Bulgarian Journal of Soil Science

90 - 103

Authors: Donald Nweze Osujieke, Pedro Ezemon Imadojemu, Michael Akpan Okon, Obinna Marcellinus Okeke

The assessment of the distribution of soil physico-chemical properties facilitates the use of proper soil management practices. Hence, the study was conducted in Izombe rainforest of Nigeria to ascertain the profile distribution of physical and chemical soil properties. Samples were collected from two profile pits base on horizon differentiation for laboratory analyses using standard procedures. Data generated were analyzed statistically using coefficient of variation and correlation. The result indicated that sand recorded 760 g kg-1 in pedon 1, 730.20 g kg-1 in pedon 2 and was predominant in the soil with higher amount at the surface horizon while clay and silt increased down the pedons. Bulk density ranges from 1.14 – 1.79 g cm-3. The AB horizon was the least acidic of the pedons. Most soil chemical properties decreased down the profile. Sand and pH had low variation (≥4.80 % ≤12.60 %) while silt, organic carbon, total nitrogen had high variation (≥41.52 % ≤79.58 %) among the horizons. Fe, Mn and Zn had moderate to high variation among the horizons. Clay correlated negatively and highly significantly (r= -0.829, r= - 0.883, p= 0.01) available phosphorus and Fe. Clay also had a positive significant correlation (r= 0.665, r= 0.641, p= 0.05) with bulk density and base saturation. pH had a significant negative relationship (r= -0.708, p= 0.05) with base saturation while cation exchange capacity had a highly significant positive correlation (r= 0.877, p= 0.01) with Pb. Fe had a negative and highly significant relationship (r= -0.838, p= 0.01) with Zn. The result indicated that most mineral element are domiciled in the A horizon and such demand proper management practices for soil nutrients sustainability.

119-133

Authors: Oluseye Olalekan Oludoye, Lanrewaju Amos Ogunyebi

High soil quality is important for agricultural activities but pollution from cement industries is of great threat to sustainable agriculture in Nigeria. The aim of this study is to assess the effect of heavy metals in cement dust on the soil enzymes activities. This study investigated the activities of some selected soil enzymes, the microbial communities’ population, the concentrations of some heavy metals, some selected soil macronutrients and the physico-chemical properties (pH, moisture, and temperature) of the soil surface (0-15 cm), within the vicinity of a cement factory in Nigeria. The pH, total organic nitrogen (TON), total organic carbon (TOC) and heavy metals decreased with increasing distance from the cement factory. The microbial population around the factory was (34.00 ± 2.64 CFU g-1) and (92.00 ± 1.00 CFU g-1) at 100 m and the control site respectively. All the soil heavy metals contents analyzed are less than the permissible limit except Cd. Moreover, the enzyme activities increased away from cement factory except alkaline phosphatase that decreases with increase in distance. The enzymes activities (except alkaline phosphatase) correlated negatively with the content of all heavy metals, the pH, the TON, the TOC and temperature but positively correlated with moisture, phosphorous and microbial populations. The inverse correlations between most of the heavy metals, the pH and soil enzymes activities could be a result of the pollution. This means that the cement production exhibits a significant effect on the enzyme activities.

143-149

Authors: Vania Kachova

A containers experiment was carried out in four variants with fertilization of ryegrass: 1th and 2nd trials, with the addition of 1ml and 5ml of organic fertilizer “Siapton” and 3th and 4th trials: a combination of Siapton (0.5 ml fertilizer in 50 ml of water ) with the mineral fertilizer "Kristalon" in quantity of 0.5 and 2 grams respectively. There was used also a control. It is accounted a higher accumulation of organic matter (content of C% and N%) in leaves of ryegrass after fertilizing in comparison with the control. Accumulation of dry matter also is higher in fertilized variants (27.09 ÷ 37.62) compared to the control (25.99g). This difference is not confirmed and does not recorded in relation to the roots of ryegrass. Acidification of soils is changed towards a higher pH (5.5 ÷ 6.4) in fertilized variants in comparison with the control (pH = 5.2). The humus composition was studied by the method of Kononova - Belchikova, but apparent differences were not accounted in relation to the use of organic and mineral fertilizers. The content of humic acids extracted with pyrophosphate calculated according the weight of soil samples is lowest in control (1.02%), where the content of fulvic acids is high (0.40%).