Effect of Organic Wastes and Incubation Periods on the Availability of Iron, Manganese, Copper and Zinc in a Calcareous Soil

Abstract

A calcareous soil incubation experiment for four tasting of 16 weeks wascarried out to ascertain the effect of compost, olive waste and lemon waste, on the amounts ofextractable iron, manganese, copper and zinc in a calcareous soil. The rates of organic materialsadded were 0, 0.5, 1.0, 1.5 and 2 % of the air-dried soil on dry weigh. The periods of samplingaffected soil pH and were the lowest (pH = 7.32) was produced at the fourth time of sampling witholive waste. Decreasing pH values with increasing rate of applied organic waste were observedat each time of sampling and with increasing time of sampling. The compost gave the highestvalues of available Fe, Mn and Zn at the fourth time of incubation (5.41, 22.04 and 5.02 mg/kgsoil, respectively), while, the olive waste gave the highest value of available Cu (5.11 mg/kg soil)at the fourth time of incubation. Generally, the available Fe, Cu, Mn and Zn were increased withincreasing organic materials rate and increasing time of sampling. The highest values of availableFe (6.16 mg/kg soil), available Zn (6.21 mg/kg soil), available Mn (23.87 mg/kg soil) and availableCu (6.71 mg/kg soil) were recorded for 2% organic material application, rate at the fourth time ofsampling.