Phosphorus fixing capacity of a volcanic soil on the slope of mount Cameroon

Abstract

The volcanic soils on the slope of mount Cameroon are deficient in available phosphorus (P) resulting in low productivity. Excess P could be a threat to the aquatic environment. There is therefore need to monitor the P-fixing capacity of these soils with depth. The transformation of applied P in soils from different horizons were examined after treatments with different P rates (0, 20, 60 and 180 mg P L -1 ) and incubation periods (one, three, seven, 14 and 28 days) under laboratory conditions. Phosphorus was extracted on each treatment combination to determine the amount of P fixed. Phosphorus recovered increased with added P. Phosphorus fixed increased with added P and depth throughout the incubation period. The soil showed a high P fixing capacity throughout the different horizons with P fixed varying between 57-99% in the upper horizons and 90-100% in the lower horizons. More than 90% of added P was fixed after one day of incubation. This therefore reduces the threat of eutrophication. Phosphorus fixed correlated positively with clay and pH, and negatively with organic carbon and available P. Clay had a significant (p<0.05) positive correlation with pH values. Clay and pH could therefore be responsible for P-fixation in this soil.

Evaluation of phosphorus sorption characteristics of soils from the Bambouto sequence (West Cameroon)

“…The highest value of adsorption observed for the sample of Femock 2 may be due to its high clay and low available phosphorus content which enhances phosphorus adsorption while the lowest value of adsorption for Baranka 1 series may be due to its high available phosphorus and lower clay content, which does not favour phosphorus adsorption. These results conform to those of Khan et al (2010), Tsado et al (2012), Idris and Ahmed (2012) and Tening et al (2013) who showed that soils with high clay content and low available phosphorus tend to enhance P adsorption.…”

Phosphorus fixation and its relationship with physicochemical properties of soils on the Eastern flank of Mount Cameroon

“…Soil clay fraction also correlated positively with K F (r = 0.67, p < 0.05) illustrating that soil texture played a major role in P adsorption of these soils. This was in conformity with the findings of Tening et al (2013) who reported a net negative significant correlation between percent fixed P and available P and attributed P-fixation to the soil pH and clay content. Clay minerals are not only important in cation exchange reactions in acidic soils but they are perhaps a major factor governing the availability of phosphate in many soils.…”

“…Harrison (2007) reported that at this pH values, Al, Fe and Mg are highly soluble and will react with the phosphate ions (H 2 PO 4 -) to form hydroxyl-phosphate which is insoluble, and unavailable for plants. The low contents of available P observed in the soils of the study area were in agreement with the studies made by Tening et al (2013) on soils collected within this region.…”

“…Knowledge of the relationship between soil properties with P-fixation is necessary for the effective application of phosphorus fertilizer on varied soils on the Eastern flank of Mount Cameroon region. Tening et al (2013) reported that P-fixation capacity correlated positively with clay content and pH, and negatively with organic carbon and available P in some soil horizons that were collected from a soil profile within this region. They also observed that between 52 and 99% of P is fixed by the surface soil horizon in this area a day after P application.…”

“…The soils from this region are generally low in available P (Tening et al, 2013). Knowledge of the relationship between soil properties with P-fixation is necessary for the effective application of phosphorus fertilizer on varied soils on the Eastern flank of Mount Cameroon region.…”