Oct. 2, 1920.] Agricultural Gazette of N.S.W. 713 



temperature after the engine has stopped work for the night, and also the 

 insulation of the water piping. Having regard to the cost of the plant, and 

 the unusual type of engine from which the heat is derived, this is probably 

 one of the best illustrations of what can be done ia the way of utilising 

 exhaust heat, and many other factories could also safely use this form of 

 power. 



A Note on Kotted Manure. 



Questions are frequently asked regarding the use of " well-rotted manure," 

 its application to the soil and the addition to it of lime. The following reply 

 to a recent correspondent M'ill perhaps answer the query of a good many 

 others : — 



" Eotted manure " — a term one frequently comes across in gardening 

 handbooks — is a description especially applicable to farmyard manure 

 produced in Europe and America, where stock are stalled and bedded ; the 

 rotting pi'oduces changes, due to fermentation in the straw and similar 

 materials, and converts it partially into humus. The term has scarcely the 

 same application in this country, as rotting in this way does not take place 

 to any extent, farmyard manure here being chiefly dung. If the manure ik 

 kept under cover, little change will occur, except that it will lose moisture ; 

 if it is exposed to the weather, rain will wash out some of the soluble 

 constituents, and its fertilising value will be diminished. 



Even under European conditions of rotting, the rotted manure varies very 

 little in composition from the fresh, but is, on the whole, somewhat richer, 

 owing to the fermentation of the insoluble organic matter, the disappearance 

 of which increases the proportionate amounts of soluble organic matter and 

 fertilising material, especially organic nitrogen compounds and phosphate of 

 lime. Old manure, provided it has not been leached by the weather and thus 

 deteriorated, has the advantage that it is not so likely to burn the plants, as 

 fresh manure becomes hot owing to fermentation. The preliminary heating 

 that the manure undergoes is also likely to destroy the germinating power cf 

 any weeds it may contain. 



Lime should not be added with manures containing nitrogen, such as the 

 above, because ammonia is driven off, not only from ammonium salts, but 

 from blood, bones and any organic manure such as dung or stable manure. 

 In such cases the escape of ammonia is apparent to the senses. If the 

 mixture were buried in damp soil, no doubt this loss would be minimised, but 

 as lime is usually applied on the surface of the soil and very lightly 

 harrowed in, and the stable manure is also superficially applied, every facility 

 is afforded for the ammonia to be driven off and lost to plant life. 



It is generally a good practice to apply the lime two or three weeks before 

 applying nitrogenous manures or sowing seed. If manure and lime are to be 

 applied together, the best plan is to make a compost heap, in which the 

 organic matter, bones, skins, ic, are fermented in the presence of lime, 

 vegetable matter and earth, and the escaping ammonia is retained by the 

 outer layer of moist earth — or better, thel ayer of powdered gypsum — with 

 which the heap is .covered. — F. B. Gutheie. 



