CHAPTER IX. 



ARABLE WEEDS. ASSOCIATION WITH SOILS. 



II. SPECIAL. 



IN order to get some definite idea of the association of 

 weeds with crops and soils from the statistical point of view 

 weed surveys have been carried on for several years in differ- 

 ent parts of the country. In the course of the investigations 

 many hundreds of fields have been visited, the crops and the 

 nature of the soil observed, and detailed notes made of every 

 weed occurring on each field with its relative abundance or 

 scarcity. The results thus obtained l have been carefully 

 analysed and compared, and have provided the figures on which 

 are based the observations made in the present chapter. The 

 weed survey is preliminary and incomplete as it only deals 

 with a limited number of districts, and the conclusions put 

 forward may be subject to modification when more data become 

 available from other parts of the country. The variety of soils, 

 however, is considerable, the areas worked were far apart 

 (ranging from Somerset to Norfolk), and the correspondence 

 in the results from the different districts is sufficiently close to 

 justify the belief that later modifications will be matters of 

 detail rather than of principle. 



In considering the association of particular weeds with 

 special types of soil the remarks made in the previous chapter 

 should always be borne in mind. A plant may be more or 

 less characteristic of a certain soil when it occurs in any 

 quantity, and yet it may be present on every other type of 



1 Brenchley, W. E. (1911), "The Weeds of Arable Land in Relation to the 

 Soils on which they Grow," I (Bedfordshire), Ann. Bot., XXV, pp. 



I55-I65- 



(1912) Ibid., II (Wiltshire and Somerset), Ann. Bot., XXVI, pp. 95-109. 



(1913) Ibid.. Ill (Norfolk), Ann. Bot., XXVII, pp. 141-166. 



(1915) " Weeds on Arable Land and their Suppression " (Nottinghamshire 



and Derbyshire), Jour. Roy. Agric. Soc., Vol. 76, pp. 14-37. 

 (1916-17) " West Country Grass-lands," Jour. Bath and West and Southern 

 Counties Society, XI, pp. 85-112. 



