No abstract

Irrigated agriculture is one of the significant contributors to the food security of the millennium development goals (MDGs); however, the modification of soil matrix by irrigation could alter the overall soil health due to changes in soil properties and processes. The objective of the study was to evaluate the effect of irrigation on soil quality status of the Ikere center pivot irrigation project site in Oyo State, southwest Nigeria. Disturbed soil samples were collected from 0 to 30, 30 to 60, and 60 to 90-cm layers from four different sites in three replicates, within the project location for the determination of soil bio-chemical properties. The average values of sodium adsorption ratio (SAR) < 13, electrical conductivity (EC) <4 μS/cm, and pH < 8.5 showed that the soil condition is normal in relation to salinity and sodicity hazards. The effective cation exchange capacity (ECEC), soil organic matter (SOM), total nitrogen (TN), and calcium ion (Ca) concentrations were low while the available phosphorus (P) was moderate. The principal component analysis showed EC, ECEC, SAR, SOM, and TN as the minimum data set (MDS) for monitoring and assessing the soil quality status of this irrigation field. In terms of bio-chemical properties, the soil quality index (SQI) of the field was average (about 0.543) while the sampling locations were ranked as site 2 > site 4 > site 3 > site 1 in terms of SQI. The results of this study are designated as baseline for future evaluation of soil quality status of this irrigation field and further studies should incorporate soil physical and more biological properties when considering overall soil quality status.

The importance of irrigation practice in food production cannot be over-emphasised, however irrigation practices impact soils and other environmental parameters negatively. This necessitates the need for continuous monitoring of the impacts of irrigation on soils and the general environment. A study was carried out on the Josepdam Irrigation Scheme (JIS) located in Bacita, Ilorin, Nigeria. This study was limited to the impact assessment of irrigation practices on the soil physical and chemical properties. Soil samples were collected from irrigated lands at depths 0-20, 20-80 and 80-120 cm from 8 OLs on JIS using soil auger. During each season of collection, samples were kept in polyethylene bags and transported within 24 hours to the laboratory for analyses. The samples were analysed immediately according to ISRIC-FAO procedures for pH, Cation Exchange Capacity (CEC), Exchangeable Sodium Percent (ESP), Mg2+, Ca2+, Na+ and Sodium Adsorption Ratio (SAR). The results indicated that the soil texture was sandy loam and sandy clay loam, In JIS, the pH of 7.2 at inception reduced to 4.6; SAR increased from 0.4 to 2.14 meq1/2 and CEC increased from 18 to 26 cmolkg-1. The impacts of irrigation on the soil was determined. The results of these evaluations were compared with FAO standards and past research results.

This research was conducted to analyze the soil physico-chemical properties of Shonga Irrigation Scheme to ascertain its suitability for rice production. The study was carried out in the dry season of 2019. Disturbed soil samples were collected from the 0–15 and 15–30 cm soil layers in five identified areas in the irrigation scheme. The samples were sent to the Soil laboratory of the Lower Niger River Basin for physical and chemical analysis. Most of the soils were strongly acidic to moderately acidic with pH values ranging between 4.8 and 5.7. The organic carbon and organic matter ranged from 0.13 to 0.19% and 0.03 and 0.32%, respectively which implies low fertility. Calcium values ranged between 2.1 and 3.75 cmol/kg, with the low values related to the soil pH status. Magnesium values averaged 2.48 and 1.95 cmol/kg in the top and lower soil layers, respectively. Exchangeable Acidity (EA) values ranged between 0.20 and 3.40 cmol/kg in the surface horizon and between 0.2 and 5.4 cmol/kg in the sub-surface horizons. Available phosphorus had an average of 40.05 and 23.14 ppm in the surface and sub surface soil layers, respectively. Analysis of variance techniques was used for significant differences within chemical properties. For all tests, a threshold of P=.05 was used to define statistical significance. Soil pH and available phosphorus were within the recommended land suitability requirement for rice cultivation. Organic carbon, organic matter, calcium and magnesium were not within the recommended range for rice production. Organic carbon and organic matter can be supplied through the incorporation of organic manure.

Eutrophication, salinization, hypoxia, and toxic algae, among other environmental damages are costly consequences of agricultural drainage water (ADW), and therefore poses a threat to ecological biodiversity, food security and agriculture sustainability. This work aimed to assess the adsorption efficiency of rice husk (RH) modified by chemical and thermal treatments for sulphate minimization from ADW. RH obtained from a local rice mill was washed in distilled water, oven-dried at 105 ˚C for 24 h, milled and sieved into 0.3–1.18 mm particle sizes. The optimum condition for carbonization was determined by varying the temperature- 200, 300 and 400 ˚C and time- 1, 1.5, and 2 h, respectively. The RH was activated by chemical (H3PO4 and ZnCl2) and thermal treatment. Batch experiments were carried out varying temperature (40-60 °C), adsorption time (15–140 min) and adsorbent dose (1 and 2 g) in an ADW with known sulphate concentration, 30 mg/L. The carbonization yield at 400, 300 and 200 ˚C varies within 18.91- 27.48%, 27.39- 32.82 % and 81.94- 95.75% respectively. It was observed that the percentage of carbon converted into silica increases with burning time; hence, the optimum temperature of 350 ˚C for 2 h was used for carbonization. Also, sulphate adsorption rate increased with contact time and dosage suggesting that the process is controlled by surface and pore diffusion. Based on the temperature study, adsorption was favourable at lower temperatures. H3PO4 and ZnCl2 treated adsorbents have similar removal efficiency; however, ZnCl2 treated adsorbent has a higher efficiency due to its ability to enhance the stability and mesoporosity of carbonaceous material. Modified RH is a potential adsorbent that could be of noble use in ADW quality minimization. However, the huge gap between literature studies and field application needs to be bridged by good extension services and appropriate policy.