N2 Fixation by Grain Legume Varieties as Affected By Rhizobia Inoculation in The Sandy Loam Soil Of Sudano-Sahelian Zone of North Eastern Nigeria.

Rhizobium – legume symbiotic association contributes considerable amount of N in tropical soils. However, low rainfall and high temperature in Sudano-Sahelian region of Northeastern Nigeria may affect the Rhizobial population in the soil. Therefore, the influence of Rhizobia inoculation on N2 fixation by cowpea (Vigna unguiculata (L.) Walp.), groundnut (Arachis hypogaea L.) and bambara groundnut (Vigna subterranean L.Verdc.) was evaluated under field condition in Maiduguri. The seeds of the crops were inoculated with their Rhizobium strains and grown for 50 days, after which they were harvested and the amount of N fixed was measured. The results showed that rhizobia inoculation increased the amount of N fixed by 46% over the control. Cowpea differed significantly (

Comparison of empirical models and laboratory saturated hydraulic conductivity measurements

Numerous methods for estimating soil saturated hydraulic conductivity exist, which range from direct measurement in the laboratory to models that use only basic soil properties. A study was conducted to compare laboratory saturated hydraulic conductivity (Ksat) measurement and that estimated from empirical models. Soil samples for the study were collected from four sites at varying depths (15cm, 30cm, 45cm and 60cm) at the Faculty of Agriculture Teaching and Research Farm, University of Maiduguri. The Ksat value for each sample was determined in the laboratory using the falling head permeameter method. Soil physical properties (bulk density, porosity, gravimetric water content, % sand and % silt) required by the models were also determined. A refined Kozeny-Carman model and model developed from multiple regression analysis were used to predict Ksat which were compared with the results obtained from laboratory  measurement. The developed model predicted values of 0.0065, 0.0010, 0.0965 and 0.0048cm/s at 15cm, 30cm, 45cm and 60cm, respectively, that is closer to the value of Ksat measured in the laboratory (0.0061, 0.0054, 0.0050 and 0.0048cm/s at 15cm, 30cm, 45cm and 60cm, respectively) while Kozeny-Carman model predicted a value of 0.2208, 0.2161, 0.2020 and 0.1974cm/s at 15cm, 30cm, 45cm and 60cm, respectively, that is far above the one measured in the laboratory. Therefore, Ksat estimating models could not fit for all locations very well.Key Words: Saturated hydraulic Conductivity, Empirical models, Laboratory measurement

Influence of tillage practices on physical properties of a sandy loam in semi-arid region

The contrasts observed in soil tillage research studies documented the need for more research in many regions of the world if the mechanics of tillage effects on soil physical properties is to be well understood. Thus, the effect of three tillage systems: no-tillage (NT), reduce tillage (RT) andconventional tillage (CT) on the physical properties of a sandy loam soil in Maiduguri, Nigeria was investigated after 9-15 years of management. During the growing season of 2010, triplicate undisturbed core samples (5.5 cm in diameter and 4 cm height) were obtained at two soil depths (0-15 cm and 15-30 cm), for determination of volumetric (.v) moisture content, bulk density (Bd), and total porosity (TP) of the soil at selected dates, while soil penetration resistance (PR) was determined using hand held digital penetrometer. Tillage systems significantly (p = 0.05) affectedBd and TP of the soil at two of the four sampling dates. The RT treatment recorded highest Bd and lowest TP at (0-15 cm) depth across most sampling dates, while at (15-30 cm) soil depth, the CT and RT treatments maintained higher Bd. Soil PR was significantly influenced by tillage systems only at the surface (0-15 cm) soil depth. The NT treatment  recorded significantly (p = 0.05) higher PR while the RT treatment recorded the least. Further, significant (p = 0.05) tillage treatment effects on the .v content of the soil was observed at both surface (0-15 cm) and sub surface (15-30 cm) soil depths. The NT and RT treatments, on average, recorded higher values of .v relative to the CT treatment. Soil organic carbon (OC) and aggregate stability in water (MAW, ASC, DR and WSI) were found to correlate (p < 0.05) well with .v content of the soil for most sampling dates particularly a surface soil layer. The study revealed that, the NT and RT treatments promotes better physical quality of the soil relative to the CT treatment. It ishowever recommended that, other reduced tillage systems such as animal traction and ridgetillage be tried to assess their efficacy of improving soil physical quality.Key words: Tillage, Tillage systems, Soil Physical properties, Moisture storage, Physical qualit

Carbonation of filler typed self-compacting concrete and its impact on the microstructure by utilization of 100% CO2 accelerating techniques

Via the use of accelerated carbonation techniques with 100% CO2 concentration, an experimental programme was performed to investigate the carbonation and associated microstructural changes of three different self-compacting concrete (SCC) in which some of the cement had been replaced by limestone powder, fly ash and/or silica fume. Accelerated carbonation tests were conducted on these “filler-typed” SCCs after 28 days water curing. Approximately 33% of the total binder (450 kg/m3) was replaced by limestone powder, fly ash or a fly ash–silica fume blend. The results revealed that the replacement of limestone powder (LP) increased the depth of carbonation during the accelerated test relative to the effect of the fly ash (FA) or the combination of the fly ash and the silica fume (FA + SF) replacements. However, the modelling of the normal pressure accelerated carbonation tests with 100% CO2 showed all the SCCs studied have no risk of carbonation induced corrosion in the natural environment. Overall, the research suggests that carbonation of filler typed SCC may not be chemically controlled, rather, the internal pore structure may play an important role. Furthermore, the effect of carbonation on the internal pore structure and the chemistry of the concrete matrices were more noticeable in SCC containing FA + SF than in those with LP and FA replacements

Effect of Organic Materials With and Without Mineral Fertilizer on Grain Yield and Nutrient Contents of Pearl Millet (Pennisetum glaucum) in ohe Sudano-Sahelian Ecological Zone of Nigeria.

The inherently low fertility of most of the soils of savanna regions particularly in North-east Nigeria is a factor limiting the development of sustainable agricultural systems. Consequently, maintenance of soil fertility and management of soil for sustained and continuous crop production are essential components of the overall management of the soil. The primary objective of the study was to investigate the effect of these soil amendment materials on the yield and nutrient contents of Millet grain grown in the study area. Field experiment involving the application of three different types of organic materials; compost, farm yard manure (FYM) and municipal refuse (MR) applied at 7.5 t/ha alone and in combination with half (30:15:15) the recommended rate of NPK and full (60:30:30) recommended rate of NPK fertilizer was conducted. The trial therefore consist of nine treatments, replicated three times and laid out in a randomized complete block design (RCBD), carried out at the Teaching and Research Farms, University of Maiduguri, North-east Nigeria. Application of FYM + ½ (30:15:15) NPK, and compost + ½ NPK increased the yield of millet (3050 and 1609 kg ha-1) respectively over the control treatment (790 kg ha-1), and resulted in improved physical and chemical properties of the soil than the use of organic materials or inorganic fertilizer alone. Although differences in nutrient content of grain were not significantly affected by the treatments, application of FYM alone gave higher N (14.70 g kg-1) and P (12.00 g kg-1) contents over the remainingtreatments, which were found to correlate significantly with N and P uptake by the millet crop at tillering and booting stages. Calcium and Mg were higher (14.00 g kg-1 and 12.14 g kg-1) in treatments with MR when applied with ½ NPK than other treatments. It was evident that the use of organic materials in combination with inorganic fertilizer increased grain yield of millet nutrient content in addition to the reduction of organic wastes. Farmers in the region are advised to prepare good quality compost using farm weeds and leguminous residues before the onset of the rainy season to realize the yield potential of millet on the soils of the study area that are inherently low in fertility status.Key words: Compost, Farm Yard Manure, Municipal refuse, Mineral fertilizer