Incubation experiment was carried out to evaluate and compare effects of some selected amendments on adsorption of heavy metals in soils and their chemical properties. The experiment was CRD consisting of twelve treatment combinations with three replications. Soil samples were collected from the vicinity of Michael Okpara University of Agriculture and amended with organic amendments at the rate 20 ton/ha and heavy metals at the rate of 60 mg/kg, thoroughly mixed and wetted daily throughout the incubation period of 30 days. 0.05M EDTA solution was used to extract heavy metals. EDTA solution was filtered from soil with Whatman No1 filter paper. The soil was analyzed for chemical properties before and after experiment using standard procedures. Higher amount of heavy metals was extracted from the control soils than the amended soils indicating retention of heavy metals by the amendments. All the amendments were significantly (P<0.05) different in adsorption of copper with poultry manure having significantly (P<0.05) the highest adsorption capacity while the control had the least. Cocoa pod was significantly (P<0.05) higher on adsorption of lead with cow dung and poultry manure not being significantly (P>0.05) different from each other. Cow dung had the highest (P<0.05) on adsorption of zinc. Heavy metals combined with amendments had significant (P<0.05) effect on soil chemical properties. Most chemical properties were significantly (P<0.05) higher in soils treated with both amendments and heavy metals than soils treated with only heavy metals. Poultry manure, cocoa pod and cow dung appeared to have greater potential in removing heavy metals from soils.

The aim of this research was to investigate the fertility status of soils under Bamboo (Bambusa vulgaris) in Akamkpa and Odukpani Local Government Areas of Cross River State. Composite soil samples were collected at the depth of 0-15 cm under Bamboo (Bambusa vulgaris) using soil auger from fourteen (14) locations. The soil samples were analysed for some physico-chemical properties using standard procedures. Results obtained showed that the soils were predominantly sandy loam in both Akamkpa and Odukpani with a significant difference in the soil pH which was very strongly acid (mean pH in water =5.0). Organic carbon was high (26.00–41.00 g/kg) in Akamkpa and Odukpani (24.00 – 41.00 g/kg). Total nitrogen was medium (2.4–4.9 g/kg) in Akamkpa and low to medium (0.19 – 0.33%) in Odukpani. Available phosphorus was generally low (1.8-2.9 mg/kg) and (1.88 – 6.63 mg/kg) in both areas. Exchangeable calcium was low to medium (3.6-7.4 cmol/kg) in Akamkpa and medium to high (5.6-14.8 cmol/kg) in Odukpani. Magnesium contents were low (0.8-6.7 cmol/kg) and high (0.4 – 12.4 cmol/kg) in both areas. While exchangeable potassium (0.08 – 0.13 cmol/kg) and (0.09 – 0.13 cmol/kg) with sodium contents (0.06 – 0.08 cmol/kg) and (0.06 – 0.10 cmol/kg) were low. Exchangeable acidity of hydrogen (0.1 – 3.7 cmol/kg) was high in Akamkpa and low to medium (0.08-2.32 cmol/kg) in Odukpani and that of Aluminum contents (0.3 – 4.0 cmol/kg) and (0.0 – 4.0 cmol/kg) were generally low. The cation exchange capacity (CEC) was low (4.5 – 11.4 cmol/kg) in Akamkpa and low to medium (7.2 – 24.01 cmol/kg) in Odukpani and those of Effective Cation Exchange Capacity (ECEC) was low to medium (9.2 – 15.9 cmol/kg) in Akamkpa but low and high (7.8 – 24.41 cmol/kg) in Odukpani. The Base Saturation was medium to high (37 – 96%) in Akamkpa and high (60.9 – 98.4%) in Odukpani. The studies revealed that soils under Bamboo had high organic matter content. This could be attributed to the bamboo leaf fall which enhances the increase of organic matter content.

Organic matter exhibit strong variations in nitrogen retention and transformation cycle in soil. However, nitrogen could be altered by seasonal variations, leading us to hypothesize that the open municipal waste dump site in Calabar exposed to dry and wet season could alter nitrogen dynamics in that soil. A total of sixty  (60) composite soil samples were collected at different landscape positions (summit crest, shoulder slope, toe slope, interfluve slope, valley floor) of a municipal dump site and a control (no refuse area) during the dry and wet seasons in Calabar and analyzed to ascertain the effects on forms and status of soil nitrogen. The soils were loamy sand across the study location with pH values of 4.50, 7.00, 6.70, 7.30, 5.00, 7.30 (dry season) and 5.00. 7.30, 7.00, 7.40, 5.90, 7.40 (wet season) for the control, summit crest, shoulder slope, toe slope, interfluve slope and valley floor accordingly. Values obtained for total nitrogen (N) from the study site were generally low (<0.21 %), with values for dry season slightly higher than the wet season. NH4+ recorded higher content in wet  than in dry season with values ranging between 12.11-14.11 mg/kg (control), 14.60 - 15.90 mg/kg (Summit crest); 18.25 - 20.05 mg/kg (Shoulder slope), 18.30 - 20.20 mg/kg (Toe slope), 12.30 - 14.00 mg/kg (Interfluve slope) and  9.24 -11.07 mg/kg (Valley floor). The Shoulder and toe slopes recorded the highest NH4+ concentration in the wet season. N02- contents documented for the control site were within the ranges of 2.78- 3.20 and 3.22-3.62 mg/kg while the dumpsite had values between 2.49-3.45 and 2.98 -3.22 mg/kg was observed for the shoulder position, the toe slope contained between 2.30-2.75 and 2.70 -2.82 mg/kg, the inter fluve slope had similar ranges of 2.32-2.90 and 2.70-3.08 mg/kg, and the valley floor 2.45-2.60 and 2.78-2.98 mg/kg. N02- values were higher for the wet than dry season. NO3- nitrogen was observed to be excessive across the dumpsite with the highest values > 80 mg/kg obtained at the valley floor. The NO3- values were higher in dry season across the all the landscape positions than in the wet season. The values were equally higher for the dumpsite than the control. It was observed that the dumpsite soils contend excessive NO3- which could be converted to nitrous oxide (N2O) thus contributing to green house (GHG) emissions.  It was also noted that seasonal variation did not significantly affect the N content at the different landscape positions of the municipal dumpsite in Calabar. It is highly recommended that municipal waste be sorted and the organic materials composted to harness the rich NO3- content as observed in this research.   Received: 22 September 2021 / Accepted: 25 October 2021 / Published: 5 November 2021