Soy and mustard effectively mobilize phosphorus from inorganic and organic sources

Abstract

AbstractWe aimed to investigate phosphorus (P) mobilization by different plant species from organic and inorganic sources in relation to different P mobilization mechanisms. Knowledge about P mobilization is important for producing crops on P sources other than phosphate rock-derived fertilizers. We conducted a greenhouse experiment with four plant species (maize, soy, lupin, mustard) and three P sources (FePO4, phytate, struvite). We determined pH and phosphomonoesterase activity in the rhizosphere using pH imaging and soil zymography. At harvest, root exudates were analyzed for phosphomonoesterase activity, pH, organic acids, and dissolved organic carbon (DOC). Plants were analyzed for biomass, root length, and P content. Struvite was more plant-available than phytate and FePO4 as indicated by higher plant P contents. Soy had the highest biomass and P content, irrespective of P source. Soy exuded up to 12.5 times more organic acids and up to 4.2 times more DOC than the other plant species. Lupin had a 122.9 times higher phosphomonoesterase activity than the other plant species with phytate. The pH in the exudate solution of mustard was on average 0.8 pH units higher than of the other plant species. P uptake by mustard and soy seemed to have also benefited from large root lengths. Taken together, our study indicates that soy has a particularly high potential to mobilize P from struvite and phytate, while mustard has a high potential to mobilize P from FePO4. Therefore, soy and mustard seem to be good options for agricultural production that relies less on phosphate rock-derived fertilizers.