Nutrient uptake and growth of spinach as affected by cow manure co-composted with poplar leaf litter

Purpose Wastes were composted and applied as the soils amendment to improve soil fertility and crop productivity. The study aimed at assessing the nutrient uptake and growth of spinach (Spinacia oleracea L.) grown in soils amended with cow manure after a co-composting process. Methods Sandy loam and silt loam soils were amended with cow manure after co-composting with poplar leaf litter at 1:0, 1:1, 1:2 and 1:3. The compost was applied to soil at the rate of 20 t ha-1. Spinach was grown for 8 weeks and then harvested to measure plant shoot biomass. Spinach shoot samples were digested and nutrient contents in the shoots were determined. Results Co-composted manure significantly improved the growth and nutrients availability to the spinach. Dry biomass, P and K contents in spinach shoot varied among manure: leaf litter ratios: 1:0\ 1:1\ 1:2\ 1:3. Conversely, N, Zn, Fe, Cu and Cd contents in spinach shoot reduced with the manure amendment with increasing amount of leaf litter. Water extractable micro-elements in the post-harvest soils were found in the order of Zn [ Fe[ Cu[ Cd. Co-compost amendments increased the P and K availability except N, NO3 and NH4 in the post-harvest soils. Trace elements in the post-harvest soils reduced with leaf additives in the compost. Conclusions Co-composted cow manure with leaf litter proved to be superior in terms of bioavailability of plant nutrients over the composted manure without leaf litter. This may also assist in mitigating the environmental contamination of heavy metals in the farm lands.