Improving soil fertility through dual inoculation with arbuscular mycorrhizal fungi and Rhizobium on a eutric cambisol cultivated with forage legumes in a semi-arid region

Sanele Mpongwana; Alen Manyevere; Johnfisher Mupangwa; Conference Thando Mpendulo; Chuene Victor Mashamaite

doi:10.1016/j.heliyon.2024.e24817

Improving soil fertility through dual inoculation with arbuscular mycorrhizal fungi and Rhizobium on a eutric cambisol cultivated with forage legumes in a semi-arid region

Heliyon. 2024 Jan 20;10(2):e24817. doi: 10.1016/j.heliyon.2024.e24817. eCollection 2024 Jan 30.

Authors

Sanele Mpongwana¹, Alen Manyevere², Johnfisher Mupangwa^{1

3}, Conference Thando Mpendulo¹, Chuene Victor Mashamaite²

Affiliations

¹ Department of Livestock and Pasture Science, University of Fort Hare, Private Bag X 1314, Alice 5700, South Africa.
² Department of Agronomy, University of Fort Hare, Private Bag X 1314, Alice 5700, South Africa.
³ Department of Animal Production, Agribusiness & Economics, University of Namibia, Neudamm Campus, Private Bag 13188, Windhoek, Namibia.

Abstract

The Sub-Saharan region of southern Africa is characterized by high temperatures, low rainfall, and poor land-use management practices such as continuous cropping without replenishment of soil nutrients. The combination of these factors has resulted in nutrient depletion and land degradation. The current study aimed at investigating the effect of arbuscular mycorrhizal fungi (AMF) and Rhizobium bacteria inoculation on soil chemical properties in field-grown forage legumes, namely, Mucuna pruriens (mucuna), Lablab purpureus (lablab) and Vigna unguiculata (cowpea), in the semi-arid region of the Eastern Cape Province (South Africa). Forage legumes were inoculated with the AMF species Paraglomus occulum and the Rhizobia bacteria species Bradyrhizobium strain and grown for 120 days. Soil samples were collected in the following sequence: prior to planting, before flowering and after harvesting the forage legumes in each of the two seasons (2017/2018 and 2018/2019) and soil chemical properties were determined using standard procedures. The results showed that the addition of dual inoculation over time greatly improved soil chemical properties when compared to the control treatment. This was advocated by the significant (P ≤ 0.05) increase in soil pH, soil organic carbon, soil organic matter, total nitrogen, phosphorus, calcium, potassium, magnesium, sodium, sulfur and iron in soils. The concentration of cation exchange capacity was significantly (P ≤ 0.05) higher in cowpea treated with Rhizobium as compared to other treatment combinations. The control treatment of mucuna forage greatly improved the concentrations of manganese, boron, copper, molybdenum, and zinc over other treatment combinations only before the flowering stage. However, the concentrations of micronutrients were significantly higher on the treatment combination of lablab and single inoculation of AMF after harvesting. Generally, dual inoculation with AMF and Rhizobia enhanced soil properties when compared to a single inoculation or untreated control.

Keywords: Arbuscular mycorrhizal fungi; Biofertilization; Chemical properties; Legumes; Rhizobium.