Effects of spray application of urea fertilizer at stem extension on winter wheat yield

Abstract

Supplying a proportion of the N requirement of a wheat crop via the foliage would potentially reduce immobilization of fertilizer N in the soil organic matter and N losses by leaching or denitrification. A field experiment was carried out at Harper Adams in Shropshire to investigate the effect on crop yield of supplying the spring N application to winter wheat as different proportions of urea as a solution rather than as conventional soil-applied urea, and to determine the physiological basis of any yield differences. A solid ammonium nitrate treatment was included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. Solid fertilizer was applied as a single dressing, whereas urea sprays were split over a number of days to reduce scorch. Nitrogen as urea sprays produced similar grain yields to N applied conventionally to the soil as solid ammonium nitrate or urea, but effects on above-ground dry matter production and harvest index depended on the time of application. Application of a large proportion of N as urea sprays, such that some of the N as urea solution was applied later in relation to crop development, produced less above-ground dry matter, but compensated by increasing harvest index. It is concluded that application of N as urea sprays could be successfully used to substitute for soil-applied N fertilizer at stem extension in winter wheat without loss of yield. Extra application costs, however, are likely to outweigh any efficiency or environmental benefits, except where applications of solid N are made to dry soils.

Comparing Soil vs. Foliar Nitrogen Supply of the Whole Fertilizer Dose in Common Wheat

“…However, damage of the flag leaf tips seems to be well tolerated by wheat, as confirmed by the appreciable yield and grain quality improvements reached by all foliar treatments, regardless of the fertilizer choice between UAN and urea. This is in agreement with the findings of several authors [11,24,26], while other studies [15,30] reported a higher threshold, i.e., 40 kg ha −1 as a single application between stages ZDS 39 (flag leaf visible) and ZDS 73 (early milk development), without compromising productivity.…”

“…In our study, many agronomic parameters, such as yield, harvest index and TSW, were preserved under low N doses supplied by foliar spraying, suggesting that this approach to fertilization in wheat is feasible, as indicated by the previous literature [24,31]. Our experimental soil had a relatively good fertility, with 0.11% N and 1.7% organic matter, which could have prevented a correct evaluation of N shortage compared to common practice.…”

“…Higher amounts, up to 60 kg N ha −1 , are possible, although severe leaf burning can occur under specific environmental conditions [22]. For these reasons, much of the research is focused on the effects of foliar N supply only late in the season, while very few studies have dealt with the use of foliar spraying to replace the main N dose conventionally applied to the soil by splitting it during the crop cycle [24].…”

Foliar uptake of nitrogen from ant faecal droplets: An overlooked service to ant‐plants

“…These workers deposit faecal droplets from rectal sac fluids and deposit them throughout their territory (Dejean & Beugnon, ; Offenberg, ), especially on flushing leaves and developing fruits, where ant activity is highest (Hölldobler & Wilson, ; Offenberg, Nielsen, Macintosh, Aksornkoae, & Havanon, ). These faecal droplets contains nutritious compounds such as amino acids and urea (Vidkjær, Wollenweber, Gislum, Jensen, & Fomsgaard, ; Vidkjær et al., ), compounds that are commonly used as foliar fertilisers in agriculture, as they can be absorbed directly by plant leaves (Abad, Lloveras, & Michelena, ; Readman, Kettlewell, & Beckwith, ; Varga & Svečnjak, ).…”

Nitrogênio e água como fatores de produtividade do trigo no cerrado

“…Nesses trabalhos, constatou-se que a resposta das cultivares de trigo a irrigação e fertilização, é caraterizada pela relação positiva entre tais fatores. A natureza desta interação, entretanto, é função das condições edafoclimáticas, cultivares e técnicas de manejo empregadas (Frizzone et al, 1996;Sandhu et al, 2002;Readman et al, 2002). A eficiência e/ou resposta dos genótipos de trigo a doses de nitrogênio em relação à produtividade, depende da disponibilidade de água.…”