THE NITRO-CULTURE QUESTION.

Otago Witness, Issue 2732, 18 July 1906, Page 4

THE NITRO-CULTURE QUESTION.

A further budget of reports upon experiments with nitro-culture carried out in the season 1905 in the United Kingdom and America has lately appeared, without affording any d-efinite conclusion regarding the value of the bacteria. The English and Irish reports agree that while in most cases the results have been negative, there is some -evidence that under certain conditions benefit has been obtained by the use of the cultures. There is also room for doubt whether in many cases the tests have been properly conducted) — that is, whether the material has been applied to the soils which were deficient in nitrogen ard to crops which could profit by it. The experiments are to be continued during the present season, and it is hoped that more definite results will be obtained. Reports from the United states are at variance, some partisan influence, apparently, having been imported into the investigations ; on one hand the best results ■which were claimed for the cultures are declared to have been obtained, while on the other the cultures are denounced as worthless, and those who proclaim their virtues -as fake prophets. The Canadian experiments, both at the Government experimental farms and conducted by the Co-operative Experimental Union, have furnished the greatest amount of krformtition on the subject, And a summary of the results has been published in a special bulletin. Seventy per cent, of the experimenters reported successful results, with increased growth of crops, most of the remainder reporting that no perceptible advantage had accrued. The general result is held to leave little doubt that the use of the culture, as it becomes better understood, will be beneficial, although the exaggerated statements which have been published are not likely to ba realised. Some of the conclusions drawn from the results of the experiments may be quoted for the benefit of the many who will probably be induced to test the cultuics in >7ew Zealand. In the first place it is impressed upon fanners and gatdeners that lb should be thoroughly understood that these nitro-cultures ore of use for legumes only, such as the clovers, beans, peas, and vetches, or, as they are sometimes termed, the pod-bearing plants. Inoculation is necessary when the land has never before been seeded down to a leguminous crop, or if legumes have grown in it without forming the characteristic nodules or tubereules. which is proof that the nodule bacteria for that particular crop are not present in the soil. In such cases as these ih-i fanner may well resort to inoculation. (Professor Jamie-son'* pronouncement ar.ta^oiiisnc \o thp roctule theory evidently ivceives no =iKI-rrsr ment in Canada.) Inoculation is also desirable if a farmer -wishes to grow a ne-»\ kind of legume on land, even though it has prev.ously grown excellent crops of a different species of legume. Tliu?, although red clover may have been sur, j-ssful'y giowr. with a lurge number of noduk-s c*n the roots, the bacteria horn these nodules may not infect alfalfa or lucerne if it were planted m the clover soil, and hence inoculation with bacteria taken from the alfalfa nodules would be desirable. bo also when introducing the culture of vetchss, of field beans, and soy beans, it would be necessary to treat the s-eed with bacteria taken from these plants. In some cases, bacteria derived from closelyrelatsd species are mutually available : thus bacteria from sweet clover (M-elilotnt.) are capable of infecting alfalfa. The employment of nitro-cultures is reconiiaende-l also on soils which produce a weak p:o"?y..h of legumes even when nodules are present, the more vigorous bacteria of the culture aiding the plant to fix' more nitrogen in those cases where the leguminous crop is not producing the highest yield. A word of warning is given with regard to failures in the use of these nitro-cultures, and also with regaid to tbeir use as a remedy for lack of care in preparation and cultivation of the soil. No benefit may be exptcte-d fmm the use of nitTO-cultures if they are improperly prepared. The directions for their use are clearly set forth, and should be stiictly followed. The ! farmer simply invites failure if, for example, as some have done, he disregards the directions and uses the culture on turnip seed, instead of for the legume for which the culture -was prepared. Failure of plants to form nodules, even when the seed is inoculated, may result if the soil is too acid or too alkaline — lime should be first applied if the sod is too acid ; or if some fertiliser with a caustic action is brought into contact with the treated seed. With regard to cases hi which little benefit may result from inoculation, the follow-

ing are given as the probable causes of failure: — (1) That the soil does not contain sufficient of the other necessary plant foods, especially potash and phosphoric acid ; (2) that the soil is too rich in nitrogen — in this case it is better to plant crops that are nitrogen feeders, rather than nitrogen accumulators ; (3) that the soil is not properly cultivated and freed from weeds ; (4) that the soil is already thoroughly inoculated with the nitrogenfixing bacteria. Experiments in New Zealand have so far been inconclusive, but many of the results are decidedly encouraging, and as the conditions necessary to success become better understood the benefits oi the inoculation are more likely to be obtained. The question is peculiarly one in which exchange of experiences amongst experimenters is highly desirable. The .history of the discovery and application of nitrogen-fixing bacteria is accurately and impartially outlined in the article by Dr Hilgendorf. of Canterbury Agricultural College, in last week's Witness. The article should have a place in the scrap-book of everyone who is interested in the subject.