A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants

Abstract

Occasionally, the classic understanding of the effect of pH on P uptake from soils is questioned through the claim that maximum P uptake occurs at a pH much lower than 6.5–7. The purpose of this paper was to thoroughly examine that claim and provide a critical review on soil processes that control how soil pH affects P solubility and availability. We discuss how individual P retention mechanisms are affected by pH in isolation and when combined in soils, and how both real and apparent exceptions to the classic view can occasionally occur due to dynamics between mechanisms, experimental techniques (equilibration time, method of soluble P extraction, and pH adjustment), and plant species that thrive under acidic conditions. While real exceptions to the rule of thumb of maximum P availability at near neutral pH can occur, we conclude that the classic textbook recommendation is generally sound.

Corn Yield and Phosphorus Use Efficiency Response to Phosphorus Rates Associated With Plant Growth Promoting Bacteria

“…Also, P use efficiency (PUE) for cereal production in the world is too low, varying between 15 and 30% (Dhillon et al, 2017). Under tropical conditions, P can precipitate as minerals of Fe, and Al (Penn and Camberato, 2019). Both minerals decrease the availability of P for plant growth (Dhillon et al, 2017).…”

Phosphorus Speciation in Long-Term Drained and Rewetted Peatlands of Northern Germany

“…The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types.Soil Syst. 2020, 4, 11 2 of 20 dynamic and may be taken up by microbes and plants, lost by leaching and drainage, and form secondary P minerals [8,9]. Thus, a complete account of P species is required to predict the P mobilization or stabilization potential in long-term drained and rewetted peatland types [10,11].Phosphorus transformations can vary according to management practices, peatland types, topographic positions, historic, and current land use types [12].…”

“…Soil Syst. 2020, 4, 11 2 of 20 dynamic and may be taken up by microbes and plants, lost by leaching and drainage, and form secondary P minerals [8,9]. Thus, a complete account of P species is required to predict the P mobilization or stabilization potential in long-term drained and rewetted peatland types [10,11].…”

Effect of Digestate on Soil Organic Carbon and Plant-Available Nutrient Content Compared to Cattle Slurry and Mineral Fertilization

“…The last relationship is particularly interesting because the dose of P in the NPK treatment was two times higher than in the Csl and Dig treatments. The main factors affecting plant-available P content are P dose, soil pH, soil temperature, and moisture [26]. Application of manure and organic fertilizers may influence P availability in the soil either directly, through an application of inorganic and organic P compounds, or indirectly, by prompting the activity of soil microorganisms as a consequence of the supply of organic C [24].…”

“…Application of digestate may influence the content of plant-available P in soil directly through incorporating inorganic P and/or indirectly through prompting microorganisms to undergo various activities [24]. The direction of the organic P transformations depends on the C/P ratio in the organic matter, while in case of inorganic P it depends on the soil pH and the presence of metal cations [25,26]. In non-calcareous soils, inorganic P in soil solutions (Pi) is strongly sorbed to metal oxi(hydro)oxides of mainly iron (Fe) and aluminum (Al), and in soils with a high concentration of exchangeable calcium (Ca), precipitation of Ca-phosphate minerals occurs.…”