(224) In Situ N Monitoring for Safe Leafy Vegetables using Quick and Advanced Tools
H. Chin, M.C. Palada
HortScience
Urban Farm DB summary
A study developed a simple, rapid method for measuring nitrate-N accumulation against a backdrop of heavy nitrogen fertilizer use in intensive leafy vegetable production in peri-urban Southeast Asia. Five vegetables—amaranth, kangkong, Ethiopian kale, choysum, and leafy lettuce—were grown under eight N fertilizer levels from 0 to 350 kg/ha applied in three splits, with nitrate-N in leaf, petiole, and whole-plant sap measured using a Cardy nitrate meter and chlorophyll measured with a chlorophyll meter. Nitrate accumulation varied by species: at 200 kg/ha N, Ethiopian kale was highest (7,000 ppm), followed by kangkong (4,000 ppm), amaranth (3,500 ppm), and leafy lettuce (1,200 ppm), with significant correlations (P < 0.001) between fertilizer rate and nitrate content and between leaf chlorophyll and yield.