Available phosphorus (P) concentration is low in dryland soils due to high pH values linked to the presence of pedogenic carbonates. Thus, dissolution and mobilization of P compounds are important controls on P availability for plants, microbes, and biocrusts. One process that has been hypothesized for dryland organisms to acquire P is the exudation of organic acids that can chelate bound P compounds. To explore this process, we assayed the critical thresholds of organic acids concentrations required to mobilize P in a range of Chihuahuan Desert soils. Soil cores (0-10 cm) were collected from three desert landforms with varying parent materials and two microhabitats (under-plant and interspace). Samples from the cores were reacted with citrate, oxalate, and malate (10 –10,000 µM). The extracts were analyzed for PO43- concentrations via the malachite green colorimetric method, total P and cations (Ca, K, Mg, Fe, and Mn) by hydraulic press/x-ray fluorescence (XRF), dissolved cations (Ca, K, Mg, Fe, and Mn), and P by inductively coupled plasma–optical emission spectroscopy (ICP-OES), and targeted organic acids by gas chromatography-mass spectrometry (GC-MS). Our results showed that: (1) Concentrations of organic acids of close to 1,000 µM are needed to effectively mobilize PO43- in all landforms and microsites we examined. (2) The in situ concentrations of organic acids in soil core samples were < 100 µM, suggesting they may be below the needed threshold to mobilize P. (3) Oxalate was the most effective in releasing PO43- as a result of removing aqueous Ca via Ca-oxalate precipitation. Overall, our results do not suggest a strong link between organic acid exudation and PO43- availability in these dryland soils due to the low in situ concentration ranges both under plant canopies and in interspaces. These results suggest that plants and microbes would need to create localized hot spots of organic acid concentration to use this P acquisition strategy. Alternately, these organisms may be relying on different P acquisition strategies or are not actively seeking P beyond what is present in the soil solution at equilibrium.