Effects of fertilizer types and application levels on phosphorus availability of saline soils and crops: A meta‐analysis

Abstract

Phosphorus deficiency limits agricultural production in saline soils. Phosphorus fertilizer (P fertilizer) affects soil and crop phosphorus availability, water eutrophication control, and rock phosphate ore resource protection. To clarify the effect of varying types and amounts of fertilizers on the phosphorus availability enhancement at different degrees of saline soil and provide theoretical basis for rational fertilization at high salt soil, a meta‐analysis of 257 datasets from 24 studies was conducted. All studies were from Asia and focused on the effects of P fertilizer on the phosphorus availability in saline soils. P fertilizer application increased soil available phosphorus (AP) and total phosphorus (TP) contents by 49.24% and 56.19% (pQ < 0.05). Further sub‐group analysis revealed that the P fertilizer types, application levels, soil salinity, soil alkalinity, and crop species affected the response variables (AP, TP, above‐ground P content, and yield), as well as derived variables such as the proportion of AP to TP content (AP/TP) and the phosphorus fertilizer utilization efficiency. Intermediate‐level pure organic fertilizer enhanced AP content by 55.66%, while high‐level pure organic fertilizer enhanced AP/TP. Intermediate‐level pure organic fertilizer showed the best effects on above‐ground P content and phosphorus fertilizer utilization efficiency. Mineral plus organic fertilizer at this level achieved the highest yield increase (122.34%). Soil phosphorus availability improved more in mild salinity and pH <8.5 soils. Therefore, integrating the overall responses, applying mineral plus organic fertilizer or pure organic fertilizer at an intermediate level (20–60 kg·ha−1·year−1) for 1–2 years could enhance soil AP content, benefit crop growth, and agricultural productivity in saline soils while managing input costs effectively.