Field experiments comparing ammonium nitrate and urea top-dressing for winter cereals and grassland in the U.K.

Abstract

The results of 173 field experiments carried out between 1957 and 1986 are presented comparing ammonium nitrate and urea as top-dressings for winter cereals and grassland.The trials show that urea was an inferior nitrogen source to ammonium nitrate. The yield from ammonium nitrate was significantly greater than that from urea for winter wheat, winter barley and for first, second and third cut silage. The results suggest (a) that winter wheat and winter barley respond differently to the two nitrogen sources and (6) that yield losses from urea are just as likely on first cut silage as second or third cut.

Evaluation of calcium ammonium nitrate and urea-based fertilisers applied to grassland in Ireland

“…This was reflected in the calculated N use efficiency which was 55% higher with CAN compared with urea, the value of URY (c.90%) and relative N uptake (c.85%). The relatively lower agronomic performances encountered with urea agrees closely with the conclusions reached by Chaney and Paulson (1988) for (early) spring applications of N. Although the uptake of un-hydrolysed urea had been reported (Mengel and Kirkby, 1987), its rate of absorption is relatively lower compared with ammonium-N or nitrate-N (Bradley et al, 1989). Watson et al (1990) suggested that the translation of N uptake into DMY may be less effective with urea than CAN.…”

“…Ammonia volatilisation increases significantly with the application rate of urea (Overrein and Moe, 1967) which is one of the main reasons for urea to result in lower yields relative to CAN or AN (Lloyd, 1992;Chambers and Dampney, 2009). This effect had been shown in earlier studies (Chaney and Paulson, 1988;Murphy, 1983;Van Burg et al, 1982) and it can be the reason for the relatively lower response to urea-N in the range of 50 to 75 kg ha -1 . The differences in the response between fertilisers are expected to be greater at higher N application rates than those used in this study (Overrein and Moe, 1967).…”

“…Herlihy and Sheehan, 1977) compared with CAN when used in spring grass production. By contrast, other work (Chaney and Paulson, 1988;Swift et al, 1988) showed lower relative efficiencies. Scholefield (2003), based on Devine and Holmes (1963), indicated that the use of urea on grass crops can result in DMY reductions in the range of 10% to 15% compared with AN depending on the conditions in which the fertiliser was applied.…”

“…Herlihy and Sheehan, 1977;Chaney and Paulson, 1988) whereas for summer applications, efficiencies are usually lower.…”

“…Scholefield (2003) indicated that the majority of the data produced were obtained from field-scale trials conducted in the UK (e.g. Devine and Holmes, 1963;Chaney and Paulson, 1988) and Ireland (e.g. Keane et al, 1974;Murphy, 1978Murphy, , 1983 before the middle of 1980's with limited information produced thereafter (e.g.…”