Enhancing the Fertilizer Value of Recycled Phosphorus for Horticulture Crops Through Acidification and Placement

Background

Placement and acidification pretreatments are strategies to enhance the phosphorus (P) fertilizer value of biowastes. However, their impact on the commercial yield of horticultural crops and the effects on the contents of undesirable elements in the edible product are not well known.

Aims

The main objective of this study was to assess how the placement and acidification of biowastes affect commercial yield and nutritional quality of vegetables.

Methods

To investigate this, we selected two byproducts from agroindustries, meat and bone meal (MBM) and digestate solid fraction (DSF), and conducted a pot experiment with peas and onions growing in 10-L pots. Four treatments were assessed for each biowaste: untreated mixed (UM), untreated placed (UP), acidified mixed (AM), and acidified placed (AP).

Results

Acidification increased the water-soluble P of both byprodutcs to over 70% of the total P. For DSF, the AP treatment yielded over 100% more than UM, with a fertilizer value exceeding triple superphosphate. However, for MBM, no significant differences were found among UM, AM, and AP treatments, with UP yielding even less than the negative control, indicating a toxicity effect, probably of ammonium that reduced plant growth. Although acidification may have increased the solubility of undesirable elements, it was not reflected in plant composition, as higher P solubility contributed to increased commercial yields, diluting undesirable element content.

Conclusions

Therefore, the placement of acidified DSF shows promise in improving fertilizer value, with no adverse effects on the content of undesirable elements in onion bulbs and pea grains.