TY - JOUR
T1 - Soil microorganisms increase Olsen phosphorus from poorly soluble organic phosphate: A soil incubation study
AU - Velasco-Sánchez, Ángel
AU - Bennegadi-Laurent, N.
AU - Trinsoutrot-Gattin, I.
AU - van Groenigen, J.W.
AU - Moinet, G.Y.K.
PY - 2024/1
Y1 - 2024/1
N2 - The potential shortage of mineral phosphorus (P) sources and the shift towards a circular economy motivates the introduction of new forms of P fertilizers in agriculture. However, the solubility of P in new fertilizers as well as their availability to plants may be low. In this experiment, we incubated an agricultural soil poor in P (28 mg P2O5 kg−1) for 63 days in the presence of a range of organic and inorganic poorly soluble P forms commonly found in new fertilizers: hydroxyapatite (P-Ca), iron phosphate (P-Fe), phytic acid (P-Org) and a combination of P-Ca and P-Org (P-Mix). Cellulose and potassium nitrate (KNO3) were added to stimulate microbial activity at the beginning of the incubation. We included a positive control with triple superphosphate (TSP) and negative controls with no P application (with and without cellulose and KNO3). We assessed the fate of the different poorly soluble P forms in NaHCO3 extracts (Olsen P) over time as a proxy for plant-available P. Soil microbial biomass, fungal to bacterial ratio, soil respiration, enzymatic activities (β-glucosidase, arylamidase and acid and alkaline phosphatase), N mineralization and soil pH were also monitored. At the beginning of the incubation, TSP showed the highest Olsen P across all treatments and P-Fe showed higher levels of Olsen P than the other poorly soluble P forms (p <.05). During the incubation, the levels of Olsen P decreased over time for TSP (positive control). Contrastingly, Olsen P increased significantly over time for all the poorly soluble P forms and the negative controls, indicating an increase in plant-available P. Particularly, levels of Olsen P for the P-Org treatment roughly doubled (shifting from 16.5 mg kg−1 to 32.9 mg kg−1) over the whole incubation period. The rate of increase in Olsen P was positively correlated with microbial biomass C:P ratio (p <.01) for all poorly soluble treatments. The higher levels of Olsen P for the P-Org treatment were also explained by a positive correlation with fungal biomass. Our results show that poorly soluble forms of P may be made available to plants under the influence of the microbial community, with a stronger effect on organic P forms.
AB - The potential shortage of mineral phosphorus (P) sources and the shift towards a circular economy motivates the introduction of new forms of P fertilizers in agriculture. However, the solubility of P in new fertilizers as well as their availability to plants may be low. In this experiment, we incubated an agricultural soil poor in P (28 mg P2O5 kg−1) for 63 days in the presence of a range of organic and inorganic poorly soluble P forms commonly found in new fertilizers: hydroxyapatite (P-Ca), iron phosphate (P-Fe), phytic acid (P-Org) and a combination of P-Ca and P-Org (P-Mix). Cellulose and potassium nitrate (KNO3) were added to stimulate microbial activity at the beginning of the incubation. We included a positive control with triple superphosphate (TSP) and negative controls with no P application (with and without cellulose and KNO3). We assessed the fate of the different poorly soluble P forms in NaHCO3 extracts (Olsen P) over time as a proxy for plant-available P. Soil microbial biomass, fungal to bacterial ratio, soil respiration, enzymatic activities (β-glucosidase, arylamidase and acid and alkaline phosphatase), N mineralization and soil pH were also monitored. At the beginning of the incubation, TSP showed the highest Olsen P across all treatments and P-Fe showed higher levels of Olsen P than the other poorly soluble P forms (p <.05). During the incubation, the levels of Olsen P decreased over time for TSP (positive control). Contrastingly, Olsen P increased significantly over time for all the poorly soluble P forms and the negative controls, indicating an increase in plant-available P. Particularly, levels of Olsen P for the P-Org treatment roughly doubled (shifting from 16.5 mg kg−1 to 32.9 mg kg−1) over the whole incubation period. The rate of increase in Olsen P was positively correlated with microbial biomass C:P ratio (p <.01) for all poorly soluble treatments. The higher levels of Olsen P for the P-Org treatment were also explained by a positive correlation with fungal biomass. Our results show that poorly soluble forms of P may be made available to plants under the influence of the microbial community, with a stronger effect on organic P forms.
KW - incubation
KW - iron phosphate
KW - Olsen P
KW - organic phosphorus
KW - P forms
KW - soil microorganisms
U2 - 10.1111/sum.12960
DO - 10.1111/sum.12960
M3 - Article
AN - SCOPUS:85168362933
SN - 0266-0032
VL - 40
JO - Soil Use and Management
JF - Soil Use and Management
IS - 1
M1 - e12960
ER -
