GREEN MANURES. 



GREEN MANURES. 



plants to be ploughed into the soil, and even 

 that crops should be raised for that purpose 

 for these, he says, " enrich the soil as much as 

 dung." And the lupin is named as an excel- 

 lent manure by very early agricultural writers 

 The white lupin is even now grown in Italy for 

 the purpose of being ploughed into the soil, an 

 operation generally performed in October. 



The white lupin, which is extensively em- 

 ployed for this purpose in Tuscany, is the 

 leguminous annual plant, well known in our 

 gardens, growing in sandy and loamy soil to 

 the height of two or three feet, with a stem of 

 equal strength with the bean, and having some- 

 what similar blossoms and pods ; but the pro- 

 duce is so bitter, that it is unfit for the nourish- 

 ment of either man or beast. It arrives to a 

 considerable size in the month of October, 

 when it is ploughed into the soil. It abounds 

 with gluten, to which, in fact, its fertilizing 

 effects have been chiefly attributed. 



Green manures, although in some measure 

 rendered subservient to the enriching of the 

 soil, as soon as man began to till the earth, and 

 dig in the weeds of his land and the remnants 

 of former crops, have never been systematically 

 employed by the farmer. He has ever been 

 more desirous of employing, as food for his 

 stock, the vegetable produce of his land, than 

 to bury it in the earth to promote the future 

 productiveness of the soil. Yet, whenever 

 green succulent substances, such as weeds, 

 river collections, sea-weed, &c., have been 

 used, the result has always been most satisfac- 

 tory. The putrefaction of the vegetables, and 

 the gases in that case emitted, appear to be on 

 all occasions highly invigorating and nourish- 

 ing to the succeeding crop. During this ope- 

 ration, the presence of water is essentially 

 necessary, and is most probably decomposed. 

 The gases produced vary in different plants: 

 those which contain gluten emit ammonia ; 

 onions, and a few others, evolve phosphorus ; 

 hydrogen, carbonic acid gas, and carburetted 

 hydrogen gas, with various vegetable matters, 

 are almost always abundantly formed. All 

 these gases, when mixed with the soil, are very 

 nourishing to the plants growing upon it. The 

 observations of the farmer assure us that they 

 are so. He tells us that all green manures 

 cannot be employed in too fresh a state ; that 

 the best corn is grown where the richest turf 

 has preceded it; and that where there is a good 

 produce of red clover, there will assuredly fol- 

 low an excellent crop of wheat: he finds also, 

 that when he ploughs in his crop of buckwheat 

 to enrich his land, that this is most advanta- 

 geously done when the plant is coming into 

 flower. The chemical explanation of these 

 practical observations is not difficult. "All 

 green succulent plants," says Davy, " contain 

 saccharine or mucilaginous matter, with woody 

 fibre, and readily ferment ; they cannot, there- 

 fore, if intended for manure, be used too soon 

 after their death. When green crops are to be 

 employed for enriching a soil, they should be I 

 ploughed in, if it be possible, when in flower, I 

 or at the time the flower is beginning to appear; j 

 for it is at this period that they contain the j 

 largest quantity of easily soluble substances, j 

 and that their leaves are most active in forming ! 

 582 



nutritive matter. Green crops, pond weeds, 

 the parings of hedges or ditches, or any kind 

 of fresh vegetable matter, require no prepara- 

 tion to fit them for manure. The decomposi- 

 tion slowly proceeds beneath the soil, the solu- 

 ble matters are gradually dissolved, and the 

 slight fermentation that goes on, checked by 

 the want of a free communication of air, tends 

 -0 render the woody fibre soluble without occa- 

 sioning the rapid dissipation of elastic matter. 

 When eld pastures are broken up and made 

 arable, not only has the soil been enriched by 

 the death and slow decay of the plants which 

 have left soluble matters in the soil, but the 

 roots and leaves of the grasses living at the 

 time, and occupying so large a part of the sur- 

 face, afford saccharine, mucilaginous, and ex- 

 tractive matters, which become immediately 

 the food of the crop, and the gradual decompo- 

 sition affords a supply for successive years." 

 (Agr. Chem. p. 280.) Nothing will aid the 

 practical farmer so much in understanding the 

 value of green manure, as a knowledge of the 

 constituent elements of plants. Woody fibre, 

 starch, sugar, gum, are compounds of carbon, 

 hydrogen, and oxygen ; the fixed and the vola- 

 tile oils, wax and resin, are constituted of car- 

 bon, with the elements of water, and an excess 

 of hydrogen ; vegetable albumen and gluten 

 contain nitrogen as an element; and it is never 

 altogether absent in plants, either in their solid 

 or fluid contents. Now, reflecting upon these 

 facts, it follows that the developement of a plant 

 requires the presence of substances containing 

 carbon and nitrogen, and capable of yielding 

 these elements to the growing organism ; se- 

 condly, of water and its elements ; and, lastly, 

 of iron, lime, and other inorganic matters es- 

 sential to vegetable life. (Liedig's Organic Chem.) 

 It is always refreshing to find the sagacious 

 conclusions of the philosopher supported by 

 the practical farmer's observations. "In Oc- 

 tober, 1819," said the late Dr. Browne, of Gorl- 

 stone, in Suffolk, in a letter which he sent to 

 me, " a violent gale of wind drove to this part 

 of the coast an unprecedented quantity of sea- 

 weeds. These were eagerly scrambled for; 

 and, from my greater vicinity to the beach, I 

 collected twenty-seven cart-loads, each as much 

 as four horses could draw; and although other 

 persons deposited their collections in their 

 farm-yards, to rot among their other manure, 

 yet I spread mine, fresh and wet, upon little 

 more than an acre of bean stubble, instantly 

 sloughed it in, and dibbled wheat upon it. On 

 he 6th of October I then salted the adjoining 

 and with three bushels per acre, manured it 

 with fifteen loads of farm-yard dung per acre, 

 and dibbled it with wheat on the 15th of No- 

 vember. The result was, that the sea-weeded 

 sortion gave three times the produce of any 

 equal part of the field." (C. W. Johnson's 

 Essay on Salt, p. 48.) 



No one more perseveringly advocated the 

 mployment of green manures than the late 

 Mr. Knight. In his paper on the question, he 

 supported his views by some ingenious expe- 

 riments, and used every argument that could 

 fairly be employed in their favour. " Writers 

 upon agriculture," he observed, " both in an- 

 cient and modern times, have dwelt much upon. 



