With so much going on in the agricultural community, the weather’s behaviour remains the most talked about and most worried about factor for farmers across the country. The biggest question being if it will rain so that we can plant?
In his latest newsletter on climate and agricultural conditions, Johan van den Berg of Santam Agriculture says that short-term rainfall forecasts (December) are positive and that the effect of El Niño is only expected in the second part of summer. This season, however, still remains a high drought risk season, especially towards the western areas.
Agricultural conditions are still on the edge of disaster in many areas. Summer crop plantings in Mpumalanga were mostly completed but were very late in many areas. Rain is needed to ensure that the crop is well established. Most of the Eastern Free State did not receive rain in time and it is estimated that less than 50% of the area is planted in time. The last recognised date for maize to emerge in this area is in the first week of December to ensure that sufficient heat units are available to complete the growing cycle.
Very little plantings were possible in the central to western summer crop production areas, except for an area from Koppies, Parys and Potchefstroom to Ventersdorp where planting rain occurred. Although the planting window is still ‘open’ until the last week of December for the western production areas, primary cultivations are not yet completed. Rain is therefore needed to first cultivate fields and then to plant, putting pressure on the time available before it is too late.
It must, however, be stated that in some areas the soil water conditions in deeper layers of the soil profile are relatively favourable, but the top layers are dry. At least 50 to 100mm is needed in most areas to plant (central to western production areas) as well as eastern production areas to prevent drought damage within the next weeks.
El Niño and the Indian Ocean
Sea surface temperatures in the Nino3,4 area (and all the other Nino areas) have exceeded the 0,5°C above average limit since the start of October. There is still, however, very little or no coupling with the atmosphere when the Southern Oscillation Index (SOI) as indicator is considered. The SOI is still in the neutral phase towards the La Niña side for the 30-day average value. Some other variables regarding El Niño are important, such as when will the peak be reached and if the period will be long enough to be classified as El Niño?
The Indian Ocean Dipole Index (IOD) now moved back from the positive phase to the neutral phase, which is less negative for rainfall conditions over Southern Africa. It can help to soften the effect of El Niño.
Expected rainfall and temperature conditions
Summer rainfall areas
Short-term forecasts indicate improved probabilities for rainfall over most of the summer rainfall area for the period 7 to 10 December, as well as for the last two weeks of December. The best probabilities for rain are concentrated towards the drought-stricken northern and north eastern parts of the country, including Gauteng, Limpopo and Mpumalanga.
Good rainfall is also possible over most of the Free State, North West, Eastern Cape and KwaZulu-Natal. Less rain is expected in the other drought-stricken areas of the central to western parts of the Northern Cape and North West provinces, but probabilities increase for the second part of December over those two areas with lighter falls expected.
There are three scenarios in terms of the current season going forward, with estimated probability of occurrence:
- Weaker than expected rainfall for December and January as well as the last part of the summer season (February to April) when the effect of El Niño will come into play (30% probability).
- Good rainfall in December and January with very dry conditions in the last part of the season due to the effect of El Niño (50% probability).
- El Niño reaction not typical. Good rainfall for the rest of the season (20% probability).
- The different scenarios will also be more valid for specific geographical areas, with the western areas leaning more towards scenario one and the eastern areas leaning more towards scenario three.
Winter rainfall areas
Some light falls of rain is still possible with cold fronts still visiting the southern tip of the country.
Improved rainfall probability in the second part of December, but there is a high risk for drier conditions in the second part of the summer season.
Reason for concern
Rainfall and agricultural conditions at the end of November are reason for concern for both summer crop production and livestock grazing conditions. Although short-term rainfall forecasts are positive for rain over the summer rainfall area, good falls are probably more likely over the central to northern parts of the country, although weaker over the western parts. – Santam Agriculture