1919] SOILS FERTILIZERS. 319 



imation of the salt survey by eye estimation. Tlie mean salt content of what 

 is considered good laud was about 0.3 per cent, of medium land 0.5 per cent, and 

 of poor haul about 0.8 per cent. Barren land contained any amount of salt up 

 to 25 per cent. Considerable quantities of both sodium carbonate and bicar- 

 bonate were found in the soils of the more northerly part of the Delta. The 

 close dependence of soil fertility upon altitude above sea level is also noted, 



Malayan rubber and coconut soils, M. Barrowcliff (Trans. 3. Internat. Cong. 

 Trap. Agr. 1914, vol. 2, pp. 410-^21). — The Malayan rubber soils are classed 

 us undulating land, flat land, and flat peaty coast land, the first and last being 

 the most productive. Mechanical and chemical analyses of 10 representative 

 samples of rubber soils showed the undulating s(-)ils to be of a light sandy 

 nature with perfect natural drainage, the flat soils to be of close and imper- 

 meable texture, and the flat peaty soils light and porous owing to their con- 

 tent of organic matter. 



The nitrogen and lime contents of these soils, while relatively low, seemed 

 sufticieut for the growing of rubber. No relation was established between 

 potash content and fertility. With the exception of the peaty soils, the soils 

 were markedly deficient in phosphates, this being apparently the limiting 

 factor. 



The coconut soils are mostly peaty soils containing much clay and organic 

 matter. " They are well supplied with nitrogen and with potash and phos- 

 phate, both in the total and ' available ' forms. Observations go to show lliat 

 if badly drained they are infertile; but that for coconuts the drainage need 

 be less deep and thtirough than for rubber." 



The effect of organic matter on soil reaction, II. E. Stephenson {Soil ScL, 

 6 {10 IS), No. 6, pp. Jil3-.'i3D). — Studies conducted at the Iowa Experiment Sta- 

 tion on the effect of albumin, casein, blood, starch, dextrose, alfalfa, and am- 

 monium sulphate on the reaction of a silt loam soil fairly rich in organic matter 

 and a sandy loam soil low in organic matter are reported. The treatments with 

 organic matter were made at the rate of 10 tons per acre. Alfalfa was applied 

 to the silt loam soil at the rate of 20 tons per acre, and ammonium sulphate was 

 applied in all cases at the rate of 1 ton per acre. 



It was found that none of the organic treatments increased the lime require- 

 ment of the soils. The highly nitrogenous materials rather bad the effect of 

 decreasing tlie acidity. This effect was very marked at the first sampling. 

 Ammonium sulphate, on the other hand, consistently caused a marked increase 

 in the lime requirement of both soils. The carbohydrate materials had a small 

 and inconsistent effect upon the soil reaction. Tlie highly nitrogenous organic 

 materials which diminshed the acidity tended to protect the carbonates of the 

 soil at the first sampling. Later, the same materials used up the limestone quite 

 completely in some cases and to a much greater extent in all cases than did the 

 soil alone. Ammonium sulphate, likewise, very consistently exhausted the lime 

 of the treated soils. The carbohydrates and the alfalfa had no more marked 

 effects in exhausting the carbonates than in inci'easing the acidity. 



Ammonification was greater in the absence of lime on both acid soils. A 

 difference in the soil flora is considered a possible explanation. Both casein 

 and albumin anmionified more rapidly than blood, which is of higher nitrogen 

 content. Ammonia did not accumulate in the presence of either carbohydrates 

 or alfalfa. 



Nitrification occurred most rapidly in the presence of lime. Nitrification was 

 slow in starting in the presence of the nitrogenous materials, except blood, prob- 

 ably due to a slight toxicity of accumulatetl ammonia and exhaustion of nitrates 

 caused by the multiplied flora. No nitrates were found in the presence of the 

 carbohydrates until the end, probably because they were consumed by the organ- 



