Compactibility of some agricultural soils in South Western Nigeria

Twelve soil samples, two each for the six major soil series representing the main agricultural soils in South Western Nigeria were collected and subjected to three levels of compaction using 5, 15 and 25 blows of a Proctor hammer in the laboratory at six different moisture levels (8, 12, 16, 18, 20 and 22% weight basis). The dry densities of the soils were measured at the different compaction loads and moisture contents. Simple and multiple correlation and regression analysis were conducted to investigate the possibilities of obtaining estimates of optimum moisture content and maximum dry density from soil components. s indicate that dry density increased slightly (P<0.05) with increase in compactive load and that the maximum values of bulk density were obtained at predetermined optimum moisture contents for compacting the soils. Optimum moisture content was positively correlated with the silt content while the maximum dry density was positively correlated with the sand content. Two regression equations were derived to relate optimum moisture with silt content and compactive load and to relate maximum dry density with sand content and compactive load. Land scape position did not influence the compaction behaviour of the soils.