102 LIME REQUIREMENT OF THE SOIL 



Although on sour clay soils basic slag fails to maintain a permanent 

 plant of clover, yet the addition of heavy dressings of lime fails to 

 improve matters in this respect. At Cockle Park, a more vigorous 

 growth of clover follows each successive dressing of slag, whilst in 

 Essex on soils well supplied with calcium carbonate there is no 

 difficulty in maintaining a permanent bottom of clover by the applica- 

 tion of phosphates. (See results from Saffron Walden.) 



WHY THE CLOVER PLANT FAILS AT COCKLE PARK 



The most important conditions necessary for the proper growth 

 and development of the clover plant in conjunction with the various 

 grasses are: 



1. A suitable supply of phosphate. 



2. A suitable supply of potash. 



3. The presence of calcium carbonate in the soil. 



4. Constant grazing to prevent the grasses shutting out the 

 light and air, and thereby choking out the clover plant. 



At Cockle Park the plots have been grazed by sheep annually, so 

 that the conditions in this respect are the most favourable possible 

 for the permanent establishment of a bottom of clover. Potash in 

 addition to basic slag on Plot 7 has not materially increased the 

 returns, nor has it benefited the clover plant, and as has been indicated 

 previously, no better results have attended the addition on Plot 8 

 of ground lime to the standard dressing of basic slag. 



A comparatively heavy dressing of phosphates (equivalent to 

 100 Ibs. P 2 O 5 per acre) has been given to Plot 4 every three years 

 and it would seem scarcely probable that a lack of phosphate was 

 the cause of the wild white clover plant being unable permanently to 

 establish itself. Nevertheless, if the botanical composition of the 

 herbage is examined over a period of years, it will be noted that 

 following every dressing of basic slag there is a marked response by 

 the clover plant. The results on Plot 8 apparently preclude any 

 possibility of the lime in the basic slag being responsible for the 

 improvement. By a process of elimination one is forced to conclude 

 that the various dressings of basic slag have never sufficed to meet 

 the need for phosphates, and that at Cockle Park the level of produc- 

 tion could be still further raised by increasing the dressing of phos- 

 phoric acid or by repeating the present standard dressing at more 

 frequent intervals. 



With the object of obtaining more precise information on this 



