Trees' Role in Nitrogen Leaching after Organic, Mineral Fertilization: A Greenhouse Experiment

Abstract

New sustainable agriculture techniques are arising in response to the environmental problems caused by intensive agriculture, such as nitrate leaching and surface water eutrophication. Organic fertilization (e.g., with sewage sludge) and agroforestry could be used to reduce nutrient leaching. We assessed the efficiency of establishing trees and pasture species in environmentally sensitive, irrigated Mediterranean grassland soils in controlling nitrate leaching. Four vegetation systems-bare soil, pasture species, cherry trees [ (L.) L.], and pasture-tree mixed plantings-and five fertilization treatments-control, two doses of mineral fertilizer, and two doses of organic fertilizer (sewage sludge)-were tested in a greenhouse experiment over 2 yr. In the experiment, the wet and warm climate characteristics of Mediterranean irrigated croplands and the plant-to-plant and soil-to-plant interactions that occur in open-field agroforestry plantations were simulated. Following a factorial design with six replicates, 120 pots (30-cm radius and 120 cm deep) were filled with a sandy, alluvial soil common in the cultivated fluvial plains of the region. The greatest pasture production and tree growth were obtained with sewage sludge application. Both pasture production and tree growth decreased significantly in the pasture-tree mixed planting. Nitrate leaching was negligible in this latter treatment, except under the highest dose of sewage sludge application. The rapid mineralization of sludge suggested that this organic fertilizer should be used very cautiously in warm, irrigated Mediterranean soils. Mixed planting of pasture species and trees, such as , could be a useful tool for mitigating nitrate leaching from irrigated Mediterranean pastures on sandy soils.

Landscape-scale modelling of agroforestry ecosystems services in Swiss orchards: a methodological approach

“…This echoes similar findings by e.g Nair et al (2007) and Jose (2009), who showed that agroforestry systems can help reduce nutrient losses by 40 to 70%. López-Díaz et al (2011) showed in greenhouse experiments that trees have a higher root density and a deeper root horizon, which led to a higher uptake of nitrate and a reduction of nitrate leaching of 38 to 85%.…”

Agronomic and environmental effects of land application of residues in short-rotation tree plantations: A literature review

“…Based on simulations associated with a review of the literature [181], it has been estimated that the contribution of sludge in forest should not exceed N dose of 0.4 Mg ha À1 every three years during the growing season to avoid contamination of groundwater and surface water [181]. Studies dealing with the subject have rarely highlighted N leak, most of which was absorbed by plants [182,183]. Most studies, however, admit to not having the necessary long term perspective to conclude clearly, and they often suggest that a longer monitoring or additional experiments are needed.…”

Técnicas alternativas de manejo de plantaciones de producción de madera de calidad en régimen intensivo

“…Esta mayor disponibilidad de N a corto plazo con el laboreo, unido a la ausencia de vegetación en el estrato inferior, produjo un incremento en el lixiviado de nitratos, lo que podría plantear problemas de contaminación de aguas subterráneas Sin embargo, el hecho de que el aumento de nitratos sólo se detectara en la zona más superficial (30 cm) y no en la más profunda (90 cm) reduce el riesgo de contaminación. López-Díaz et al (2011), en un ensayo realizado en invernadero en el que se comparaba el lavado de nitratos bajo cuatro sistemas distintos de vegetación (suelo desnudo, pasto, arbolado y sistema agroforestal) observaron que bajo los sistemas agroforestales el lavado de nitratos se reducía considerablemente en profundidad, al igual que obtuvieron (Van Der Salm et al, 2006), gracias principalmente a la presencia del arbolado, que es capaz de aprovechar el nitrógeno tanto a nivel superficial, donde también se desarrollan las raíces de las herbáceas, como en capas más profundas (Moreno et al, 2005).…”