A SOIL'S REQUIREMENTS.

Auckland Star, Volume LIX, Issue 237, 6 October 1928, Page 6 (Supplement)

A SOIL'S REQUIREMENTS.

The four essentials which are necessary to he present in all soils are nitrogen, phosphoric acid, potash, and lime. It is largely owing t6 the quantities present of each of these in the soil that, regulates its< degree of fertility. Ihese four essentials are taken up in varying quantities, by different crops; and. it is to supply the resulting loss that artibcial manures are used.' It. should be remembered'that should one or. more of these not lie present or bo in .too small quantities the soil' becomes' infertile until the shortage of the one or more be made'up. For instance, a soil may be rich' iii everything but nitrogen, aiid yet o\vin»- to "lack' of this be infertile. This is known as of the Minimum," and can be stated briefly thus: "Plant development is regulated by the •available supply of that essential plant food-clement that is present in the soil in the least amount." . ;