May 3, 1920.] Agricultural Gazette of N.S.W. 319 



In spite of the favourable results on the coast, the writer maintains that 

 ■farmers growing maize on the alluvial soils here can render the purchase of 

 potash unnecessary for some time yet, if the supply of decaying organic 

 matter in the soil is kept up by green manuring — preferably with legumes, 

 for on soils where the yield is limited by a shortage of available nitrogen, 

 potash fertilisers may stimulate leaf development and growth sufficiently 

 to give a profitable increase. This is borne out by the fact that on soils 

 in which decaying organic matter was definitely known to be present in 

 sufficient quantities, potash manures have not given any increase in yield. 

 This is directly shown at Coramba, where fertiliser experiments have been 

 carried out for five years, and where no increase was recorded from potash 

 fertilisers during the first two years, but where increases have been obtained 

 from these fertilisers in later years — probably owing to the deficiency of 

 decaying organic matter in the soil which naturally ensues with continued 

 cultivation if no measures are taken to replace it. 



With the high prices ruling for potash at present, it is recommended that 

 no purchase be made of fertilisers for maize supplying this ingredient until 

 the need for it is shown by actual experiment; even then, the soil should 

 ■contain an abundance of decaying organic matter before any defini 

 conclusions can be drawn as to whether potash fertilisers are required. 



Lime. 



Lime is not strictly a fertiliser, though it may in some cases act as a 

 stimulant in producing larger crop yields. It should be regarded more as a 

 means of improving the texture of soils — particularly heavy clay soils. 



By promoting conditions favourable to nitrifying bacteria and thus 

 rendering nitrogen in organic matter more readily available, lime hastens 

 to some extent the decomposition of vegetable matter ploughed under and by 

 chemical action sets free some potash from insoluble compounds. It also 

 has some action in preventing the formation of insoluble (iron and alumina) 

 phosphates where it is present in sufficient quantity in the soil to which 

 superphosphate has been added. In very acid soils it promotes the growth 

 of legumes, and thereby is a means of increa>sing the yield of the following 

 maize crop on account of the greater amount of nitrogen and organic 

 matter added to the soil when these legumes precede maize. In Alabama* 

 an increase of nearly 3 bushels per acre of maize was obtained from an 

 application of lime to velvet beans (for ploughing under) due to their 

 increased growth. 



As a direct application alone to the soil for maize, lime has not met with 

 much success. The following results were obtained from the application of 

 lime for maize on red soils in Ehodesia,f found to be distinctly acid : — 



Yield per acre. 



Unburnt lime, 1 ton per acre 49 bushels 10 lb. 



Quicklime, ^ ton per acre ... ... ... 53 ,, 14 ,, 



U nt reated 56 „ 50 „ 



* A'abama Agr. Expt. i-^ta. Bull. lU. t Rliodesia Ayr. Jour., December, 1918. 



