Rhizosphere phosphorus solubility and plant uptake as affected by crop in a clay soil from the Central Plateau Region of Haiti

The nutrient Phosphorous (P) can be available in forms not available for plant uptake, and it is often a limiting factor in tropical crop production. However, certain plants are particularly efficient at extracting phosphorous. These plants can be effective cover crops because they improve phosphorous availability and uptake for the subsequent crop. This study examines the ability of seven different crops to improve phosphorous availability for farmers in Haiti’s Central Plateau. Surface soil from the Central Plateau was air dried and shipped to researchers in the US, where treatments of black bean (Phaseolus sp.), chickpea (Cicer arietinum L.), cowpea (Vigna unguiculata [L.] Walp.), grain sorghum (Sorghum bicolor [L.] Moench), lablab, pigeon pea, and velvet bean were applied in a controlled-environment chamber. After forty-nine days the plants were uprooted and samples of rhizosphere and bulk soil were analyzed. Phosphorous uptake did not differ among the seven species studied. However, researchers found that P uptake positively correlated with rhizosphere P and dry weight. Velvet bean was found to have the high quantity of dry mass, a positive characteristic for a cover crop.