Agroclimatological water balance approach for the determination of optimum planting dates for Egun maize (Zea mays) in southwest Nigeria

The study determined the preparatory period, rain onset, and the sowing period limit. It also assessed the planting dates in relation to growth parameters and evaluated the effects of the planting date on the yield of a local maize variety known as Egun maize. This research used an agroclimatological water balance method based on rainfall and potential evapotranspiration (P – PE) model to find the best time to plant Egun maize (Zea mays) in Abeokuta. Three planting dates derived from the (P – PE) model were used: D1(April 27) when the accumulated difference between rainfall and half potential evapotranspiration was zero (ƩP-0.5PE = 0): D2 (May 4) when ƩP-0.5PE = 6mm: and D3 (May 11) when ƩP-0.5PE = 10mm. The Egun maize was planted in a randomized complete block design with three replicates. Descriptive and inferential (analysis of variance) statistics were used for data analysis. Result showed that the optimum planting dates of Egun maize was April 27, with yield of about 3229.17 kg/ha. Planting dates had no significant effects (p>0.05) on the growth parameters of Egun maize. The schedule of farm operations for maize cultivation showed that land preparation should commence as soon as the accumulated difference between P and 0.5PE approaches zero while ridging and planting could be done simultaneously. The rainfall variability was limited in extreme condition of wetness due to prolonged wet spells, and loss of soil nutrients might increase with higher accumulated difference between P and 0.5PE as planting season progresses. This implies that early planting of Egun maize is encouraged in the study area because of higher nutrients availability at the early dates of sowing. The study concluded that planting Egun maize around April 27 optimizes grain yield by ensuring better nutrient availability and reducing the risk of nutrient loss due to prolonged wet spells.