Release Kinetics of Carbon, Nitrogen, Phosphorus, and Potassium During Co-composting of Poultry Manure Mixed with Different Ratios of Wheat Straw and Zeolite

The present study was conducted to investigate the decomposition of organic carbon (OC) and release of nitrate (NO3-), ammonium (NH4+), P, and K from 4 mixed treatments including T1 [85% poultry manure (PM) + 15% wheat straw (WS)], T2 (75% PM + 25% WS), T3 (75% PM + 15% WS + 10% zeolite), and T4 (65% PM + 25% WS +10% zeolite) at specified intervals over 133 days. The results indicated that 38-43% of initial OC was decomposed at the end of the composting process. The amount of NO3- at the beginning of the process varied from 9.8 to 13.3 g kg(-1) and finally ranged from 23.3 to 39.3 g kg(-1). The amounts of NH4+ varied from 1.9 to 3.0 g kg(-1) at the end of the composting process. The amount of P released at the beginning of the composting process ranged from 2.8 to 4.3 g kg(-1), which reached 3.4-4.0 g kg(-1) at the end of the process. The release of K occurred increasingly during the first two weeks and after a slight decrease in the third week, it showed a steady trend until the end of the composting process. The pseudo-second-order equation provided the best fit to the data. Treatment T4 was the best treatment in this study because the application of lower amounts of PM resulted in the production of compost with similar chemical properties to other treatments with higher PM participation. [GRAPHICS] .