The contribution of organic and chemical fertilizers on the pools and availability of phosphorus in agricultural soils based on a meta-analysis

Fertilization have a potential to improve soil phosphorus (P) pool and availability, which are largely concentered in the surface layer of soils. However, the mechanism of fertilizer types on soil P pools and availability as well as their differentiations in soil depth and experimental duration remain uncertain. Therefore, we conducted a meta-analysis based on 817 observations from 142 previous researches to evaluate the impacts of fertilization on soil P pool and availability. Our meta-analysis indicated that fertilization significantly improved organic carbon (SOC, by 18.17%), total P (TP, by 37.46%), organic P (OP, by 22.01%) and available P (AP, by 89.43%) contents in soils. We also found that the soil P pool and availability were differentially impacted by fertilizer management practices (or fertilizers types). Moreover, AP level is affected by soil depth and experimental duration, of which the higher level is showed in surface layer (0–10 cm, by 136.89%) and medium-term (5–10 years, by 236.92%) under fertilization. Although the P pool reaches high level at medium-term (by 51.40%), its increase is largely attributed to the direct effect of fertilizers and the contribution of organic matter. Conversely, the P availability is observed to be significantly and positively associated with TP, OP and MBP (p < 0.0001). Our findings also suggesting that fertilizer management practices could increase soil P pool (by 37.46%) and availability (by 89.43%), but their variations with depth and duration are related to the quality and type of fertilizers, tillage practices and the ability of the treatments to supply energy and substrates to microorganisms and phosphatases. Overall, our meta-analysis provides evidences for fertilizations to improve soil P pool and availability, and also provides insights into reasonably adjust fertilization practices for sustainable agriculture.