Improving the short-term efficiency of rock phosphate-based fertilizers in pastures by using edaphic biostimulants

Abstract

Background: The use of reactive rock phosphate (RP) in acidic soils as a phosphate (P) source for pastures and crops presents attractive economic advantages with respect to soluble phosphate. However, some studies have demonstrated that the short-term (1-year) efficiency of RP, compared with that of water-soluble P, is relatively poor. This fact penalizes not only the yield and quality of the earlier harvests, but even the whole final yield when the crop is affected by some abiotic or biotic stress at the beginning of the cycle. In the present study, we investigated the ability of new edaphic biostimulants to increase the short-term efficiency of RP-based fertilizer as a P source for pastures cultivated in acid soils. To this end, we have granulated rock phosphate with two edaphic biostimulants: tryptophan and a heteromolecular organic complex formed by humic acid and tryptophan through iron bridges, and compared their short-term P fertilizer efficacy with that of single superphosphate and rock phosphate. Results:Soil incubation studies showed that the heteromolecular complex humic acid-tryptophan and Tryptophan were able to increase soil CO 2 production compared with native soil, rock phosphate, and superphosphate. Likewise, the presence of humic acid-tryptophan complex and Trp significantly increases plant-available phosphate compared with rock phosphate, up to levels similar to those of superphosphate. Plant (ray grass)-soil-pot studies showed that rock phosphate/(humic acid-tryptophan) formulation yielded values for both ray grass dry matter production and shoot P concentration, clearly higher than those of rock phosphate and rock phosphate/tryptophan. In addition, the results associated with rock phosphate/(humic acid-tryptophan) were similar to those for superphosphate, after 3 months of cultivation.Conclusions: Taken together, these results showed the suitability of the use of specific humic acid-based edaphic biostimulants to improve the short-term effect of rock phosphate fertilizers as a phosphate source for pastures cultivated in acid soils.

Biotic and abiotic effects of soil organic matter on the phytoavailable phosphorus in soils: a review

“…Currently, several strategies based on microbial technologies have been designed to increase the agronomic effectiveness of P-fertilizers in terms of P-use efficiency for crop production (e.g., [ 3 , 19 , 70 , 77 , 85 ]). A combination of technologies can be used to increase phosphate solubilization activity.…”

Improving the quality of media and Robusta coffee seedlings with mycorrhizal (AMF) and rock phosphate

“…Rock phosphate has several advantages, including its slow release so that the residue can be used for the next growing season and contains Ca, Mg, and micronutrients making it suitable for acid soils [12] [13]. However, the problem is that this fertilizer contains lower levels of nutrients and relatively slower levels of solubility available [14]. Inoculation of mycorrhizal fungi and rock phosphate fertilizer on Robusta coffee plants will be more effective if the application is carried out at the nursery because it provides a greater opportunity for mycorrhizae to infect plant roots.…”

Novel Humo-Pectic Hydrogels for Controlled Release of Agroproducts

“…HS and HULIS were found to be active as plant biostimulants, − while their applications to soil are known to increase soil fertility, crop production, soil physical stability, and macronutrient availability . HS and HULIS may be generally described as supramolecular associations of heterogeneous and relatively small molecules (hardly larger than 600 Da), that are assembled in apparently high molecular sizes by weak interactions, like hydrogen and hydrophobic bonds, and whose conformations can be disrupted by the organic acids exuded by plant roots, thereby releasing organic bioactive molecules as well as nutrients. − However, notwithstanding the existing large specific literature, no reports are yet present that have considered the use of hydrogels made of pectin and either HS or HULIS as delivery systems for agriculture.…”