Phosphorus (P) is an important soil nutrient that often limits plant growth and microbial activity in humid tropical forests. These ecosystems receive a large amount of rainfall that helps create frequent anoxic events in soils. Our results show that anoxic conditions reduced the strength of soil minerals to bind P even though a large amount of P was still bound to minerals. Our study suggests that anoxic events might serve as hot moments for plants and microbes to acquire P.