Using Tithonia diversifolia (Hemsl.) Gray in a Short Fallow System to Increase Soil Phosphorus Availability on a Costa Rican Andosol

Abstract

This study evaluated aboveground pruning biomass production in a naturally regenerated fallow (NF), and in monoculture with a leguminous species (CF), and a non-leguminous species (TF) on an Andosol in Costa Rica.  The effect of pruning biomass removal or addition on bean grain yield and soil P fractions was also evaluated.  Biomass production and nutrient input was significantly greater (p>0.05) in the TF treatment.  Macronutrient content of the pruned biomass was not significantly different (p>0.05) between treatments, but C/N and C/P ratios were significantly lower (p>0.05) in the CF treatment.  Bean grain yields were significantly greater (p>0.05) only when TF biomass was added to the soil as mulch.  There was no significant difference (p>0.05) in the amount of P in the labile and potentially labile fractions between treatments, and the inter-conversion mechanisms between non-labile soil P and labile fractions occurred in diverse directions, not necessarily following the inverse strength sequence of the Hedley P fractionation procedure.