Vol. X. No. 238. 



THE AGUICULTUEAL NEWS. 



183 



Ooveriuiient would seem likely to take stops to hasten its 

 development. It is stated tliat the Govi'iiiment will grant 

 subventions annually to syndicates undeitaking cotton-gi ow- 

 ing; at the same time the Xoi-th Eastern States ure lieing 

 opened u}) by an e.\ten.sive network of railways, and irriga- 

 tion works are in progress. In Alagoas and Pernambuco 

 especially, the Great Western of Brazil Uaihvay Company 

 is opening up important cotton-gniwing districts. The 

 Government has founded an e-\periuientat stalicn in 

 Maranham. 



Cotton fields as known in tlie United States and other 

 countries are not to be found in ISi.'izil, \\here cotton is, as 

 a rule, grown by small fanners in conjunction with other 

 crops, such as maize, beans and mandioca, the cultivation 

 being of a primitive kind. Progress is retarded chiefly by 

 lack of capital and also by the absence of skilled labour; the 

 (government have recently contracted with some United 

 States experts to visit the plantations and give practical 

 instruction. Progress is retarded also by the want of improved 

 machinery for the cleaning of the cotton; most of the ginning 

 machinery in the north of Brazil is antiquated, and the fibre 

 suffers in consequence. 



In states such as Ceara, which aie devastated by 

 drought, cotton is being grown on fields watered almost 

 entirely by irrigation, and seed imported from Egyjit pro- 

 duces cotton which sells in Liveri)Ool for almost the .same 

 prices as that from Egypt. {The Board of Trade Journal, 

 Vol LXX, p. 600.) ■ 



OXIDATION IN SOILS. 



One of the most recent publications of the Bureau of 

 Soils of the United .States Department of Agriculture, namely 

 Bulletin N^o. 3 entitled Studies in Soil U.ridation, contains 

 the results of work that has been undertaken for the pur[)ose 

 of determining the ways in which the addition of oxygen 

 to substances in s^-''^ takes place. A ?unimary of the con- 

 clusions shows thau different kinds of oxidation have an 

 important share in both the mineral and organic changes 

 that take place in soils. It is the purpose of the following 

 abstract to draw attention to the chief matters in this 

 summary. 



Boots in soils were shown to have the power of pixiduc- 

 ing either oxidation or its opposite, reduction, these kinds of 

 action being capable of taking place together and being 

 dependent on the state of the soil. Demonstration was also 

 made of oxidation within the soil itself, and it is stated that 

 this appears to take place mainly without the interference of 

 living organisms, as the result of actions between inorganic 

 bodies in the soil and certain types of organic matter, as well 

 as by those of inorganic or organic suljstances alone. This 

 kind of oxidation was found to be increased by the addition 

 of salts of manganese, iron, aluminium, calcium and mag- 

 nesium, especially in the presence of such acids as citric, 

 tartaric, malic, glycollic, or their salts. Manganese salts gave 

 the best oxidation, and this is stated to provide an explana- 

 tion of the stimulating action of .such salts used as manures, 

 where the manganese acts by improving the conditions in the 

 .soil, rather than by possessing a nutritive value itself. Salts 

 used as manures may increase or decrease the power to 

 cxidize of the .soil; and some kinds of organic matter reduce 

 this power, although the presence of such matter in plentiful 

 amounts generally increases it. In regard to the plants in the 



soil, excessive oxidation is harmful. Another matter that 

 was found with respect to salts used as manure was that they 

 increase the oxidizing power of roots, and the soil that has 

 been treated with them has a greater oxidizing power after 

 the crops have been removed than it possessed before they 

 were grown. 



Evidence is adduced to .show that soils oxidize substances 

 in much the same manner as this is done by the oxidases, and 

 as these substances play an important part in the life-processes 

 of pilants, it is easily seen, from analogy, that the power of 

 the soil to oxidize forms a measure of its ability to support 

 plants. This leads to the final conclusion in the bulletin, 

 namely: 'Whatever decreases the oxidation in soils tends 

 also to bring about the conditions which decrease growth, 

 and the factors which favour o.vidation are the factors which 

 favour soil productivity.' 



THE INFLUhlNCB OF RADIOACTIVE 



SUBSTANCES ON PLANTS. 



A paper giving information relating to this subject is 

 contained in the Journal of the Department of Ai/riculture, 

 Victoria, for JIarch 1911, p. 1.5.5. It points out that the 

 large amount of work that has been done already in connexion 

 with the matter has not taken cognizance, for the greater 

 part, of the kinds of radiation, or of the possible difference 

 between the action of direct contact of the radium emanation 

 from radium itself and from radioactive minerals. This pro- 

 bably accounts for some of the variations in results obtained 

 by different investigators. 



The award of a Government research scholarship under 

 the Department of Agriculture of A'ictoriahas enabled definite 

 work to be done on the subject during the past year. Before 

 the results of this are given, attention is drawn to the fact 

 that investigators have generally found that intense radia- 

 tions of the kind cause the death of plants, while, when they 

 are less intense, they bring about a stimulation of the growth, 

 thus possessing much the same effect as plant poisons. The 

 latter fact suggested that it woulil lie of interest to deter- 

 mine: 'whether the addition of small (quantities of radioactive 

 minerals to the soil would sufficiently stimulate the growth 

 of such plants as wheat, for example, to make their use profit- 

 able on an agricultural scale.' For the purpose, finely ground 

 and strongly radioactive rock was applied to ditt'erent plots 

 of wheat singl}', as well as in conjunction with superphos- 

 phate, and finely ground phosphate rock. 



In the result, the plants on all the plots were slightly 

 attacked by corn mildew (A'c/sv/^/^c yr((//(/uis), showing that 

 the [iresence of a radioactive mineral in the soil does not 

 afford protection to plants against parasitic fungi. In regard 

 to the effect on the yield of wheat, the results are not concord- 

 ant, and the experiments require repetition, but they seem 

 to indicate that the presence of the radioactive mineral in 

 fairly large quantities tends to increase the weight of the crop; 

 the composition of the mineral .shows that this effect could 

 not be due to any manurial value that it may have possessed. 

 The suggestive matter is that the greatest increase occurred 

 where the seed was placed immediately upon the radioactive 

 mineral. It is not possible, however, as has been mentioned, 

 to draw definite conclusions from the results of the experi- 

 ments, so far. Enough has been indicated to show, neverthe- 

 less, that ecfmomically useful results may ultimately be 

 obtained from experimentation of the kind. 



