SOIL SURVEY

Wairarapa Times-Age, 19 July 1939, Page 3

SOIL SURVEY

INVESTIGATION OF WAIRAU PLAINS. RECENTLY ISSUED BULLETIN. Bulletin No. 72 of the Department of Scientific and Industrial Research by Messrs C. S. Harris and K. S. Birrell, Soil Survey Division, deals with the alluvial soils of the Wairau Plains in Marlborough. The survey of the portion of the Plains bordering the Wairau River from Blenheim up to the Wye River—a distance of 34 miles—was undertaken primarily for the Public Works Department which is reporting on the possibility of irrigation. From a map on a scale of one mile to an inch exhibiting the various kinds of soils by different colours the engineer can see the distribution of light, heavy, and medium soils. This is necessary information, for the amount of water and intervals of irrigation depend on the texture of the soil. At present the Public Works Department is making moisture determinations on selected soil types to find out over what period crops suffer because of lack of moisture. Of further assistance is the chemical analyses which allow comments to be made on the natural fertility of each type. Some of the soils near Blenheim are extremely fertile ranking with the highly productive soils of Hastings and Gisborne flats. Following a description of each kind of soil are notes concerning the farming. Although jnuch remains to be done in this direction there is sufficient to demonstrate that the class of farming is related to soil types, e.g., much cropping is done on some kinds of soils—a few are specially favoured for malting barley as s'ields in good seasons are particularly high.

In the final section of the bulletin the saline soils near the mouth of the Wairau River are described. The salt content of the soil types which are shown on a separate map ranges from small amounts, in those furthest from the sea, to large amounts, toxic for most pasture plants, in those near the sea. Improvement of conditions in this district, 'it is pointed cut can be accomplished only by the lowering of the level of the ground water, which contains soluble salts.