The effects of applied crop residues on losses of Fe, Mn, Cu and Zn in run‐off from a soil prone to crusting

Abstract

Tillage practices may reduce the organic matter content in near-surface soil horizons causing crust formation. Surface conditions may cause an increase in surface run-off, thus enhancing contaminant transfer of heavy metals or an acceleration in nutrient loss. This study examines the effect of applying crop residues to the surface of tilled soils on heavy metal losses by run-off. Losses in iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) were analysed. Run-off and sediment yield were measured on 1 m 2 plots using a rainfall simulator with a constant 65 mm ⁄ h intensity. Four successive rainfall applications were performed, the first three at 25 mm each and the last at 65 mm. Added corn straw varied between 0 and 4 t ⁄ ha in the five studied treatments. After 140 mm cumulative rainfall, total heavy metal losses were as follows: Fe from 137 to 950 mg ⁄ L, Mn from 2.3 to 12.83 mg ⁄ L, Cu from 0.09 to 0.72 mg ⁄ L and Zn from 0.31 to 2.46 mg ⁄ L. Dissolved fractions were as follows: Fe from 0.014 to 0.229 mg ⁄ L, Mn from 0.034 to 1.45 mg ⁄ L, Cu from 0.002 to 0.013 mg ⁄ L and Zn from 0.02 to 0.12 mg ⁄ L. Total concentrations of the studied elements decreased exponentially due to the effect of corn straw on soil loss. However, dissolved contents of Fe and Cu scarcely varied. Significant positive linear correlations were observed between total heavy metal content and soil and sediment loss by run-off. It is concluded that the addition of straw to a soil of low fertility prevents heavy metal loss.

Crop Residue Effects on Total and Dissolved Losses of Fe, Mn, Cu, and Zn by Runoff

“…By contrast, the silt loam soil described in former studies (Mirás-Avalos et al, 2009a;2009b), had a lower OM (3.14 %) content and aggregate stability, as measured by the mean weight diameter method (Paz Ferreiro and Vidal Vázquez, 2010); this soil was also prone to surface crusting as assessed by observations of the evolution of the surface under simulated rainfall (Mirás-Avalos et al, 2009c). A c c e p t e d M a n u s c r i p t 5 Soil was manually packed in the five microplots to simulate chisel plowing from structural units, clods and aggregates of different size.…”

“…The amount of rainfall applied to the well structured loamy soil (520 mm in 8 events of one hour each, with 65 mm h -1 intensity) was greater than the amount used in previous studies with the silt loan soil prone to crusting (Mirás-Avalos et al, 2009a, 2009bMirás-Avalos et al, 2012). The main objective of this study was to evaluate the effect of applying corn straw residues on runoff losses of four selected A c c e p t e d M a n u s c r i p t 4 micronutrients (Fe, Mn, Cu, and Zn).…”

“…Increasing amounts of corn straw residues reduced soil and water losses and also decreased losses of most nutrients. Nonetheless, micronutrient losses in runoff from this particular soil were rather high, which was attributed to its low structural stability (Mirás-Avalos et al, 2009b). …”

“…The main objective of this study was to evaluate the effect of applying corn straw residues on runoff losses of four selected A c c e p t e d M a n u s c r i p t 4 micronutrients (Fe, Mn, Cu, and Zn). In addition, soil and micronutrient losses from the loamy soil with high OM content studied here were compared with those from the silt loam soil with low OM content previously studied (Mirás-Avalos et al, 2009a;2009b).…”

El conflicto de uso del suelo y la calidad de los alimentos The soil use conflict and food quality

“…Los problemas no se limitan u´nicamente a la gestio´n de suelo urbano y periurbano, sino tambie´n a la ordenacio´n de suelos forestales y agrı´colas. La intensificacio´n agrı´cola causa un aumento de la carga de sedimentos, elementos traza y contaminacio´n bio´tica en los cursos de agua superficiales por efecto de la degradacio´n de la capacidad de infiltracio´n de los suelos (Mira´s Avalos et al, 2009;Sande Fouz, Mira´s Avalos, & Paz Gonza´lez, 2007). Con respecto a la gestio´n del suelo agrı´cola, uno de los mayores problemas de seguridad alimentaria es la intensificacio´n de las mareas rojas litorales (inducidas por ciclos naturales de incrementos de temperatura) en condiciones de sobrecarga de nutrientes procedentes de la fertilizacio´n de los cultivos.…”