Na 2 O 11 5 4 4 K 2 O 58 10 7 5 MgO 92 33 19 7 CaO 134 17 14 11 P 2 O 5 7 1 7 3 N 44 11 13 16 S 13 7 7 6 Fe 2 O 3 341 155 111 46 By chemical and mechanical analysis, the chief component parts per 100 parts of air-dried soil are Clay 46 29 12 10 Sand 40 67 86 84 Organic matter 3·7 1·7 0·6 4·1 Hygroscopic water 6·3 1·3 0·8 1·9 Weight of a litre in grams 1150 1270 1350 960 The black earth excels the other soils in many respects, but naturally its stores are also exhausted by cultivation if nothing be returned to it in the form of fertilisers; and the improvement of a soil (for instance, by the addition of marl or peat, and by drainage and watering), and its fertilisation, if carried on in conformity with its composition and with the properties of the plants to be cultivated, are capable of rendering not only every soil fit for cultivation, but also of improving its value, so that in the course of time whole countries (like Holland) may clearly improve their agricultural position, whilst under the ordinary régime of continued exhaustion of the soil, entire regions (as, for instance, many parts of Central Asia) may be rendered unfit for any agriculture.
— from The Principles of Chemistry, Volume II by Dmitry Ivanovich Mendeleyev