Drylands (hyperarid, arid, semiarid, and dry subhumid ecosystems) cover almost half of Earth’s land surface and are highly vulnerable to environmental pressures. Here we provide an inventory of soil properties including carbon (C), nitrogen (N), and phosphorus (P) stocks within the current boundaries of drylands, aimed at serving as a benchmark in the face of future challenges including increased population, food security, desertification, and climate change. Aridity limits plant production and results in poorly developed soils, with coarse texture, low C:N and C:P, scarce organic matter, and high vulnerability to erosion. Dryland soils store 646 Pg of organic C to 2 m, the equivalent of 32% of the global soil organic C pool. The magnitude of the historic loss of C from dryland soils due to human land use and cover change and their typically low C:N and C:P suggest high potential to build up soil organic matter, but coarse soil textures may limit protection and stabilization processes. Restoring, preserving, and increasing soil organic matter in drylands may help slow down rising levels of atmospheric carbon dioxide by sequestering C, and is strongly needed to enhance food security and reduce the risk of land degradation and desertification.

The influence of prehydration in water or priming in – 1.5 MPa polyethylene glycol 8000 solution for various periods, followed by redrying, on germination rate and longevity of lettuce (Lactuca sativa L.) seeds (achenes) was determined during controlled deterioration at 10% moisture content (fresh weight basis) and 40°C. Short prehydration treatments (up to 1 h) had little effect on either germination rate or longevity, but significantly improved root growth rates. Increasing durations of prehydration or priming reduced the mean time to germination by up to 61% relative to untreated seeds, but also reduced mean seed longevity by as much as 84% Prehydration and priming altered the relationships between germination rate and viability and between normal and abnormal seedlings during ageing. Prehydration in abscisic acid or at a temperature inhibitory to germination did not prevent the reduction in longevity under controlled deterioration conditions. While prehydration or priming treatments effectively accelerate subsequent germination rates of lettuce seeds, the redried seeds are nonetheless highly susceptible to deterioration in storage.