Soil water balance approach in root zone of maize (95-TZEEY) using capacitance probe (Diviner 2000) in northen Guinea Savannah of Nigeria

Water balance approach is the simplest method in the study of plant water consumption. The experiment was established in 4.0 x 5.0 m plots in a randomized complete block design containing six (6) treatments water application (3-days, 4-days, 5-days, 6-days, 7-days and 8-days which correspond to T1, T2, T3, T4, T5 and T6 respectively) using gravity methods with four replications giving a total of twenty four (24) plots. One Polyvinylchloride (PVC) access tube was installed in the centre of each plots and measurements were taken daily over the growth season of March to June. The Diviner 2000 uses the method that utilizes the high dielectric constant of water compared to soil and air to determine water content of the soil. The research result from the experimental field of maize (95-TZEEY) on measurement of soil water status using capacitance probe (Diviner 2000) for three dry seasons are presented. Keywords: Water, Diviner, Probe, Soi

Forms of iron in soils on basement complex rocks of Kaduna state in northern guinea Savanna of Nigeria

The forms of iron extracted by different methods were studied in soils developed on four basement complex rocks within Northern Guinea Savanna of Nigeria namely: migmatite gneisses, older granite, quartzites and mica schists. The study shows that forms of iron generally decreased in the order of total elemental iron (FeT) determined by XRF > double acid extractable total iron (Fea) > dithionite extractable iron oxide (Fed) > oxalate extractable iron oxide (Fex) > pyrophosphate extractable iron oxide (Fep) > 0.1M HCl extractable micronutrient available iron (Feh). Variation in content of total irons (FeT and Fea) were not significant in the soils, but content of Feh, Fed, Fex and Fex/d significantly varied in the soils on the various parent materials. Therefore processes and extent of pedogenesis were considered to influence the variations resulting in recrystallization and increase in content of Feh and Fed in these soils. The significant correlation between various forms of Fe (Fea, Fed, and Fex) with active iron ratio further affirmed that as soils on basement complexes increase in their pedogenetic age, Fe content generally increases irrespective of total forms of iron. The strong correlation between FeT, Fea and Fed indicate that these forms of iron were extracted from similar sources.Keywords: Iron, basement complex rock, pedogenesis, Northern Guinea Savanna, Nigeria

Lablab purpureus—A Crop Lost for Africa?

In recent years, so-called ‘lost crops’ have been appraised in a number of reviews, among them Lablab purpureus in the context of African vegetable species. This crop cannot truly be considered ‘lost’ because worldwide more than 150 common names are applied to it. Based on a comprehensive literature review, this paper aims to put forward four theses, (i) Lablab is one of the most diverse domesticated legume species and has multiple uses. Although its largest agro-morphological diversity occurs in South Asia, its origin appears to be Africa. (ii) Crop improvement in South Asia is based on limited genetic diversity. (iii) The restricted research and development performed in Africa focuses either on improving forage or soil properties mostly through one popular cultivar, Rongai, while the available diversity of lablab in Africa might be under threat of genetic erosion. (iv) Lablab is better adapted to drought than common beans (Phaseolus vulgaris) or cowpea (Vigna unguiculata), both of which have been preferred to lablab in African agricultural production systems. Lablab might offer comparable opportunities for African agriculture in the view of global change. Its wide potential for adaptation throughout eastern and southern Africa is shown with a GIS (geographic information systems) approach

Nitrogen mineralization kinetics and parameter estimates in soil amended with Neem seed cake and inorganic fertilizer in Samaru, Nigeria

A field study was conducted to assess the effect of neem seed cake (NSC) on the kinetics of net nitrogen mineralization and parameter estimates. The experiment consisted of sorghum plots to which milled NSC (with %N > 3) and urea (inorganic N source) were applied. Ammonium-nitrogen and nitrate-nitrogen were determined after 0, 2, 4, 6, 8, 12, 19 and 34 weeks from soils covered with PVC tubes inserted into the sixteen treatment combination plots. Inorganic N concentration in the amended plots and the control were analysed using five mathematical N mineralization models. N0, Ne, h and k were estimated from the fit of each mathematical model. The treatments were highly variable in their respective N mineralization characteristics, but the peaks for mineralized N content were observed at early incubation periods, i. e., 10 -28 days. Potential respective mineralizable N (N0) content of the first order rate, consecutive (h ‚ k), consecutive (h = k), Gompertz and mixed order rate constant was -927E-22, 430.90, 1.9E-21, 568.40 and 427.20 mg kg-1 soil and the respretively rate constant (k) was -5E+21, 0.2269, 2E+23, 0.0954 and 0.8116.respretively Net N mineralization was best described by a mixed order rate model (R2 = 0.992) and residual mean square error (RMSE)was = 28.41. A Gompertz function also fitted the data closely (R2 = 0.999; RMSE = 52.47). The two models recognize that N mineralization is not just a function of substrate N concentration but also of the capacity of the microbial community to adjust to substrate quality and composition affecting their growth and activity.Key words: mineralization model, neem seed cake, N mineralization, parameter estimates, PVC tube

Determination of saturated and unsaturated hydraulic conductivity using diviner 2000 capacitance probe

The estimation of hydraulic conductivity indicates how fluids flow through a substance and thus determine the water balance in the soil profile. In determining the saturated and unsaturated hydraulic conductivity of soil, five plots of 5.0 x 4.0 m were prepared with a PVC access tube installed in each plot. The plots were ponded profusely and surface covered with grass to prevent water loss by evaporation or water input by rain. The readings were taken twice daily for over a period of 5 days using capacitance probe with trade name Diviner 2000. The Diviner 2000 uses the method that utilizes the high dielectric constant of water compare to soil and air to determine water content of the soil. The trend lines of hydraulic conductivity has its linear regression r = 0.8296 - 0.9273 and its saturated hydraulic conductivity in the range of 5.09 cmh-1 – 14.03cmh-1 and unsaturated hydraulic conductivity in the range of 0.700 cmh-1 – 0.785 cmh-1. This reveals that soil water content can be obtained reasonably well from a capacitance probe which will allow for a determination of the pattern and use of the referred soil