Comparative study and evaluation of yam zone soils and the performance of six cultivars of white yam (Dioscorea rotundata) in Southeastern Nigeria

ThesisThesis, University of Nigeria, 198

Sustaining Biodiversity and Income against Climate Change through Food Value Chain System by the Small-Holder Farmers in Southern Nigeria

Biodiversity and sustainable income are very necessary in ecosystem stability. The food value chain (FVC) introduced in Nigeria to transform agriculture is commendable because through the system farmers receive various incentives as highly subsidized inputs from government and loans of low interest rates from designated Agricultural Banks and Central Bank. However, the system encourages specialization in the production of the reference crops but intercropping and mixed cropping systems practiced by most small-holder farmers because of its inherent advantages is de-emphasized or completely abandoned. This paper presents the results of two surveys of sole pepper and maize growers in 2015 and 2016 respectively as affected by sudden stoppage of rainfall in Nsukka area. The analyses showed that on the average > 70 % of the pepper farmers lost ≈ 65 % of their pepper fields while ≈ 57 % of the maize fields were lost. For a substitute intercropping system, plantain yield data from plantain plus moringa intercrop trials carried out in 2014 and 2015 were analyzed and projected to incorporate a food crop within inter-alleys. The mean plantain yields from the trials were 20 kg plant-1 for fresh bunch and 7 suckers stand-1. Based on a 6 m x 5 m (≈330 plants ha-1) spacing and the 2016 prices of bunches and suckers, these yields translated to a minimum net income per annum of N 1 320 000.00 (N 330 000.00 from bunches and N 990 000.00 from 6 suckers (net) stand-1). Proceeds from the food crop, moringa seed and leaf extracts used as liquid fertilizer took care of the cost of other inputs and cultural practices. The inter-row spacing of 6 m allows mechanical cultivation of any food crop by the farmer. This system was considered a reliable insurance against climate change and pest insurgence and can be adopted by farmers in the entire southern Nigeria because both plantain and moringa can do very well in the subregion

Cost constraints on root and tuber crops production in yam based cropping system of South East Nigeria

Draf

Multivariate modeling of some metals concentrations in agrarian soils: distribution and soil fertility implications in the tropics

Predicting metals concentration in agricultural soils is a sine qua non in establishing environmental policies and evaluating the soils’ agricultural potentials in an area. The relevance of metals to ecological health, agriculture and pollution has sprung a lot of related studies. This study was setup to determine the concentration and profile distribution of aqua regia (AR) extractable Fe, Al, Mn, Mg and K in agricultural soils, and to predict AR extracted elements via Al2O3 (Alx), K2O (Kx), physical and chemical properties for soil fertility interpretations. One soil pit was randomly sited in each slope transition obtained via digital elevation models (DEM), resulting in 27 composite soil samples. Soil samples meant for AR and X-ray florescence were analyzed in triplicate. The soils were dominated by AR extractable Fe with mean concentrations showing the trend; Fea > Ala > Mga > Mna ≈ Ka and ranges of 639.09–125,719.46, 1252.63–14,895.13, 67.61–2408.36, 4.51–2162.91 and 161.84–1356.23 mg/kg, respectively. The distribution of AR metals in the entire soils was quite similar, however, higher values of soluble Fe occurred in the 0–37 cm depth of IH1P1. Multiple linear regression functions were within acceptable and best prediction criteria (R2 = 0.55–0.77). The best performing models were Ka and Mna, with lower errors. The models selected Kx, Mg and CEC which contributed 89.9, 79.9 and 73.4%, respectively to the 44.2% contribution of PC1 to data variation. The dominance of Kx and Alx with ranges of 2381.0–50,401.0 and 57,766.67–119,433.35 mg/kg, respectively, over Ka and Ala is due to limitations associated with AR extraction of elements in silicate minerals, hence the necessity for extracting soil mineral elements by more than one method

Estimating soil organic matter: a case study of soil physical properties for environment-related issues in southeast Nigeria

The different deposition periods in sedimentary geological environment have made the build-up and estimation of soil organic matter ambiguous to study. Soil organic matter has received global attention in the ambience of international policy regarding environmental health and safety. This research was to understand the inter-relationship between soil organic matter and bulk density, saturated hydraulic conductivity (Ksat), total, air-filled and capillary porosities for organic matter estimation, via different multiple linear regression functions (i.e., leapbackward, leap forward, leapseq and lmStepAIC), in soils developed over the sedimentary geological environment. Eight mapping units were obtained in Ishibori, Agoi Ibami and Mfamosing via digital elevation model. Two pits were sited within each mapping unit, and 53 soil samples were used for the study. In soils over shale–limestone–sandstone, two pits were sited, six in alluvium, four in sandstone–limestone and four in limestone. Overall correlation between SOM with Ksat (r = 0.626) and BD (r = − 0.588) was significant (p < 0.001). The strongest correlation was obtained for SOM with BD (r = − 0.783) and Ksat (r = 0.790) in soils over limestone. In contrast, soils over shale–limestone and sandstone geological environment gave the weakest relationship (r < 0.6). Linear regression gave a similar prediction output. The best performing was leapbackward (RMSE = 11.50%, R2 = 0.58, MAE = 8.48%), which produced a smaller error when compared with leap forward, leapseq and lmStepAIC functions in organic matter estimation. Therefore, we recommend applying leapback linear regression when estimating soil organic variation with physical soil properties for solving soil–environmental issues towards sustainable crop production in southeast Nigeria