Mr. C. P. Ogilvie, one of the most astute authorities on the development of Argentina, and whom I had the pleasure of meeting in Buenos Aires, has demonstrated how the growing of alfalfa is useful for resting the land after crops of wheat, maize, etc. I have already told of the way this sanfoin plant has the property of attaching to itself micro-organisms which draw the nitrogen in the air and make it available for plant food. Every colonist knows the value of alfalfa for feeding his cattle, says Mr. Ogilvie, but it is not every colonist who knows why this plant occupies such a high place amongst feeding stuffs. Alfalfa is easily grown, very strong when established, and, provided its roots can get to water, will go on growing for years. The _raison d'être_ for growing alfalfa is the feeding of cattle and preparing them for market, and for this purpose a league of alfalfa (6,177 acres metric measurement) will carry on an average 3,500 head. When grown for dry fodder it produces three or four crops per annum, and a fair yield is from six to eight tons per acre of dry alfalfa for each year. A ton of such hay is worth about twenty to thirty dollars, and, after deducting expenses, there is a clear return of about fourteen dollars per acre. The figures supplied by one large company show that on an average cattle, when placed upon alfalfa lands, improve in value at the rate of two dollars per head per month, so it is easy to place a value upon its feeding properties.
[Illustration: CONVEYING ALFALFA TO A RAILWAY STATION.]
Thus, Mr. Ogilvie proceeds, we will take a camp under alfalfa capable of carrying 10,000 head of cattle all the year round, where, as the fattened animals are sold off, an equal number is bought to replace them. Such a camp would bring in a clear profit of 200,000 dollars sterling. An animal that has been kept all its life on a rough camp, and when too old for breeding is placed for the first time on alfalfa lands, fattens extremely quickly, and the meat is tender and in quality compares favourably with any other beef. No business in Argentina of the same importance has shown such good returns as cattle breeding, and these results have been chiefly brought about by the introduction of alfalfa, and a knowledge of the life history of alfalfa is of the greatest importance to the cattle farmer. All cereal crops take from the soil mineral matter and nitrogen. Therefore, after continuous cropping, the land becomes exhausted, and generally poorer. Experience has taught us that rotation of crops is a necessity to alleviate the strain on the soil.... If soils were composed of nothing but pure silica sand, nothing would ever grow; but in Nature we find that soils contain all sorts of mineral matter, and chief among these is lime. Alfalfa thrives on land which contains lime, and gives but poor results where this ingredient is deficient. The explanation is simple. There is a community of interest between the very low microscopic animal life known as bacteria and plant life generally. In every ounce of soil there are millions of these living germs, which have their allotted work to do, and they thrive best in soils containing lime. If one takes up with great care a root of alfalfa, and care is taken in exposing the root, some small nodules attached to the fine hair-like roots are easily distinguished by the naked eye, and these nodules are the home of a teeming microscopic industrious population, who perform their allotted work with the silent persistent energy so often displayed in Nature. Men of science have been able to identify at least three classes of these bacteria, and to ascertain the work accomplished by each. The reason for their existence would seem to be that one class is able to convert the nitrogen in the air into ammonia, whilst others work it into nitrate, and the third class so manipulate it as to form a nitrate which is capable of being used for plant food. Now, although one ton of alfalfa removes from the soil 50 lb. of nitrogen, yet that crop leaves the soil richer in nitrogen, because the alfalfa has encouraged the multiplication of those factories which convert some of the thousands of tons of nitrogen floating above the earth into substance suitable for food for plant life. As a dry fodder for cattle, three tons of alfalfa has as much nutrition as two tons of wheat.