Influence of El Niño-Southern oscillation (ENSO) on agroclimatic zoning for tomato in Mozambique

- ENSO warm and cold phases were found to affect tomato crop zoning.
- High air temperatures during El Niño reduce crop suitability.
- La Niña was associated with extended planting date window.
- Farmers can use ENSO forecast and expected anomalies to adjust management practices.

Mozambique is a country dependent on agriculture as 70% of the country's population lives in rural areas, and approximately 80% of the nation economically active population works on agricultural jobs. Using climate/weather information in agriculture helps to reduce risks and benefit from favorable conditions for crop development. Agroclimatic zoning is one of the most useful tools to define suitable regions and spatial, temporal and environmental bounds for crop production. These bounds, however, are not static and can vary with sources of climatic variability such as the El Niño-Southern Oscillation (ENSO) phenomenon. Incorporating information about primary drivers of interannual climate variability, like ENSO, allows for better management adaptation. Tomato has a high economic impact in Mozambique's economy and its cropping success is highly dependent on weather conditions. The objectives of this study were to create an agroclimatic zoning for tomato production in Mozambique identifying regions and planting dates with optimal crop development for each phase of ENSO and to understand how ENSO phenomenon impacts the zoning. A third objective was to create an online tool (http://mz.agroclimate.org/plantio/) to assist farmers, extension agents and researchers to plan the crop season. Gridded data of daily air temperature and rainfall were collected between 1984 and 2014 from the Climate Forecast System Reanalysis (CFSR) and Famine Early Warning System Network (FEWS-Net) datasets provided by the US National Oceanic and Atmospheric Administration (NOAA). A generic tomato variety with growing cycle of 90 days was evaluated considering 24 planting dates throughout the year. Each growing cycle and planting date was classified as ideal, marginal, or unsuitable according to the conditions for tomato development. During summer months, the air temperatures were excessively high for tomato production except at high elevations. During fall and winter, most of the country is suitable for tomato production. Both El Niño and La Niña impacted the zoning, especially from November to May. During La Niña, suitable conditions were more frequent than during El Niño extending the planting window. High air temperatures during El Niño reduce crop suitability. Disseminating this information in a timely and accessible way will reduce climate risk for tomato production in Mozambique through the definition of location and planting dates with lower risk associated with climate variability.