H.—34.

A few elevated rolling areas have survived the general dissection. Erosion is not so pronounced as 011 the southern continuation of the belt near Kuripapanga. Rainfall ranges from about 55 in. to 70 in. Where it is over 60 in. rimu-matai forest takes the place of fern and scrub and imparts a higher natural fertility to the soils, which are otherwise extremely poor. Access to the area is poor, and the steep or elevated rolling, fern, and scrub-clad landscape is rarely varied by paddocks in permanent pasture. (2) The central easy rolling country is a belt about four miles wide trending north-east and centred on the Napier-Wairoa main road between Tutira and Putorino. The contour is again determined by gently tilted sandstones and mudstones with a little limestone or conglomerate, broken by deep gorges, and covered by the Gisborne shower* (and earlier pumice ash shower ejected from Taupo). The rainfall ranges from 50 in. to 60 in. Practically all the soils are reputed to be " bush sick." The new Napier-Wairoa railway runs through the middle of this belt, containing many thousands of acres of easy rolling ploughable soils, the great bulk of which is in fern and scrub. These soils are of low natural fertility, but have an excellent physical condition. (3) The coastal belt of moderately steep to steep country is formed of strongly dissected beds of mudstones, sandstones, and limestones. The coating of volcanic ash in this area was originally thin and has now been almost completely removed, so that the soils are derived from the underlying rocks and bush sickness is not recorded. Rainfall is less than 50 in. and pasture has replaced the former fern cover. The fertility of the soils in the natural state is relatively much higher than that of the other belts, but as a rule they are not ploughable. In general, it may be said that in the Napier-Wairoa area the country is largely covered by a blanket of volcanic ash, thick towards the west and north-west, but gradually thinning eastwards until in the coastal area it has disappeared ; that the fertility of the soils increases as the volcanic-ash deposit becomes thinner ; and that most of the ploughable country lies in the middle portion of the district. Classification of Soils. In earlier reports the normal soils of Hawke's Bay —i.e., soils other than those derived from limestone or volcanic ash —were tentatively called podsols. Podsols are soils that are well leached of their fertility elements, and those soils on which this process is far advanced generally present some difficulties in their development. But Hawke's Bay soils are treated somewhat unfairly in being so classed, for if one or two of the plant-foods which are low are supplied they can be ranked as very suitable for pasture. The soils are not well leached owing to their original high lime content and are tentatively placed in I New Group." Following the American classification, stages are recognized in the group according to the amount of leaching the soil has undergone. The names formerly given to the soils are placed in brackets. Description of Soil Types. New Group. (a) Recent (skeletal podsol) soils have profiles consisting almost entirely of unweathered parent material. They are so youthful that clay or other material has not had time to be washed down from the surface to the subsoil, and no horizons can be recognized in the vertical profile other than, say, discolouration of the topsoil by humus. They are thus developed only on recently deposited alluvium in valley-bottoms or on steep hillsides where periodic slipping allows constant renewal of the soil profile. In the area discussed they are developed from mudstone rocks on very steep hill slopes or valley walls, so that, although common throughout the area, they occupy only a small acreage on the map. (b) Young (immature podsol) soils are a little more weathered than recent soils. A small amount of clay has been washed down into the subsoil, which is slightly more compact. They are also developed on steep country from mudstone of sandstone rocks. They occupy about 15 square miles in the Tutira-Putorino district, and about 5 square miles in other areas. The mudstone soil is of high natural fertility, having a base saturation! of over 60 per cent., and is near neutrality in reaction, but is subject to constant slipping and in low rainfall areas dries out badly. The sandstone soil has not previously been described. A profile is : — 6 in. heavy sandy loam, black, free. On very heavy sandy loam, creamy-yellow, more compact. It is derived from marine pumiceous sandstone and is much less fertile than the mudstone type. It dries out to a greater degree. (c) Immature (mildly podsolized) soils are moderately weathered, and have a distinct clay accumulation in the subsoil, which is often fairly compact. They have developed sufficiently to enable the processes associated with the New Group to be detected in the soil profile by field and chemical .evidence, as indicated in the last annual report. A leached, somewhat greyish or yellowish, horizon appears below a humus topsoil. Immature soils are most common in the coastal belt, where they occupy about 150 square miles west and north of Napier. The main soil type is developed on moderately steep unploughable slopes from marine pumiceous sandstone. A profile is : — 6 in. sandy loam (heavy), greyish-black. 8 in. sandy loam (heavy), creamy-grey to light brown. On sandy clay loam, dull yellowish-brown. This type occurs on country not as steep as the immature type developed on the same parent rock. It is low in natural fertility (though much higher than the ash soils), the available phosphate being low, although the percentage base saturation is fairly high. It dries out badly, however. Sheet and other forms of erosion are active, and will be discussed later. Because of their marked influence on * See p. 58 for the definition of the Gisborne Shower. f Soils with a base saturation of 60 per cent, are generally regarded as very fertile.

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