Wild and Anderson. — Absorption of Lime by Soils. 



469 



In the next table we give the lime requirements of some typical Canter- 

 bury Plains soils. These, it will be remembered, give an acid reaction to 

 litmus, but do not markedly respond to lime. 



Table IV. — Lime Requirements of Acid but Unresponsive Canterbury Plains 



Soils. 



Average lime requirement, 0-104 per cent. 



These figures merely confirm what has already been observed — namely, 

 that while the Hutchinson-MacLennan method enables us to distinguish 

 between soils demanding lime and soils not requiring it so urgently, yet we 

 cannot agree to the statement that a complete failure of crop is the accom- 

 paniment of an absorption of 0-18 per cent. For there are Southland soils 

 naturally requiring lime that, after a dressing of lime that experience shows 

 to be sufficient for the practical purpose of soil-amelioration, may still show 

 as high an absorption as 0-24 per cent. ; while those of the Canterbury 

 Plains and of the Southland river-flats, though having an absorption of 

 0-104 and 0-139 per cent, respectively, have nevertheless not shown any 

 marked demand for lime, and certainly are being farmed very profitably 

 without it. Hutchinson and MacLennan would apparently, in the light of 

 their experience, lime a soil till its absorption is reduced to nil. In connec- 

 tion with field experiments at Woburn Station they say, " Without neces- 

 sarily indicating that the controlling factor in crop-production of these 

 (barley) plots is one of physiological resistance to soil acidity, there is still 

 a very close agreement between yields and soil reaction. In all cases where 

 the soil is neutral in reaction high returns are obtained ; where the require- 

 ment is more than 0-18 per cent, the crop shows almost if not complete 

 failure. . . . Somewhat similar data were obtained with the soils from 

 the permanent wheat plots, although in this case the crop was more resist- 

 ant to acid conditions, and persisted until the soil showed an absorption 

 of over 0-22 per cent." 



Unfortunately, we have not in this country a series of experimental 

 results bearing on this matter, but practical farm methods in the districts 

 we have visited appear to indicate that the limits suggested in the above 

 statement are too narrow for adoption here. Thus, to take the case of the 

 Wallacetown soil, one giving a markedly acid reaction ard with an indi- 

 cated lime requirement of 0-265 per cent., it is found that a dressing of 

 even 1 ton — ■ and certainly of not more than 1| tons ■ — of burnt lime is 

 ample for the practical purpose of putting the soil into condition to yield 

 an abundant harvest, while, owing to the high price of lime, a phenomenal 



