No abstract

La evaluación del efecto de los sistemas agrícolas sobre el ambiente es fundamental para minimizar sus impactos negativos. Este estudio evalúa las pérdidas de agua, sedimentos y herbicidas por escurrimiento en distintas secuencias agrícolas, luego de una precipitación próxima a la pulverización. Fue realizado en parcelas de escurrimiento bajo lluvia natural, en INTA Paraná. Las secuencias de cultivo evaluadas fueron: soja continua (S), soja continua con trigo como cultivo de cobertura (CC-S) y trigo/soja (T/S) bajo siembra directa, las cuales fueron pulverizadas con glifosato y cletodim. Considerando el total de los datos analizados, los porcentajes perdidos en escurrimiento de glifosato y cletodim respecto a lo aplicado oscilaron entre 5,3-13,5% y 2,6-5,9%, respectivamente. Las pérdidas de suelo y AMPA (concentración) fueron mayores para S. Se resalta la importancia de las condiciones meteorológicas posteriores a las pulverizaciones para reducir el riesgo de aportes difusos de agroquímicos hacia cuerpos de agua.

No abstract

The addition of organic and inorganic amendments can improve soil structure and reduce soil compaction. In this context, this study aimed to evaluate whether the application of amendments reduces penetration resistance (PR) in the short term and describe the spatial variability of PR in the surface horizon of an Aquic Argiudoll under no-tillage in northeast Argentina. Four treatments, consisting of surface applications of 7.5 Mg ha−1 poultry litter (PL), 3.0 Mg ha−1 gypsum (G), the combination of PL+G, and untreated control (T), were arranged in a complete randomized block design with three replications. Two more treatments were added to the experiment 12 months later, consisting of PL reapplications on half of the surface of the PL+G and PL treatments (PL+G+PL and PL+PL, respectively) in a split-plot design with three replications in 4×20-m plots. PR was determined in the field with an Eijkelkamp penetrologger following a 2-m long transect perpendicular to the sowing direction at 10 different spots separated 0.2 m from each other. The spatial variability was quantified for each treatment using semivariograms. The highest PR was observed in the T treatment (1.96 MPa) and the lowest PR in PL+G+PL (0.21 MPa). All treatments showed a high spatial dependence (94.9 to 99.9%). Treatments with PL reapplication (PL+PL and PL+G+PL) showed profiles with lower PR and more homogeneous kriging maps. PL reapplication on PL treatments showed no effects on PR values. However, PL reapplication on the PL+G treatment led to positive effects in all PR ranges. Thus, the PL+G+PL treatment, which had the highest PR values, showed a decrease in PR from 54.17 to 6.65% with the reapplication 12 months later. The addition of organic and inorganic amendments reduced specific compacted soil areas on the surface horizon of an Aquic Argiudoll under no-tillage.

The widespread degradation of the structure of silty soils under no‐till systems (NT) that has been observed in recent years is characterized by the presence of a Platy structure (P) near the soil surface. Under these conditions, addition of organic and inorganic amendments could have beneficial effects on soil physical properties. We assessed structural regeneration following addition of amendments in an Argiudoll of Paraná, Argentina. Poultry litter (PL) and gypsum (G) were applied, providing an organic and inorganic amendment, respectively. Four treatments were tested: PL (7.5 Mg ha−1), G (3 Mg ha−1), the combination of PL+G (7.5 + 3 Mg ha−1), and control (T) with no amendment. Description and quantification of the structural state of the soil profile was made using a Visual Soil Evaluation method: “Le profil cultural”. Aggregate stability, bulk density, total porosity, pore size distribution and soil shear strength for each soil structure and soil organic carbon (SOC) were determined at two depths. Twenty months after the amendment applications, both PL and PL+G treatments led to a significant increase of SOC in the upper 5 cm of soil. The proportion of Gamma (Γ) structure increased and P declined under PL and PL+G compared with G and T inn the A horizon. Treatments G and PL+G contributed to an increase in average diameter of aggregates in Γ only. The use of PL amendment alone or in combination with G could be a promising strategy to regenerate, in the short term, the degraded soil structure under NT.