Mulches are known to conserve soil moisture, provide organic matter, protect soil and improve the soil as a growing environment. A field experiment was conducted to assess the effect of various mulch materials viz. dry oil palm bunch, saw dust and dry elephant grass at 25, 50 and 25 tons ha-1, respectively along with black plastic mulch on some soil physical and chemical properties and the performance of castor bean plant (Ricinus communis). All the mulches were applied to a mulch thickness of 5cm in this study. Results showed that pH values, organic carbon content and total nitrogen were all significantly improved by mulching. Bulk density values were reduced to 1.10 - 1.18gcm-3 across all treatments, when compared to the control at 1.33gcm-3. At 6 WAP, plastic mulching increased number of leaves from 16 to 40 leaves per plant and capsule weight from 63.1 to 161.3g/plant; when compared with the control.

The castor bean seed when cooked and fermented, is a staple food condiment in Nigeria, but its production is low in the humid rainforest zone of Southern Nigeria. A field experiment was conducted in the Rivers State University Teaching and Research Farm in Port Harcourt Nigeria, to evaluate the effect of various nitrogenous soil amendments on the growth and yield of castor bean plant (Ricinus communis). The treatments included 120kgNha -1 equivalent of urea, NPK 20-10-10, poultry droppings, piggery dung and no amendment (control). These were replicated thrice and laid out in randomized complete block design. A Chinese improved variety of castor bean plant (Zibocastor No 5) was planted at a spacing of 1m x 1m within and between row, at a population of 5,000 seeds per hectare. Results showed that the various nitrogenous soil amendments significantly affected all growth and yield parameters measured, but germination was negatively affected. Piggery dung gave the best values of 52.6cm, 24.0, 85.0cm 2 , 191.5, and 350gplant -1 for plant height, number of leaves, leaf area, number of capsules and capsule weight respectively, when compared to the control with 24.5, 8.0, 40.0cm 2 , 28.4, 153gplant -1 . Results of the physico-chemical properties of the soil showed significant increase in total nitrogen and available phosphorus, and a decrease in exchangeable calcium and magnesium with no significant changes in pH; following soil amendment and cropping. Amending the soil with piggery dung increased yield by 397.0% over the control.

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Evaluation of carbon stock in soil is an essential step in estimating the carbon storage potential of an ecosystem. A field study was carried out on a humid tropical Rainforest and Mangrove soils at the Forestry Unit of the Rivers State University Teaching and Research Farm and the Eagle Island quantify the effects of vegetation and seasons on soil organic carbon, organic carbon stock and other physical to attributes of the soils. Results revealed that seasons and vegetation did no change the soil texture, but influenced other properties of the soils. Bulk density was significantly low (p<0.05) at 0.64 g cm-3 in Mangrove soils in the peak of dry season. Saturated hydraulic conductivity (Ksat) was moderately rapid (20.88 cm h-1) in Rainforest soil, and moderately slow (15.59 cm h-1) in the Mangrove soils. Soil organic carbon (SOC) was significantly higher (p<0-05) in mangrove soils at 53 g kg-1 during the rains, and 16 g kg-1 in Rainforest soils during the same season. Soil organic carbon stock (SOCS) was significantly higher at 65.4 kg m-2 in Rainforest soils (p<0.05), compared to 8.4 kg m-2 in Mangrove soils during the same season. SOCS correlated positively bulk density (BD) (r = 0.679, p<0.05) and clay content (r = 0.892, p<0.01). The model: Y = 0.165+4.068x can be used to predict SOCS and bulk density, also the model Y = -0.246+0.361x can be used to predict the effects of clay content on SOCS in the two soils during the seasons. The Rainforest was found to have the potentials to store carbon in the soil than the Mangrove.

Soil acidity is a potentially serious land degradation issue. When soil becomes too acidic it can decrease the availability of essential nutrients. Investigation on the effect of activated biochar on soil properties of coastal plain sands of Port Harcourt was conducted at the high tunnel hoop house located at the Teaching and Research farm, Rivers State University Port Harcourt. Separate biochars were produced using following materials: Wood Shavings (WS), Corn Cob (CC), Wood (WD), Palm Kernel Shell (PK), and Animal Bone (AB), And a Control (CO). The 6 treatments made up of the various biochars were replicated three times and fitted into a Randomized Complete Block Design. Soil samples were taken before and after treatment application and for determination of physical and chemical properties. Result shows that the pH values significantly increased from 6.63 – 7.73, when compared to the original soil with a pH of 4.97(P = 0.05). The organic matter content was significantly higher (P>0.05) across all the biochar amended soils. Palm kernel biochar (PK) had 31.4% increase in organic matter when compared to the initial organic matter of 1.19%. There was also substantial increase in the soil total nitrogen (100%) for palm kernel biochar. Available phosphorus was also increased by almost 100% for soil treated with the respective biochars; ranging from 0.33 – 0.43 cmolkg-1 when compared to the original value of 0.18 cmolkg-1. Remarkably, the values for most of the exchangeable bases increased significantly (P= 0.05) after treatment application, ranging from 5.68-18.10, 6.01 – 24.1 and 3.93-6.13cmolkg-1 for K+, Na+ and Mg2+ respectively, as compare to the initial values of 4.36, 2.2 and 1.0cmolkg-1.