Cover crops alter phosphorus soil fractions and or

Authors: Hollie Hall Yuncong Li Nicholas Comerford Enrique Arévalo Gardini Luis Zuniga Cernades Virupax Baligar Hugh Popenoe

Publish Date: 2010/07/06

Volume: 80, Issue: 3, Pages: 447-455

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Abstract

In many tropical soils excessive weathering of primary minerals confounded by intense agricultural production has resulted in the depletion of organic matter and plant available forms of phosphorus P Longterm growth of cover crops in tropical agroforestry systems have been shown to influence nutrient cycling and soil organic matter pools The objective of this experiment was to assess the affect of 2 years of covercrop cultivation on organic matter accumulation and P bioavailability using Mehlich I and sequential fractionation methods The experiment included six treatments in the understory of a cacaoplantain agroforestry system adjacent to lower montane tropical forests of the San Martin district of Eastern Peru Cacao and plantain formed the primary canopy on otherwise abandoned agricultural land The treatments consisted of four perennial leguminous cover crops Arachis pintoi Calopogonium mucunoides Canavalia ensiformis and Centrosema macrocarpum a nonlegume cover crop Callisia repens and a control treatment no cover crop After only 2 years of cultivation results suggest that all cover crop species accessed residual P pools in 0–5 cm soil depths as indicated by a decrease in the 05 M HCl extractable P pools when compared to control Additional use of residual P pools by A pintoi and C macrocarpum were indicated by significant reduction in the 60 M HCl extractable P pool Relative to control there was no treatment effect on soil organic matter content however significant differences occurred between treatments The C ensiformis C mucunoides and C repens treatments in 5–15 cm soil depths contained significantly more organic matter than the A pintoi treatment In 15–30 cm soil depths the C ensiformis treatment contains significantly more organic matter than the A pintoi treatment Continued research should focus on monitoring the longterm effects of cover crop cultivation on the bioavailability of soil P pools in surface soil horizons development of organic matter pools and the productivity of the agroforestry speciesThe authors would like to thank the many sources of assistance that made this work possible In terms of laboratory and field assistance the authors would like to acknowledge the many people at the Forest Soils Laboratory Tropical Research Education Centers Soil and Water Sciences Laboratory and at the Instituto de Cultivos for the generosity of their time Specifically at the Forest Soils Laboratory the authors thank Aja Stoppe At the Tropical Research Education Centers Soil and Water Sciences Laboratory the authors thank Guingin Yu Yun Qian and Laura Rosado At the Instituto de Cultivos Tropicales the authors thank the all of their employees In terms of funding the authors would like to thank the Latin American Studies Research Grant fund and the Tinker Grant fund at the University of Florida

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