Biochar and phosphorus fertilization improved soil quality and inorganic phosphorus fractions in saline-alkaline soils

ABSTRACT

The establishment of high-yielding agricultural production systems is severely restricted by low soil organic carbon (SOC) and high Na⁺ concentration in saline-alkaline soils. In order to confirm the effects of biochar and phosphorus (P) fertilization on SOC sequestration, soil physical structure and inorganic P (Pi) fractions, as well as optimize the amount of P fertilizer, a field experiment was designed with two factors: with biochar at 0 (C0), 1% (C1) and 3% (C2); with P at 0 (P0), 64 (P1) and 128 kg ha⁻¹ (P2). The results indicated that biochar input enhanced SOC, however, the effect of P application on SOC and soil physical structure were negligible. Compared to C0, SOC was increased by 98–113% for C1 and 180–195% for C2. Due to the SOC enhancement and reduction of soil Na⁺ concentration, biochar input decreased ρb, increased MWD and WSMA. For Pi fractions, soil Olsen-P, Ca₂-P, Ca₈-P, Fe-P and Al-P were increased, mainly due to the direct supply, retention and the improvement of biological availability. Overall, C2P1 was the most efficiency treatment to enhance SOC, improve soil physical structure, and C2P2 avail to increase the supply capacity of soil P, but had no significant difference with that in C2P1.

KEYWORDS:

• Biochar
• phosphorus fertilizer
• soil organic carbon
• inorganic phosphorus fractions
• saline-alkaline soils

Acknowledgements

We would like to express our gratitude to the anonymous editor and reviewers for their suggestions, which have greatly helped the improvement of the article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key Research and Development Program [2018YFD0800303], the Fundation of High-level Talents of Qingdao Agricultural University [663/1119025], the Soil and Cultivation Position of Modern Agricultural Technology System Innovation Team of Paddy in Shandong Province [SDAIT-17-05], the Natural Science Fund in Shandong Province [ZR2017MC015].