Vertical Topsoiling, A Practicable Technique to Manage Soils with Markedly Compact Subsoils

Abstract

The effects of vertical topsoiling, vertical mulching, deep plowing and a combination of vertical mulching and deep plowing were studied in field experiments conducted on a Mabí clay soil, a Vertisol in east-central Puerto Rico. The results obtained in these experiments indicate that any mechanical soil modification technique that disturbs the subsoil of Mabí clay and similar soils, which comprise around 90,000 acres in Puerto Rico, tends to increase sugarcane and corn yields. Vertical mulching and deep plowing resulted in significant increases of 0.5 tons of sugar over the control in the first cane crop, whereas vertical topsoiling resulted in significant and highly significant increases of 0.5 and 0.64 tons in the first and second crop, respectively. Water infiltration rates were generally 2 to 3 times higher in the vertical mulching and vertical topsoiling plots than in the control although the differences were not statistically significant due to extreme variations. A combination of deep plowing and vertical mulching resulted in a 70-percent increase of shelled Mayorbela corn over the control, while vertical topsoiling alone produced a 57-percent increase. Vertical topsoiling induced abundant root penetration to a depth of 30 inches whereas roots in the control were confined mostly to a depth rarely exceeding 10 inches.