Strampelli (1907) tested the effect of manganese dioxide, carbonate, and sulphate, and of a manganiferous mineral from the Argentine upon wheat, and found that while all four substances exercised a favourable influence on the vegetation, the best result was obtained with the sulphate. When however other manures were used in conjunction with the manganese compounds the balance of improvement shifted. With nitrogen, applied as nitrate of soda, manganese dioxide proved the most beneficial, with farmyard manure the manganiferous mineral[14], and with blood the carbonate. It was also found that a manganese compost did not increase production when phosphatic manure was applied as basic slag. [14] As no analysis of the mineral is given it is obviously impossible to say to what constituent the increase is due in this case. Feilitzen (1907) indicated that the nature of the soil plays its part in determining whether manganese acts as a stimulant or not. His experiments were made in the field on poor moor soil, which carried a little Sphagnum turf and Eriophorum, and which was poor in food salts. The soil was prepared and manured and then the plots were watered with a solution of ·1 gm. MnSO₄.4H₂O per litre at the rate of 10 kgm. sulphate per hectare, six control plots being left untreated. Oats were sown and the soil rolled. During growth no difference was noted between the various plots, and after harvesting the weights of the different crops showed that the manganese had not caused increase of crop in either grain or straw on this poor moor soil. The great bulk of the work on this problem has been carried out by various Japanese investigators, whose work extends over several years. Loew and Sawa (1902) found that small quantities of manganese sulphate in soil cultures stimulated the growth of rice, pea, and cabbage. They suggested that soils of great natural fertility contain manganese in an easily absorbed condition, and that this forms one of the characteristics of such soils. Nagaoka (1903) dealt with plots in the rice fields which had not been manured for the three previous years and which were then treated with manure at the rate of 100 kgm. ammonium sulphate, 100 kgm. potassium carbonate and 100 kgm. double superphosphate per hectare. Twelve series were worked in triplicate and received manganese sulphate in varying quantities, equivalent to 0–55 kgm. Mn₂O₃ per hectare, one set of three being left untreated. The cultivation was normal and the application of manganese was found to influence the yield of rice. 25 kgm. per hectare gave the best result and increased the harvest of grains by one-third; higher doses of Mn₂O₃ gave no better crop. The percentage of grain relative to the straw was also increased. The increase in both respects was evident all through the series from 10 to 55 kgm. Mn₂O₃ per hectare. The conclusion was reached that the application of this salt to soils poor in manganese would be a commercial advantage.