Omeke, J.O.

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Tillage and rhizobium inoculation may affect nodulation and subsequent N release to the soil, thereby influencing soil productivity. The response of an improved soybean variety (TGX-1448-2E) on nodulation and soil nitrogen to rhizobium inoculation under different tillage practices in a Savanna Alfisol of Nigeria was evaluated at the Institute for Agricultural Research, Ahmadu Bello University, Samaru. Treatments consisted of two tillage systems; conventional tillage (CT) and reduced tillage (RT) and rhizobium inoculation; [inoculated (IN) and uninoculated (UNIN)]. These were tested in a splitplot experimental design with three replications. Data obtained were evaluated for total nitrogen (soil property), nodule number, nodule weight, grain nitrogen, protein (plant parameters) and statistically analysed using general linear model procedure of SAS 9.3 software. Results of soil N and protein content were higher in RT compared to CT with 3.98 % and 24.89 % differences respectively. Soil N and grain N obtained under inoculated plots were significantly higher than uninoculated plots with differences of 44.04 % for soil N and 24.44 % for grain N. Similar observation was obtained for protein content with 46 % difference. The results showed that RT recorded lower nodule number (34 nodule plant-1) and lower nodule weight (239.31 mg plant-1) compared to CT with 36 nodule number plant-1 and 272.86 mg plant-1 of nodule dry weight. The nodule number and nodule dry weights were consistently higher in inoculated plots with 89 % (nodule number) and 68.74 % (nodule dry weight) significantly difference. These findings suggest the need for rhizobium inoculation to improve soil N and soybean nodulation under reduced tillage practice for sustainable crop production. Key words: Tillage, Rhizobium Inoculation, Soil N, Nodulation, Alfisol