particularly the London clay soils of Essex 

 is the wet condition under which they lie throughout the winter and 

 late spring. As a rule a hot and dry spell of weather succeeds, lasting 

 during the greater part of May and June. The soil whether under 

 pasture or arable conditions dries up rapidly, sets as hard as a brick 

 (caps), and cracks badly. 



These unfavourable conditions were very obvious at the Horndon 

 Experimental centre during 1919. Following a wet April the remains 

 of a heavy fall of snow were still visible on the plots on May 3rd. 

 A spell of dry hot weather set in and lasted without any recordable 

 rain falling until the third week in June. The condition of the un- 

 treated plot was difficult to describe. There was practically no growth 

 and the surface was covered with innumerable cracks, some of them 

 wide enough to allow of the insertion of the greater part of the arm. 

 What little growth there was shrivelled up by the second week in 

 June. It was obvious, however, that the plots receiving phosphates 

 were not suffering nearly so badly. The cracks were fewer, and required 

 looking for, and the thick matted bottom of clover provided a con- 

 tinuous feed for the grazing stock throughout the season (Plate VI). 

 The marked difference between the condition of the soil on the slag 

 plot and untreated plot suggested a better regulation of the moisture 

 supply on the former plot. 



It was unfortunately not possible during 1919 to follow up the 

 enquiry which these observations suggested, but during the season 

 of 1920 a series of moisture determinations and temperature records 

 were made on Plot 17 (basic slag) and Plot 16 (untreated) at 

 Horndon. 



