THE PRODUCTION OF WHEAT 27 
its range of successful cultivation extending from regions 
bordering on the tropics—such as California and India, 
almost to the Arctic circle, as in Siberia and Northern 
Canada. Most countries in which its growth is practised 
have cold winters and moderate summers. The most 
noteworthy fact about this aspect of the subject is that 
the range of successful culture is gradually extending 
into colder regions, which shows that wheat possesses a 
certain power of adaptation to its environment. 
A cool, prolonged, but not too wet spring, followed by 
moderately dry, sunny weather, during ripening, is most 
favourable to the largest yield of best quality. The 
most favourable ripening requires a mild temperature 
with a slightly clouded sky. All these attributes New 
Zealand possesses in a remarkable degree, and the 
relation of yield to them will be considered later. 
The rainfall is an important matter—wheat being very 
sensitive to extremes of drought or moisture. The most 
suitable rainfall ranges between 20 and 30 inches, but 
good quality wheat can be grown with from 15 to 20 
inches in quantities up to 20 bushels per acre. These 
conditions prevail in Australia, but New Zealand here 
again possesses the necessary attributes almost perfectly. 
(c) Cultural Methods—Too much stress cannot be 
laid upon the importance of a careful cultivation. Not 
only does tillage render the seed-bed specially adapted 
to growth, but by cultivating in the right way at the 
right time moisture is conserved in the soil and the 
growth of weeds discouraged. A fine but firm seed-bed 
is necessary for efficient production. For the methods 
of cultivation ploughing, discing, harrowing, etc., a great 
deal depends upon the character of the crop which the 
land has just produced. For instance, after grass or 
clover the land should be skim ploughed in early March, 
and left for six or eight weeks. Then cultivation should 
proceed with a firm discing and then deep ploughing, 
etc. No attempt is going to be made here to treat this 
part of the subject in elaborate detail; but from the few 
facts noted it is hoped that sufficient weight has been 
given to the necessity for careful and continuous 
cultivation. 
