The plan of 



Encyclopaedia of Gardening 229 



The plan of calculating the value of manure by the proportions 

 which it contains of the four ingredients quoted is a good one, 

 because they are the principal requirements of crops; at the same 

 time, it should be pointed out that the proportions vary with the 

 food of the animals. The excrement of cows fed on Turnips is not so 

 rich as that of animals which are allowed cake. We see that pig 

 manure is nominally the richest, but that much the largest propor- 

 tion of its fertilising constituents is lime, and that is not so im- 

 portant as any of the other three. On the whole, manure from 

 stables is the best; but cow manure is preferable on dry soil. A 

 double use should be got from every cartload of fresh manure in a 

 garden. The first use is to yield heat, and this the manure will do 

 if, when taken from the stables, it is turned in and out on 3 suc- 

 cessive days, and then trodden down into a hotbed (see Hotbeds, 

 Annuals, Mushrooms (Kitchen Garden), Violets, and other crops). 

 After it has served its purpose as a hotbed it will be thoroughly de- 

 cayed and in excellent condition for manuring. When manure 

 has to be laid up for a time the heap should be made at a spot 

 remote from dwellings, and on a bed which will retain the ammonia- 

 enriched liquid that drains out of the heap. A light coat of gypsum 

 will fix the ammonia. A good quantity of manure to use is 2 

 barrow -loads per square rod of ground, or 30 tons per acre. In heavy 

 soils it serves the best purpose when worked under the top spit in 

 bastard trenching towards the end of winter (see Kitchen Garden). 

 In light soils over sand or chalk it is best laid on the top after autumn 

 bastard trenching, and dug into the top spit in spring. Human 

 excrement is best laid up in a heap with ashes, and turned into 

 ground which is to be cropped with coarse Green vegetables. Fowl 

 manure is very strong, and is best mixed with a considerable bulk 

 of earth or ashes before use. Dried blood is a good fertiliser, especi- 

 ally for Green vegetables and Onions. When manure decays in the 

 soil humic acid accumulates, and it sometimes happens that after a 

 piece of ground has been manured for several consecutive years 

 crops do badly on it. To use the gardener's phrase, it has become 

 " manure -sick." To speak with greater exactitude, an excess of 

 humic acid has accumulated. The best plan in such a case is to- 

 dress the ground with broken chalk or lime. 



Sterilisation. It has been noticed that sterilising soil by burning 

 it increases its fertility. The reason is supposed to be that the 

 burning destroys large quantities of bacteria which prey on the 

 nitrifying bacteria, that is, on those which are working on the nitro- 

 genous elements in the soil, and converting them into nitrates. 



Nitro-bacterine. The existence of beneficent organisms in the soil 

 is unquestioned, and one microbe, Pseudomonas radicicola, has the 

 power of fixing free nitrogen from the atmosphere in the root- 

 nodules of leguminous crops, such as Peas, Beans, and Tares. The 

 plan has been tried of applying laboratory cultures of this microbe, 

 under the name of nitro-bacterine, to the soil, not altogether without 

 success in some cases, although without apparent result in others. 



Artificial manures. The fact that natural manures owe their 

 value to the proportions which they contain of certain ingredients 

 has led to the development of what are called artificial or chemical 



