The stability of cultivated sloping areas is investigated considering the interplay between atmospheric soil-water exchanges, resulting distribution of pore water pressures with depth, modified agricultural conditions, and irrigation techniques. For an averaged one-year time climatic history, the water balance for grassland, newly planted, and high yield apple orchards is analyzed; results of the analyses allow to trace the evolution of suction and shear resistance along potential failure surfaces. Infiltration under precipitation and irrigation, evapotranspiration from soil and plant are considered; they depend on the climate time history at ground surface and the suction-saturation response of the soil-vegetation system. Stability analyses are limited to planar failure surfaces and ground level, neglecting the reinforcing effects of grass and tree roots.