Distribution Of Peach Latent Mosaic Viroid In Commercial Orchards Of Peach In The North Of Tunisia

peer reviewe

The California drought: Coping responses and resilience building

Building resilience to extreme events is very complex. It involves consideration of climatic and non-climatic factors, human and natural environments and their dynamics, and governance systems that include groups with wide-ranging authorities, influence and interests. In this article, we analyse the effects of the latest multi-year drought (2011–2016) in agricultural production in California; impacts on food security; and coping responses of several actors. We found that despite the drought and water shortages, California continued to be the leading state for fruit and tree nuts and that it did not affect food security. We also found that these results were strongly influenced by the numerous policy, regulatory, institutional, and management decisions taken at the local, state and federal levels, as well as to availability of groundwater, the primary drought reserve. The California case can be considered an example for the rest of the country, and the world, that extreme events require extraordinary preparedness and response measures just to cope with them, not to mention adapting to them, and that building resilience is a long-term process

Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils

Increasing soil organic carbon (SOC) via organic inputs is a key strategy for increasing long-term soil C storage and improving the climate change mitigation and adaptation potential of agricultural systems. A long-term trial in California's Mediterranean climate revealed impacts of management on SOC in maize-tomato and wheat-fallow cropping systems. SOC was measured at the initiation of the experiment and at year 19, at five depth increments down to 2 m, taking into account changes in bulk density. Across the entire 2 m profile, SOC in the wheat-fallow systems did not change with the addition of N fertilizer, winter cover crops (WCC), or irrigation alone and decreased by 5.6% with no inputs. There was some evidence of soil C gains at depth with both N fertilizer and irrigation, though high variation precluded detection of significant changes. In maize-tomato rotations, SOC increased by 12.6% (21.8 Mg C/ha) with both WCC and composted poultry manure inputs, across the 2 m profile. The addition of WCC to a conventionally managed system increased SOC stocks by 3.5% (1.44 Mg C/ha) in the 0-30 cm layer, but decreased by 10.8% (14.86 Mg C/ha) in the 30-200 cm layer, resulting in overall losses of 13.4 Mg C/ha. If we only measured soil C in the top 30 cm, we would have assumed an increase in total soil C increased with WCC alone, whereas in reality significant losses in SOC occurred when considering the 2 m soil profile. Ignoring the subsoil carbon dynamics in deeper layers of soil fails to recognize potential opportunities for soil C sequestration, and may lead to false conclusions about the impact of management practices on C sequestration