The effect of soil carbon on symbiotic nitrogen fixation and symbioticRhizobiumpopulations in soil withTrifolium repensas host plant

Abstract

Soil organic carbon (SOC) is the main attribute of high-quality soil. The amount of nitrogen fixed by Rhizobium symbiotically with Trifolium repens (white clover) is ultimately determined by the quality of the soil environment. The effect of SOC on the total number of symbiotic and saprophytic rhizobia was determined. Subsequently, the amount of nitrogen (N) fixed was assessed by using the N difference technique. Most Rhizobium was detected between a SOC content of 2.03% to 3.80% in both inoculated and non-inoculated soils. Inoculation increased the number of rhizobia in soil. Most N was fixed in the soil with the lowest SOC content. Although the amount of N fixed increased as the level of SOC decreased, the efficiency of N fixation decreased proportionally to SOC. Subsequently, more N was rhizodeposited. It was concluded that symbiotic rhizobia introduced by the inoculant were more efficient than free-living rhizobia in soils with higher carbon content, which highlights the importance of inoculation in improving the sustainable production of T. repens pastures.

Diversity of native rhizobia isolated in south Brazil and their growth promotion effect on white clover (Trifolium repens) and rice (Oryza sativa) plants

“…These data reinforce the proposal that the diversity of PGP characteristics displayed by the bacterial isolates also varies according to the soil type and host plant (Akers 1983;Hu et al 2009;Laheurte and Berthelin 1988;Rodríguez and Fraga 1999;Sundara et al 2002;Costa et al 2013). The biological N fixation performed by rhizobia species has been demonstrated to supply all the N necessary for leguminous development (Zahran 1999) of several host plants: faba beans (Beck and Duc 1991;Delgado et al 1994), peanuts (Raverkar and Konde 1988;Jonah et al 2012), soybean (Delgado et al 1994;Masson-Boivin et al 2009;Giraud et al 2013), and clover (Swanepoel et al 2011). In our study, the most promising native rhizobia isolated for the growth promotion effect in white clover plants was POA3.…”

Variability of soybean response to rhizobia inoculant, Vermicompost, and a legume-specific fertilizer blend in Siaya County of Kenya

“…Vermicompost not only was a source of slow-release N, but also other essential nutrients such as Ca, Mg, and K, which are essential for optimal plant growth. Organic sources of N also improve soil organic carbon, which has a significant effect on soil fertility including rhizobia survival [57]. In general, soil total N and organic matter are highly correlated as found in this study.…”

Variability of soybean response to rhizobia inoculant, vermicompost, and a legume-specific fertilizer blend in Siaya County of Kenya

“…Vermicompost not only was a source of slow-released N, but also other essential nutrients such as Ca, Mg K among others, which are essential for optimal plant growth. Organic sources of N also improve soil organic carbon, which has a significant effect on soil fertility including rhizobial survival (Swanepoel et al, 2011). In general, soil total N and organic matter are highly correlated as found in this study.…”