TY - JOUR

T1 - Combining Multiple High-Resolution in Situ Techniques to Understand Phosphorous Availability around Rice Roots

AU - Fang, W.

AU - Williams, P.N.

AU - Zhang, H.

AU - Yang, Y.

AU - Yin, D.

AU - Liu, Z.

AU - Sun, H.

AU - Luo, J.

PY - 2021/10/5

Y1 - 2021/10/5

N2 - Resolving chemical/biological drivers of P behavior around lowland/flooded rice roots remains a challenge because of the heterogeneity of the plant–soil interactions, compounded by sampling and analytical constraints. High-spatial-resolution (sub-mm) visualization enables these processes to be isolated, characterized, and deciphered. Here, three advanced soil imaging systems, diffusive gradients in thin-film technique coupled with laser ablation-ICPMS (DGT-LA-ICPMS), O2 planar optode, and soil zymography, were integrated. This trio of approaches was then applied to a rice life cycle study to quantify solute-P supply, through two dimensions, in situ, and low-disturbance high-resolution (HR) chemical imaging. This allowed mechanisms of P release to be delineated by O2, Fe, and phosphatase activity mapping at the same scale. HR-DGT revealed P depletion around both living and dead rice roots but with highly spatially variable Fe/P ratios (∼0.2–12.0) which aligned with changing redox conditions and root activities. Partnering of HR-DGT and soil zymography revealed concurrent P depletion and phosphatase hotspots in the rhizosphere and detritusphere zones (Mantel: 0.610–0.810, p < 0.01). This close affinity between these responses (Pearson correlation: −0.265 to −0.660, p < 0.01) cross-validates the measurements and reaffirms that P depletion stimulates phosphatase activity and Porg mineralization. The μ-scale biogeochemical landscape of rice rhizospheres and detritusphere, as documented here, needs greater consideration when implementing interventions to improve sustainable P nutrition.

AB - Resolving chemical/biological drivers of P behavior around lowland/flooded rice roots remains a challenge because of the heterogeneity of the plant–soil interactions, compounded by sampling and analytical constraints. High-spatial-resolution (sub-mm) visualization enables these processes to be isolated, characterized, and deciphered. Here, three advanced soil imaging systems, diffusive gradients in thin-film technique coupled with laser ablation-ICPMS (DGT-LA-ICPMS), O2 planar optode, and soil zymography, were integrated. This trio of approaches was then applied to a rice life cycle study to quantify solute-P supply, through two dimensions, in situ, and low-disturbance high-resolution (HR) chemical imaging. This allowed mechanisms of P release to be delineated by O2, Fe, and phosphatase activity mapping at the same scale. HR-DGT revealed P depletion around both living and dead rice roots but with highly spatially variable Fe/P ratios (∼0.2–12.0) which aligned with changing redox conditions and root activities. Partnering of HR-DGT and soil zymography revealed concurrent P depletion and phosphatase hotspots in the rhizosphere and detritusphere zones (Mantel: 0.610–0.810, p < 0.01). This close affinity between these responses (Pearson correlation: −0.265 to −0.660, p < 0.01) cross-validates the measurements and reaffirms that P depletion stimulates phosphatase activity and Porg mineralization. The μ-scale biogeochemical landscape of rice rhizospheres and detritusphere, as documented here, needs greater consideration when implementing interventions to improve sustainable P nutrition.

KW - rice root

KW - soil imaging systems

KW - in situ sampling

KW - high-resolution visualization

KW - phosphorus lability

KW - iron lability

KW - phosphatase activity

U2 - 10.1021/acs.est.1c05358

DO - 10.1021/acs.est.1c05358

M3 - Journal article

VL - 55

SP - 13082

EP - 13092

JO - Environmental Science and Technology

JF - Environmental Science and Technology

SN - 0013-936X

IS - 19

ER -