WHEAT-GROWING AND ITS PROBLEMS 



?95 



in determining their fertility. The following table may be given 

 in illustration of this point, showing the yields obtained on a 

 very good wheat soil in Sussex compared with two other soils 

 less suited for wheat---one a light soil in Surrey, the other a 

 loam at Rothamsted. The Sussex soil is not manured anything 

 like as heavily as the Rothamsted soil and does not contain so 

 much plant food, yet it invariably gives higher crops. The 

 yields in bushels are : 



Good Years : 

 1885 . 

 1887 . 

 1899 . 



Bad Years: 



1879 . 

 1892 . 



Average of 5 years- 

 1900- 1 904 . 

 1 905- 1 909 , 



Good 

 wheat soil. 



A Sussex 

 soil. 



54 



50 



52S 



32 

 27 



41? 



Soils less suited to wheat. 



Rothamsted. 



Unmanured. 



i5t 

 I4f 



12^ 



4| 

 9l 



I2| 



Dung. 



401 



34| 



42* 



16 



III 



Ilk 



Complete 

 artificial 

 manures. 

 Very heavy 

 dressing. 



36I 



34* 

 39I 



20^ 

 384 



38* 

 405 



Complete 

 artificial 



manures. 

 Lighter 



dressing. 



22 

 23i 



10^ 



22 



24t 



A Surrey 

 soil. 



35 



It is characteristic of good wheat soils that they favour the 

 production of stiff straw well set with corn. No amount of 

 manure added to the Rothamsted or Surrey soil will give 

 crops as large as those raised on the Sussex soil ; the additional 

 manure produces only a weak-strawed crop which cannot stand, 

 and is therefore difficult to harvest. In countries of intensive 

 culture, like England, the wheat-grower aims at producing, not 

 the maximum crop that could possibly be produced, but the 

 maximum crop that will stand up ; the strength of the straw, 

 therefore, commonly sets a limit to the size of the crop. It 

 was at one time supposed that the strength of the straw was 

 due to silica, but Lawes and Gilbert long ago disproved this 

 view. Much further investigation is needed, since some of the 

 most pressing of modern field problems centre round this 

 point. 



The exhaustion of virgin soils by continual wheat cropping 

 has always attracted a great amount of interest, and has been 



