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duced, and (5) to the small proportion of the most important manurial constituents of the roots which is retained by store or fattening animals consuming them, the rest returning as manure again; though, when roots are consumed for the production of milk, a much larger proportion of the constituents is lost to the manure. Cereal Crops—Barley and Wheat.—Experiments upon the growth of barley for nearly fifty years in succession on rather heavy ordinary arable soil have resulted in showing that the produce by mineral manures alone is larger than that without manure; that nitrogenous manures alone give more produce than mineral manures alone , and that mixtures of mineral and nitrogenous manure give much more than either used alone—generally twice, or more than twice, as much as mineral manures alone. Of mineral constituents, whether used alone or in mixture with nitrogenous manures, phosphates are much more effective than mixtures of salts of potash, soda, and magnesia. The average results show that, under all conditions of manuring—excepting with farmyard manure the produce was less over the later than over the earlier periods of the experiments, an effect partly due to the seasons. But the average produce over forty years of continuous growth of barley was, in all cases where nitrogenous and mineral manures (containing phosphates) were used together, much higher than the average produce of the crop grown in ordinary rotation in the United Kingdom, and very much higher than the average in most other countries when so grown. The requirements of barley within the soil, and its susceptibility to the external influences of season, are very similar to those of its near ally, wheat. Nevertheless, there are distinctions of result dependent on differences in the habits of the two plants, and in the conditions of their cultivation accordingly. Wheat is, as a rule, in the British Isles sown in the autumn on a heavier soil, and has four or five months in which to distribute its roots, and so it gets possession of a wide range of soil and subsoil before barley is sown in the spring. Barley, on the other hand, is sown in a lighter surface soil, and, with its short period for root-development, relies in a much greater degree on the stores of In proceeding to discuss the various classes of crops, it plant-food -within the surface soil. Accordingly, it is more will be convenient to deal with them under the three susceptible to exhaustion of surface soil as to its nitrogenseparate heads of root-crops, cereal crops, and leguminous ous, and especially as to its mineral supplies; and in the crops, and then to inquire into their inter-relations when common practice of agriculture it is found to be more benefited by direct mineral manures, especially phosphatic grown in rotation. Root-Crops. — Experiments upon root-crops — chiefly manures, than is wheat when sown under equal soil conwhite turnips, Swedish turnips (swedes), and mangels ditions. The exhaustion of the soil induced by both — have resulted in the establishment of the following barley and wheat is, however, characteristically that of conclusions. Both the quantity and the quality of the available nitrogen; and when, under the ordinary condiproduce, and consequently its feeding value, must depend tions of manuring and cropping, artificial manure is still greatly upon the selection of the best description of required, nitrogenous manures are, as a rule, necessary for roots to be grown, and on the character and the amount both crops, and, for the spring-sown barley, superphosphate of the manures, and especially on the amount of nitro- also. Although barley is appropriately grown on lighter genous manure employed. At the same time, no hard soils than wheat, good crops, of fair quality, may be grown and fast rules can be laid down concerning these points. on the heavier soils after another grain crop by the aid of Independently of the necessary consideration of the general artificial manures, provided that the land is sufficiently ' economy of the farm, the choice must be influenced partly Leguminous Crops and the Acquisition of Nitrogen.— by the character of the soil, but very much more by that The fact that the growth of a leguminous crop, such as of the climate. Judgment founded on knowledge and aided by careful observation, both in the field and in the red clover, leaves the soil in a higher condition for the feeding-shed, must be relied upon as the guide of the subsequent growth of a grain crop—that, indeed, the practical farmer. Over and above the great advantage growth of such a leguminous crop is to a great extent arising from the opportunity which the growth of root- equivalent to the application of a nitrogenous manure for crops affords for the cleaning of the land, the benefits of the cereal crop—was in effect known ages ago. The growing the root-crop in rotation are due (1) to the large Romans recognized it two thousand years since, for Varro amount of manure applied for its growth, (2) to the large writes, “ Certain things are to be sown, not with the hope residue of the manure left in the soil for future crops, (3) of any immediate profit being derived from them, but to the laru-e amount of matter at once returned as manure with a view to the following year, because being ploughed again in the leaves, (4) to the large amount of food pro- in and then left in the ground, they render the soil after-
of different manurial dressings. So much, indeed, does the character of the herbage vary from plot to plot that the effect may fairly be described as kaleidoscopic. Repeated analyses have shown how greatly both the botanical constitution and the chemical composition of the mixed herbage vary according to the description of manure applied. They have further shown how dominant is the influence of season. Such, moreover, is the influence of different manures that the gross produce of the mixed herbage is totally different on the respective plots according to the manure employed, both as to the proportion of the various species composing it, and as to their condition of development and maturity. The experiments with farm animals began in 1847, and amongst the points that have been investigated are the following:—(1) The amount of food, and of its several . constituents, consumed (a) in relation to a given live weight of animal within a given time, (6) to produce a given amount of increase in live weight. (2) The proportion and relative development of the different organs, or parts, of different animals. (3) The proximate and ultimate composition of the animals in different conditions as to age and fatness, and the probable composition of their increase in live weight during the fattening process. (4) The composition of the solid and liquid excreta (the manure) in relation to that of the food consumed. (5) The loss or expenditure of constituents by respiration and the cutaneous exhalations—that is, in the mere sustenance of the living meat-and-manure-making machine. (6) The yield of milk in relation to the food consumed to produce it; and the influence of different descriptions of food on the quantity and on the composition of the milk. ' Incidentally, the results obtained from these inquiries have furnished data essential to the consideration of such problems as (a) the sources in the food of the fat produced in the animal body; (b) the characteristic demands of the animal body—for nitrogenous or non-nitrogenous constituents of food—in the exercise of muscular power; (c) the comparative characters of animal and vegetable food in human dietaries.
