concentration from 0 to 75%. They concluded that, as gravel

concentration and, therefore, total solids increased, porosity and

consequently water-holding capacity decreased.

 Ghuman and Lal (1984) studied differences in field-water

percolation and redistribution rates on a tropical Alfisol under

conventional plowing and no-till management. The soil had a naturally

occurring gravel horizon from the 10 to 80-cm depth that contained about

45% gravel by weight. Soil having an initial water content of 0.035

cm3/cm3 exhibited infiltration rates of 43 and 120 cm/h for the

conventional and no-till systems, respectively, upon application of 5 cm

of floodwater to the surface. The infiltrating water under both tillage

treatments reached the 30-cm depth before flood conditions ceased, at

which time the plots were covered to prevent surface evaporation.

Within 1 h the water had passed the 80-cm depth. The redistributing

soil water had stabilized after 5 h and the soil water content with

depth remained constant until cessation of observations at 48 h. Higher

initial soil-water contents resulted in slower infiltration rates. Even

under very dry conditions, the gravel horizon did not prohibit the

downward movement of infiltrating water.

 Research Topics


 The unique physical properties and generally unknown behavior of

 tropical, stone-line soils lead to many questions regarding their

 agricultural management. However, extrapolation of properties and

 behavior of soils that simply contain stones can lead to the development

 of management practices based on incorrect assumptions. Soil scientists