Bio-based slow-release fertilizers (SRFs) have drawn significant attention because their applications for crop production can improve nutrient utilization efficiency as well as prevent environmental pollution. However, current commercial SRFs still exhibit uncontrollable release patterns, use a large quantity of synthetic coating materials, and are unable to adapt to complex soil conditions (e.g., arid soil). In this study, a double-layer SRF was formulated from a low-cost lignin−clay nanohybrid composite to not only achieve controllable and slow nitrogen fertilizer release but also improve the water-holding property. The low-cost and hydrophobic lignin−clay nanohybrid was cross-linked with bio-based alginate to prepare the core-layer material, followed by a coating process using a highly water-absorbent polymer poly(acrylic acid) (PAA) to achieve a double-layer SRF. We examined the chemical structures, urea release rates, and water-holding capacities of the double-layer PAA−lignin−clay nanohybrid composite coated SRF (PLC-SRF). The results showed that PLC-SRF released 13−40% less urea and absorbed 23% more water than SRFs coated with only alginate. Its urea release rate is slower than that of previously reported SRFs using other materials. This nanocomposite coating material has great potential for producing a new type of bio-based SRFs that are beneficial to sustainable crop production.

Flooding is a major risk for commercial vegetable production in south Florida, especially in the south Dade County area. Flooding causes oxygen deficiency, or hypoxic stress, causing the plants to produce less energy. This shortage in energy prevents the absorption of nutrients like nitrogen, phosphorous, and potassium. This revised 4-page fact sheet discusses several different management practices for overcoming flood damage, including the use of nitrogen and potassium fertilizers, oxygen fertilizers, growth regulators, and fungicides. Written by Goudong Liu, Yuncong Li, and Xiangju Fu, and published by the Soil and Water Science Department, December 2015. SL 206/SS425: Practices to Minimize Flooding Damage to Commercial Vegetable Production (ufl.edu)

Potatoes are an important crop in the United States, and Florida is ranked the 7th producer nationwide for potato production. In Florida, potatoes are mainly planted on sandy soils with low nutrient- and water-holding capacities. Nitrogen is the most limiting nutrient in these soils. Adopting efficient fertilization methods such as fertigation is imperative for minimizing leaching and improving use efficiency of nitrogen. This new 12-page article provides step-by-step guidelines for fertigation practices for commercial potato production. Written by Xiangju Fu, Guodong Liu, Lincoln Zotarelli, Steven Sargent, Kati Migliaccio, and Yuncong Li, and published by the UF/IFAS Horticultural Sciences Department.https://edis.ifas.ufl.edu/hs1361