Variations in rhizosphere soil total phosphorus and bioavailable phosphorus with respect to the stand age in Pinus massoniana Lamb

Yaowen Xu; Xiaogai Ge; Benzhi Zhou; Lei Lei; Wenfa Xiao

doi:10.3389/fpls.2022.939683

Variations in rhizosphere soil total phosphorus and bioavailable phosphorus with respect to the stand age in Pinus massoniana Lamb

Front Plant Sci. 2022 Aug 1:13:939683. doi: 10.3389/fpls.2022.939683. eCollection 2022.

Authors

Yaowen Xu^{1

2}, Xiaogai Ge^{1

2}, Benzhi Zhou^{1

2}, Lei Lei³, Wenfa Xiao³

Affiliations

¹ Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China.
² Qianjiangyuan Forest Ecosystem Research Station, National Forestry and Grassland Administration of China, Hangzhou, China.
³ State Forestry Administration, Key Laboratory of Forest Ecology and Environment, Research Institute of Forest Ecology, Environment and National Protection, Chinese Academy of Forestry, Beijing, China.

Abstract

Phosphorus (P) is a nutrient limiting plant growth in subtropical regions. However, our understanding of how soil P responds to an increase in stand age is rather poor. In particular, little is known about how bioavailable P pools (soluble P, exchangeable P, hydrolyzable P, and ligand P) shift with a change in stand age. Moreover, the P cycle in rhizosphere soil has the most direct and significant influence on plants. The aim of the present study was to determine the concentrations of total P in various rhizosphere soil bioavailable P fractions in 5-, 9-, 19-, 29-, and 35-year-old stands of Pinus massoniana Lamb. According to the results, total P (TP) concentration and N:P ratio in rhizosphere soil first decreased, and then increased with an increase in stand age. Soluble P concentration decreased first, and then increased with an increase in stand age; exchangeable P and ligand P decreased first, and then tended to be stable with an increase in stand age, whereas hydrolyzable P increased first, and then decreased. Structural Equation Model results suggested that ligand P and soluble P were the major factor affecting the TP. In addition, soil microorganisms and acid phosphatase-driven hydrolyzable P play a crucial role in soil bioavailable P cycling. Overall, the results of our study provide a mechanistic understanding of soil bioavailable P cycling under low available P conditions, and a basis for an effective P management strategy for the sustainable development of P. massoniana plantations.

Keywords: bioavailable phosphorus; phosphorus fractions; phosphorus recycling; rhizosphere soil; stand age.