Vol. XIII. No. 327 



THE AGRICULTURAL NEWS. 



361 



EXPERIMENTS WITH GREEN MANURING 

 IN INDIA. 



Till' ini|iiirtaiife of green dressing is acknowledged by 

 every planter. Experiments tlierefore in green manuring, 

 carried out most carefully under tropical conditions in India, 

 should lie r>f interest to the readers of the Agricultural Neirs. 

 The following is an abstract of Bulletin No. 40, issued by 

 the Imperial Department in India, on Green Manuring 

 Experiment, 191l'-I3, carried out at the Agricultural Research 

 Institute, Pusa, under the supervision of Mr. C. M. Hutchin- 

 .son, Imperial Agricultural I'.acteriologist, and Mr. .S. ililligan, 

 Imperial Agriculturist. 



It is pointed out ' in the first place, that the decomposi- 

 tion of plant tissue in soil is carried out by a number of 

 various organisms, and that it would probably be wrong to 

 assiime that all soils contain equally the necessary organisms 

 for this ])rocess. The rapirlity of decay also depends largely 

 upon an adecjuate supj)ly of moisture for the needs of these 

 saprophytic organisms. Hence the decomposition of ycjunger 

 j)lants is more rapid than that of maturer ones under the 

 same conditions of rainfall. So that any shortage of rainfall 

 after burying a green leguminous crop would naturally tend 

 to diminish considerably its value. But apart from an 

 adequate water-supply, the complete decomposition and 

 nitrification of the green manure will depend on the proper 

 aeration of the soil. In the experiment at Pusa, sann hemp 

 buried in soil in which the water content was kept up to 

 20 per cent., but without stirring the soil, failed to decompose 

 after twelve weeks, whereas 16 per cent, of water was suffi- 

 cient to produce complete disintegration when the soil was 

 .stirred up once a week. 



As the full benefit of green manure does, hcjwever, 

 depend more upon the presence of moi^^ture in the soil than 

 upon any other factor, the experimenters at Pusa suggest 

 a preliminary treatment of the green crop before burying it, 

 so as to diminish possibly the degree of uncertainty resulting 

 from entire dependence on weather conditions. The general 

 method suggested is that the green manure crop should be 

 cut, steeped in water, and allowed to ferment in heaps, after 

 which it should be put into the land. It is promised that 

 the best method of doing this, and the relative cost and value 

 of such a procedure as compared with the ordinary practice 

 will form a future subject of investigation. 



In conclusion, a warning is given as to superabundance 

 of moisture in the soil after burying in a green crop. When 

 too heavy a rainfall has produced waterlogging of a soil 

 crintaining Ijuried green manure, and there is insufficient 

 drainage to remove such waterlogging with sufficient rapidity, 

 an accumulation of toxins may take place sufficient to do 

 serious harm to the following crop. Hence the necessity 

 for proper tilth and efficient drainage. 



Manganese as a Fertilizer. — A circular has been 



received from a local merchant, containing an account of 

 a new manure called 'Increaso'. This manure, according 

 to its characteristics as described, would appear to be 

 a substance containing manganese sulphate. The com- 

 munication states that large increases have been obtain- 

 ed from the employment of 'Increase' of, say, about 

 76 lb. per acre. For example, in the case of rice, an 

 increase of 34 per cent, of grain and 30 per cent, of straw 

 was obtained. As regards the nature of the action of this 

 new fertilizer, it is explained that it is probably indirect, 

 constituting an anti-toxic agent which destroys the poi.sons 

 said to be secreted by the plant in the soil. The price of 

 this manure is $70 per ton 



Reference to information oh manganese as a fertilizer,, 

 tiled at this Office, shows that manganese is likely to be 

 of some value as a inanurial agent. A u.seful review of the 

 subject is contained in Circular No. 7.5 of the Bureau of 

 Soils, United States Department of Agriculture. This refers 

 to increases that have been obtained, apparently in Europe, 

 with a large variety of crops. In considering the nature of 

 the eti'ect of manganese it is said that it is due most prob- 

 ably to its oxidizing activity, and its influence on the oxidizing 

 power of plants, micro-organisms, and soil. ilanganese 

 sulphate .seems to be the best form to use, though the dioxide 

 has also given satisfactory results in certain places. In 

 regard to the sulphate, another reference says that the value 

 of this salt rests with the sulphate, and not with the 

 manganese, this latter part of the salt being regarded 

 as actually injurious. Again, other information from 

 Hawaii, after referring to the great fertility of the manganese ■ 

 soils in that territory, maintains that the benefit is due to 

 the improved physical condition of the soil which manganese 

 has the power to bring aliout. 



In conclusion it would certainly seem that manganese- 

 fertilizers may be regarded as useful catalytic agents, by 

 which is meant agents which are able to assist in producing 

 beneficial effects without themselves undergoing any change 

 or playing any direct part in nutrition. It must be remem- 

 l>ered, however, that the general value of manganese has not 

 yet been established, and in certain places, for example in the 

 Tropics, it may have difterent effects to those produced, .say, 

 in England. At all events the considerations brought for- 

 ward in this note call attention to the need for more exten- 

 sive experimentation. It would seem decidedly worth while 

 to arrange experiments with a substance like 'Increase' in 

 certain of the West Indian islands. 



Humus in California SoUs.— Humus, which is 



produced by the decay of vegetable and animal matters of all 

 kinds in the soil under certain conditions of warmth and 

 moisture, is considered one of the most valuable ingredients, 

 of fertile soils, both because of its physical effect, and because - 

 of its nitrogen content, which is made available to plants by 

 the action of bacteria, and also because the mineral elements 

 potash and phosphoric acid held by it are of value as- 

 fertilizers. 



In a paper entitled Humus and Humus-Nitrogen ia 

 California State C!olumns, by R. H. Loughridge, published by 

 the University of California Press, August 2.5, 1914, there 

 is an interesting statement of the condition of the soils of 

 that State owing to the presence to a great depth of humus. 

 The writer .says that the humus of those soils is very gener- 

 ally derived from plant roots, instead of from accumulations 

 of vegetable material at various depths as the soil was being 

 built up. He notices also that the black colour of a soil does 

 not always denote a high humus content, the colour being 

 sometimes attributable to the presence of black substances 

 derived from the disintegration of rocks. The investi- 

 gations of Professor Lipman show that nitrifying bacteria 

 are present and active in California soils to depths of 

 6 feet, and ammonifying bacteria to a depth of 1 2 feet, thus 

 rendering the nitrogen of the humus available to plants to 

 those depths. 



The fertility and value of the land in California therefore 

 are not only based upon the nature of the surface soil and 

 subsoil, but chieHy upon the freedom with which plant roots 

 are able to penetrate to many feet, and secure moisture and 

 the abundant food supply that exists at great depths in all 

 California soils. 



