Quantification of some soil properties as affected by land use, and its implication for vegetable farm systems

摘要

Sustainability of vegetable farms depends on development of farming systems that can at least arrest soil deterioration, and ideally improve soil fertility. We assessed of soil quality as baseline for a larger study on farming systems redesign in Uruguay. Specific aims were to quantify soil properties in vegetable crop fields on different soils; to evaluate the effect of past land use on these properties; and to assess how this changes could affect soil moisture supply capacity. Samples were taken from 4 cropped fields and from adjacent undisturbed land in pairs on 16 farms with soils representative of the region, Hapluderts and Argiudolls. In cropped fields, SOC at 20 cm depth was 14.9 g/kg on average, and 11.3 g/kg on the coarser Argiudolls. Compared to the undisturbed situation SOC depletion was 35% on average, and 41% on coarser Argiudolls. Geometric mean diameter of stable aggregatates decreased from 2.72 mm to 2.36 mm. Soil moisture supply capacity - a main function of soil is negatively affected by the depletion of SOC and decreased aggregation. Given the increasing frequency of drought and constraints on irrigation capacity, soil management alternatives that improve these properties are needed.