[177] See paper on "Manurial Experiments with Turnips" by author, in 'Transactions of the Highland and Agricultural Society of Scotland;' 1891.
[178] Storer's 'Agricultural Chemistry,' vol. i. p. 498.
[179] Division III. p. 130.
[180] Mr F. J. Cooke, who has already been quoted, has kindly furnished the author with his views on the peculiar functions of farmyard manure as a manure. He says: "I look upon it, broadly speaking, as chiefly of value in restoring to good land, after cropping, those particular advantages which good land alone can give, and in helping better than any other manure, when applied to poor land, to bring it up to the level of good land in those particular merits which belong alone to fine soils. I speak now of an inherent value in good soils, beyond that attaching to them as mere reservoirs of abundant plant-food. For instance, one may supply a poor soil by artificial manure with much more food—and in a highly soluble condition—than is needed by the crop to be grown upon it, and yet not get so good a crop as upon a naturally richer but otherwise similar soil less abundantly filled with immediately available food. This may arise from a more perfect distribution of the plant-food in the rich soil, or from the steady way in which it becomes available to the crop, as well as for other reasons. But whatever the cause, there, I think, is the broad fact of the power of farmyard manure to enrich poor soils, so to speak, more naturally—that is, in a way which makes them more nearly correspond to better soils than artificial manures can."
Hence the indirect benefit to the farmer from farmyard manure is probably greater than its direct value as a mere manure. And the usual provision and use of it amongst all straw-growing farmers is sufficiently justified. The extent, however, to which that course may be beneficially carried, is one of the most important of the many difficult economic and scientific problems which the farmer has to face.
On the economic side must of course be considered the cost of manufacture in individual instances, as ruled by the market value of the straw, and the different circumstances and conditions under which the various farm animals are kept and fed (I have the figures by me of one well-known farmer, which show the cost to him of every ton of home-made manure to be 20s. or more); the price the resultant crops may be expected to command; the cost at the moment of artificial manures, &c., &c. Whilst on the scientific side must be considered the nature of the soil, the particular rotation of crops, &c.
It was, amongst others, just these scientific and yet very definite and practical problems we have tried to throw light on in the series of field experiments conducted for several years by the Norfolk Chamber of Agriculture. (See reprint of summary of same in last year's Report of the Board of Agriculture.)