THE FARMER'S MAGAZINE. 



349 



gressively beneficial. Arrived, however, at a certain 

 condition of organic repletion on the one hand^ and of 

 inorganic depletion on the other, its capacity to support 

 in health and vigour the same vegetation which formerly 

 it did, at last failed ; and hence a scant and morbid yield 

 was the consequence. 



Such, briefly expressed, is the aspect in which rotation 

 husbandry has presented itself of late years to reflective 

 minds, not only in Norfolk, which we have selected 

 merely as affording the best illustration of these com- 

 ments, but throughout all the other best-farmed dis- 

 tricts of England. Such, also, are the circumstances 

 under which has sprung up the enormously extended 

 practice of extraneous manuring, general or special : 

 general, as where all the alienated substances contained 

 in the marketed produce are sought to be replaced in 

 the soil ; special, as where restitution is made of only 

 some of the withdrawn elements, or where manurial 

 stimulants, themselves perhaps innutritions, are ad- 

 ministered. 



It is this important subject of special manuring which 

 has so largely occupied the experimental enterprize of 

 Messrs. Lawes and Gilbert, at Rothamsted. In our 

 prior notices, we explained the nature and result of 

 their trials in the cultivation of wheat and barley with 

 various substances external to the farm, and both gene- 

 ral and special in their character. Experiments in grass 

 and clover, conducted in the same way, will be related 

 and examined in a subsequent paper. The present 

 article is devoted to a series of observations suggested 

 by trials made by the same indefatigable experimentalists 

 in the special manuring of turnips. The ground in 

 which these were conducted is called Barn Field, part 

 of the Rothamsted farm, and its quality is described in 

 the experimental report, as "a somewhat heavy loam, 

 not well adapted for turnips." Respecting cultural 

 treatment, connected either with the working of the land 

 or its condition of cleanness, or the reverse, during the 

 trials, the report is altogether silent, except that, inci- 

 dentally, it appears that the seed and manure were de- 

 posited in drills, and that more or less injury to the 

 germinating plants was caused by commingling the seed 

 and manure together. The experimental plots were 

 between twenty and thirty in number. The endurance of 

 the trials was ten successive years, from 1843 to 1852 

 inclusive j but the experimentalists' conclusions, which 

 we are about to examine, were formed and promulgated 

 at the termination of the third year, and we are not 

 aware that anything has ever been reported of the 

 remaining seven. Prior to the institution of the 

 trials, the field had grown wheat, clover, and wheat 

 in succession, and during their continuance the 

 turnip produce was wholly carted off the land. Each 

 year the number of plants reaching maturity were 

 counted, and the average weight of each bulb produced 

 on each different plot determined. Finally, a most 

 elaborate series of analytical experiments was resorted 

 to, to ascertain what chemical differences existed amongst 

 the products of the different plots, and whether the 



diversity was correlative with the several manures put 

 in trial. 



The leading conclusion arrived at, on the termination 

 of this triennial investigation, and announced to the 

 world through the pages of the Royal Agricultural 

 Journal, vol. viii. (1847), was that the factitious com- 

 pound, superphosphate of lime, was to be regarded as 

 specifically appropriate to the healthful and abundant 

 produce of the turnip plant. 



But here it may be surmised by the reader, that surely 

 these experimentalists possessed data for this declara- 

 tion of opinion, of a much more comprehensive kind 

 than could possibly be aff"orded by a body of trials which, 

 however elaborately, and carefully conducted, gave only 

 the result of a highly exceptional case of successive 

 annual cultivation, and were performed, not in several 

 localities, on various kinds of soils and for a consider- 

 able number of years, but merely for three years, in one 

 single small field, and on land admittedly ill fitted for 

 the growth of turnips. In point of fact, however, be- 

 yond these narrow and anomalous limits, the experimen- 

 talists sought no data from external sources, but on their 

 own circumscribed area of observation deemed them- 

 selves warranted in asserting, virtually, that although 

 the turnip plant requires for the formation of its tissues 

 a large supply of organic nutriment of which super- 

 phosphate of lime contains none, and a no less essential 

 though smaller proportion of inorganic elements, eight 

 in number, of which superphosphate contains only four, 

 nevertheless, in all soils and climates, at least in 

 those of England, its use as a manure is peculiarly bene- 

 ficial to that tribe of the botanical order of cruciferous 

 plants to which the turnip belongs. It may be added, 

 that for reasons not explained, that most perfect of all 

 commercial manures, Peruvian guano, had no place 

 amongst the manurials put in trial. Those which besides 

 superphosphate of lime underwent investigation, are set 

 forth in the following table. 



Table I., showing the various manurial substances 

 employed in the Rothamsted experiments in turnip 

 growing. 



1 . Mineral manures containing no pliosphoric acid ; viz., 

 the carbonate? of potash and soda, coiumou salt, mag- 

 ncsian limestone, and sulphate of lime. 



2. Mineral manures containing phosphoric acid ; namely, 

 tlie phosphate of potash and soda, and phosphate of lime in 

 its mineral condition, or as bones, and used both in its 

 natural state, or decomposed by acids into superphosphate. 



3. Organic substances ; so called, because containing ni- 

 trogen, as nitrate of soda, and sulphate and phosphate of 

 ammonia. 



4. Carbonaceous substances, and to wliicli only ought 

 the term organic to be apphed, viz., yeast, train oil, rape- 

 cake, and farm-yurd manure. 



Finally, these various substances were exhibited in 

 intermixed prescriptions ; but in three instances, farm- 

 yard dung, rape- cake, and superphosphate of lime, 

 were experimented with separately, and their results in 

 each of the three reported years separately registered. 

 The following table furnishes a brief conspectus of the 

 entire series of trials : 



A A 2 



