YIELD 421 



soils, which require the application of much manure and careful cultiva- 

 tion before they will give remunerative returns of this cereal. 



Cultivation and Manuring. The influence of cultivation of the soil 

 and the manuring cannot be discussed here : they are nevertheless im- 

 portant factors in determining yield. Early ploughing in order to sow 

 on a stale furrow is a maxim followed by all farmers who obtain the best 

 yields of wheat. 



With this cereal as with all other crops the application of suitable 

 manures improves the returns. 



For the highest yields the soil should be rich in phosphates and potash 

 and well supplied with available nitrogen. 



The two former elements are often obtained from the residues of 

 fertilisers used for the previous crops rather than from direct application 

 to the wheat plant, although the addition of superphosphates and kainit 

 may be profitably employed where the land is in poor condition. The 

 nitrogen is frequently obtained from the residue left by leguminous crops, 

 but the application of nitrate of soda or sulphate of ammonia to the plant 

 in spring is generally practised where heavy crops are obtained. 



Amount of Seed. The amount of seed sown has a large influence upon 

 the yield per acre, for upon it depends, in measure, the number of ears 

 which are produced, and it is these and the grains which they bear which 

 determine the yield. 



In countries where the rainfall is low, the growing season short, and 

 the yield necessarily limited, the amount sown is often less than i bushel. 

 In Australia 40-60 Ibs. per acre is general, and in many parts of the 

 United States 45-60 Ibs. are often sown. 



In Western Europe, with its higher rainfall, better cultivation, and 

 expected yield of 30 bushels or more per acre, very much larger quantities 

 are sown, the amount varying between 2 and 4 bushels (126-252 Ibs.) 

 per acre. 



About 2 bushels per acre were recommended by the ancient Roman 

 agriculturists, Varro and Columella, and this quantity has been in general 

 use in Great Britain, apparently from the time of the Roman occupation 

 to the present day. 



Since the seventeenth century it has been the practice to increase 

 the seed sown, 2 bushels being found insufficient in many instances to 

 provide the best number of plants or ears for a good crop of grain. 



On land in a high state of fertility in a warm district, 2 bushels is 

 sufficient to produce a thick enough " plant " for the production of a 

 maximum crop. Where the soil is infertile, dry or cold, and in districts 

 in which adverse climatic conditions prevail, the amount is increased with 

 advantage up to 3 or 4 bushels per acre. 



When fixing the amount of seed to sow, it is necessary also to take into 



