Nitrogen Use Efficiency Using Controlled-release and Soluble Urea in Tomato Grown on Raised Conventional and Compact Beds on Coastal Plain Sands

Nitrogen (N) is an essential macronutrient for plant growth; however, intensive management of vegetable production systems may lead to inefficient N use, often as low as 30% to 50%. Among emerging solutions, the one-time preplant application of controlled-release urea (CRU) offers significant advantages over soluble urea by incorporating innovative polymer coatings that retain nutrients in the soil longer and release them in alignment with plant demand. This approach reduces the frequency of fertigation, saving time, energy, and labor. In addition, taller and narrower compact beds, compared with wider conventional beds, may lower seasonal production costs by reducing water and nutrient application rates, pesticide use, and plastic waste, while minimizing leaching. Our research study addresses the challenges of low N use efficiency (NUE) and environmental concerns using CRU and different bed sizes. A replicated field study comparing polymer-coated CRU and urea was conducted on tomato (var. HM 1823) grown in sandy soils under two plastic-mulched bed sizes (conventional and compact). Seasonal differences were found in yield, dry matter weight (DMW), N, and carbon (C) accumulation across both bed systems. CRU treatments consistently resulted in significantly higher yield, DMW, and accumulation of N and C compared with control treatments, whereas urea treatments showed variable effects. Although higher N rate (224 kg/ha) increased yield, the highest NUE was observed at lower rates, highlighting the need to balance productivity with environmental and economic considerations. Overall, applying CRU at optimal rates in conventional raised beds improves yield and NUE, offering a more sustainable approach for tomato production in the sandy soils of north Florida.