Nitrate leaching through climatologic water balance in a fertigated coffee plantation

Abstract

RESUMO Lixiviação de nitrato por meio do balanço hídrico climatológico na cultura de café fertirrigadaAs perdas de nitrato no perfil do solo por lixiviação devem ser monitoradas preferencialmente em ocasiões de altas precipitações pluviométricas e irrigações quando o uso de insumos nitrogenados é elevado. Foi utilizado o balanço hídrico climatológico empregando os modelos de Thornthwaite e Penman Monteith na obtenção da estimativa de evapotranspiração potencial para calcular os fluxos de drenagem de água abaixo da zona de raiz em lavoura de café fertirrigada. A extração da solução do solo a uma profundidade de 1 m permitiu o cálculo do nitrato lixiviado. A concentração de nitrato na solução do solo nas parcelas que receberam 400 kg ha Nitrate losses from soil profiles by leaching should preferentially be monitored during high rainfall events and during irrigation when fertilizer nitrogen applications are elevated. Using a climatologic water balance, based on the models of Thornthwaite and Penman Monteith for potential evapotranspiration, drainage soil water fluxes below the root zone were estimated in a fertigated coffee crop. Soil solution extraction at the depth of 1 m allowed the calculation of nitrate leaching. The average nitrate concentration in soil solution for plots that received nitrogen by fertigation at a rate of 400 kg ha , surpassing the limit of the Brazilian legislation of 10.0 mg L -1 , only during one month. For plots receiving 800 kg ha -1 of nitrogen, the average was 25.01 mg L -1 , 2.5 times higher than the abovementioned limit. This information indicates that nitrogen rates higher than 400 kg ha -1 are potentially polluting the ground water. Yearly nitrate amounts of leaching were 24.2 and 153.0 kg ha -1 for the nitrogen rates of 400 and 800 kg ha -1 , respectively. The six times higher loss indicates a cost/benefit problem for coffee fertigations above 400 kg ha -1 .

The Brazilian Cerrado: assessment of water and soil degradation in catchments under intensive agricultural use

“…However, the role that nitrogen leaching plays in agricultural Cerrado is inconclusive. In the eastern Cerrado, Bortolotto et al (2012Bortolotto et al ( , 2013 reported extremely high N-applications during fertigation (irrigation combined with fertilizer application) in coffee plantations at a rate of up to 800 kg N ha À1 a À1 . Most commonly, nitrogen fertilizer (for cotton up to 180 kg ha À1 N and maize~90 kg ha À1 ) is applied as urea with 1/3 of the total N rate during the seeding stage of the second crop (usually maize or cotton) after the soybean harvest.…”

“…Gücker et al (2009) provided evidence for nitrate leaching, that is, significantly high levels, in groundwater samples influenced by agriculture. In the eastern Cerrado, Bortolotto et al (2012Bortolotto et al ( , 2013 reported extremely high N-applications during fertigation (irrigation combined with fertilizer application) in coffee plantations at a rate of up to 800 kg N ha À1 a À1 . In field experiments, they confirmed that nitrate leaching and groundwater pollution would occur.…”

Nitrate and potassium movement in a sandy loam soil cultivated with fertigated grapevine (Vitis vinifera /L.) in the Brazilian semiarid

“…Therefore, a correct management of water and fertilizers is necessary to avoid increases in production costs and minimize damages to the environment. Among the problems that arise from an excessive application of fertilizers, we can mention contamination of water tables, by which elements are leached to depths below the root system, and may reach water sources and pollute the environment (BORTOLOTTO et al 2013). Among the fertilizers that may cause pollution as a consequence of an inadequate management, we can highlight N fertilizers, with an emphasis on the nitrate ion (NO 3 -) and its action in the contamination of groundwater (ANDRADE et al, 2016), and potassium fertilizers, which may raise the levels of K + in the soil to levels above those required for crops when applied excessively (SILVA et al, 2014).…”

Condutividade Hidráulica E Drenagem Interna Em Latossolo Cultivado Com Café Adubado Com Elevadas Doses De Nitrogênio

“…Os empreendimentos agrícolas têm utilizado doses cada vez mais elevadas de fertilizantes e pesticidas com o intuito de propiciar condições ótimas para o desenvolvimento das culturas e, assim, elevar as produtividades. Essas aplicações podem representar riscos ambientais às áreas cultivadas, já que pode haver contaminação do lençol freático (BORTOLOTTO et al, 2013).…”