COXSTITLESTS OF SOILS.

Otago Witness, Issue 2848, 14 October 1908, Page 9

COXSTITLESTS OF SOILS.

A few yeare ago the late Emil Raul in, a French experimentalist, completed a long st-ries of experiments which' had been conducted eino 1890 at Pierre Booite, in France, with the object of ascertaining in what proportions the chief constituents of j foils — clay and sand, chalk and humusshould be present in a combined form in order to produce a maximum crop of the chief plants of the farm. Four plots of land, each an "are" in extent (an are being the one-hundredth of a hectare of two an<l a -half a?res), were selected. They were respectively very candy, very chalky, heavy clay, and i black soil full of hnmus, I ai:<l tLov contained tho following proportions of ihe manurial constituents of scii^-.

It vHI be noticed that the last set of figures thDAw the constituents of the mixture of the four M>iis, all a<lde<J in •equfl \olume, not jn weight, and this for ihe purpose of comparison. In every ca-=e each plot of land was di\id-ed into two parts of equal tiz/?, and on every plot .mangel wtirzel was grown in tlie first year The weight of ihe bulbs on the ea.nd wa-3 10^ tilo grammes in round numbers, on the clay 11^. on the chalk soil 196, and en tlie black or peaty coil 165. while on the mixed soil the weight reached 295 i kilogrammes — a kuo being 2 l-51b. In the next year the crop was potatoes, which i\erc p.lanted in the spring, followed by wheat in October. In the year after the crop was mangele, and this was followed by clover, which remainet? down ii> 1895. In every case a plot was manured to one-half its extent with artificials, while the other half was unmanured, the artificials consisting of sul-p.hat-e of ammonia, potash, and- precipitated

. ) i' phosphate; but in one year, 189+-5, tho ' sulphate was omitted. The following ' j figures will show tho quantity of the vari- 1 j ous crops which were grown on each kind 1 of soil as well a« on the mixture in tho j yeais which have been enumerated: —

{ If th* total crops of each variety for the 1 four different soils are averaged, with or without manure, and compared with the crops grown upon the- mixed coils, the following reeultd^pill be found: — 1 • / I

I It will . be noticed that the results ob- j tain«d upon the- mixed! goils^ with and with- j out maamrp, instead of being the averages i of those grown upon the individual coils, I were in o-n-e case more than double and in tJi« j othar nearly, double. Thus we awive at an (^example ; of what can bo learned from 1 Nature. ' Sand makes a clay workable, I pervious, and warmer, prevents it from~ ; baking, and allows the root hairs of the j plants to travel in search of focd ; clayv I makes a sandy soil more homogeneous and stable, it holds the water as far a® necessary, sr-d provides plenty of substance to the soil ; peat provides humus in abund- ! 1 ance, a«d consequently 1 rJtrogcn, while it ', also holds water ; it ' makc'3 the soil per- ; ■vious. workable, and Tight, and, further, ir assists in warming it during the process of tJecomposition. A chalky soil gives i not only a. mechanical help, but provides i food and assists in retaining moisture. Inj deed, each elacs of soil of ireelf provides • something, but when all are mixed together , in equal volume, not in weight, one helps | the other, with the result that we get an ! almost perfect soil. If a man is farming heavy clay he does ail its can to maka it lighter by employing sand, ashes, road scrapings, and even burnt clay itself. But this is not all ; he supplies it with humus by growing clover and ploughing in the roots, or mustard or vetches, and ploughing in the crops; but he can only supply { 1 ime by ad-ding abundance of chalk or regularly distributing lime itself.. : The increase of the yield of crops grown i with the- assistance, of manure, 10yond that which was grown without any manure vhat- ! ever, is shown by the following table: —

Thus is seen the importanoe of the Irish plan, of adding artificial manures to peat, j which, uuliko the other soils, requires farniyai'd manure much lose in proportion and responds much better to nitrogen and phosphates in artificials. And the came remaik almost equally applies- to tho J growth of mangels and clover on chalky I (=oile\ No experiment, however, is needed ! to demonetrato that similar quantities of , th<! came manures distributed on the dif- ' ferent soils command the same results, and j i it i% for this reason that great •diserimina- j I lion is needed in selecting artificials which , suit the soil the farmer occupies. In ont ' r-e^peet the inequality of the fertility of the j different £oil= is owing to two causes — ■ the inequality of the quantity of the ferj tilioinjr matter present and the unequal power of appropriation of the food it con- , tains by the* plants themselves. It does not fellow that because a soil contains manure it is all available. One reason is owing 1 to the difficulty which the plant roots experience in travelling in eo&rch of fotxl, as in a heavy clay, and another is in the want of moisture, which precludes a plant absorbing the food which may possibly be abundant. In the case of the Randy soil the feeding matter may possibly I have been, carried into the subsoil by the I rain, and so out of the reach of the roots of tho plants, while in dry weather a tenacious soil may be 6O dry that the manure distributed upon it has not been carried to a. sufficient depth to reach the plant { root*. — " Merlin," in the Field.

Sand .. Clay Peat Calcareous Mixture o ie.3 24.4 43.7 27.3 26.4 c* « tsDm 3.2 47 5.0 11 14.5 22 16.8 84 10.0 93 1.2 10.05 9.10 41.00 61.14 37.00 I-P-2 i •3 a I 19.11 ! 12.40 I 30.30 47.31 41.Q0

j3S 8 ft Potatoes oh« *• h« h Kilos. gg; SS Wheat. bo i- 1 io lvilOs. IOK) HP,, . O O V io bi u-IJOS. > w p pa 5> UloV€r. 0 M (0 09 IVIIO3.

few £ w (r < llfilllplllill toS otto Kio J3S> ckh : O I*. o w en io o '*• io en Potatoes, 1891. Kilos. pi Si pi to . jo -j <i n> tn ps og kob en - bten ©to ■ O CM *■ (0 IO <1 M JO M tO Total crop. <j Kilos. g Total grain. ?t Kilo ? . to to i-" io to to ' iZo qm4 wsi os-i Sen Mangels, 1803. Kilos. SS gg gg gg S;§ Clover, 1894-5. Kilos.

Phosphoric 2Citro£eu. Acid. Potash Per 1000. Per 1000. Per 1001 Clay soil .. .. 0.377 1.359 1 742 Sandy =oi!.. .. 0.145 1239 0.226 Black soil .- .. IS-860 0 592 0 601 Calcareous soil.. 0.200 1480 0120 Mixture 2.320 1.469 0.C28