Assesment of Tillage Erosion Rates on Steepland Oxisols in the Humid Tropics Using Granite Rocks.

TitleAssesment of Tillage Erosion Rates on Steepland Oxisols in the Humid Tropics Using Granite Rocks.
Publication TypeWorking Paper
AuthorsThapa BB, Cassel DK, Garrity D
Secondary TitleSoil Science Society of North Carolina Proceedings, Volume XLI (1998)
Call NumberPP0057-04
PublisherSoil Science Society of North Carolina
Year of Publication1998
Publication LanguageEnglish
AbstractSoil trans location by animal-powered tillage may lead to land degradation in small scale steep land agriculture in the humid tropics. This study evaluated tillage-induced soil trans location on an Oxisol with 25 and 36% slopes in Claveria, Philippines. The three tillage systems were contour moldboard plowing (CMP), moldboard plowing up and down slope (UMP), and contour ridge tillage (CRT). Rocks 3 to 4 cm in “diameter” used as soil movement detection units (SMDU) were placed at 10-cm intervals in a narrow 5-cm-deep trench near the upper boundary of each plot, the position of each rock recorded, and the trench backfilled. Five tillage operations used to produce one corn (Zea mays L.) crop were performed during a one month period: two moldboard plowing operations for land preparation (except for CRT), one moldboard was plowing for com planting and two inter-cultures (inter-row cultivation) operations. After these operations, over 95% of the SMDU were recovered manually, their exact locations recorded, and their movement used to estimate soil transport due to tillage. Mean annual soil flux for the 25% slope was 365 and 306 kg m -1yr-1 for UMP and CMP, respectively. For the 36% slope, comparable values were 481 and 478 kg m -1yr-1. Estimated tillage erosion rates for the 25% slope were 456 and 382 Mg ha-1yr-1 for UMP and CMP, respectively, and increased to 601 and 598 Mg ha-1yr-1, respectively, for the 36% slope. The mean displacement distance, mean annual soil flux, and mean annual tillage-induced soil loss for both slopes were reduced by approximately 70% on both slopes using CRT compared to CMP and UNEP. The present rapid rate of land degradation by moldboard plowing could be dramatically reduced with the adoption of ridge tillage.
Keywordsgranite rocks, humid tropics, Oxisols, soil, tillage erosion
Citation Key604