Effects of combined mineral and sewage sludge fertilization on soil properties and growth of two Zea mays (L.) varieties in Western Highlands of Cameroon

Abstract

This study aimed at evaluating the effects of combined application of dewatered sewage sludge (SS) and mineral fertilizer on the chemical properties of the soil and growth of <i>Zea</i> <i>mays</i>. Six treatments: T0, negative control; T1, positive control of 120 kg N/ha; T2, 2 t/ha sewage sludge (SS) + 60 kgN/ha; T3, 4 t/ha SS + 60 kgN/ha; T4, 8t / ha SS+ 60 kgN/ha and T5, 8 t/ha SS were applied in completely randomized block experimental design. The following parameters: height of plants, diameter of stem, number of healthy leaves, leaves area index, root and shoot biomasses were measured on plants at 30, 44 and 58 days after sowing. For the soil parameters, electrical conductivity (EC), redox and hydrogen potentials were measured at the same frequency. The results showed that the height, the stem diameter, the number of leaves, the leaves area index and the biomass of Zea mays increased in response to soil supplementation with sewage sludge combined with mineral fertilizers. The treatment that best stimulated the growth of maize was T4 (8t/ha SS+ 60 kgN/ha). The soil chemical properties were modified by sewage sludge application. In general, pH and conductivity decrease with sludge application, while, redox potential increased. This shows that combined sewage sludge to NPK (20 10 10) leads to changes in chemical parameters of the soil and thus, influencing the nutrients uptake by plants to improve their growth.