Studies on agar and powder legume inoculants

Abstract

Inoculation of legume seed with the specific root nodule organism is probably the most significant and certainly the most practical achievement of the soil microbiologist. The usual method of inoculation is to convey the right type of bacteria through the seed, for the establishment and rapid multiplication in the soil. A recognition of the merits of this practice in increasing crop yield and maintenance of soil fertility and with the consequent adoption of the same as a routine farming practice necessitated the production and distribution of the inoculants as pure cultures on a large scale. The demand for these cultures from the farmers has been so great in recent years that it attracted even private commercial enterprise in United States of America, Australia and more recently in New Zealand. Needless to say, that it is primarily on the quality of these cultures rests the prosperity and future of the business. But a continued supply of poor or totally ineffective cultures not only impairs the business but also discredits the very fundamental merits and scientific truth of this important soil practice. It is to this end that certification schemes for the legume seed inoculants were set on foot to guide the farmers in their choice of the desirable type of cultures.

In New Zealand the Plant Diseases Division of Department of Scientific and Industrial Research has been supplying agar cultures to the farmers during the past 27 years, but the division in 1935 decides to terminate this service and to allow supply thence forward to be the concession of private enterprise. The division has however ensured efficiency and satisfaction by instituting a legume inoculants certification scheme.

At present powdered cultures manufactured in U.S.A. and Australia along with those prepared in this country are being sold to farmers through several private agencies. A study has been made, among other things, to determine the nature and efficiency of these cultures with the object of ascertaining as to how far the cultures made in New Zealand compare with the imported ones. The results of these investigations covering the period of nine months (February to October) are presented in this thesis.