Differential Phosphorus Uptake and Use Efficiency Among Selected Nitrogen‐Fixing Tree Legumes over Time

Abstract

A study was carried out on three nitrogen (N2)‐fixing tree legumes, i.e., Gliricidia sepium cv. ILG50, Leucaena leucocephala cv. K28, and Albizia lebbeck to assess their differential phosphorus (P) nutrition capability over time. Dry‐matter (DM) yields, P concentration, P uptake and partitioning in plants, and P use efficiency were estimated at 4, 8, 12, and 16 months after planting (MAP). The trees showed a large interspecific variation both in DM yields and P uptake. Concentration of P ranged from 0.042 to 0.275% and varied both among parts in each tree and among tree species over time. Leaves P concentrations showed a greater reduction with tree age than either stems or roots. Phosphorus uptake correlated significantly with plant DM (r = 0.893–0.946) across tree species, and had a steady increasing pattern up to at least 12 MAP. Over ages, Gliricidia outperformed the other species in P uptake. However, Leucaena was the most efficient user of P followed by Albizia and Gliricidia, in that order. Further, Leucaena revealed an attractive feature for alley cropping in that it stored up to 37% of the P accumulated in its leaves in contrast to only 24.1% for Gliricidia and 19.2% for Albizia. Therefore, the low P supply by trees into alley cropping is in part due to its unbalanced partitioning into stems to the expenses of leaves. The study shows also that P concentration in perennials is lower than it is reported in annual crops.