- Judth K, Vincent MO, Geoffrey KN. "Impact of longterm Inorganic Fertilization with Emphasis on Heavy metals, Soil pH and Total Organic Carbon on Maize Farm soils in Trans Nzoia Kenya. ." International Journal of Science and Technologe. 2014;2(11):183-188.
This research was carried out to analyze the effect of long term use of inorganic fertilizers on the Cd, Cr, Cu, Pb, Zn, soil pH and TOC in maize farm soils in Kenya. Samples of soil were collected from 12 experimental sites from Kerita farm that has experienced more than 20 years of inorganic fertilizer application and 2 samples from the control site (Kiptuimet primary school), Trans Nzoia in Kenya while fertilizer samples were purchased from the nearby Kolongolo Market. Results obtained showed that the mean concentration for Cu, Pb, Cr and Zn in maize farm soils was 8.52±1.56mg/kg, 37.72±3.44 mg/kg, 42.11±3.25 mg/kg and 29.36±2.74 mg/kg, respectively while the mean concentration for Cu, Pb, Cr and Zn in the control soils was 5.12±0.71 mg/kg, 18.98±0.88 mg/kg, 19.15±1.56 mg/kg and 14.71±0.63 mg/kg respectively. The mean concentration for Cu in both the control site and maize farm soils was below the detectable limits of the instrument. Soil Ph in maize farm soils and control site was 5.034±0.25 and 6.35±0.21 respectively while soil TOC was 1.11±0.87% and 0.915±0.01% in maize farm soils and control site respectively. The results revealed that maize farm soils had higher levels of heavy metals than the control site suggesting that inorganic fertilizers had had an impact. However the concentration of these toxic elements after long term use of inorganic fertilizers did not exceed the maximum allowable levels set by the USEPA and WHO. Also the levels of these metals in the inorganic fertilizers used in the maize farms were within acceptable levels set by the USEPA and Kenyan standards. Soil pH levels showed a difference between the maize farms and the control site with control having higher pH values than the maize farm soils indicating long term application of inorganic fertilizers effect on soil pH. However both the two sites had generally a low pH of less than 7.0 which was attributed to the composition of the parent rock from which the soils were formed and inherent factors affecting soil pH
which cannot be changed. There was a difference in total organic carbon values between the maize farms and the control site with higher values of TOC in maize farm soils compared to the control site indicating that long-term chemical fertilizer application alone can increase soil total organic carbon.
Keywords: Heavy Metals, Soil pH, TOC, Fertilizers, Maize Farms, Kenya