Soil physical and chemical properties under continuous maize and a maize-mucuna rotation on hillsides in Honduras

A maize (Zea mays L.)-mucuna (Mucuna deerinniana) rotation is used by more than half of the hillside farmers in northern Honduras. While maize yields are reported by local farmers to increase under the rotation, there is conc ern that this rotation increases water infiltration and thereby increases t he incidence of landslides under high rainfall conditions. This study was c onducted during the summer of 1994 to determine if mucuna in the cropping s ystem provides measurable differences in soil physical properties. The on-f arm study used adjacent paired plots of continuous maize (Treatment C) and a maize-mucuna rotation (Treatment M) conditions on hillsides at three loca tions near La Ceiba. In each plot bulk density, saturated hydraulic conduct ivity (K-sat), wet aggregate stability, total and macro-porosity, and mecha nical impedance (MI) were intensively measured in the 0-10 cm depth at 40 r andom sites, and in the 10-20 cm depth at 5 random sites. Four soil samples were collected from the 0-15 and 15-30 cm depths for determination of orga nic C and total N. The soil temperature was measured three times during the study. Bulk density and MI in the 0-30 cm depth were not affected by the t reatments. Treatment effects were inconsistent for macro-porosity and K-sat in the 0-10 cm depth. Soil temperature at the 8 cm depth was 3 degrees C l ower in Treatment M than Treatment C. Mean aggregate stability for the 0-10 cm depth was significantly higher in Treatment M (92.5 for maize vs 90.6% for maize-mucuna). Soil organic matter was higher in Treatment C in the 15- 30 cm depth (2.40% for maize vs 2.13% for maize-mucuna). Total N was higher (P = 0.05) in Treatment M in the 0-15 cm depth (0.24% for maize vs 0.27% f or maize-mucuna). Overall, the maize-mucuna rotation did not further improv e the excellent soil physical properties present under continuous maize.