FACTS FOR FARMERS. (From Johnson's Art of Farming.) ROTATION OF CROPS.

Waikato Times, Volume IV, Issue 224, 16 October 1873, Page 2

FACTS FOR FARMERS. (From Johnson's Art of Farming.) ROTATION OF CROPS.

Experience has demonstrated that one crop ofttr another of the same kind greatly reduces the fertility of all classesof soils. This conclusion might be drawn from reiwon as well as expei ience, since it is reasonable to suppose tnat crops of the same kind tako the same sort of food out of the samekind of soil. Experience has also demonstrated that one crop after another of a different kind does not, materially reduce the condition of soils. This deduction then seems fair —that the condition of the soil is best maintained* by taking different crops after another ; and, as every crop, though of a different kin^, and deriving support from the soil, assists in exhausting it, a limit must be put to the number of crops that should follow one another. Accordingly, in practice,., a limit is placed on the number of crops taken in succession* of whatever kind, and this number and succession is called & •« rotation of crops." Though all crops derive support from the soil, onHgnd appropriates food in a different degree to another^ajWkne crop also takes food of a different sort to another, one Trap will thrive on land on which another would notsu&ist. When a crop is allowed to seed it requires a different iubstance from the soil, to mature the seed, from what ik doesto produce the stem ; and it i» well-known that the producing of the seed taxes the soil more strongly than the stem, or the leaves, or the bulbs. It is trufr that the same sort of grain can be grown on the^ same soil for years in succession, without apparent deterioration of the soil f but it must be done by the- iratrumentality of manure. Theoretically, if the ingredients takenfrom the soil by any crop are restored to it, the soil will not be deteriorated. The power of plants to excrete objectionable substances . ha» been denied by, many theorists. Some affirm that though plants have no power of selection, but take into their texture any solution offered, they havo little or no power of" again excreting it, that any excretions are only the true sap. But the theory which agrees most with practice is, to my mind, the one most to be relied on, Tiz, that different species of plants require a particular nutriment from barley or oats, . or from any of the green crops, and that if it were cultivated, perseveringly for a number of yean it would entirely exhaust the soil for wheat. Upon- this idea the present barren state of the northern coast of Africa, and of the island of Sicily, . has been attempted to be explained 1 . It has been conceived that the constant growing of wheat in those countries to • supply the wants of the Roman people, after they relinquished ■ their own agriculture, impoverished the soil to its present condition. The progress of physiology soon made - it appear that the organs of" each plant derive their many juices from substances which' concur in the nutrition of plants generally. In effect, planti the most opposite in botanical character and properties, alimentary as well a» poisonous, will live and flourish 1 on* the same mound of earth, . and on the same manure ; but this- does not prove that each plant has not the power of taking' up* the particular substances which suit its own character and 'composition, and which alone will nourish and support it. It appears rery clear that although all plants may use a certain quantity of ' the same substance contained in<the soil,' there ii yet some.' other ingredient which one must have -and' another can do i without. I have said that wheat requires a different nutriment from barley or oats — this is corroborated by the • analyzation of the plants. Wheat has been proved to contain one substance, at least, which is not found in either of the others. To sum up the different opinions of theorists on this important matter, I think the following will appear rational. That there is no absolute necessity for alternation' of crops, . when manure and labour can be easily procured* Nevertheless there are certain plants which cannot be reproduced 1 upon the same soil advantageously, exceps at intervals more or less remote. The cause of this • exigence on.- the part of" certain plants is still obscure, and the hypothesis propounded for clearing it up far from satisfactory. The reason this subject has not engaged the attention of * the practical agriculturist more than it has, is, that on all the ■ farms where a system is observed, the rotation of the different crops is necessary to keep up the system. Cattle require so - much of one kind of fodder, so much litter, and so much, green feed every year; and tbesequtntities cannot be secured , without a regular course of cropping. But the practical farmer knows from experience quite enough to confirm him in the belief that crops taken in rotation are much more • profitable than when successively grown. They also know that if they attempt to grow one crop successively they run , every risk of a failure. In the south of England, where the - clovers were found so advantageous for sheep feeding, and were at one time grown every four years, they are obliged to • grow them less frequently — six or eight years now being the usual interval. He knows, too, that lucerne and sainfoin, . which is sown for a permanent crop, will not keep its plant for more than eight years in the best descriptions of sous,, and that that time is gradually on the decrease. Our own colonial farmers have proved too completely for their own> interests, that wheat cannot be grown- successfully on one soil ; and those who have sown lucernej.rren on the deep alluvial deposits, are now proving to their great disappointment that their lucerne plants are beginning to die out, and the natural grasses are taking their place. Those who arefamiliar with the fairy-rings in the old pastures of EpgHnd can give a useful lesson on this subject. These are-spoU, or circles of luxuriant green grass, some times two-or threeyards in circumfeience, sometimes the same in diameter.. They have attracted the attention of men of science, and' various hypothesis have been suggested to account for/them. Dr Wollaston and Professor Way have at laat settled the controversy. It is now generally admitted that fairy-rings result from the centrifugal development of a certain fungi. The spot where it at first takes root becomes unfitted fon itssupport, and the spawn extends outward from a centre to new soil, unfitting that soil to which it extends for the immediate nourishment of grass, but enriching it afterwards by" its own decay — the decayed fungi, containing not a little of" the phosphate of potash, is a high stimulant for grasses. It is believed by many that this fungi does not occupy the same ground more than one year before it exhausts the soil of all the nutriment it contains for the nourishment of the iungi,. but the preparation of the land for the increased production of grass, by its deoayed substance, is somewhat wonderful, it can be seen for very considerable distances, and stock «eem to enjoy it, for it is always eaten close to the ground, and yet it retains its verdant hues. In conclusion on this subject I would remind those who are interested in this question, that there can rtmain. little doubt in the minds of any who take the least trouble to investigate, that it is of the highest importance to change crops every season, and in making that change it is necessary to bear in mind the fact some crops borrow largely from the atmosphere, and others very little, the alternate growing of suoh crops muat be advantageous, that by so doing they are veering towards that system which will enable them to obtain the greatest amount of vegetable produce with the least manure, and in the shortest possible time.