68 INFLUENCE OF VARIETY OF SEED. 



from one which is poor in organic matter ; or that a soil which 

 abounds in lime will decompose compound bodies more ener- 

 getically than one in which lime is deficient ; or that an open 

 soil will admit of, and promote, chemical alterations which a 

 stiff clay will almost or altogether prevent. In these differ- 

 ences, therefore, we have an important source of discordant 

 field results. 



I 'give a special case. Common salt applied alone on certain 

 sandy or loamy soils, in which lime is not deficient, has the 

 recognised effect of brightening and strengthening the straw. 

 To effect this, we at present suppose that it must previously 

 have undergone a decomposition in the soil forming, probably, 

 first carbonate, and afterwards soluble silicate of soda. To 

 effect this decomposition, however, both the lightness of the soil 

 and the presence of lime maybe necessary; and hence on other 

 soils the same beneficial effect may by no means follow from the 

 use of common salt applied alone : mixed with lime its success 

 would be more probable. Used in this state of mixture upon 

 an open soil, the chances of success would be further increased. 



6. Influence of different varieties of seed in causing discord- 

 ances in the observed effects of different manures. 



In the raising of turnips, as of almost every other cultivated 

 crop, it is known that the kind of seed employed, independent 

 of all other circumstances, has much influence upon the amount 

 of produce obtained. This is true, especially of what may be 

 regarded as different sw&-varieties of the plant, of which we are 

 now familiar with so many. 



In illustration of this, I quote an experiment made by Mr 

 M'William on the farm of Sheriffston, in Morayshire. He 

 manured three acres uniformly with 13^ loads of farmyard- 

 dung per acre, and 72 Ib. of bones dissolved in 46 Ib. of sul- 

 phuric acid and 400 gallons of water, and sowed on them two 

 sub- varieties of common yellow turnip Dale's hybrid, of which 

 the seed had been raised on his own farm, and Gibb's red-topped 

 yellow (London seed.) The weights of the crops were, respec- 

 tively, per imperial acre 



