Abstract
ABSTRACT Application of stabilized and controlled-release urea blends can reduce the losses of N-NH3 as compared to conventional urea. The aim of this study was to quantify ammonia volatilization from conventional nitrogen fertilizers and blends of urea + (urea + NBPT) + controlled release urea applied in drip irrigated coffee system. The experiment was conducted under field conditions in in a Red Latosol located in Lavras-MG, Brazil. The randomized complete block design with six treatments: Urea = 450 kg ha-1 yr-1 N (100% of the recommended dose) divided in three splittings equal to 150 kg ha-1 N with an interval of 50 days; ammonium nitrate = 450 kg ha-1 yr-1 N (100% of the recommended dose) in three splittings equal to 150 kg ha-1 N with an interval of 50 days; Polyblen Extend(r)-100%= 450 kg ha-1 yr-1 (100% of the recommended dose) applied in two splittings, 315 kg ha-1 N in the 1º split and 135 kg ha-1 N in the 2º split; Polyblen Extend(r)-70% = 315 kg ha-1 yr-1 N (70% of the recommended dose) in two splittings, 220.5 kg ha-1 N in the 1º split and 94.5 kg ha-1 N in the 2º split; Polyblen Montanha(r)-100% = 450 kg ha-1 yr-1 (100% of the recommended dose) in an unique application in the 1º split and Polyblen Montanha(r)-70% = 315 kg ha-1 yr-1 N (70% of the recommended dose) at an unique application in the 1º split, with three repetitions. Total accumulated N-NH3 losses followed the decreasing order: Urea (83.2 kg ha-1 N) > Polyblen Extend(r) - 100% (60.3 kg ha-1 N) > Polyblen Montanha(r) - 100% (46.8 kg ha-1 N) > Polyblen Extend(r) - 70% (35.1 kg ha-1 N) > Polyblen Montanha(r) - 70% (24.2 kg ha-1 N) > nitrate ammonium (2.0 kg ha-1 N ). The use of Polyblen Montanha(r) decreases two splittings compared to conventional sources such as urea and ammonium nitrate, by applying only 70% of the recommended dose without affecting yield and coffee crop nutrition.
Highlights
Agronomic coffee growing holds a prominent position in Brazilian agricultural, generating jobs and bringing revenue into the country
The experiment was conducted in the field between August 2014 and August 2015 on soil classified as a dystroferric Red Latosol, equivalent to an Oxisol at US Soil Taxonomy Classification System (Buol et al, 2011; EMBRAPA, 2013), on a commercial coffee farm in Lavras, state of Minas Gerais, Brazil
The soil was further sieved through a 2 mm mesh sieve, and sub-samples were taken for chemical and physical analyses, which were conducted according to the methodology of the Soil Fertility Committee of Minas Gerais State – CFSEMG (1999), Brazil (Table 1)
Summary
Agronomic coffee growing holds a prominent position in Brazilian agricultural, generating jobs and bringing revenue into the country. The coffee plant yield is influenced by several factors, including the nutritional status of the plants. The nitrogen nutrition of the coffee tree deserves special attention because nitrogen (N) is the nutrient required in the greatest amount and the second most exported nutrient in grains (Carelli et al, 2006; Fenilli et al, 2007; Bruno et al, 2011; Martinez et al, 2014). In Brazil in 2014, 830,374 metric tons of N as urea were produced, and another 1,644,545 metric tons were imported, totaling 2,474,919 metric tons of N (ANDA, 2015). Of the total N delivered to farmers, 64% was applied as urea. Economic factors related to the production and logistics processes make urea the most used nitrogen fertilizer in the world. Due to the high concentration of N (45%), urea has a lower cost per unit N compared to that of sulfate and ammonium nitrate (Roy; Hammond, 2004; Fernandes et al, 2015)
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