Limited effects of phosphorus application on growth and yield of industrial hemp in Florida

Abstract

Phosphorus (P) is one of the three most limiting essential nutrients for crop growth and yield. However, information on the optimum P application rate for production of industrial hemp (Cannabis sativa L.) is very limited, especially in Florida. The objective of this study was to determine the impact of various P application rates on growth and yield parameters of industrial hemp in two sites in Florida (Central FL and Northwest FL). The experimental design was a randomized complete block with four replications. Treatments consisted of five P rates—0, 34, 67, 101, and 135 kg P ha⁻¹. Data were collected on plant stand count and plant height at 15, 30, and 50 days after planting, while data for aboveground biomass were collected at harvest in both locations. Additionally, stem biomass in Northwest FL site and seed yield in Central FL site were collected. There was no significant effect of different P rates on plant height, plant stand count, and aboveground biomass in either location (p ≥ 0.05). Also, the P rate effect was nonsignificant for stem biomass (p = 0.512) in Northwest FL site and seed yield (p = 0.250) in Central FL site. The 135 kg P ha⁻¹ yielded numerically higher ground biomass in Central FL site (2200 kg ha⁻¹) while 100 kg P ha⁻¹ was higher in Northwest FL site (9432 kg ha⁻¹). Similarly, 135 kg P ha⁻¹ yielded numerically higher stem biomass (6000 kg ha⁻¹) in Northwest FL site and seed yield (900 kg ha⁻¹) in Central FL site. Thereby, the results suggest that P fertilization has a limited effect on biomass and seed yields for industrial hemp production in Florida sandy soils.