DEEP PLOUGHING OR DEEP STIRRING.

Timaru Herald, Volume XC, Issue 13278, 6 May 1907, Page 3

DEEP PLOUGHING OR DEEP STIRRING.

"New Zealand Fanner.") It is essential to discriminate clearly between deep ploughing and deep stirring. There is a viotl difference between the two; so much so, that whereas, perhaps, not one farmer in a hundred, could, from his practical experience, urge lh? adoption of the former, there must be very few who could not conscientiously speak favourably of the beneficial; influences rf the latter." Much of course 'depends upon th; nature ofthe land, and particularly of the sub-soil, but tli3 stirring of the In iter to the depth of even 2in or Zin. b:lojv ihe ordinary furrow can rcaicely fail to have a rse f ul eifsct in promoting the: prosperity of the succeeding crop;, for {he reason that by breaking up the plough pan. r.nd rtherVise loosening the subsoil it enables- the plant roots to extend over a. larger area and with !c.<v> exertion in search of nutriment and moisture. Obviously it- must, be a very friable subsoil that would nob derive benefit from deep stirring at occasional intervals. The objection to desp ploughing, on the other hand, is that, instead of loosening the subsoil and leaving it where it was, it brings it to the surface, and involves the burying of. the mor°. fertile tcp soil to a depth at which the nutriment it contains is available only to the plants affcfr tl'ev may be-said to hiv- Vroerged from the delicate and pr a cari' l "s stages of development. The r.-°.w soil that is brought to the top would in course of time no doubt becom? as mellow in texture and as rich in the elements of plant food as that which it has displaced, bi;t a certain pc-riod must elapse before thii ran be accomplished, and in the meantime the farmer who brings this hungry soil to the surface incurs the risk 1 of reaping inferior crops until, by heavy expenditure in tillage and liberal manuring, he has enriched and refined tho new surface soil. Deep ploughing, therefore, is in average cases to be avoided for the two-fold reason that it involves diminished yields and increased expenditure to tho farmer for at least a rotation.

Scientifically, as well as praotically, the bringing, up of the subsoil to the surface is a disabva-ntageous proceeding. As is now generally 1-flwon, tbi fertility aind yielding properties of a soil nre largely regulated by the action of useful bacteria therein.. But for the presence and activity of tie various micro-organisms in the land, /crop production would be unprofitable, if not impossible, and, consequently bacterial life may be said to- constitute the veiy essence of fertility. Having regard in this fact, it is necessary, in relation to> the question under notice, to consider the conditions that are m n st conducive to bae'erial activity. Scienti: ts are unanimous and definite on tJ>e point-. Nmnsrors searchinsr investigations have shown that .the fertilising bacteria are much, more plentiful in the. surface nr th?. regularly cultivated {oil than in the lower s'rat.a. Therefore, the importance of refining the foil that teems with bacterial lire on the surface is evident- and indisputable. If this soil, in which the bT.r'Vial micro-organ-isms are cons'antly fulfilling their iridis.per.snble functions, is buried beow soil in which bacteria are comparatively scarce, it is clear that unfortunate confeqrences result- On the whole, it must be evident- that deep ploughing is an unprofitable and highly inadvisable proceeding on ordinary' soils, but, on the other hand, subsoil" stirring' may .be of appreciable benefit under normal conditions.