Phosphate Sources Influence Soil Phosphorus Extractants, Availability, and Phosphorus Uptake by Chickpea and Their Residual Effects on Wheat and Soybean

Phosphorus (P) management is a key aspect of sustainable agriculture. However, its effectiveness also depends on the phosphate source. We investigated whether phosphate sources contribute to soil P availability, grain yield (GY), and P uptake by chickpea, wheat, and soybean cropping sequences. We conducted a pot experiment under controlled conditions, with six commercial phosphate sources, a rate of 150 mg P kg−1 of soil, one control, and four replications. Triple superphosphate (TSP) increased the GY by 25.6%, whereas the lowest yields, −20.9 and −18.4%, were recorded from the Alvorada and Gafsa phosphates, respectively, for chickpea. With respect to the residual effect, only Bayóvar increased the wheat GY by 20.5%; in contrast, compared with the control, the residual effect of all the phosphate sources applied increased the soybean GY, compared to the control. However, the variation in the P concentration in plant tissues was influenced by the phosphate source and P use efficiency (PUE). Additionally, phosphate sources increased soil P availability, depending on the phosphate source, soil pH, and extractant used. Finally, Olsen P and Mehlich-3 were significantly correlated with the GY and P concentrations in the plants. Under low-P conditions, plants increased their root growth to mine P and PUE and sustain development and yield. More soluble phosphate sources, such as TSP, are better for immediate crop response, whereas phosphates with less solubility contribute more to long-term soil P availability. However, the limitation of some current methods for accurately reflecting the true P status of the soil can be a challenge.