TULL, JETHRO. 



above 20 times more space to collect the same 

 quantity of food. But, in this fine soil, the 

 most weak and tender roots have a free passage 

 to the utmost of their extent, and have also an 

 easy, due, and equal pressure everywhere, as 

 in water." 



He did not confine his attention to the ad- 

 vantages of thoroughly pulverizing the land : 

 he was also an advocate for much deeper 

 ploughing than was usual in his time, and in 

 one or two places laments the supineness of 

 the farmers in this respect, and the idleness 

 of the ploughmen, in only half-penetrating the 

 soil, for fear of injuring the appearance of their 

 horses ; and he illustrated the advantages of 

 his proposed mode of ploughing by the best 

 means in his power, not only by general ob- 

 servation, but by also appealing to several 

 very ingeniously-contrived little experiments 

 upon the habits of plants. 



Tull saw very clearly that this theory of the 

 advantages of pulverizing and deepening soils 

 would be strongly supported if it could be 

 shown that the roots of the commonly culti- 

 vated grasses would, under favourable circum- 

 stances, penetrate to more considerable depths 

 than the ordinary shallow soils of the farmer 

 allowed them. He paid, therefore, considerable 

 attention to the roots of plants, not only in his 

 small experimental glasses and pots, but in his 

 fields. He found, by some observations on the 

 roots of some wheat plants growing in a deeply 

 loosened soil, that their roots had penetrated to 

 more than double the depth of the commonly 

 ploughed land of the farmer; and all this I can 

 support from my own observations on the roots 

 of the crops growing on the edge of chalk and 

 loam pits, and in other situations where the 

 soil has been loosened to great depths. Tull, 

 too, noticed the very considerable and rapid 

 extension of the roots of trees growing near 

 to old dunghills, sewers, &c., and he hence ad- 

 duced another argument in favour of the advan- 

 tages which are derived from assisting, in the 

 best ordinary way then known, the roots of 

 plants to penetrate deeper into the soil. Had 

 Tull lived in our days, he would have been an 

 ardent advocate for the subsoil and subturf 

 ploughs : he would not then have confined his 

 efforts to the increased use of the common 

 plough and the trenching-spade. 



A century has now elapsed since Jethro Tull 

 thus earnestly endeavoured to draw the atten- 

 tion of the farmers of England to the import- 

 ance of deepening, pulverizing, and mixing 

 their soils. Tull, unfortunately for himself, 

 lived an age or two too soon : had to encounter 

 the ignorance and the obstinacy of his work- 

 men, the apathy of his neighbours, the ridicule 

 of those who understood him not, and the anger 

 of the indolent. The principles, however, which 

 he inculcated have survived and overcome all 

 these obstacles; are yearly more prized, be- 

 cause better understood. Tull thought that the 

 earth, and the earth alone, did every thing for 

 vegetation; astonished at the effects which 

 were produced by merely deepening and pul- 

 verizing, he allowed his enthusiasm to carry 

 him too far. "Every plant," he tells us, "is 

 earth, and the growth and true increase of a 

 plant is the addition of more earth ;" and in 

 1058 



TULL, JETHRO. 



another place he. adds, "too much nitre cor- 

 rodes a plant, too much water drowns it, too 

 much air dries the roots of it, too much heat 

 burns it ; but too much earth a plant never can 

 have." Thus impressed with the value and 

 the all-sufficient powers of earth to support 

 vegetation, it need hardly surprise us that Tull 

 soon came to the conclusion that, under a pro- 

 per management of the plough and the scarifier 

 (for a rude instrument of this kind was known 

 in Tull's days), the land might be so pulverized 

 and deepened as to bear its crops without the 

 addition of any decomposing manures. 



Tull deceived himself, in this instance, by 

 not attending to the quantity of finely-divided, 

 slowly decomposing substances, which all cul- 

 tivated soils contain in some shape or other. 

 By ploughing and pulverizing, the progress of 

 the putrefaction of these organic matters was 

 accelerated, they were rendered more soluble, 

 and then the succeeding crop was, by their de- 

 composition, sufficiently nourished. But these 

 operations could not be long continued ; at 

 each repetition of the experiment the amount 

 of the stubborn, slowly decomposing matters 

 of the soil became reduced, and, in conse- 

 quence, the crops produced under the system 

 became less. Tull's farm at Shalborn was 

 well adapted to try the effect of this theory; it 

 is situated on the crown of a rising ground, 

 whose thin-skinned soil is a light loam mixed 

 with gravel, resting on chalk ; of such a soil 

 the organic matters, of necessity, are speedily 

 exhausted by cropping and pulverizing. Tull 

 soon found this out; he struggled hard against 

 the necessity, but he finally had recourse to 

 the employment of manures ; he found at last, 

 that, however valuable good tillage is to the 

 application of fertilizers, it is utterly incapable 

 of supplying their place. The failure of Jethro 

 Tull, therefore, in this great effort was com- 

 plete ; but it was the failure of a man of genius. 

 He tardily admitted the value of dunging the 

 land; but he still explained its operation in 

 such a way as to refer all the benefit to the 

 earth, when he told the farmers of those days, 

 "its use is not to nourish, but to dissolve, that 

 is, divide the terrestrial matter which affords 

 nutriment to the mouths of vegetable roots."" 

 To a very considerable extent Tull was cor- 

 rect in this explanation of the mode in which 

 common manure operates in rendering the soil 

 more fertile ; for it renders the land more per- 

 vious to the atmospheric gases and vapour, 

 and, in consequence, all vegetation growing 

 upon the land is better nourished. But the 

 benefit, as Tull imagined, does not end here ; 

 the organic matters of the compost, as they 

 slowly dissolve in the soil, gradually give out 

 a considerable proportion of various gases, 

 such as carburetted hydrogen and carbonic 

 acid gas, all of which are absorbed by the plant 

 at the moment of their extrication, enter into 

 new combinations, and promote its vigorous 

 growth. That this is not a merely mechanical 

 advantage is proved in several ways ; for in- 

 stance, the benefit of the application of the de- 

 composing compost is proved to be just as 

 advantageous in some instances to the crop 

 where it is not even mixed with the soil. This 

 is shown by the effect (known to every gar- 



