Abstract

Poultry manure (PM) is limited by large quantity required for large scale vegetable production, to avert this problem, integrating inorganic (urea) with organic (PM) fertilizers is recently been advocated. Hence, two field experiments were carried out in years 2016 and 2017 at Landmark University, Omu-Aran, Kwara State, Nigeria to evaluate the effects of sole and integrated applications of poultry manure (PM) and urea fertilizer (UF) on soil chemical properties, growth, yield and quality of green Amaranth (Amaranthus hybridus). The study was laid out in 2 x 4 x 4 factorial experiment with two years (2016 and 2017), four levels of PM (0, 40, 80 and 120 kg N/ha) and four levels of UF (0, 40, 80 and 120 kg N/ha) application. The sixteen treatment combinations were arranged in a randomized complete block design having four replications. Results showed that UF and PM alone or their integration improved soil organic matter (OM), N, P, K, Ca, Mg (urea alone did not increase OM, P and K significantly), yield and growth indices, minerals (urea alone only increased leaf N), moisture, fibre, protein, dry matter, ash and reduced fat content of Amaranthus leaves compared with the control. Although fresh plant weight/plot (yield), plant height, leaf N and moisture contents of Amaranthus increased up to 120 kg N/ha, for both sole UF and PM (yield was 280 kg in 2016 and 310 kg in 2017 for PM while yield for UF was 250 kg in 2016 and 247 kg in 2017, plant height was 0.75 m in 2016 and 0.81 in 2017 for PM while UF was 0.67 m in 2016 and 0.65 m in 2017, Leaf N was 2.98% in 2016 and 3.41% in 2017 for PM while UF was 2.50% in 2016 and 2.44% in 2017, moisture content was 87.60% in 2016 and 90.20% in 2017 for PM and 86.4% in 2016 and 89.60% in 2017 for UF), soil and leaf K, Ca and Mg, ash, protein, dry matter and fibre were increased only up to 80 kg N/ha for PM and 40 kg N/ha for UF. This levels (80 kg N/ha for PM and 40 kg N/ha for UF) correspond to the optimum level for the production of quality Amaranthus in the agro ecological zone or similar soil elsewhere. For improving the overall quality, integrating UF at 40 kg N/ha with PM at 80 kg N/ha is recommended.