Recycling of date palm foliar waste into a biofertilizer using siliceous minerals and Trichoderma lignorum

Abstract

Purpose: Palm pruning produces a huge amounts of wastes containing high amount of crude fiber, which slows down its decomposition in soil. This study aims to optimize the process of date palm leaves recycling into an effective biofertiliser using inoculation with Trichoderma lignorum, siliceous minerals and organic fertilizers. Method: Pot experiments simulating date palm leaves degradation included the following treatments: (1) fresh date palm leaves; (2) date palm leaves inoculated with T. lignorum, manure, analcite; (3) date palm leaves inoculated with T.lignorum, manure, diatomite; (4) date palm leaves inoculated with T.lignorum, peat, analcite; (5) date palm leaves inoculated with T.lignorum, peat, diatomite. Assessment of phytotoxicity of the substrate was carried out by Neubauer–Schneider bioassay using winter wheat as a test–plant. The biochemical and agronomical analysis of the substrate has been conducted. The effect of the natural siliceous minerals on T. lignorum growth was evaluated in–vitro. Results: Both analcite and diatomit stimulated growth of T. lignorum in vitro. All tested soil amendments stimulated growth and photosynthesis in test–plants of Triticum aestivum, decreased the content of free phenolic compounds, reduced redox potential, pH, concentrations of nitrate and ammonia nitrogen, mineral carbon, but increased concentration of organic carbon and conductivity of the substrate. The mixture of inoculated palm leaves, manure and diatomite demonstrated the highest positive effect on the soil biochemical and agronomic characteristics. Conclusion: Biofertilizers based on date palm leaves inoculated with T. lignorum and mixed with siliceous–organic fertilizers are promising for improving soil fertility and productivity of agricultural crops. Research Highlights • Siliceous minerals stimulate Trichoderma lignorum growth and sporulation • Manure with diatomite had the best effect on date palm leaves mineralisation by lignorum • Tested biofertilizers optimize soil biochemical regime • Tested biofertilizers improve the balance between ammonium and nitrate nitrogen • Tested biofertilizers stabilize organic carbon and nitrogen

Keywords

• Date palm leaves waste
• Biofertilizer
• T. lignorum
• Siliceous minerals
• Peat
• Manure