Rate and mode of application of the urease inhibitor N‐(n‐butyl) thiophosphoric triamide on ammonia volatilization from surface‐applied urea

Abstract

A laboratory study evaluated the effect of rate (0, 100, 250, 500, 750 or 1000 mg ⁄ kg) and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) (coating the urea granule, adding to the urea melt or adding to urea ammonium nitrate (UAN) solutions) on NH 3 volatilization from urea, at three temperatures (5, 15 and 25°C), with four contrasting soil types. Daily ammonia loss was measured for up to 21 days after surface N application, using ventilated soil enclosures. Ammonia loss from unamended urea varied with soil type and temperature and ranged from 8.2 to 31.9% of the N applied. nBTPT was highly effective in lowering NH 3 volatilization from urea and in delaying the time of maximum rate of loss. The average % inhibition over all soils, temperatures and formulations was 61.2, 69.9, 74.2, 79.2 and 79.8% for the 100, 250, 500, 750 or 1000 mg ⁄ kg nBTPT concentration, respectively. The % inhibition with nBTPT was lower at 15°C compared with at 5 or 25°C and was lower in UAN solutions than in granular products. There was little difference between the melted and coated granular products in lowering NH 3 loss or in soil N transformations. The stability of nBTPT in urea products was dependent on its mode of application and on the storage temperature. Incorporating nBTPT in the urea melt produced a more homogeneous product with superior stability than coating the urea granule.

Nitrogen loss by volatilization of nitrogen fertilizers applied to coffee orchard

“…N, in coffee orchard, relating to climate data (c). The pH in the soil surface layer (0-5 cm) is one of the chemical attributes that mostly affects the volatilization of ammonia to the atmosphere, and an increase in its value accelerates the loss (Watson et al, 2008;Menendez et al, 2009). In this study, the soil pH in the 0-5 cm layer was reduced from the 1 st to the 3 rd N fertilization of coffee (Table 3).…”

“…Several compounds have been found to reduce the conversion of urea [(NH 2 ) 2 CO] into ammonium and, ultimately, ammonia in soil (Roberts, 2014). The main substances and elements that have been used for this purpose are NBPT (Watson et al, 2008;Cantarella et al, 2008;Menendez et al, 2009;Pereira et al, 2009;Trenkel, 2010;Silva et al, 2011), copper (Cu) and boron (B) (Krajewska;Zaborska;Chudy, 2004;Heringer, 2008;Gabrovska;Godjevargova, 2009;Faria et al, 2013;Nascimento et al, 2013;Stafanato et al, 2013).…”

Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations

“…NBPT delays the rate of urea hydrolysis to NH 4 + -N and hence moderates the localised zones of high pH and NH 4 + -N concentrations, which result from urea hydrolysis and which are conducive to NH 3 volatilisation. The urease inhibitor has been shown to be highly effective at low concentrations (<500 ppm by weight of urea), lowering NH 3 losses from surface-applied urea (Watson et al, 2008) and increasing yield and N uptake compared with unamended urea (Watson et al, 2009). In the UK, field trials on grassland and tillage land showed that NBPT reduced ammonia emissions from untreated granular urea by 73% on average when used at a concentration of 500 or 1000 mg kg -1 (Chambers and Dampney, 2009).…”

Ammonia volatilization from enhanced-efficiency urea on no-till maize in brazilian cerrado with improved soil fertility

“…Consequently, the ammonium (NH 4 + -N) and nitric (NO 3 --N) forms are also diminished. These forms of urea are the most labile for ammonia volatilization, de-nitrification and leaching in the soil-plant-atmosphere (Grohs et al, 2011;Pereira et al, 2009;Sanz-Cobena et al, 2008;Scivittaro et al, 2010;Stafanato et al, 2013;Watson et al, 2008).…”

“…Moreover, the industry should aim to minimize negative environmental impacts, avoid mineral leaching into the water table or volatilization, and minimize the emissions of N oxides (a greenhouse gas) (Novoa;Tejeda, 2006;Stehfest;Bouwman, 2006;Vilain et al, 2014). These objectives have been achieved by aggregating available technologies with conventional fertilizers, such as urea, by reducing N losses and by increasing agronomic efficiency (Watson et al, 2008;Trenkel, 2010).…”