184 Fertilisei'S [pt. hi 



In farm practice the good effect of farmyard manure 

 is intensified by another interesting property. It has a 

 remarkable effect on increasing the growth of clover. 

 This was well shown on the Little Hoosfield Plots in 

 1917 and 1918. Those which had received farmyard 

 manure in the preceding year, and even two or three 

 years before, gave a much better clover crop than those 

 which had only received artificials, and this was followed 

 by a better wheat crop. 



Dung for Artificials No manure 



previous for previous for previous 



crop crop crop 



Clover hay: cwts. per acre, 1917 65-6 41-9 41-1 



Wheat: bush, per acre, 1918 44-0 37-1 36-8 



When clover is good it makes the next crop good also 

 because it enriches the soil in organic matter and in 

 nitrogen taken from the atmosphere. Thus, farm^^ard 

 manure not only itself adds to the organic matter of the 

 soil, but also ensures a further supply through the 

 agency of the clover crop. 



Farmyard manure considerably influences the micro- 

 scopic population of the soil, causing the numbers of 

 bacteria and other organisms to increase and bringing 

 into prominence certain changes that are not con- 

 spicuous in ordinary soils. 



On the heavily dunged Broadbalk plot (14 tons 

 annually) about 30 to 50 per cent, of the nitrogen in 

 the dung is absorbed by the crop or washed out, and 

 about 20 per cent, accumulates in the soil, but the re- 

 mainder cannot be accounted for, and the simplest 

 explanation is that it is lost as gaseous nitrogen. 

 Equally serious losses seem to occur wherever dung is 

 used in heavy dressings, e.g.. in market gardening, in 

 certain glasshouse work, and in intensive mangold grow- 



