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Field microplot studies were conducted under zero-till conditions on a fine sandy loam (Orthic Black Chernozem) to determine the effect of the urease inhibitors N-(n-butyl) thiophosphoric triamide (NBPT) and ammonium thiosulphate (ATS) on volatile losses of NH3 from urea and urea ammonium nitrate (UAN). Two studies were conducted, one in late May and one in early August. Losses of NH3 were measured on days 1, 2, 4 and 7 after fertilizer application, using ammonia traps. Ammonia losses were higher in the second study due to the higher soil temperatures and lower soil moisture later in the growing season. Total NH3 losses increased in the order Control < UAN + NBPT = Urea + NBPT < UAN + ATS = UAN < Urea. Total loss of NH3 during the 7 d after fertilizer application was higher from urea than from UAN, particularly in the first study. Use of NBPT was effective in reducing NH3 volatilization from both UAN and urea during 7 d after fertilizer application while use of ATS had little influence on NH3 loss from UAN. The NBPT may delay losses by slowing the hydrolysis of urea, but volatilization may persist for a longer duration. The delay in urea hydrolysis could allow time for rainfall to carry the urea into the soil, thus reducing total volatilization losses from surface fertilizer application. Key words: N-(n-butyl) thiophosphoric triamide, zero tillage

Climate warming has delayed the end of the growing season (EOS) in temperate and cold ecosystems. However, it is unclear whether asymmetric warming (higher warming at night than during the day) has triggered different responses in the timing of EOS. Here we used satellite‐observed EOS of alpine vegetation to reveal its asymmetric responses to nighttime and daytime warming on the Tibetan Plateau. Increased preseason minimum temperature could postpone EOS by 7.92 day K−1 (P < 0.01), probably by slowing low‐temperature induced leaf senescence, whereas increased preseason maximum temperature could advance EOS by 3.57 day K−1 (P < 0.05), likely due to the confounding effects of water limitations. The delaying effect of nighttime warming was stronger in more arid areas of the plateau, where daytime warming has a stronger advancing effect on EOS. Our results provide new insights into understanding and modeling autumn vegetation phenology on the Tibetan Plateau and grassland ecosystems in other temperate and cold regions.

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