Effects of organic fertilization on phosphorus availability and crop growth: Evidence from a 7-year fertilization experiment

ABSTRACT

Organic fertilization, a critical agronomic practice for improving nutrient availability and crop growth, may increase the risk of phosphorus (P) loss. To investigate the effect of organic fertilization on P availability, crop growth and P loss, a paddy field experiment was conducted in the saline-alkaline paddy soil. We designed four treatments: CK (no fertilizer), NPK (mineral fertilizer), and NPKC1 and NPKC2 (mineral fertilizer with low and high levels of organic fertilizer, respectively); the amounts of N, P₂O₅, and K₂O were equal in the NPK, NPKC1, and NPKC2 treatments. Compared with the NPK treatment, organic fertilization enhanced the content of total, organic, and available P in the topsoil. Moreover, organic fertilization significantly improved both the growth and P removal of crops. The content of oxalate Fe, Al, and dissolved organic carbon, the main carriers of P loss, in the soil was the highest in the NPKC2 treatment. The soil P saturation ratio (PSR) in the NPKC2 treatment was 0.25, exceeding the threshold PSR for P loss of 0.16. Therefore, organic fertilizer application could improve P availability and crop growth; however, high-level organic fertilization increases the risk of P loss in coastal saline-alkaline paddy soils.

KEYWORDS:

• Organic fertilizer
• phosphorus fraction
• crop growth
• phosphorus loss
• saline-alkaline paddy soil

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National key research and development projects 2021YFD1900901-06 (2021YFD1900901 - 06), the Soil and Cultivation Position of Modern Agricultural Technology System Innovation Team in Shandong Province SDAIT-17-05 (SDAIT - 17 - 05), the Natural Science Fund of Shandong Province (ZR2020MC154) and the Postgraduate Innovation Program of Qingdao Agricultural University (QNYCX21048). We thank Professor Timothy George for his critical reading and revision on the manuscript and Dr. Zhang Lin for his suggestions on the manuscript.