Nitrogen fertilizer leaching in an Oxisol cultivated with sugarcane

Abstract

Nitrogen (N) leaching below the crop-rooting zone represents not only a valuable loss of nutrients for the plant, but also a potential pollution source of groundwater. The objective of this work was to quantify leaching losses of native N and that derived from fertilizer in an Oxisol that was cultivated with sugarcane (Saccharum officinarum) during the crop plant cycle. The sugarcane was planted and fertilized with urea in the planting furrow, with 120 kg ha -1 of N. In order to determine the fate of the fertilizer -N, four microplots with 15 N enriched fertilizer were installed. Input and output of N at the depth of 0.9 m were quantified from the flux density of water and the N concentration in soil solution. During the evaluation period the rainfall was 141 mm less than the historical average (1,315 mm), and the climate was drier than normal in January. The average concentration of mineral N in soil solution was 1.8 mg L -1 . The abundance of 15 N was very high at the beginning (first week) of the assessment period and remained approximately constant (0.453 atom% of 15 N) until the end of the period. The internal drainage was 91 mm of water and the N leaching loss was 1.1 kg ha -1 of N, with only 54 g ha -1 derived from fertilizer. Therefore, under high demand of N by the crop in a system without burning before planting, the leaching of N was not considerable, mainly because the surplus of water between the months of December and March was lower than expected and also because the extraction of nitrogen by the crop was high. Key words: Saccharum spp., sustainability, solute transport, environmental quality, pollution Nitrogênio lixiviado num Latossolo cultivado com cana-de-açúcarRESUMO: A lixiviação de nitrogênio (N) abaixo da zona radicular representa uma valiosa perda do nutriente para as plantas e uma fonte potencial de poluição do lençol freático. Quantificaram-se as perdas de N por lixiviação num Latossolo Vermelho Amarelo cultivado com cana-de-açúcar (Saccharum officinarum) durante o ciclo agrícola de cana-planta. A cultura foi implantada e fertilizada no sulco com 120 kg ha -1 de N-uréia. Para conhecer o destino do fertilizante, foram instaladas quatro microparcelas onde o fertilizante era marcado com o isótopo 15 N. As entradas e saídas de N a 0,9 m de profundidade foram quantificadas diariamente pela densidade de fluxo de água e a concentração de N da solução no solo. No período de avaliação, a precipitação pluvial foi 141 mm menor que a média histórica (1.315 mm) sendo janeiro mais seco que o normal. A concentração de N mineral média foi 1,8 mg L -1 . A abundância de 15 N foi superior à abundância natural do isótopo, especialmente no início do período de avaliação, permanecendo logo constante (0,453% de 15 N). A drenagem interna foi de 91 mm de água e a perda por lixiviação foi 1,1 kg ha -1 de N com apenas 54 g ha -1 derivados do fertilizante. Portanto, com elevada demanda de nutrientes e elevada incorporação de restos culturais, não foram registradas perdas apreciáveis de N por lixiviação d...

Nitrogen fertilizer (15N) leaching in a central pivot fertigated coffee crop

“…Boaretto et al (2007) report that for citrus trees, the absorption of N is hindered in rainy periods due to leaching losses. According to Oliveira et al (2002) and Franco et al (2008) N losses by leaching may be negligible because most of the 15 N studies in sugarcane indicate very little leaching losses, as also recently reported by Ghiberto et al (2011), however, for Silva et al (2006) and Duete et al (2008) these low losses cannot be disregarded.…”

Enhanced-Efficiency Fertilizers in Nitrous Oxide Emissions from Urea Applied to Sugarcane

“…However, NIs are not commonly used in Brazil because they add cost to fertilizers and because these products do not always bring yield increases (Trenkel, 2010), especially in situations where N loss by nitrate leaching is low. Cantarella (2007), Ghiberto et al (2009), andGhiberto et al (2011) observed very little NO 3 -leaching from N fertilizers in sugarcane using fertilizers labeled with 15 N. Although losses of N as N 2 O are environmentally important, they are a small fraction of fertilizer costs, and sugarcane growers may not be willing to pay the cost of NIs if no yield increases accompany this environmental benefit. Mitigating N 2 O emissions from agriculture may, therefore, require broader approaches, such as the internationalization of costs of GHG abatement Venterea et al, 2012), in addition to the technical solutions found by researchers.…”

“…Leaching losses, which could be reduced by the NI or CRF treatments, are considered to be of little significance for sugarcane grown in the southeastern region of Brazil (Ghiberto et al, 2009(Ghiberto et al, , 2011. To minimize soil variability and to focus on the GHG evaluations, the treatments were concentrated in a small area of a sugarcane field with a uniform plant stand.…”

Characterization, agricultural potential, and perspectives for the management of light soils in Brazil

“…2016 DOI: 10.1590/S0100-204X2016000900001 Nutrient losses by leaching in sugarcane fields have been studied in Brazil, mainly in the state of São Paulo. Among the factors that determine leaching losses, can be mentioned: crop stage, fertilizer doses and solubility, and rainfall distribution in the region (Oliveira et al, 2001;Cantarella et al, 2007;Ghiberto et al, 2011). Table 4 shows nitrite, nitrate, and ammonium drainage and losses in a sugarcane crop in the municipality of Pirassununga, in the state of São Paulo, in a sandy clay loam Latossolo, with mean sand content of 680 g kg -1 in the 0 to 1-m layer.…”