In addition to the constituents tabulated above, this soil contained .105 per cent. of calcium nitrate and .086 per cent. of magnesium nitrate. To the presence of these hygroscopic nitrates and the chloride of magnesium the sweating tendency was most probably due. CRADOCK. No. 94, collected at Roodewal, was a light yellow very clayey Karroo soil which had been under cultivation, but, though kraal manure is generally used in the district, this particular soil had not been manured and is said to have yielded poor returns of wheat and oats. The surface soil was 18 inches deep, with 8 feet of greyish friable sub-soil below. Water from the Pauls River had been used for irrigation, and white alkali spots are said to have been noticed on the soil at times. The analyses resulted as follows. No. 95 was collected on the farm Eerste Verlies, on the Vlekpoort River, and was intended for lucerne cultivation. The analyses of these two soils resulted as follows: No. 94 yielded .102 per cent. of total soluble salts on extraction with distilled water. A partial mechanical analysis gave the following figures: This soil, which was apparently derived from weathered slates, furnishes an instructive example of the manner in which a soil containing satisfactory amounts of the different plant foods, and therefore apparently all that can be desired from a chemical point of view fails in productiveness because the physical condition of the soil is defective. In this case the soil, though rich in lime, magnesia, and potash, together with quite satisfactory proportions of phosphates, gave poor results, obviously on account of its stiff, clayey nature. It seemed to require opening up more than anything else. It is true that the amount of nitrogen was low, but admixture of organic matter could remove this defect. The ploughing in of green peas was recommended with this object, as well as the addition of straw or stable manure to open the soil, permit of easy access of air and moisture, and so improve the general texture of the soil and so prevent its caking, which is highly detrimental to plant growth. The soil represented by No. 95 is well supplied with lime, but is poor in the other constituents of plant food. As the land was to be used for lucerne growing the application of phosphatic and potassic fertilizers was advised. EAST LONDON. Of the fourteen Gonubie Park soils (Nos. 96 to 109), Nos. 96 and 97 were respectively a surface soil and its sub-soil from the experimental camp. The next six soils were taken from the Gonubie lands; of these Nos. 98 and 99 were respectively a light surface and sub-soil. Nos. 100 and 101 were similarly a surface soil and its sub-soil from the south-eastern corner of the lands, and Nos. 102 and 103 surface and sub-soil respectively from the south-western corner. No. 104 was a surface soil from the orange lands, and No. 105 its sub-soil. The remaining four soils of the series were collected from Barber's Kloof, Nos. 106 and 107 being a surface and sub-soil respectively, taken at the drift, and Nos. 108 and 109 a surface and a sub-soil taken 100 yards south of the drift. At Barber's Kloof there is a very remarkable shell deposit, extending over probably five or six acres at depths varying from six inches to three feet from the surface. The usual agricultural chemical analyses yielded the figures shown in the following table: Partial mechanical analyses of these soils resulted in the figures given in the following table: Nos. 96, 97, 98, and 99 are deficient in all the mineral plant food constituents. No. 100 is poor in lime and phosphoric oxide, and No. 101 in the latter constituent only. A fair reserve of plant food is contained in Nos. 102, 103, 104, and 105. The presence of shells renders the soil from which Nos. 106, 107, 108, and 109 were collected very rich in lime, but potash is deficient in all four of those soils. The coarser residues of the mechanical analyses were largely made up of shell fragments in the case of Nos. 108 and 109, and entirely so in the case of Nos. 106 and 107. HANOVER. In connection with an irrigation project on the farm Krugers Poort, the soils represented by Nos. 110 to 129 were sampled from the area which it was proposed to place under irrigation. The farm is intersected in an east and west direction by a large dolerite dyke, and it was in a gap in this dyke through which a branch of the Seacow River flows that it was proposed to construct the dam. Four holes were dug to a depth of five feet at different points within this irrigable area, and from each hole five 12-inch samples were collected. Nos. 110, 111, 112, 113, and 114 represent the successive soil levels at one of these points, No. 115 the surface soil, and Nos. 116, 117, 118, and 119 the lower levels at the second hole, and so on. The object of the analyses was to ascertain whether any unsuspected layers of brack exist in the soil, which, under irrigation, might rise to the surface, and in course of time result in such an accumulation of alkali salts as to render the surface soil too brack to yield profitable returns. The following analytical results were obtained, the alkali and other soluble salts being expressed in percentages of the soil as sifted through a 3 mm. sieve. ⚫010 116 215 .682 .210 1.107 Nil Nil .113 Nil Nil .028 1.248 1.308 596 Nil Nil .088 Nil Nil .026 .710 .724 126 .012 .010 Nil 127 ⚫011 ⚫015 Nil .027 .004 Nil Nil .050 128 .011 .014 Nil ⚫025 Nil ⚫022 Nil Nil Nil .043 .092 129 ⚫013 .005 Nil ⚫018 Nil ⚫013 .004 Nil Nil .041 .076 .082 .007 Nil Nil .049 ·095 094 117 .124 .090 With regard to the presence of brack salts, there seems to be no ground for alarm in respect of the localities represented by the surface soils Nos. 110, 120, and 125, the total soluble salts in the first five feet of soil at those points being considerably below danger limit, sodium carbonate (black brack), moreover, being absent. At the spot indicated by No. 115, on the other hand, a very different condition of things exists; there the alkali salts are present to such an extent as to impede plant growth, and a large quantity of these salts has been concentrated in the surface layer of soil. This portion of the area is distinctly brack, although it is possible that it may be improved, provided efficient under-drainage is capable of being carried out. Hilgard considered that, even for barley, which is more resistant to alkali than wheat, the total alkali salts in the surface four feet of soil should not exceed 2 per cent. At the locality in question this limit is exceeded more than sixteen times over, and for lucerne cultivation it is certainly excessive in its present condition. HERBERT. Nos. 130 to 132 were taken from different holes made to a depth of eight inches on certain lands proposed to be placed under irrigation by means of a pumping station from the Vaal River. Nos. 133 to 138 were taken from two points on the same farm, from a place where what were regarded as white incrustations appeared on the surface of the soil. Nos. 133, 134, and 135 represented respectively the surface, second, and third twelve inches at a point three-quarters of a mile from the river. Nos. 136, 137, and 138 were taken at a distance of 500 yards from the river, also from the three successive twelve-inch layers in depth. Nos. 139 and 140, from the farm Smithfield, Ward No. 2, were respectively a soil and a sub-soil, both reddish brown and clayey. These soils were taken from a level stretch of country where the a of soil averages seven to eight feet, and on which the indigenous ve tation is Karroo bush and ganna. Within two miles of the spot whene the samples were taken is a saltpan. The land had been irrigated from dams and had received one application of kraal manure during the last five years; with good irrigation mealies and oats had been successful, but the soil lost its moisture rapidly, resulting in a wilting of the crops. Three samples of soil, Nos. 141, 142, and 143, were collected on the farm Mazelsfontein, in the Douglas District, from a tract of twenty-two acres which had been sown with lucerne. The beds had been well laid out and had a fall of five inches in 250 yards; nevertheless the crop failed to make progress. The upper surface of the soil was apt to dry out very rapidly under the action of the burning sun and the drying winds. No. 141 represents a reddish-brown soil, containing a considerable proportion of clay. No. 142 was a similar soil, but with apparently rather less clay. No. 143 was less clayey than either of the other two, and of a less pronounced red colour. Partial mechanical analyses gave the results shown in the following table: The usual determinations associated with the reserve of plant food in the soils resulted as follows: Partial analyses, with a view to gain some information as to the amount of alkali (brak) salts in the above fourteen soils were made. |