Droughts Legacy Effects on Phosphorus Transformation from Residues and Mineral Fertilizers in Calcareous and Carbonate-Free Soils

A ³³P Labeling Study

authored by

Naila Farooq, Manisha Koirala, Sara Loftus, Xi Zhang, Kazem Zamanian, Callum C. Banfield, Michaela A. Dippold

Abstract

Background: While well-described for soil properties, we barely know how microbial traits determine the availability of various phosphorus (P) forms to crops. Aims: We traced the dynamics of mineral- versus residue-derived P applied to two contrasting soil types during wheat cultivation. Methods: The legacy effect of three pre-sowing moisture conditions was investigated: drought (30% water holding capacity, WHC), alternating cycles of drying (30% WHC) and wetting (70% WHC), and well-watered conditions (70% WHC). ³³P-labelled cowpea residues (Vigna unguiculate) and KH₂³³PO₄ were applied as fertilizers to calcareous and carbonate-free soils. Results: Under pre-sowing drought conditions, microbial incorporation of ³³P from residue P into polar lipids was four times higher than from mineral P. Calcareous soils showed double the microbial biomass than carbonate-free soils. However, when fertilized with residue P, carbonate-free soils exhibited twice the acid phosphatase activity and a 3- to 6-fold greater ³³P uptake into phospholipids normalized per unit microbial biomass C. Conclusion: Residue P enhances microbial growth, leading to increased P immobilization, especially in carbonate-free soils. Drought-triggered microorganisms efficiently acquire P from organic sources like residues. This increased microbial P immobilization under pre-sowing drought does not negatively affect plant growth, when a mineralizable organic P pool is consistently available. Regardless of the pre-sowing moisture conditions, residue P fertilization promotes a rapidly cycling microbial biomass-necromass pool, specifically in calcareous soils. This implies that residue P fertilization could be a sustainable, long-term strategy for continuous P supply in P-immobilizing calcareous soils, even under increasing drought conditions due to climate change.

Organisation(s)

Institute of Earth System Sciences

External Organisation(s)

University of Göttingen
Jiangsu Academy of Agricultural Sciences
University of Tübingen

Type

Article

Journal

Journal of Soil Science and Plant Nutrition

ISSN

0718-9508

Publication date

15.11.2024

Publication status

E-pub ahead of print

Peer reviewed

Yes

ASJC Scopus subject areas

Agronomy and Crop Science, Soil Science, Plant Science

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1007/s42729-024-02120-1 (Access: Open)