Efficiency and future potential of urea for temperate grassland

Effects of Biosolids-Derived Organomineral Fertilizers, Urea, and Biosolids Granules on Crop and Soil Established with Ryegrass (Lolium perenne L.)

“…This is explained by late timing of N application relative to maximum rate of growth of ryegrass (Orr et al 1988), and combined effects of high temperatures around the time of fertilizer application with surface-application of fertilizers leading to losses of N by volatilization of NH 3 . The latter is recognized to be the main reason for inefficiency of urea-based fertilizers compared with other straight N fertilizers such as ammonium nitrate (Watson et al 1990). Urea-based fertilizers can have similar efficiencies to ammonium nitrate when applications are conducted in spring but can be lower in summer (Watson et al 1990).…”

“…The latter is recognized to be the main reason for inefficiency of urea-based fertilizers compared with other straight N fertilizers such as ammonium nitrate (Watson et al 1990). Urea-based fertilizers can have similar efficiencies to ammonium nitrate when applications are conducted in spring but can be lower in summer (Watson et al 1990). In Y1, NUE recorded in urea-and OMF-treated grass were within the range reported in the literature (e.g., Whitehead, Jones, and Barnes 1978;Morrison, Jackson, and Sparrow 1980;, but exceeded those obtained in Y2 which were similar to values obtained by Williams, Rowarth, and Tregurtha (2000).…”

Field studies on the value of organomineral fertilisers as amendments for perennial ryegrass (Lolium perenne L)

“…The relatively dry and warm conditions recorded in April 2010 (Figure 1) support the possibility of N losses by volatilisation of NH 3 after the fertiliser application. For urea-containing fertilisers, these losses are enhanced at higher N application rates or with increased temperature (range of 10° to 30°C) (Watson et al, 1990).…”

“…In the drier year (2010), the efficiency of biosolids-N was affected by lower microbial activity which reduced the mineralisation rate of organic-N in the material. For OMF and urea water shortages translated into greater N losses by volatilisation of NH 3 , hence, N availability to the grass crop and reduced N uptake (Watson et al, 1990) which is reflected in the relatively lower agronomic efficiencies obtained in the second year.…”

“…The application of N should follow the general guidelines given in RB209 (DEFRA, 2010). Therefore, N application rates for individual cuts should not exceed 120 kg ha -1 ; this is an important consideration given that OMF contains urea which is prone to volatilisation at high N application rates (Watson et al, 1990). For the first cut, which is typically the one that requires the highest N dressing (e.g.…”