An average estimate of six trading houses showed the government's Crop Estimates Committee (CEC) may inch up the year's forecast to 13.94 million tonnes from previous estimates of 13.89 million tonnes.
The forecasts ranged between 13.89 million tonnes and 14 million tonnes. Maize is the staple crop in South Africa.
Largest crop since 1981
The CEC said in March a harvest of 13 million tonnes or above will be the largest in more than three decades. South Africa harvested 14.4 million tonnes in 1981.
Expectations of a bumper crop have pulled maize prices back from record highs of more than R3300 a tonne hit earlier this year.
The most traded December white maize contract ended 0.22% lower at R1 791 a tonne on Friday.