624 Jonnuil of AgriculUirc. Vicloria. [lo Oct.. 1912. 



Other Results of Lime. 

 \\W\\i' tht^ effect of lime ui lil)er;iting plant food from the soil is chiefly 

 seen in an increased production of nitrates, it has also some effect in. 

 rendering a\ailable the mineral co nstituents. This action is most important 

 in connexion with potash and phosphoric acid, for both of which farm: 

 crops make considerable demands. 



The Libe ation of Potash. 



The effect of lime in liberating potash from insoluble compounds will" 

 be chieflv felt in the heavier class of soils. Like lime, potash is a base, 

 and in the less stable hydrated double sil'cates of potash and alumina' 

 (zeolites) present in clav soils, lime and potash tend to change places. 

 The liberation of potash by lime is less important for cereals than for roots 

 and legumes, the latter of which require large amounts of potash. The- 

 largely increased vield of lucerne and clover which commonly follows an- 

 applicat'on of lime mav often be traced to the liberation of potash within- 

 the soil. 



The Liberation of Phosphoric Acid. 



The addition of lime also increases the availability of the soil phos- 

 phoric acid, particularly where this exists in union with iron and alumina.. 



FIG. 3. — SH(.)\\ING HOW LIME HELI'.S IXSCJUELE PHOSPHATES TO ACT. 



Fig. 3 represents the stage, at the time of writing (15th September), of 

 some experiments conducted by the Department during the present .season. 

 The primary object of these experiments is to test the relative efficiency 

 of phosphates from different sources, but in certain cases lime has been in- 

 troduced in order to obtain greater variety in the conditions. Pot 5 receives 

 a native lime phosphate, Pot 6 the mineral Wavellite — an aluminium 

 phosphate, and Pot 7 the mineral Vivianite — a phosphate of iron. The- 

 phosphates were ground up, but not dissolved. No lime was given in- 

 these pots. Pots 25, 26, and 27 received the same phosphates respec- 

 tively as Pots 5. 6, and 7, but get carbonate of lime in addition. A 

 uniform and sufficient quantity of easily available nitrogen and potasb 

 was appled to all the pots, and the phosphoric acid in each case A-as 

 used in equivalent amounts. Federation wheat is the crop grown. 



From the results at the present stage it appears that lime has in- 

 crea.sed the action of all the insoluble phosphates, but the improvement 

 is more marked with the phosphates of alumina and iron than with the- 

 lime phosphate. Much of the phosphoric acid occurring in Victorian 

 soils is combined with iron and alumina, and as there is a general ('■ 

 ficiency of available phosphoric acid partly on this account, the liberatior* 

 of phosphoric acid by lime may have considerable practical moment. 



