92 THE farmers' handbook. 



Lime-content of the Ash of some Native Timbers and Plants. 



The following are a few examples of the lime-content of the ash of some 

 individual timbers, and of wood ashes from mixed sources examined in the 

 laboratory 



... 73-8 Vine cuttings 20-0 



The composition of these mixed ashes will be seen to vary very considerably. 

 This will always be the case, both on account of the nature of the timber 

 from which they are derived and also the length of time to which they have 

 been subjected to the weather and the amount of leaching they have under- 

 gone. 



Other Lime Compounds. 

 (6) — Carbonate of Lime. 

 Carbonate of Lime is used in several forms — such as chalk ground lime 

 stone or shells, and " mild " or " agricultural " lime, which latter is old burnt 

 lime which has been exposed to the air and become converted into carbonate 

 by absorption of carbonic acid. The term "agricultural lime" is also applied 

 to the screenings from builder's lime, or to lime rejected by the mortar 

 makers. Its addition to the soil promotes nitrification, sweetens sour soils, 

 and prevents clay soils from puddling, though it is less powerful in the latter 

 respect than burnt-lime. It is milder in its action and, as a rule, burnt-lime 

 is to be preferred for lightening stiff soils, though for sweetening sour soils 

 or for supplying lime to soils deficient in that ingredient, it is equally effective. 

 It should be applied in quantities of not less than 1 ton per acre. 



(c) — Gypsum. 



Gypsum or plaster (sulphate of lime) may also be sometimes used to advan- 

 tage. Its action is principally that of a direct plant-food on soils poor in 

 lime ; hence it is most useful for such crops as clover, and other leguminous 

 fu-ops on soils poor in lime. It is best applied moist, or in wet weather, at 

 the rate of 2 to 3 cwt. per acre. Gypsum is also often used as a " fixer " — 

 that is to say, when added to dung or urine or decaying animal and vegetable 

 matter, it decomposes the carbonate of ammonia which is being continually 

 evolved from such substances, and converts it into sulphate of ammonia, in 

 which form ammonia does not escape into the air. If a heap of dung 

 from which the odour of ammonia is perceptible, be covered with a few 

 shovelfuls of moist gypsum, the smell will be found to have disappeared — 

 in other words, the ammonia is " 6xed," and its loss prevented. . 



Gypsum is also of great value in lands which are charged with alkali, or 

 irrigated by alkaline water. For this purpose it is either sown on the land 

 in proportions depending on the amount of alkali in the soil, or it may be 

 introduced in boxes in the irrigation sluices, or added to the tanks if the 

 water is stored. 



For a fuller description of the uses of lime, see Farmers' Bulletin, No. 115, 

 " Lime on the Farm." 



