486 



Use of Bracken as Litter. 



[OCT., 



soil and allowing air to enter and water vapour to escape 

 it tends to bring about a loss of water. Humus, on the 

 other hand, has a binding tendency, and causes a light soil to 

 hold better together, it increases the water holding power 

 of the soil and keeps the soil moist. The properties of fibrous 

 material may often make it very useful on a heavy soil where 

 its power of lightening the soil and promoting aeration is an 

 advantage, and its drying out tendency is no disadvantage 

 because of the ample supply of water ; but on a light dry soil 

 fibrous material may be harmful because it leads to loss of 

 water, of which there is already a deficit. Dung in which the 

 litter decomposes slowly will therefore be less useful on a light 

 soil, but may be more useful on a heavy soil than dung in which 

 the litter rots down quickly. 



The respective behaviour of straw and fern dung was 

 investigated by marking out two small plots and digging dung 

 into them in November at the rate of 20 tons to the acre ; 

 one p]ot received the straw dung, the other the fern dung 

 analysed above. At the end of March the ground was carefully 

 forked over. The straw dung was found to have decomposed 

 fairly completely into black humus, the fern dung had not, 

 the leaves had decomposed, but the stems remained and indeed 

 they seemed almost unaltered. It appears, then, that fern 

 dung decomposes less rapidly in the soil and leaves behind it a 

 larger residue of unchanged fibrous material than straw dung, 



These observations enable us to explain a local preference 

 that seems at first sight entirely a matter of prejudice. 

 Gardeners on the light sands at Haslemere, where both straw 

 and fern-made dung are available, prefer the straw dung and 

 are willing to pay . a higher price for it, alleging, among other 

 reasons, that it is better and lasts longer in the soil. A little 

 further off;, however, on the heavy clay soils the fern dung 

 is considered better. As is often the case with local preferences 

 this is not entirely prejudice, but is capable of rational explana- 

 tion. The fibrous residue remaining for some time after the 

 application of the fern dung tends to open up the soil, to let 

 in air and to let out water vapour on the light sand, already 

 sufficiently aerated but insufficiently supplied with water 

 this is a disadvantage and goes to counteract the good effect 

 of the rest of the manure, making it on the whole probably 



