EFFECT OF SOME PHYSICAL AND CHEMICAL FACTORS ON THE RATE OF HYDROLYSIS OF NITRAPYRIN (N-SERVE)

The effectiveness of Nitrapyrin (NI) as a nitrification inhibitor is largely determined by the rate at which it is hydrolyzed. A procedure was developed in which Cl- liberated during NI hydrolysis was used to follow NI degradation in laboratory studies. The procedure allowed determination of Cl- from as little as 0.5 mg·l-1 Nitrapyrin and permitted analysis of up to 20 samples h-1. The method must be restricted to experiments where background Cl-1 can be either removed by leaching or corrected for by use of control samples. Temperature was the most important factor affecting NI hydrolysis and the process was not biologically-mediated. The rate of hydrolysis was not affected by pH in the range 2.7-11.9, or by sorption on colloidal surfaces providing the surfaces remained in contact with the solution. Hydrolysis was slower in a soil at field moisture capacity than at saturation. The findings also showed that experiments conducted in containers with lipophilic components (e.g. rubber or polyethylene) may be suspect due to sorption of NI. © 1979.