A micro-plot field experiment with reduced urea <sup>15</sup>N application was conducted to study the effects of urease inhibitor NBPT (N-(<i>n</i>-butyl) thiophosphoric triamide) and nitrification inhibitor DMPP(3,4-dimethyl-1H-pyrazolium dihydrogen) on the fate of applied urea <sup>15</sup>N; it aimed to find an efficient way to reduce the urea N application rate while improving the agronomic and environmental benefits. Five treatments were installed, i.e., 180 kg N/ha (N<sub>1</sub>, conventional application rate), 126 kg N/ha (N<sub>2</sub>, reduced to 70% conventional application rate), N<sub>2</sub> + NBPT, N<sub>2</sub> + DMPP, and N<sub>2</sub> + NBPT + DMPP. Compared with treatment N<sub>1</sub>, all the other treatments had a significantly higher total <sup>15</sup>N recovery by both soil and plant (<i>P</i> < 0.05 48.20, 41.39, 37.69, 38.85 and 34.83% soil recovery for N<sub>2</sub> + NBPT + DMPP, N<sub>2</sub> + DMPP, N<sub>2</sub> + NBPT, N<sub>2</sub> and N<sub>1</sub>treatment, respectively; and 42.68, 40.86, 40.25, 37.18 and 36.30% plant recovery for N<sub>2</sub> + NBPT + DMPP, N<sub>2</sub> + DMPP, N<sub>2</sub> + NBPT, N<sub>2</sub>, and N<sub>1</sub> treatment, respectively). In the plant <sup>15</sup>N recovery, the <sup>15</sup>N absorbed in grain/stem was highest in treatment N<sub>2</sub> + NBPT + DMPP. The maize biomass and the maize yield had a slight increase in treatment N<sub>2</sub> + NBPT + DMPP, compared with those in treatment N<sub>1</sub>. In sum, for the maize production in study area, N<sub>2</sub> + NBPT + DMPP application method would be a feasible way to ensure the normal maize yield while improving yield quality, saving urea fertilizer, and protecting the environment.
Molecular rearrangement of waxy and normal maize starch granules during in vitro digestion