170 



THE AGRICULTURAL GAZETTE. 



[Mak. 16, 



acid, by which it is carried into the plants, and here again ' 

 the importance of the latter substance is seen. 



The clay of marl is especially useful to such soils as are 

 subject to drought, because a soil may contain all the 

 substances required for the nourishment of plants in 

 sufficient quantity, and still be unproductive, if it is 

 deficient in water, which has to convey the nutritive 

 substances into them ; and clay retains water for plants 

 in dry weather. Besides that, the alumina of the clay, 

 which has a great affinity for humic acid, will also some- 

 what decompose the coal of humus and the vegetable 

 matter of the soil. It is also to be remembered, that 

 alumina, the protoxide of manganese, lime and magnesia, 

 potash, soda, and the oxide of iron of the marl will equally 

 prevent the decomposition and useless volatilisation of the 

 humic acid, as these substances fix it chemically. 



Marl also improves vegetation by the silica which it 

 contains, i. e., in those soils which arc deficient in this sub- 

 stance, for instance moor, peat, or marshy soils. The 

 sorts of marl which are very rich in lime, and at the same 

 time sandy, improve clayey soi's by loosening then. 



If marl contains (which is sometimes the case) sulphu- 

 ret of iron, it will be converted, l>y contact with air, into sul- 

 phate of the ox ide of iron, which again becomes decomposed 

 by the carbonate of lime, so that gypsum will be formed, 

 which will naturally increase the manuring quality of the 

 marl, as we shall see hereafter. 



Marl, however, contains at times a substance detrimen- 

 tal to vegetation, viz., carbonate of the protoxide of iron. 

 I have found this to be the case in two instances. Such 

 marl is generally found nnder marshy soils, and contains 

 remains of fresh-water shells. In using this sort of marl 

 we must guard aga t ploughing it under too soon ; it 

 must be spread and left lying on the ground till the prot- 

 oxide of iron has been changed into oxide of iron, which 

 will be seen by its grey colour having changed into yellow, 

 which, however, will take up sometimes a whole summer. 

 If a marl conta : ning much carbonate of th 5 protoxide of 

 iron is ploughed under too soon, the humic acid of the 

 soil will combine with the protoxide of iron into a salt, 

 which is very noxious to plants. Carbonate of iron will, 

 like carbonate of lime, efferv see if acids are poured upon 

 it, and this may ad us into error when calculating the 

 amount of lime which a marl may contain. From the 

 different statements I have made about the action of marl, 

 it will have been seen that it is not merely the carbonate 

 of lime or the clay which constitutes its worth as a manure; 

 still, generally speaking, those sorts are considered best 

 which contain most of the former substance. It is, 

 therefore, mostly tested only as to the amount of carbonate 

 of Ume it contain?, but it would be as well to take notice 

 of all its other component parts. 



The question, how long will marl act ? has been often 

 raised. If, however, we consider that it supplies the 

 plants with different nutritive substinces, which occur in 

 it in very different proportions — that these substances are 

 taken hold of by plants in ve-y different degrees — that many 

 of these ingredients are carried away by rain or snow- 

 water ; if we consider, in short, that plants are also de- 

 prived of part of the lime and magnesia by these latter 

 substinces combining with the silica into substances in- 

 soluble in water, it will be seen that this question can 

 never be accurately answered, even were the amount 

 of marl spread on a certain area accurately known. 

 The repetition of the marling is always dependent on 

 the quantity used at any former occasion — on its che- 

 mical constituents — on the component parts of the soil 

 —on the sort of crop reared — on the nature of the sub- 

 soil — and ou the annual amount of rain. If, for in- 

 stance, any sort of marl owes its manuring properties to 

 the gypsum and phosphate of lime which it contains, its 

 application will have to be often repeated, as it rarely 

 contains much of these substances, and the gypsum be- 

 comes easily extracted by the water. The same is the 

 case if it improves vegetation by the magnesia which it 

 contains, as of this also most marls contain but very little. 

 If, on the other hand, the value of marl depends on its 

 carbonate of lime (which will be the case whenever the 

 soil possesses the other nutritive substances to a sufficient 

 amount,) it will require to be repeated only after a lapse 

 of twenty or thirty years, it being understood that the first 

 supply has been to a considerable amount. Because, 

 though a small quantity of lime be dissolved and carried 

 off by the rain-water, which contains carbonic acid, or 

 though another portion of it combines with the silica of 

 the soil, still enough will remain for the use of the plant, 

 supposing that only 10,000 lbs. of a calcareous marl have 

 been conveyed on one acre of land. Whoever wishes to 

 ascertain before hand, with some degree of accuracy, how 

 long a certain quantity of marl will act, has to subject to 

 chemical analysis the marl itself, as well as the soil to be 

 manured by it ; and having accurately ascertained the 

 component parts of both, he may form an estimate, by 

 deducting the amount consumed by every crop, and 

 that which is annually carried off by the rain. Though, 

 however, all the nutritive substances of marl have been 

 consumed by plants, it will act beneficially on dry soils 

 for centuries, if it contains much clay ; both because this 

 will supply the plants with moisture, and because the 

 drier the soil the smaller the quantify of soluble matter 

 that can be absorbed by the crops. 



ON THE APPLICATION OF CHEMISTRY~TO~ 

 AGRICULTURE UPON RATIONAL 



PRINCIPLES.— No. X. 



(Continued from page 155.) 



As I divided the chemical composition of plants into 

 organic and inorganic, the same division must be adopted 

 in treating of their food ; but it will be more convenient 

 to discuss the subject under the general head of 



Manure, or the Food of Plant*. — If any person has 



anv difficulty in comprehending how manure applied to 

 the soil, serves as nourishment to the plant, let him 

 reve t to the fact which he may daily witness in that 

 beautiful process which is undergone in the incubation of 



the egg. 



If a chemist analyses the white and yolk of the egg, 

 he finds them identical in chemical composition, with the 

 source of all animal nutriment— the blood ; and he thus 

 lias no difficulty in solving the problem, how they are 

 converted or organised into the perfect bird. So, if he 

 examines the plant upon which animals feed, he finds 

 there also the essential elements of blood from which all 

 organised animal structure is formed. And again, if he 

 examines the proper food, or manure of the plant, he finds 

 in that the elements necessary for the structure of the 

 vegetable. All difficulty at once vanishes from the sub- 

 ject, except a knowledge of how the mysterious principle 

 of life performs its agency. Of this we know nothing, 

 and it is not probable that a finite mind will ever be able 

 to comprehend it. 



Chemists, then, ha7e no difficulty in deciding, that plants, 

 to be grown in perfection, must have a supply of food which 

 is similar in composition to their own ultimate structure. 

 But Nature is sometimes obstinate in refusing the inter- 

 ference of man ; she is always so when, from ignorance of 

 her laws, that interference is misapplied. Granting that 

 plants must be fed, it must always be remembered that, 

 like animals, they require due attention to be paid to the 

 quantity and quality of their food. For instance, although 

 quite true that to form Gluten and Starch in the seed of 

 grain, the plant must have supplied to it the elements of 

 these substances, it by no means follows, that if Gluten 

 and Starch in their pure state were given to the plant, that 

 it would appropriate the food so offered. We must in 

 these inqufries study and follow out the plans of Nature 



herself. 



In primeval forests, where the trees grow to an enor- 

 mous height, live, and flourish, and die, without the inter- 

 ference of man, how does Mature provide their food ? The 

 question is not difficult to solve. Of organic matter they 

 require the elements carbon, hydrogen, and oxygen, to 

 form the fabric of the plant ; and in many cases, a fourth 

 element, nitrogen, either for the perfection of their seed, 

 or to be stored up for ulterior purposes. 



The carbon is supplied from the atmosphere. The 

 carbonic acid in the atmosphere is about one part in a 

 thousand ; and yet Liebig has calculated that this appa- 

 rently small amount would produce more solid charcoal 

 than all the vegetable kingdom and all the brown coal 

 on the surface of the earth. By the decomposition 

 of water the other elements, oxygen and hydrogen, are 

 provided. Then, of nitrogen we have a source in the 

 atmosphere, which Liebig has proved to contain a con- 

 stant quantity of ammonia. But the atmosphere only 

 nourishes plants in part. The Oak, with its immense 

 branches, has roots as large in the interior of the earth 

 const intly at work in selecting and appropriating proper 

 food to the purposes of nutrition. 



This food in the earth is supplied by the decomposition 

 of the leaves and branches, forming humus ; by the decay 

 of animal matter, forming ammonia; and from rain, 

 charged with this substance, which is const mtiy falling 

 upon the surface of the earth. Of inorganic matter the 

 supply is derived from the disintegration of the subjacent 

 rocks. 



In the wilds of Nature, with the food of Nature, we see 

 these works of the Creator in their boldest magnificence 

 and beauty, and there every living thing finds the means 

 of subsistence ; but civilisation, want of luxuries, and, 

 above all, the gradual increase of mankind, create the 

 necessity of bringing into action the aid of science in 

 developing the resources of Infinite Wisdom. 



In the food of plants which Nature restores to the soil 

 we observe that the process of decomposition takes place 

 before it can be appropriated by the vegetable organism 

 to the purposes of nutrition. Vegetable matter decom- 

 posing is converted into humus. Humus is converted, by 

 decomposition of its constituents, into carbonic acid — it is 

 burnt, in fact, by the action of oxygen. Carbonic acid, 

 again, i3 resolved, by chemical agency, into carbon and 

 oxygen. And thus the ultimate elements of the old plants 

 are reconverted into what are termed the proximate ele- 

 ments of the new, and woody fibre, starch, gum, &c, are 

 the result. This cycle of changes is in never-ceasing 

 activity throughout the scale of living beings. It does 

 not, however, apply to inorganic matter, which serves no 

 purpose in the nutrition of the plant, properly so called. 

 Their use in the vegetable economy is either to give 

 strength and durability to portions of the fabric, or to be 

 stored up in its cellular structure, with the evident and 

 beautiful design of being appropriated by the animals 

 which feed on it. 



Decomposition, then, is the first great principle to be 

 attended to in the preparation of organic manures. 



The second is to secure to the plant the results of de- 

 composition, by fixing the volatile salts, which would 

 otherwise be lost. 



And having prepared the manure, a third object will 

 present itself— that of applying it, with a due regard to the 

 chemical composition of the crop to be grown, and to the 

 necessities of the soil in which it is to be planted. — C. Ii. 

 Bree, Stow market. 



(To be continued.) 



Home Correspondence. 



Lucerne. — An article appeared in a recent Number of 

 the Gardeners' Chronicle calculated to mislead many 

 farmers who might be induced to adopt the method 

 recommended by Mr. John Sandford and Mr. A. Hall 

 for the cultivation of Lucerne. All husbandmen, particu- 



larly those who would know " the true princirn^oTn 

 lage " and grow Lucerne in the proper way, should n»i 

 Jethro Tull " On Drill Husbandry." This valuable book 

 was written more than a century ago, but there was 

 reprint some few years since by the late William Cobbett* 

 It will require no great penetration to discover by 

 perusing this work, that the principles of Mr. J. Sand 

 ford, and Mr. A. Hall, of the Chepstow Farmers' Club 

 are not "the true principles of tillage." Lucerne roots 

 deeply, so deeply that a dry surface will not materially 

 affect its growth. If properly cultivated the crown of a 

 plant will spread as widely as the palm of the hand, and 

 Grasses of any kind (its greatest enemies) will, if pes. 

 mitted to grow, always injure it, and ultimately destroy 

 it. — Nicodemus. 



'Scotch Agriculture. — The following extract, taken 

 from the account of the parish of Dunbar, published in 

 the "Statistical Account of Scotland," may be interesting 

 to some of your readers, as bearing on the questions 

 regarding the food of plants. It is from the pen of the 

 clergyman of the parish, who is an able man and zealous 

 Agriculturist. " The soil being tfry, is easily pulverised 

 and cleared of root-weeds, therefore there is comparatively 

 but little fallow. The rotation of crops is:— 1. Turnips, 

 upon two or more ploughiDgs, dunged, and generally fed 

 off; when carried off, a compost of lime and earth is gener- 

 ally applied. 2. Wheat, with Clover and Rye-grass seeds. 

 3. Grass, fed off with cattle or sheep. 4. Potato Oats. 

 5. T3eans, drilled and dunged. 6. Wheat. Instead of 

 Oats, Wheat is sometimes taken, and then the rotation is 

 confined to four crops. This course, peculiar to the 

 parish, has been called the Dunbar system; but objections 

 have been made to it. Wheat every second year, it is 

 said, exhausts the soil ; the answer is, that the food of 

 plants in the soil may be exhausted by any crop, while the 

 soil itself cannot be exhausted. Where there is a com- 

 mand of manure, there is no system which will so richly 

 repay the labours of the husbandman. It was adopted 

 here for many years on one of the best farms, without any 

 diminution of either quantity or quality. And in order to 

 ascertain whether soil is injured by frequent crops of 

 Wheat, the glebe of Dunbar (the clergyman's allotment 

 of land), was properly dressed, either with sea-weed, 

 street dung, or soot, and cropped with Wheat for five suc- 

 cessive years. The result was, an extra crop every year, 

 and the land left in a condition that it may produce a crop 

 or two of any kind without additional manure. The least 

 crop in the succession was on the third year — 10 J bolls 

 •(5J quarters) per acre ; it promised to be the greatest, but 

 it was lodged flat as the surface soon after it came into 

 ear. All the other crops were above 12 bolls (G quarters) 

 per acre. One season, exactly suited to the soil, there 

 were 16| bolls per acre ; and the last of the five years there 

 were 14 bolls per acre. It was ascertained that on each 

 of three of these years there were more than 300 stones 

 of straw per acre. The soil is a sandy loam. There 

 is another field in the parish which has produced Oats 

 four successive years with increasing produce and fertility. 

 Hence it seems to follow that land, properly cultivated and 

 manured, may produce abundantly the same kind of crop 

 in regular succession. If the food of plants is exhausted 

 in exact proportion to the weight of crop produced, it is 

 worthy of investigation whether the advantage of changing 

 the kind of crop arises, not from one kind giving off food 

 for another kind, but solely from the different modes of 

 cultivation which different kinds of crop admit of at 

 diffeient seasons." Thus far the Minister of Dunbar. I 

 will only add, that the parish is in East Lothian, and, 

 stretching along the sea-coast, enjoys one of the warmest 

 and driest climates in Scotland. — J. S. 



Dairy Management.— Our Somersetshire dairymen 

 are complaining bitterly of the great depression in &« 

 value of their dairy produce. It would be happy t° r 

 them, if their complaints would lead them to see nearly 

 the necessity of a change of system in their dairy rnanage- 

 ment, which is generally as bad as it can !*• -* ne c , 

 are out ail the winter, and the pasture Jmd is very raucn 

 exposed to land floods, as it lies very low, especially in 

 the neighbourhoods of Wales and Glastonbury; the con 

 sequence of which is, that the Grass resembles a P l0 "S^ 

 field, from the constant tread of the animals, ana i 

 deep impressions which their feet make m the sou 

 filled with water. Rarely do you see any s he as r 

 shelter. The Grass, of course, cannot provide sufficient i 

 for them, and Hay is brought to them and thrown uo 

 in different lots, which again injures the pasture lana, 

 it is completely trodden down, and worked up _ oy 

 treadings of the animals, and in rainy * eatMr d 

 nourishing juices of the Hay are soon washed °^' feed . 

 very great waste is the consequence of this mode . 



ing. It is evident also that the manure M conip j 

 wasted. Under such a system, it cannot be reasui ^ 

 expected that the produce of milk can be ver ^° rioas 

 The constant exposure to cold and wet must be inj ^ 

 also. The greatest want of economy appears 

 whole of this system.— A Zummerzetshire man. 



Steeping of Seeds.— Animated by the "tatementy 

 January Number of the " Agricultural Journal, x ^ 

 menced a series of trials of soaking seeds in s° lu "° of 

 the sulphate of soda, ammonia, magnesia, and on ^ 

 potash, guano liquified, &c, both singly, and in* 

 combinations. The seeds subjected to the process > 

 those of Wheat, Beans, Oats, and Turnips, and u 

 In every instance the vitality of the seed has been ° C "J * 

 I have entered upon a new set of experiments witn ^i 

 of much greater dilution ; such as 1 oz. of the : sai ^. 

 pint of water : but I feel this is mere guess worK, an i 

 to inquire whether you have made any attempt to - 

 within what limits these saline solutions may ■ oe i ■■ 

 employed. I fear the quantity recommended in j 

 Paper No. 4, viz., 5 lbs. of the salt dissolved in * 



