GASES. 



GASES. 



Part* of nitrogen. 



Chaff of wheat nearly ripe - 1 



Common grasa, not growidf freely - 4'4 



growing freely - - 5'6 



Turnip, when attacked by the fly 

 Cabbage, not attacked by insects 



partly eaten by insects - *5'7 

 The insects themselves - - 14 



Red clover stems - * 



Leaf of do. 43 



r of do. 3 



Potato itself * 



- leaves 



- 



4-6 



corolla ..... 

 - PtiU 



It is also well worthy of the farmer's atten- 

 tion, that Mr. Rigg found that when barley was 

 made to vegetate in the shade, the increase in 

 the quantity of its nitrogen was nearly 50 per 

 cent., but when vegetating exposed to the direct 

 rays of the sun, the increase was only 30 per 

 cent; and he also made the observation, that the 

 more rapidly the plants vegetate, the more ni- 

 trogen they are found to contain. It is also 

 well known to the cultivator, that plants grow- 

 ing in the shade have usually a deep green 

 colour, vegetating with much luxuriance, and 

 that certain animal manures applied to plants 

 produce similar results in a remarkable degree, 

 such as gelatin, oils, urine, blood, fish, ammo- 

 nia, &c. Now these fertilizers all contain 

 nitrogen, and which gas must be evolved in 

 some shape or other during their decomposi- 

 tion in the soil ; gelatin, containing 16-998 

 per cent., albumen, 15-705, the fibrin of blood 

 19-934, urea 46-66 per cent.; and although ni- 

 trogen usually exists in plants in very small 

 proportions, yet I am entirely disposed to agree 

 with Mr. Rigg in his conclusion, that more at- 

 tention should be paid than has hitherto been 

 done, in the examination of vegetable sub- 

 stances, "to those products, which, though so 

 minute in quantity as to be with difficulty de- 

 tected in our balances, have nevertheless been 

 wisely assigned to discharge the most import- 

 ant functions." (Phil. Trans. 1838, p. 406.) 



Such, then, are the essential and highly im- 

 portant uses of the three gases of the atmo- 

 sphere, nRrogen, oxygen, and carbonic acid, 

 to all vegetation ; an attentive consideration of 

 which will explain to the farmer the cause of 

 many of the phenomena he daily witnesses, 

 and suggest to him an unanswerable argument 

 for the adoption of those modes of cultivating 

 his land, the results of careful and scientific 

 investigations, which such chemical researches 

 suggest and render intelligible. 



, the absolute necessity for all crops re- 

 ceiving a regular supply of carbonic acid gas, 

 will explain to him why his crops always 

 yield an inferior produce when they are sur 

 rounded by thick plantations of timber trees 

 and why the portion of all kinds of plantations 

 growing on the side of the field the most ex- 

 posed to the winds is almost always of the 

 most luxuriant growth ; it will explain to him 

 the reason why many skilful farmers drill their 

 corn so that the most prevalent winds may 

 with the more facility, circulate along the rows 

 instead of across them; and why all farmers 

 find that their crops prosper better in mode 

 rately windy weather than in calms ; since in 

 all these instances, and in many other wel 

 OH 



known popular observations of the same kind, 



the copious supply of the carbonic acid and 



xygen gases of the atmosphere is naturally 



mpeded by thick plantations of other vegeta- 



le substances, and promoted by the winds. 



The consumption of oxygen gas by the roots 

 f plants, and their increase of growth and 

 igour when their usually impeded supply is 

 ncreased, is equally fraught with instruction 

 o the cultivator ; for it serves to explain the 

 eason why stirring the soil around the roots 

 f trees, according to the fashion of the early 

 ine and olive cultivators of Italy, or merely 

 isturbing the rows of cabbages and turnips, 

 as practised by the best English farmers, is 

 attended with decided advantage, since it suf- 

 ers the air to have more free access to their 

 oots. It renders apparent, too, one of the 

 hief reasons why mere subsoil-ploughing 

 dds so materially to the luxuriant produce of 

 ven the poorest cultivated lands, since, as the 

 oil is deepened and pulverized, the atmosphere 

 more freely and more copiously penetrates to 

 he roots of the vegetation it supports. The 

 a me facts explain the advantages of deep- 

 loughing, of sub-turf ploughing, and of trench- 

 ng ; why the indolent farmer in vain tries to 

 ender productive his shallow-ploughed lands ; 

 nd why, when the industrious cottager en- 

 loses his garden from the barren waste, too 

 )oor to sufficiently manure it, he yet renders it 

 reductive of excellent crops, by merely 

 renching it to the depth of 18 or 20 inches. 



And it is vain for the cultivator to urge that 

 his benefit is not to be mainly attributed to the 

 Veer circulation in the soil of the gases and 

 watery vapour of the atmosphere, but that it 

 s owing to the mixture of the surface-soil with 

 he substratum. For such a conclusion is not 

 nly opposed by the fact, that many soils do not 

 iiffer in composition from the substratum on 

 vhich they rest, and yet are materially bene- 

 itted by trenching or subsoiling, but is contra- 

 dicted by many agricultural facts with which 

 every cultivator is familiar ; and if any other 

 answer were requisite, that would be amply 

 supplied by the recent experiments of Sir Ed- 

 ward Stracey, with his new subturf plough, 

 which merely passes under the turf at a depth 

 of ten inches, and disturbs and loosens very 

 effectually the soil ; but when the plough has 

 passed under, every thing resumes its former 

 position, although every portion has been tho- 

 roughly agitated, and rendered more permeable 

 to the atmosphere. The soil is neither displaced 

 nor mixed, and yet this mere loosening is pro- 

 ductive of the highest advantage, the produce 

 of grass is extensively and permanently im- 

 proved. Sir Edward Stracey, after describing 

 the increased produce of the grass as being 

 very remarkable, tells us that there are no marks 

 left by which it can be known that the land has 

 been so ploughed, except from the lines of the 

 coulter, at the distance of about fourteen 

 inches from one another. In about three 

 months from the time of ploughing, these lines 

 are totally obliterated, and yet the quantity of 

 aftermath, and the thickness of the bottom, 

 have been the subject of admiration of all his 

 neighbours. (Jour. Eng. dgri. Soc., vol. i. p, 

 253.) 



