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

Improving Efficiency of Urea Fertilizers by Inhibition of Soil Urease Activity

“…(1996) and Phongpan et at. ( ,1997) on a flooded rice field located on a clay soil (PH 5.1) in the Central Plain region of Thailand, urease inhibitors were also used in combinations.…”

“…(1996) and Phongpan et at. (1997), the algicide terbutryn [2-(t-butylamino )-4-( ethylamino )-6-(methylthio )-s-triazine], the nitrification inhibitor acetylene (provided by wax-coated calcium carbide, Cac2), and the urease inhibitors nBTPTA, PPDA, N-(diaminophosphinyl)benzamide (DAPBA), and acetohydroxarnic acid (AHA) were studied.…”

“…The second experiment, described by Phongpan et al (1995Phongpan et al ( , 1997, was carried out during the dry season of 1992. The algicide terbutryn (again at 0.2 mg/l floodwater) was applied at 4-day intervals in all treatments.…”

“…In the field experiment described by Freney et al (1995) and Phongpan et al (1997) (see page 249), the rice grain yield of3.14 tlha in the urea-only treatment was increased to 3.17-3.81 tlha in the treatments with inhibitors. The increase was not significant when urease inhibitor was not used and significant (P<0.05) when the urease inhibitors cyclohexyl-PTA and N-(n-butyl)-PTA with or without the nitrification inhibitor phenylacetylene were applied together with the algicides copper sulfate and terbutryn.…”

“…In the rice field experiments conducted by Chaiwanakupt et al (1996) and Phongpan et al (1995Phongpan et al ( , 1997 in Thailand (see page 182), the grain yields increased in parallel with the reduction of volatile ammonia losses. In the experiment carried out during the 1991 wet season, the highest yield was recorded in the treatment with algicide + mixed urease inhibitors (4.66 tlha), which is significantly higher than that obtained in the control treated with algicide + urea (4.00 tlha).…”