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Fluid Journal : Summer 2016
21 The Fluid Journal Summer 2016 The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Summer 2016 • Vol. 24, No. 3, Issue #93 Drs. Eros Francisco, Fabio Dias, Raffaella Rossetto, Yebin Zhao, and Luis Prochnow Sugarcane sits as the third most important crop in land use in Brazil, after soybeans and maize, occupying over 9.0 million ha that produced 630 million tons last season, which represented 35.5 million tons of sugar and 28.7 billion liters of ethanol. Nitrogen (N) is the second most applied nutrient for sugarcane production, about 750,000 tons every year, just after potassium (P). Nitrogen use efficiency (NUE) may be interfered by chemical reactions generating losses by leaching or volatilization, therefore the use of distinct sources is strategic to overcome such problems. As most of the sugarcane fields are harvested without burning, a thick layer of straw remains on the top soil, which enhances the chances of N losses through volatilization. That is why, in many sugarcane areas of Brazil, farmers are testing different sources to increase N use efficiency (NUE). Sources The main sources of N for sugarcane in Brazil are ammonium nitrate (AN), ammonium phosphate (AP), and urea, with an estimated use of 50%, 10%, and 35%, respectively, while urea-ammonium nitrate solution (UAN) is used by very few farmers. Many studies have evaluated N volatilization from urea application in sugarcane fields as estimated to be between 30 to 50%, depending on weather and soil conditions, according to Nascimento et al. (2013). Choosing the right source of N will also depend on the operational ability of the UAN, AN Effective For Sugarcane in Brazil ▼ DOWNLOAD Field studies show them more effective than urea. Table 1. Analysis of variance regarding source, rate, and locality of application of N for gross yield (GY) and industrial characteristics1. Control treatments were disregarded in this analysis. Cause of variation GY TRS TPH TSH ton/ha kg/ha ton/ha Source UAN 81.72a 126.74a 10.34a 10.36a AN 81.14a 125.71ab 10.14a 10.17a Urea 74.38b 119.30b 8.81b 8.91b Rate 60 78.35 123.80 9.68 9.74 120 80.50 123.72 9.92 9.97 180 78.39 124.23 9.68 9.73 Locality In furrow 79.24 123.03 9.71 9.76 Surface 78.92 124.81 9.82 9.87 CV(%) 11.79 7.56 15.35 14.76 Mean 79.08 123.92 9.76 9.81 1 Industrial characteristic: total recoverable sugar (TRS), total POL per hectare (TPH), and total sugar per hectare (TSH). Means followed by the same letters do not differ (Duncan P>0.05). farmer in order to apply it at the right rate, at the right time, and at the right place such as to avoid losses, maximizing its efficiency. Objective A study was set to evaluate agronomic effectiveness of three N fertilizers for sugarcane in a tropical soil in the state of São Paulo. Also, two other important factors, which affect N fertilizer effectiveness, were studied: rate of N and place of application. Methodology Trial was installed using a complete randomized block design with 4 replicates in a factorial 3x3x2 and 4 controls such as: 3 N sources (UAN, Urea and Ammonium Nitrate), 3 N rates (60, 120, and 180 kg/ha), and 2 localities of application (in furrow and surface). Controls were: no N application (in furrow and surface) and 120 kg N/ha via Ammonium Sulfate (in furrow and surface). Soil. Original soil conditions (0-20 cm) were pHCaCl2 5.4, P-Resin 6 mg/dm3, CEC Summary: Nitrogen application is a key practice for high sugarcane yields, but the right source must be selected in order to avoid losses under certain soil and climate conditions.