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 soilsamendment to improve soil fertility and crop productivity.The study aimed at assessing the nutrient uptake andgrowth of spinach (Spinacia oleracea L.) grown in soilsamended with cow manure after a co-composting process.Methods Sandy loam and silt loam soils were amendedwith cow manure after co-composting with poplar leaflitter at 1:0, 1:1, 1:2 and 1:3. The compost was applied tosoil at the rate of 20 t ha-1. Spinach was grown for8 weeks and then harvested to measure plant shoot biomass.Spinach shoot samples were digested and nutrientcontents in the shoots were determined.Results Co-composted manure significantly improved thegrowth and nutrients availability to the spinach. Dry biomass,P and K contents in spinach shoot varied amongmanure: leaf litter ratios: 1:01:11:21:3. Conversely,N, Zn, Fe, Cu and Cd contents in spinach shootreduced with the manure amendment with increasingamount of leaf litter. Water extractable micro-elements inthe post-harvest soils were found in the order ofZn[Fe[Cu[Cd. Co-compost amendments increasedthe P and K availability except N, NO3 and NH4 in thepost-harvest soils. Trace elements in the post-harvest soilsreduced with leaf additives in the compost.Conclusions Co-composted cow manure with leaf litterproved to be superior in terms of bioavailability of plantnutrients over the composted manure without leaf litter.This may also assist in mitigating the environmental contaminationof heavy metals in the farm lands.