| Abstract |
Climate change in conjunction with poor soils, has resulted in a decrease in the yield of most crops planted within the Kavango East Region. Arenosols, sandy, porous soils that are infamous for retaining very little moisture and nutrients, predominate in the area. These combined variables adversely affect most smallholder farmers because they lack the financial means to improve their soils with chemical fertilizers. However, rhizobia, a bacterium found in soil, can help boost plant development and productivity. This study aimed to ascertain how two, Vigna unguiculata (cowpea) varieties respond to an introduced bio-inoculant strain 1-7 and whether growing them in a natural environment resulted in increased production and growth, to compare the biomass of the shoots, grains, and roots of the cowpea varieties and the crop yield performance between the conservation agriculture (CA) and traditional agricultural (TA) field. The two cowpea varieties named, Silwana (Si) and Nakare (Na) were cultivated in field experiments at the Mashare Agricultural Development Centre (MADI), in the Kavango East Region of Namibia. The experimental field was subdivided into the TA and CA field. The cowpea varieties were grown in three replicates and subjected to three treatments: one using chemical fertilizer, one using a bio-inoculant of Bradyrhizobium strain 1–7, and a third serving as a control. At 128 days after seeding, the cultivars were harvested, and various yield parameters were evaluated. Compared with the fertilizer treatments and the untreated control, cowpeas receiving bio-inoculant applications recorded superior yields. For the Na treatment, shoot, grain and root yields reached 2330.28, 3758.64 and 406.14 kg ha⁻¹, respectively, while the Si treatment produced 2553.87 kg ha⁻¹ of shoot biomass, 2564.07 kg ha⁻¹ of grain and 427.14 kg ha⁻¹ of root biomass. Field management practices also influenced productivity. The CA field demonstrated greater overall performance than the TA field. Shoot biomass in the CA field measured 1589.27 kg ha⁻¹ (Na) and 1942.07 kg ha⁻¹ (Si), compared with 741.01 and 611.80 kg ha⁻¹ under TA management. Grain yield followed a similar trend, with CA recording 1978.80 kg ha⁻¹ (Na) and 1915.94 kg ha⁻¹ (Si), exceeding the corresponding TA values of 1779.84 and 648.13 kg ha⁻¹. In contrast, root biomass was slightly lower under CA (190.55 kg ha⁻¹ for Na and 221.58 kg ha⁻¹ for Si) than under TA (215.59 and 205.56 kg ha⁻¹, respectively). Overall, bio-inoculant application improved crop productivity, suggesting a cost-effective and environmentally sustainable alternative to synthetic fertilizers for smallholder farming systems. |
? |
