Influence of Tillage - Seedbed and Manure - Npk - Micronutrient Management Options on Selected Soil Properties of Sandy - Loam Ultisols Evaluated Using Sweet Potato

This study assessed the effects of tillage and nutrient management practices on selected soil properties of degraded coarse-textured Ultisols and responses of sweet potato in Nsukka, southeastern Nigeria. It involved three tillage-seedbed types viz zero-tilled flatbed (ZT-FB), conventionally tilled-flatbed (CT-FB) and conventionally tilled tie-ridge (CT-TR), each with seven soil fertilizer amendments. They were sole application of poultry droppings at 20 t ha–1 (PD20) and NPK 15:15:15 at 400 kg ha–1 (NPK0.40) as well as their complementary use (PD10+NPK0.20), each with and without Agrolyzer fertilizer for micronutrients at 2 kg ha–1 (AGF), also including a no-amendment control. The study was thus laid out as a 3 × 7 split-plot in a randomized complete block. Soil sampling was done at the initial stage and at the harvest of sweet potato. Results showed that tillage significantly improved soil total porosity, soil pH and available phosphorus (AvP), with CT-TR having the highest porosity (50.81%). Soil pH (6.4) and AvP (80.88 mg kg–1) were, however, highest in ZT-FB. As regards the soil amendments, the least improvements in soil properties occurred in the control. It not only showed the highest soil bulk density (1.47 g cm–3) and hence the lowest total porosity (34.15%), but also the lowest soil pH (5.9), and AvP (13.1 mg kg–1). The tillage type CT-TR improved the growth and tuber yield parameters of sweet potato, while PD10+NPK0.20 with and without AGF improved soil properties and tuber yield parameters, respectively. Overall, the treatment CT-TR with PD10+NPK0.20+AGF improved most soil properties better than the other treatments and also gave the best tuber yield of sweet potato.