Phosphorous and nitrogen changes in compost-amended schist soils in vineyards in the D.O. Priorat wine-producing area (NE Spain)

Abstract

The impact, on nitrogen and phosphorous dynamics, of applying compost at different rates was investigated in soils developed on schist in new terraced vineyards (NTV) and in undisturbed areas (NC). Repacked soil columns amended with 0 (control), 50 t ha -1 (T1) and 100 t ha -1 (T2) of compost were studied under laboratory conditions simulating both situations. The columns were maintained for 1 year, during which time a total of 300 mm of simulated rainfall was applied in ten 30 mm applications. Soil organic matter (OM), nitrogen and phosphorous contents were analysed at the end of the study period and leachates were analysed after each simulated rainfall event. Significant differences in nitrate leaching were observed between the control and the treated soils and these differences were greater in the NC (control = 1.368 g, T1 = 1.526 g and T2 = 1.686 g) than in the NTV soils (control = 0.61 g, T1 = = 1.068 g and T2 = 1.283 g). The relative effect was greater in the NTV soils (T1/control = 1.11 vs. 1.75 and T2/control = 1.23 vs. 2.1 for NC and NTV, respectively). The nitrate concentration in the leached water reached up to 400 mg L -1 , which implied a risk of groundwater pollution. Phosphorous losses through leaching were very low with concentrations of < 0.15 mg L -1 , without any significant differences between treatments. The phosphorous concentrations in the surface horizon increased by 50.8% in T1 and by 66.8% in T2 in the NC soils, compared with increases of 20.3% and 38%, respectively, in the NTV soils. Due to the high infiltration capacity of the study soils, leaching effects must be considered in order to prevent groundwater pollution.Additional key words: land terracing; leaching; nutrients; soil properties. Resumen Cambios en las concentraciones de fósforo y nitrógeno en suelos desarrollados sobre esquistos tratados con compost en viñedos de la region vitícola del Priorat (NE de España)Se analizan los efectos de la aplicación de diferentes dosis de compost en la dinámica del nitrógeno y el fósforo en suelos no alterados (NC) y de viñedos aterrazados (NTV) desarrollados sobre esquistos. Para cada suelo se montaron tres series de columnas (control y dos dosis de compost: 50 t ha -1 (T1) y 100 t ha -1 (T2)), que se mantuvieron durante 1 año. Se aplicaron 300 mm de lluvia simulada en 10 sucesos de 30 mm. Después de cada lluvia se recogieron los lixiviados y se analizó el nitrógeno y el fósforo disuelto. Al final del estudio, se analizó el contenido de materia orgánica, nitrógeno y fósforo en el suelo a diferentes profundidades. La concentración de nitratos en los lixiviados llegó a ser de 400 mg L -1 . El nitrato total lixiviado fue significativamente mayor en los suelos NC (control = 1,368 g, T1 = 1,526 g y T2 = 1,686 g) que en los NTV (control = 0,61 g, T1 = 1,068 g y T2 = 1,283 g), siendo el efecto relativo mayor en los suelos NTV (T1/control = 1,11 vs. 1.75; T2/control = 1,23 vs. 2,1 en NC y NTV, respectivamente;). Las pérdidas de fósfo-ro por lavado fueron muy pequeñas, con concentraciones < ...