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Research Overview
Research Overview
Research Themes
Research Themes
- Nutrient Management: Enhancing nitrogen use efficiency in agriculture to reduce inputs and environmental risks
- Soil Health: Evaluating the impact of cover crops and other practices on soil biological, chemical and physical indicators
- Sustainable Agriculture: Developing strategies to improve productivity while minimizing environmental impacts
Key Findings
Key Findings
15N Technique for Nitrogen Use Efficiency
15N Technique for Nitrogen Use Efficiency
Using the isotopic 15N analysis, I demonstrated that soil N (40%) and N fertilizers (60%) contribute significantly to nitrogen uptake in tomatoes, but only a small fraction of applied nitrogen fertilizer is efficiently utilized (<16%). These findings provide critical insights into reducing nitrogen overapplication to minimize environmental impacts and cut costs for farmers.
Carbon and Nitrogen Dynamics
Carbon and Nitrogen Dynamics
My research on tomato production systems revealed that the recommended nitrogen application rate (224 kg ha⁻¹) is more than sufficient for maintaining optimal carbon and nitrogen dynamics in plant tissues and soil under sandy soil conditions. Findings showed no significant improvement in total carbon or nitrogen concentrations at higher nitrogen rates, supporting the need to optimize nitrogen fertilizer use. This work underscores the potential for sustainable practices like reduced fertilizer inputs and organic matter incorporation to enhance soil fertility and nutrient cycling.
Controlled-Release Fertilizer
Controlled-Release Fertilizer
- Efficiency and Yield: CRU maintained similar nitrogen uptake and accumulation as conventional urea, with no appreciable yield improvements observed at nitrogen rates above 140 kg ha⁻¹. This suggests that CRU can reduce nitrogen application rates by up to 38% compared to the recommended 224 kg ha⁻¹, without compromising productivity
- Economic and Environmental Benefits: The use of CRU aligns with cost-saving strategies for stakeholders by reducing nitrogen input costs and lowering the environmental risks associated with excessive nitrogen application
- Sustainability in Management: Both CRU and conventional urea provided steady nitrogen availability, ensuring that crop nitrogen requirements were met throughout the production cycle. The polymer coating in CRU facilitated a gradual nitrogen release, mitigating leaching losses and synchronizing nutrient availability with plant demand
Economics of Nitrogen Management in Tomato Production
Economics of Nitrogen Management in Tomato Production
Our research evaluated the economic viability of alternative nitrogen (N) management strategies for fresh-market tomato production in north Florida, with a focus on controlled-release urea (CRU) compared with conventional soluble urea fertilization. Using field data collected across four production seasons (Fall 2019–Spring 2021), the study assessed how fertilizer source and application strategy influence production costs, yields, and farm profitability
Key findings include:
Profitability of Controlled-Release Fertilizers:
Despite higher upfront fertilizer costs, controlled-release urea consistently generated higher net returns than conventional urea, particularly during spring production seasons when nitrogen losses are more likely.
Reduced Nitrogen Inputs Without Yield Loss:
Results showed that nitrogen application rates could be reduced by up to 38% below Florida’s recommended rate without sacrificing marketable yields, improving nitrogen use efficiency and lowering unnecessary input costs.
Season-Specific Economic Benefits:
Economic performance varied by season, with controlled-release formulations performing best under warm, high-leaching conditions, while conventional split-applied urea was more competitive during cooler fall seasons.
Improved Risk Management for Growers:
By simplifying fertilizer application and reducing yield variability, controlled-release nitrogen strategies provided a more stable economic outcome, helping growers balance profitability with environmental stewardship.
Biomass Partitioning
Biomass Partitioning
My analysis of biomass partitioning in tomatoes revealed that both controlled-release urea and conventional urea treatments at lower nitrogen rates (140 kg ha⁻¹) effectively promoted shoot over root growth, with minimal differences observed at higher rates.
Harvest Index
Harvest Index
The harvest index showed that nitrogen fertilization, particularly with CRU, optimized biomass allocation to fruits, with up to 82% of above-ground biomass being partitioned to reproductive structures.
Soil Plant Analysis Development Meter
Soil Plant Analysis Development Meter
SPAD meter analysis confirmed its utility as a non-destructive tool for assessing chlorophyll content and nitrogen status. SPAD readings remained stable above 40 across all treatments, reflecting adequate nitrogen availability throughout the growing season. Controlled-release urea treatments provided steady nitrogen release, reducing late-season declines in SPAD values, and enhancing chlorophyll retention during critical growth stages, especially under warm production seasons. These findings support the SPAD meter's role in precision agriculture and its effectiveness in monitoring nitrogen application strategies in north Florida tomato systems.
Soil Health: Cover Crops
Soil Health: Cover Crops
Our research demonstrated that incorporating cover crops into agricultural systems significantly improves soil health and supports sustainable farming practices. The study evaluated a range of cover crops, including sunn hemp, sorghum-sudan, and winter rye, across multiple seasons and regions in Florida. Early findings of the project include:
- Soil Health Improvements: Cover crops showed potential to enhance microbial activity, soil protein content, and active carbon, contributing to better soil structure and nutrient availability.
- Nutrient Cycling Efficiency: Initial results suggest that cover crops help retain nutrients like nitrogen and phosphorus, reducing potential losses and improving soil fertility.
- Microbial Diversity: Trends indicate an increase in beneficial microbial communities, supporting nutrient cycling and soil resilience.
- Tailored Strategies: Findings highlight the importance of site-specific cover crop selection, as benefits varied across different soil types and conditions in Florida.
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