92 EFFECT OF RAINFALL 



yield of hay on the untreated plot at this centre. Owing to a wet 

 July in 1918 and 1920 the crops had to remain uncut during a spell 

 of wet weather, which had little or no influence on the growth of 

 the crop. In order to overcome this difficulty the rainfall figures 

 from 1st May to June 30th have been taken for each year. One point 

 in the curve falls far out of line, namely that representing the rainfall 

 and the hay yield for 1919. The reason for this divergence, however, 

 is clear. Aiter an exceptionally dry May and June, the first week 

 of July was wet, -47 inch of rain falling on the 2nd of the month 

 and -29 inch on the 3rd. The crop was not cut till three weeks 

 later, and during that time considerable growth was made, particu- 

 larly by the clover plants. If the rain falling on the first four days 

 of July is taken into consideration the divergence of this particular 

 point is rectified. 



In Fig. 24 the effect of rainfall on the yield of hay from the un- 

 treated plot at Tree Field, Cockle Park, is shown, and the curve 

 affords an interesting contrast to those representing the Essex centres. 

 At Cockle Park rainfall does not influence the yield of hay on the 

 untreated plot, whilst in Essex rainfall at certain centres is the most 

 important limiting factor, and at all centres it has a great influence 

 on the yield of hay. 



THE EFFECT OF RAINFALL ON THE YIELD OF HAY 

 FROM THE PLOTS RECEIVING PHOSPHATES 



The field experiments recorded show that at all these centres the 

 application of phosphates results in a considerable increase in crop. 

 The increase is least at Saffron Walden and greatest at Horndon. 

 The results at Tysea Hill indicate, however, that even poor as this 

 soil is in phosphoric acid, the heavy dressing of 200 Ibs. of phosphoric 

 acid per acre is more than the soil requires over a period of five years, 

 as equally good results accrue from the lighter dressing of 100 Ibs. 

 In Figs. 25 and 26 the increase resulting from the application of phos- 

 phates at each centre is correlated with the rainfall. It will be seen 

 that at Latchingdon and Saffron Walden the increase in the hay 

 crop on the phosphate plots steadily progresses with the rainfall, 

 clearly demonstrating that rainfall is the controlling factor, and that 

 with the limited rainfall at these centres little or no increase may be 

 expected from other than phosphatic manures. At Tysea Hill and 

 Martin's Hearne on the other hand the increase in the yield of hay 



