Differential Soil Acidity Tolerance of Tropical Legume Cover Crops

Abstract

In tropical regions, soil acidity and low soil fertility are the most important yield‐limiting factors for sustainable crop production. Using legume cover crops as mulch is an important strategy not only to protect the soil loss from erosion but also to ameliorate soil fertility. Information is limited regarding tolerances of tropical legume cover crops to acid soils. A greenhouse experiment was conducted to determine the differential tolerance of 14 tropical legume cover crops to soil acidity. The acidity treatments were high (0 g lime kg⁻¹ soil), medium (3.3 g lime kg⁻¹ soil), and low (8.3 g lime kg⁻¹ soil). Shoot dry weight of cover crops were significantly affected by acidity treatments. Maximum shoot dry weight was produced at high acidity. Jack bean, black mucuna, and gray mucuna bean species were most tolerant to soil acidity, whereas Brazilian lucern and tropical kudzu were most susceptible to soil acidity. Overall, optimal soil acidity indices were pH 5.5, hydrogen (H)+ aluminum (Al) 6.8 cmol_c kg⁻¹, base saturation 25%, and acidity saturation 74.7%. Species with higher seed weight had higher tolerance to soil acidity than those with lower seed weight. Hence, seed weight was associated with acidity tolerance in tropical legume species.

Keywords:

• Base saturation
• Oxisol
• shoot dry weight
• soil pH

ACKNOWLEDGMENTS

We thank Dr. C. D. Foy for his valuable comments and suggestions on improving the manuscript.

Notes

1. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that also may be suitable.