Use of urease inhibitors to reduce ammonia loss from broadcast urea and increase grain yield of flooded rice in Thailand

Abstract

In Thailand a series of field experiments were run over three years from 1991 to 1993, testing the effects of urease inhibitors on ammonia loss from urea broadcast to flooded rice as well as on grain yield. The results showed that amendment with the algicide terbutryn and the urease inhibitors PPD and NBPT, either alone or in combination significantly reduced NH3 loss and increased grain yield. Experiments with the algicide in combination with the urease inhibitors NBPTO and CHPT demonstrated their effective action in reducing NH3 loss. When used alone urease inhibitors had no effect on grain yield, on the uptake of applied 15N by the grain nor on the uptake of 15N by the whole plant unless an algicide or algicide + nitrification inhibitor was added.