Growth and Yield Effects of Nitrogen Split Applications on Sesame (Sesamum indicum) in a Rainfed Field Setting.

Fertilizer application timing is a fundamental component of any crop fertility program to ensure that the crop obtains nutrients at its most demanding stage. Split applying nitrogen throughout the growing season is a Best Management Practice for Florida that may enhance nutrient use efficiency, and prevent excessive nitrogen leaching. For new crops entering Florida agroecosystems, the optimal nitrogen split application is not known. Studies directly addressing the effects of nitrogen ratio splits in sesame are lacking. The aim of this study was to determine the growth and yield effect of different splits of a standard 68.25 kg per hectare rate of ammonium sulfate on sesame production in a rain-fed production system. Physiological point measurements, leaf area index (LAI), and seed weight were assessed in a RCBD experiment over two years. One fertilizer rate of 68.25 kg of nitrogen (N) per hectare was applied at two separate time points during the season (planting and first bloom), in 5 different ratios of at plant and first bloom applications including 0:100% (F1), 50%: 50% (F2), 33%: 66% (F3), 66%: 33% (F4), and 0:100% (F5). There was an interaction of N treatment with date for LAI, such that the F5 treatment had the lowest LAI value for the first three dates. In addition, height to first capsule on the main stem of the plant was significantly different between the F1 treatment and all others. On average, F1 plants resulted in a height to the first capsule being between 14 to 16 cm while all other treatments averaged between 18 and 20 cm. These effects on canopy architecture and phenology did not translate into a significant yield difference between the treatments; average yield was 1,123 kg per hectare. Exploring nutrient timing effects on agronomic properties of new crops helps optimize nutrient use efficiency of agroecosystems.