Extractability of potassium from some organic manure in aqueous medium and the effect of pH, time and concentration

Abstract

The effect of pH, time and concentration on the extractability of potassium from five types of organic manures (cow dung, local chickens, duck and commercial chickens, faeces on bedded and unbedded floor) were studied. Experiments were conducted in water at 40oC. Cumulative extraction curves of potassium resulting from a 2-hour equilibration period indicated an initial fast process, the rate of which slowed down at later extraction numbers. Corresponding curves of extraction of the element as affected by selected factors showed that pH, concentration of the nutrient and equilibration time were important in influencing the readiness with which manures release potassiuim in aqueous medium. Individual character of each of the manures in releasing the element was also exhibited, but in general, the bedded floor commercial birds manures produced the highest rate, while duck and cow dung showed the least. The effect of the bedding material in enhancing the release of the nutrient from these manures is explained in terms of their relatively smaller particle size. The possibility of contribution to the nutrient resource of the manure by the material itself may be an additional factor.