Arbuscular mycorrhizae increase biomass and nutrient uptake of tomato fertilized with struvite compared to monoammonium phosphate

Purpose: Struvite is a wastewater-derived P mineral that offers a means to redirect wastestream P flows to agroecosystems. The low water solubility of struvite (< 3%) has been reported to limit early-season crop P uptake. Arbuscular mycorrhizae (AM) could enhance dissolution of struvite and thereby increase crop utilization of struvite-P. We tested the hypothesis that AM would increase struvite dissolution and thereby enhance plant P uptake and biomass in a P-deficient soil. Methods: We employed a tomato (Solanum lycopersicum L.) genotype model with a wild-type mycorrhizal tomato (MYC) and a reduced mycorrhizal mutant (rmc). Monoammonium phosphate (MAP) was used as a highly water soluble P fertilizer for comparison with struvite. Results: Struvite granules underwent 4-fold less dissolution (% mass remaining) than MAP granules, and apparent struvite dissolution was similar under MYC and rmc. However, scanning electron microscopy revealed qualitative differences in surface morphology of residual struvite between MYC and rmc. Under struvite fertilization, biomass of MYC was 22% greater than rmc, and P and N shoot uptake (mg plant⁻¹) were 32% and 34% greater than rmc. Shoot biomass was 24% greater for MYC fertilized with struvite than with MAP, and shoot P and N uptake were 26% and 34% greater, respectively. Conclusion: Increased N and P uptake by AM-associated tomato plants fertilized with struvite suggests AM as a strategy to surmount solubility constraints to the use of struvite as a fertilizer.