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Title: Differential Soil Acidity Tolerance of Tropical Legume Cover Crops

item FAGERIA, N.K.
item Baligar, Virupax
item LI, Y.C.

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2007
Publication Date: 2/18/2009
Citation: Fageria, N., Baligar, V.C., Li, Y. 2009. Differential Soil Acidity Tolerance of Tropical Legume Cover Crops. Communications in Soil Science and Plant Analysis. 40:1148-1160.

Interpretive Summary: Soil acidity and low fertility are the major constrains for good growth of legume cover crops in tropical tree crops. Legume cover crops with greater tolerance to soil acidity and low fertility are essential for establishing vegetative cover that reduces soil erosion and increases soil fertility and productivity of nutrient poor tropical soils. In this study we evaluated the capacity of 14 different leguminous cover crops to tolerate acid soils under greenhouse conditions in Brazil. Jack bean, Mucuna species, Crotalaria, lablab, and sunnhemp were the most acid soil tolerant leguminous cover crops. These tolerant legume species could be utilized as cover crops for the cacao plantations established on low fertility acid soils. These findings will be useful to cacao growers in South and Central America, to reduce soil erosion losses, reduce weed infestation and improve soil fertility and increase yield potentials of cacao, the source of chocolate.

Technical 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 ameliorating 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, H+Al 6.8 cmolc kg-1, and base saturation 25% and acidity saturation 23%. 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.