HUMUS IN SOIL

Wairarapa Times-Age, 29 July 1939, Page 3

HUMUS IN SOIL

HOME FOR BACTERIA. LUPINS AS GREEN CROP. Lupins are of value for building up fertility, particularly on light and sandy soils naturally deficient in humus or vegetable organic matter. Not only do they add humus and readilyavailable nitrogen to the soil, but when they are turned under as a green crop they alter the texture of the surface soil, enabling it to retain moisture at and near the surface, where plant roots can utilise it. Humus, nitrogen and moisture are the most valuable ingredients in a porous soil. Humus, alone, provides a home for soil bacteria, which, in life and death, provide an abundant supply of available plant food. Unlike most other legumes, lupins will also grow reasonably well on soils deficient in lime, and hence are Valuable on acid soils which it is desired to build up as cheaply and quickly as possible. Sowing can take place in early autumn and a heavy bulk of sappy greenstuff will be ready for turning under in spring in preparation for a spring-sown crop. Once lupins have been ploughed under on light and sour soils, it is safe to apply a dressing of lime to correct the acidity, after which almost any crop can be grown successfully.

Blue lupins, and also a non-alkaloid variety of yellow lupin recently developed in Germany, make excellent sheep fodder. In many instances light and poor soils can be profitably built up by passing the crop through the stock in this way. There is little doubt that a great area of light country in this Dominion could be cheaply and profitably brought into rich productivity through the utilisation of lupins.