Vol. X. No. 230, 



THE AGKICULTURAL NEWS. 



59 



A METHOD OF STUDYING PROBLEMS 



IN SOIL FERTILITY. 



In the Journal of Agricultural, Sciencr for Septeiiilier 

 1910 (Vol. Ill, p, 297), a method is described by which it 

 appears that certain problems in soil fertility may be studied 

 in a convenient manner. Particulars are given of work that 

 has been actually conducted so far with the aid of the method 

 described; this refers to the action of leguminous plants in 

 assisting in increasing the amount of nitrogen in the soil. 



The devising of the method arose from the fact that the 

 attention of the writer of the article was called to the circum- 

 stance that oats made better growth than was the case ordin- 

 arily, if they were .sown with field peas. The idea was 

 strengthened in the mind of the writer by further observa- 

 tions and enquiry, so that it appeared evident to him that 

 when legumes and non-legumes are raised together the latter 

 receive an advantage because they are .supplied with nitrogen 

 compound.s, which are provided either by the decay of the 

 roots of the legumes or from the passage of soluble material 

 out of those roots into the surrounding soil. 



After giving examples .showing the extent to which the 

 two kinds of plants are often sown together, the writer draws 

 attention to the importance of the matter, giving the opinion: 

 ' that if it should be demonstrated that non-legumes could be 

 provided with an abundant .supply of nitrogen even in poor 

 .soils, by being grown together with legumes under proper 

 conditions, it would become practicable not only to dispense 

 with all or a portion of the nitrogenous manures employed 

 for certain crops, but also to secure non-legumes with an 

 increased proportion of protein in the dry matter.' 



The apparatus employed in the investigation consisted of 

 two earthenware pots, one smaller than the other, the latter 

 being i)laced inside the former. The outer pots had 

 a capacity of about 5 gallons, the smaller ones were made of 

 a very porous flint mixture, while some were glazed and others 

 left unglazed. 



In the trials, the smaller pots were placed inside the 

 larger, and both were filled with white quartz sand to which 

 was added the essential mineral food required by plants, to- 

 gether with a small amount of water that had been shaken 

 up with soil in order to provide the bacteria necessary to 

 enable the legununous plants to form nodules. 



The invention and arrangement of this apparatus arose 

 from the idea that if leguminous plants allow soluble nitrogen 

 compounds to be given off from their nodules and roots, these 

 compounds would pass through the porous walls of the un- 

 glazed inner pots and supply nitrogen to the non-legumes that 

 were growing in it. This would not be the case, on the other 

 hand, if such passage did not take place, so that if the non- 

 legumes were not given nitrogen they would starve for want 

 of this element. 



The procedure was, therefore, to plant such leguminous 

 plants as field peas in the outer pots while oats were grown in 

 the inner pots, some of which were glazed and some unglazed; 

 no nitrogen was given in either case, and the moisture condi- 

 tions were kept uniform. 



In the result, it Avas found that where unglazed inner 

 pots were used the oats made the best growth and were of 

 a deeper colour than those in the glazed inner pots. In the 

 words of the author: 'every indication was... supplied that 

 soluble nitrogen compounds were diffusing through the un- 

 glazed porous wall and were being utilized by the oats.' It 

 was found subsequently, that when the oats growing in glazed 

 and unglazed pots were weighed and analyzed, the latter gave 

 not only a much larger amount of dry matter and nitrogen 

 than the former, but that the dry matter contained nearly 



twice as much nitrogen as that from the oats grown in 

 the glazed pots. 



It is pointed out that this method of experiment may be 

 employed in a similar manner for studying the influence of 

 various crops on the bacteria contained in soils; here the crops 

 would be grown in the outer pots, while nothing would be 

 raised in the inner, the soil from which would be examined 

 bacteriologically and the results compared, in the glazed and 

 unglazed pots. Other investigations might include the 

 study of various manures in their effect on certain groups of 

 soil bacteria; for that of the effect of crops on one another, 

 both when grown continuously and in rotation; and for 

 investigations in regard to the supposed toxic effect of 

 excreta from the roots of plants. 



The article concludes with a description of the material 

 for making the porous inner pots. This con.sisted of clay, 

 mixed with 25 per cent, of hard coal and the same proportion 

 of soft coal, fired in the usual way. Fi>r providing controls 

 on the glazed pots, those coated with asphaltum paint were 

 employed, as tests in the laboratory had .shown that they 

 were impervious to diffusible salts. 



AGRICULTURE IN HAWAII, 1908-9. 



Among the matters dealt with in Diplomatic and Coii,- 

 sular Reports, No. 4601 Annual Series, which was issued in 

 November last, there is an account of the Agriculture of the 

 territory of Hawaii from which the following information is 

 taken. 



The chief industry, namely sugar production, has 

 progressed to such an extent that more than .§70,000,000 is 

 invested in it, and the area devoted to sugar-cane is 213,000 

 acres, of which about one half is irrigated The yield per acre 

 is nearly twice as great on irrigated lands as on those which 

 are not irrigated. In 1908, 125,123 short tons of sugar wa.s 

 obtained from 101,379 acres, which gives an average of 5-14 

 tons per acre. The production for 1907 and 1906 was 

 440,017 and 429,213 .short ton.s, respectively. 



In regard to other chief industries, the output of rice is 

 valued at about S2,500,000; most of it is consumed in the 

 territory. The outturn of coflee is variable; last year, an 

 amount worth .'t!238,083 was exported from about 4,500 acres. 

 The rubber industry has not passed beyond the experimental 

 stage; on the six principal plantations there are now about 

 1,600 acres, containing about 600 Castilloa trees, 66,700 

 Hevea trees and 444,450 Ceara trees. 



Among the new industries, the greatest progress is being 

 shown by the pine-apple industry, the exports in connexion 

 with which have increased from 2,000 cases during 1900-] 

 — the first year under the protective taritf — to 411,000 eases 

 for 1908-9. Other matters of interest are the flotation of 

 new tobacco companies, renewed activity in regard to the 

 sisal industry, and the steadily growing production of honey, 

 the present value of the last being about $70,000. 



A paper in the Journal d' Agriculture Tropicale, No. 106, 

 p. 99, describes observations which support the conclusion 

 that the abortion of the flowers of Coffea arahica is due to 

 faulty nutrition of the plant. Among the particular causes, 

 in this connexion, there are stated to be the provision of too 

 much shade, together with too heavy applications of green 

 dressings and artificial manures, as well as too thorough 

 pruning where the shade is heavy. 



