Carbon input threshold for soil carbon budget optimization in eroding vineyards

Previous studies have documented that, relative to conventional tillage (CT), alternative soil management (reduced tillage, mulching, or cover crops) decreases soil erosion and increases soil organic matter (SOM) in vineyards. These previous studies, however, failed to consider the loss of soil organic carbon (SOC) with erosion that could occur with the adoption of agro-environmental measures (AEM) in a semiarid environment. Accordingly, the aims of this study were to determine whether changes in SOC content under AEM management are always positive and to develop a conceptual model for estimating the "SOC threshold". The SOC threshold was defined as that level of SOC in an AEM-managed vineyard above which erosion will result in greater loss of C than occur in a comparable vineyard with CT management. SOC was analyzed at a 100 paired sites (vineyards with AEM management vs. CT). The results showed that in some cases the loss of C was higher with AEM than with CT. Overall, the results indicate that the SOC threshold may be a key parameter in determining the best AEM measures for vineyards that are on slopes and therefore vulnerable to erosion

Mapping Ash CaCO3, pH, and Extractable Elements Using Principal Component Analysis

Ash cover in fire-affected areas is an important factor in the reduction of soil erosion and increased availability of soil nutrients. Thus it is important to understand the spatial distribution of ash and its capacity for soil protection and to provide nutrients to the underlying soil. In this work, we aimed to map ash CaCO3, pH, and select extractable elements using a principal component analysis (PCA). Four days after a medium to severe wildfire, we established a grid in a 9 \uc3\u9727m area on a west facing slope and took ash samples every 3m for a total of 40 sampling points. The PCA carried out retained five different factors. Factor 1 had high positive loadings for ash with electrical conductivity, calcium, and magnesium and negative with aluminum and iron. Factor 2 had high positive loadings in total phosphorous and silica and factor 3 in manganese and zinc. Factor 4 had high negative loadings in CaCO3and pH and finally, factor 5 had high positive loadings in sodium and potassium. The spatial pattern of the factors was different. The Gaussian model was the best fit for factor 1, the linear model the most accurate for factor 4, and the wave hole effect for the loadings of factors 2, 3, and 5. The map generated with the factor scores of factor 1 had a specific pattern, while the map of factor 4 scores had a low accumulation of the explained elements in one area and high in the other. The maps produced from the factor scores of factors 2, 3, and 5 showed a cycled pattern. Ordinary kriging provided the best estimate for factors 1, 2, and 4. Mapping ash in the period immediately after the fire is very important to identify the level of soil protection and the ash nutrient input in the underlying soil

Quantitative comparison of initial soil erosion processes and runoff generation in Spanish and German vineyards

The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and M\ue1laga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40mmh(-1)) and sampling intervals (30min of test duration, collecting the samples at 5-min-intervals) was used over a circular test plot with 0.28m(2). The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6\ub18% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses