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TEE AGBICUL TUBAL JOURNAL. 



from which the growing parts receive 

 their supply and power of further develop- 

 ment. 



Grown on pure sand the development 

 of the plant would cease after the 

 exhaustion of the seed food supply, as 

 there are no necessary mineral constituents 

 present from which it can draw, but if 

 these constituents were added to the sand 

 the plant would continue to live and 

 develop. And so it is with the soil, 

 provided it is properly cultivated and 

 well supplied with all the constituents 

 necessary for the well being of the plants, 

 it will go on carrying crops year after 

 year, a natural medium through which 

 we can feed and rear our crops under the 

 conditions which by nature are most 

 adapted to them. 



The question of supplying the plant 

 with food material in the cheapest and 

 most approved form, is a living one at 

 the present day. The more cheaply and 

 efficiently we can manure, the more satis- 

 factory will be the returns, and in casting 

 around for cheap sources the one of green 

 manure presents itself as an inexpensive 

 way of furnishing the valuable nitrogenous 

 constituent in an inexpensive manner. 

 The subject of artificial manure has 

 already received a little attention from 

 me in the Journal, but that of green 

 manuring was delegated for future con- 

 sideration, as I considered it too important 

 to be discussed under the short notices 

 that I wrote on artificials. 



It will be as well, in the first place, to 

 consider some of the objects and effects of 

 soiling crops. If a crop of some des- 

 cription were grown and ploughed under, 

 nothing would be added to the soil in 

 the shape of minerals ; carbon and oxygen 

 would certainly be increased by absorp- 

 tion through the crop from the atmos- 

 phere, but the mineral constituents such 

 as phosphoric acid, potash, and lime, 

 already derived from the soil, would 

 simply be returned to it, in no way 

 increased. Nor has the nitrogei- (with 

 the exception in one order of plants) 

 become more abundant ; and the natural 

 question arises "where does the benefit 

 of green manuring appear ? 



A great change has been effected by the 

 green crop, it has sent its roots horizon- 

 tally and vertically, far and wide, in 



search of food, it has been at work dis- 

 solving out mineral matter, building up 

 its system and storing food, accumulating 

 much valuable material during its growth, 

 which in the process of decay is readily 

 yielded up in a much more valuable and 

 accessible form to those plants which. 

 succeed it. The various constituents 

 drawn together enrich the soil, not in an 

 increased quantity of these constituents, 

 but in their concentration and ready 

 availability. Besides which the land is 

 enriched by the addition of their humus 

 of vegetable matter which, as is well 

 known, has a powerful influence on the 

 conservation of moisture, giving body, 

 especially to sandy soils, and keeping the 

 land friable and in good heart. The 

 effects of the added vegetable matter are 

 far reaching ; while decaying it assists in 

 the liberation of fertilizing constituents, 

 regulates the soil temperature, it is the 

 home of useful bacteria, aud, in fact, must 

 be looked on as a necessary ingredient in 

 our soils. 



There are, broadly speaking, two classes 

 of green manures, viz. :— Leguminous 

 and others. The former order of plants 

 includes the clovers, peas, beans, vetches, 

 lupins, lucerne, etc., and is the most 

 important class for soiling purposes. The 

 latter includes all other plants, but pre- 

 cedence is given to those which are fast 

 growing, easily and inexpensively culti- 

 vated. They are mainly grown for the 

 reasons mentioned, i.e., rapidity of growth, 

 collection of mineral matter, and the 

 supply of humus material which they 

 give. 



The legumes are, however, the clasri 

 essentially adapted for this purpose, as 

 they not only fulfil all the functions of 

 the other, but enrich the land in nitrogen, 

 the most expensive ingredient which has 

 to be supplied in artificials. This unique 

 property is due to the bacteria which 

 live in the root nodules ; they have the 

 faculty of drawing on the inert nitrogen 

 of the atmosphere, and passing it on m 

 an assimilable form to the plants on which 

 they live. Only this order of plants have 

 been observed "to be attended by these 

 nitrogen-absorbing bacteria, and to them 

 the plant is indebted for its main supply 

 of nitrogen, so that when the plants 

 mature and are ploughed in, they increase 



