PHYSICAL ANALYSIS OF SOILS.

Otago Witness, Issue 2815, 26 February 1908, Page 9

PHYSICAL ANALYSIS OF SOILS.

Whi'-e phvsuvl analysis of soils recognises but eight division?, classified from the size of soil grains, the direct application to the field will show a great many more factors, since other considerations are in effect here, as the humus content, the arrangement of soil grains, the lay of the land, the ancestry of the soil, and the climatic help or hurt. ~ The force of this is shown where humus is added to a soil. You find two soils alike in every way. Add humus to one — the texture is changed, the water-holding capacity is increased, the productivity is made zreatei. You have not changed the size of the soil grains, the basal principal of type remains the same. Another example: Take two sand soils, of the same basal type precisely, the iomporents in both instances being the same. One is located in a section where the rainfall is abundant and where it is frequent. The other soil in a section where just tha opposite- extremes exist. It follows, without .lis'cusaion, that, other conditions being present — fcod 1 , warmth, seed, and culture— the moist soil will generally produce a satisfactory ciop and the dry 6oil an unicmuneiative crop.

W»s rfeceive assistance when we know soil types, for we have a helpful guide hoie at hand. But we have no positive rule to follow in the selection of crops -eve shall grow With more study, nith more investigation, we may in future year 3 predict with greater safety the behaviour of soil under cultivation and when given pertain crops that seem to fancy these special types best Bear these things in mind : (1) That sand areas, Trrhcn properly reinforced with humus, water, and vlamt food, are peculiarly adapted to ail kinds of truck crops ; (2) that early truck crops are more safely produced when a maximum of eand ana a minimum quantity of clay prevail; (3) that general ox la*© truok <jn>P s •*© mOst "afelj Pro-

duced when the eand type carries the minimum of the coarser and the maximum of The finer sand grades ; (4) that fruit-grow-ing calls for considerable clay as a part of the sand type : (5) that the best corn crops are produced where neither sand nor qU? predominates — the silt materials prodt.<AKy ihe best results ; (6) that the general grain crops are best suited when furnished with a silt type of soil ; (7) that wheat is most at home in soils where fine silt and clay predominates; (8) that grass fancies mofcr those soils that carry a high percentegc of day ; (9) that, potatoes prefer a sand type wheie medium sand prevails, where silt is present in a, medium quantity, and where clay is present only in moderate quantities : C 10) that with those special types must be included good tillage, humus, air, moisture, aud plant food.— -Professor Burkett on soils.