Effects of compost amendment on the available soil water and grape yield in vineyards planted after land levelling

The aim of this research was to compare the effect of compost amendment on soil water and on the available water for vines planted in levelled soils in comparison to those planted in undisturbed soils. Two vineyards, one levelled before vineyard establishment and one planted in the original soil, were compared. In each of them, the effect of compost application on the surface was compared with a control (without compost application). Soil characteristics such as soil texture, organic matter content, hydraulic conductivity and soil sealing were evaluated in each area. In addition, soil water was monitored at different soil depths in each treatment. Available soil water was evaluated along the growing cycle in two years with different rainfall distributions. Soil hydrological properties improved with compost amendment, in particular soil water holding capacity at different pressures. Soil water distribution within the soil profile and available water varied between the years depending on rainfall characteristics. For a given year, it varied significantly between levelled and unlevelled plots and between treated and untreated areas. In dry years, the available soil water reached very low values within the growing cycle, being lower in the levelled plot and higher in compost-amended areas in both plots. Compost amendment increased yield to a lesser proportion in the levelled soils but more in the dry than in the wet years. The results indicate the need to use different management strategies within the plots to optimize the use of water due to the differences in the final soil characteristics after land levelling operations.