Recent survey in the Soubré region of Côte d’Ivoire has showed high soil fertility depletion. The cost of mineral fertilizer is high and does not always yield a positive return on investment. Soybean can use atmospheric nitrogen through biological fixation by establishing a symbiotic relationship with Rhizobium bacteria. Nitrogen (N) is subject to intense chemical and microbiological transformation processes and is, therefore a very mobile nutrient element in the soil-plant-atmosphere continuum. A study was conducted at Logboayo and Soubré to evaluate the effect of IRAT-FA3 Bradyrhizobium japonicum strain inoculum on the nodulation and some growth parameters of five soybean varieties (Glycine max) named Canarana, Doko, V3-2013, V6-2013 and IT-235. A randomized complete block design with a split plot replicated three times was used. Inoculation was the main factor and variety the subplot treatment. Data were collected on seedling emergence, growth parameters and nodulation. Results showed that lowest emergence time of 6.49 Days After Sowing (DAS) was recorded at Soubré compared to 6.91 DAS for Logboayo. Doko variety had the highest number (11) of nodules per plant in inoculated treatments. The variety V3-2013 showed ability to nodulation with indigenous rhizobia. Seeds inoculation resulted in an increase of nodules and growth of organs. The results of the present study opens up option for soybean to be grown along other crops in order to address soil fertility problems in the project area. © 2016 J.C. N’Zi et al.
Tag: inoculation
Infection potential of farm soils as mycorrhizal inocula for Leucaena leucocephala
A greenhouse experiment was conducted to assess the arbuscular mycorrhizal (AM) fungi inoculum potential for Leucaena leucocephala in a range of nutrient-depleted farm soils in western Kenya. Leucaena was grown in 12 uninoculated farm soils with pH 5.0–6.7, with or without rock P and farmyard manure. Root infection, nodulation, and shoot and root weight were determined 25, 46, and 69 days after planting. Spore concentrations in the farm soils at the start of the experiment ranged from 44 to 126 live spores per 100 g dry soil with 6–10 species per soil, principally Scutellospora spp. and Acaulospora spp. Nodulation was absent or poor in all soils, indicating the need for rhizobial inoculation of species belonging to the leucaena crossinoculation group in this agrosystem. Rock-P alone increased final shoot dry weight by a factor of 1.4, manure alone by 1.8, and rock-P plus manure by 1.9, compared with no ameliorant. Root infection with AM fungi was detected in all soils 25 days after planting and increased linearly in the different farm soils to values of 33–65% 69 days after planting. Soil pH and root infection 25 days after planting accounted for much of the variation in final shoot weight among soils with no amelioront (87%). As early root infection increased from 20 to 40% at soil pH 5.0, the predicted final shoot dry weight was doubled, and the response to ameliorants was reduced by two-thirds. The growth responses to increased infection became smaller as pH increased from 5.0 to 6.5.
The Effect of Biochar Amendment, Microbiome Inoculation, Crop Mixture and Planting Density on Post-Mining Restoration
Ecological restoration with a multispecies and multifunctional approach can accelerate the re-establishment of numerous ecosystem services. The challenges with land that is degraded, damaged, or destroyed post-mining are the low productivity of soil and the high potential for contaminants. Herein, we evaluated the multispecies and multifunctional approach to restoration strategy through a mixture of woody and herbaceous species, microsymbiont and biochar amendments, and plant spacing. The experiments were conducted using greenhouse and field trials located in Quebec, Canada. We used a mixture of tree species (Alnus viridis (Chaix) DC. ssp. crispa (Aiton) Turrill, Picea glauca (Moench) Voss, Populus tremuloides Michx. and Salix arbusculoides Andersson) and herbaceous species (Avena sativa L., Festuca rubra L. and Trifolium repens L.) on two types of gold-mine waste materials (fine tailing and waste rock). The biochar amendment and microbial inoculation were applied on both greenhouse and field trials. We found both positive and negative effects of plant spacing, biochar amendment and inoculation depending on their interactions. The net positive effect was shown by combining high plantation density, biochar, and inoculation factors on Alnus viridis ssp. crispa. Overall, plantation density was shown to be the most important factor in generating the net positive effect. We suggest that the mechanism was correlated with the improvement in microclimate through soil plant water conservation and microbial activity enhancement over soil temperature modification. Hence, we propose to put emphasis on microclimate improvement for accelerating the restoration processes, along with other combined factors, including microbial inoculation and biochar amendment.