St. Ignatius Loyola and the Jews

James J. Brodrick, S.J., reflects on St. Ignatius of Loyola and his special affection for the Jewish people

St. Ignatius Loyola and the Jews

James J. Brodrick, S.J., reflects on St. Ignatius of Loyola and his special affection for the Jewish people

Environmental constraints to nodulation and nitrogen fixation of Phaseolus vulgaris l. in Tanzania. II. Response to N and P fertilizers and inoculation with Rhizobium

Addition of P fertilizer (26 kg P ha-1) was shown to increase dramatically the number of root nodules and seed yields of Phaseolus vulgaris in experiments on farmers' fields in the West Usambara Mountains in northern Tanzania. Both nodulation and seed yields varied enormously between the different sites even where fertilizers were applied. Nitrogen fixation was measured in two of these experiments using the 15N isotope dilution method with a non-nodulating variety of P. vulgaris as a non-fixing reference plant. Without addition of P fertilizer the amount of N2 fixed was only 2-8 kg N ha-1 (25-27 %N derived from N2-fixation) and this was increased to 8-16 kg N ha-1 (48-51 %N derived from N2-fixation) with addition of 26 kg P ha-1. Inoculation with Rhizobium together with P addition increased nodulation and N2-fixation marginally above that with P alone but did not increase seed yields. Seed yields were only marginally improved by addition of P or N fertilizers at two sites in the Kilimanjaro/Meru region of northern Tanzania. At one of these sites (Kilacha) inoculation with P more than trebled the number of nodules but only marginally increased total N accumulation. Across all sites, addition of N fertilizer (45 kg N ha-1) increased yields slightly above those found with P alone. The need for further assessments of nodulation and N2-fixation under soil fertility conditions prevailing on farmers' fields is emphasised.L'addition de la fertilisation de P (26 kg P ha-1) a beaucoup augment\ue9 le nombre de nodules racinaires ainsi que le rendement en graines de Phaseolus vulgaris en champs des fermiers dans la r\ue9gion montagneuse ouest d'Usambar au nord de la Tanzanie. La nodulation et le rendement en graines variaient amplement entre les diff\ue9rents sites trait\ue9s \ue0 la fertilisation. La fixation de l'azote atmosph\ue9rique \ue9tait mesur\ue9e dans deux de ces essais par la m\ue9thode de dilution de l'isotope 15N avec une vari\ue9t\ue9 non nodulante de P. vulgaris servant de t\ue9moin non fixateur. En l'absence de la fertilisation, seulement 2 \ue0 8 kg N ha-1 soient 25-27%, d\ue9rivaient de la fixation de N atmosph\ue9rique tandis qu'avec l'addition de 26 kg P ha-1, la fixation azot\ue9e \ue9tait \ue9lev\ue9e \ue0 8-16 kg ha-1 soient 48-51%. La combinaison de Rhizobium avec le fertilisant P a l\ue9g\ue8rement augment\ue9 la nodulation ainsi que la fixation de N par rapport au traitement de fertlisant P mais sans toutefois augmenter le rendement en graines. Le rendement en graines \ue9tait l\ue9g\ue8rement am\ue9lior\ue9 par l'addition de P et de N dans les deux sites au sein de la r\ue9gion de Kilimanjaro/Meru au nord de la Tanzanie. Dans l'une de ces deux sites (Kilacha), le traitement au P a plus que trippl\ue9 le nombre de nodules tandis que la quantit\ue9 d'azote total s'est l\ue9g\ue8rement augment\ue9e par rapport au seul traitement de P. Le besoin de poursuivre ce genre de travail en vue d'examiner la nodulation et la fixation de N dans les conditions de sol qui pr\ue9valent en plein champ des fermiers est soulign\ue9