Recycling plant nutrients in mixing several organic to serve hydroponic cultivation of vegetables and herbs, enhancing circulatory economy

Abstract

Abstract Urine, rich in Nitrogen (N), Phosphorus (P), and Potassium (K), shows promise as a nutrient solution for cultivation, benefiting both nutrition and waste management. This study focuses on producing plant nutrients from human urine using biochar to absorb urine, soybeans meal residue, biogas waste, and fish heads & bones. These nutrients were evaluated against Vietnamese standards (TCVN). The nutrient solutions were tested on green mustard and Gynostemma pentaphyllum in a hydroponic system. Results indicated that the nutrient solution from desorbed human urine reached a maximum solute concentration of 2343.3 ppm after 15 days, surpassing other materials. Though slightly lower in total nitrogen compared to fish heads & bones (68.2 mg/l vs 69.5 mg/l), urine nutrients had higher total P2O5 and available potassium (171.8 mg/l and 592.5 mg/l, respectively). The urine solution performed comparably to soybeans meal residue and the inorganic Hoagland solution. Green mustard treated with urine solution had the best dry content, vitamin C, and low heavy metals. For Gynostemma pentaphyllum, the urine solution yielded the highest saponins, flavonoids, and minerals. Economic analysis of hydroponic models using urine solution showed significant promise, indicating its viability in hydroponics.