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Blending polymer-sulfur coated urea (PSCU) and conventional urea (U) for maize (Zea mays L.) fertilization can supply nitrogen (N) during the crop cycle with a single application. Proper placement of PSCU + U (0.15 m below and 0.1 m to the side of seed row) in band application at sowing is necessary to reduce salt stress that can decrease dry weight (DU) and N uptake (NU) of maize plant compromising maize yield. It is not clear the proper N rate in the proper placement for band application of PSCU + U at maize sowing to avoid salt stress. In the current literature, reduction of N rates are being recommended using PSCU + U without consider the probably salt stress provided by high rates of PSCU + U. DW and NU in maize plant as well as soil pH and electrical conductivity (EC) were evaluated in a greenhouse pot trial. N treatments were equivalent to 0, 90, 180, 360 and 540 kg N ha−1 applied incorporated in band in two contrasting soils (Rhodic Eutrustox and Typic Haplustox) using 70%PSCU + 30%U. At V10 (vegetative leaf stage 10), DW and NU of maize aerial part had quadratic behavior in response to increase N rates in the Typic Haplustox soil. In the Rhodic Eutrustox was not observed known behavior for DW and NU in response to increase N rates. Soil pH and EC was higher in the fertilizer row than sowing row. A N rate above of 180 kg N ha−1 using 70%PSCU + 30%U incorporated in bands can reduce DW and NU in early maize plant growth associated with salt concentration of N fertilizer in a Typic Haplustox soil, which could compromise maize yield. [ABSTRACT FROM AUTHOR]

A single application of polymer-sulfur coated urea (PSCU) and conventional urea (U) blends can supply nitrogen (N) throughout the maize (Zea mays L.) cycle but it could become harmful for plants if not properly placed in the soil due to a possible salt stress which would reduce dry weight (DW) and N uptake (NU) in maize. DW and NU in maize plant as well as soil pH and electrical conductive (EC) were evaluated in a greenhouse pot trial. Treatments consisted of different placements (0.05, 0.1 and 0.15 m below and 0, 0.05 and 0.1 m to the side of seed row) of fertilizers (70%PSCU + 30%U, and 100%U) applied at maize sowing in band at a rate equivalent to 180 kg N ha−1 in a Rhodic Eutrustox soil. Control treatment (without N) was also included. At V7 (vegetative leaf stage 7), N fertilizers placed 0.15 m below of seed row provided higher total DW, total NU, EC and pH (in fertilizer row) than 0.05 m and 0.1 m. 70%PSCU + 30%U provided higher total DW and total NU than 100%U in placement 0 m. In addition, 70%PSCU + 30%U placed 0.1 m to the side of seed row provided lower total NU and EC (in fertilizer row) than 0 m. 70%PSCU + 30%U and 100%U placement can negatively interfere maize in vegetative stage when applied incorporated in band at sowing. The proper placement for this condition was 0.15 m below and 0.1 m to the side of seed row. [ABSTRACT FROM AUTHOR]

Urea treated with urease inhibitors (UI) in association with humic substances (HS) is expected to improve urea efficiency by reducing ammonia losses and also provide the benefits of HS such as improve nitrogen (N) recovery by plants. Ammonia volatilization (AV), 15N recovery efficiency in the soil (NRE) and 15N use efficiency (NUE) were evaluated in maize (Zea mays L.) in a greenhouse pot trial. Treatments consisted of 15N-urea treated with UI (0, 0.4% boron (B) +0.15% copper (Cu), 0.64% B, and NBPT (N-(n-butyl) thiophosphoric triamide)) and three levels of HS (0%, 0.6%, and 1.2%). A control treatment (without N) was also included. N treatments were applied at V4 (vegetative leaf stage 4) on soil surface. HS was not efficient on AV reduction, NBPT had the greatest reduction in AV, and B had higher efficiency on AV reduction than Cu. At V8 (vegetative leaf stage 8), NBPT had the greatest NUE followed by B. At VT (tassel fully emerged), NUE from urea treated with NBPT reduced when increased levels of HS, and NBPT had the greatest NRE. UI in association with HS treated-urea does not reduce AV and it does not improve NUE by maize in vegetative stages. [ABSTRACT FROM AUTHOR]

A single application of polymer-sulfur coated urea (PSCU) and conventional urea (U) is expected to ensure nitrogen (N) throughout the maize (Zea mays L.) growth cycle being U the likely main N-fertilizer supplier at the beginning and PSCU during the maize growth cycle. This research aimed to evaluate N fertilization management (split, incorporated, and broadcast application) and fertilizer blends (30%PSCU + 70%U and 70%PSCU + 30%U) on volatilization of ammonia (AV) and soil N mineral content (NM); plant N uptake (NU) and 15N-fertilizer recovery (NR); and yield (GY). Field experiments were conducted for two growing seasons (2017–2018 and 2019–2020) in Rhodic Eutrustox soil. U was treated with NBPT (N-(n-butyl) thiophosphoric triamide). N rate was 180 kg ha−1. AV reached 12% of the applied N (broadcast-applied 70%PSCU + 30%U, 2017–2018). The 30%PSCU + 70%U application resulted in higher NM at 40–60 cm depth in vegetative and reproductive stages in both seasons. The 70%PSCU + 30%U application resulted in the highest GY in 2017–2018, and the N treatments did not affect GY in 2019–2020. NR was 3% on average at vegetative leaf stage 4 (V4), and PSCU, the main N-fertilizer supplier applying 70%PSCU + 30%U. After V4, the main N-fertilizer supplier is PSCU for 70%PSCU + 30%U and U for 30%PSCU + 70%U application. These blends (incorporated, broadcast, and split application) can ensure N during the maize growth cycle, with NR of 72.5% at maturity (R6) being 47.9% in the grain. [ABSTRACT FROM AUTHOR]