Effects of Poultry Biochar on Electrochemical Properties of an Alfisol and Vertisol of Northern Nigeria

This study was aimed to know the effects of biochar on charge properties of an Alfisol and Vertisol of semi-arid soils of Northern Nigeria. A laboratory experiment was conducted to determine the effects of biochar on point zero charge of soils. Experiment was laid out in a complete randomized design and consisted of two factors; 2 soil types and biochar at 4 levels giving a total of 8 treatment combinations with 3 replications each.The results obtained from the study showed that the pH in KCl of the incubated soils ranged from 7.3 to 7.4 and 7.6 to 7.9 for the Alfisol and Vertisol; 7.5 to 7.7 and 7.9 to 8.3 pH in H2O, was obtained for the Alfisol and Vertisol respectively. Electrical conductivity obtained ranged from 3.22 to 4.72 and 2.88 to 4.21 dS m-1 for Alfisol and Vertisol respectively. Electrical potentials ranged from -19.70 to -35 and -31.45 to -63.04 for the Alfisol and Vertisol respectively. The Point Zero Charge of soils correlated positively with the properties of the soils and the biochar rates.The addition of biochar to soils modified the PZC, increased the pH, electrical conductivity (ECe) and cation exchange capacity (CEC) of the soils.

Morphological characterization and biocontrol potential of Trichoderma species isolated from semi-arid soils

Se aislaron, identificaron y caracterizaron especies de <em>Trichoderma</em> spp. asociadas a plantas de <em>Pachycereus pringlei</em> y<em> Jatropha cinerea</em> como agentes de biocontrol hacia hongos fitopatógenos. Los agentes antagónicos se aislaron de seis sitios en Baja California Sur, México. La identificación se realizó en base a sus características morfológicas y se determinó; abundancia, frecuencia de ocurrencia y antagonismo<em> in vitro</em> hacia <em>F. oxysporum</em>, <em>F. solani</em>, <em>R. solani</em>, <em>C. gloeosporioides</em> y <em>A. alternata</em>. Se obtuvieron 18 aislamientos de <em>Trichoderma</em> concentrados en siete especies: <em>T. asperellum</em>,<em> T. atroviride</em>, <em>T. harzianum</em>,<em> T. koningii</em>, <em>T. viride</em>,<em> T. longibrachiatum</em> y <em>Trichoderma</em> sp. La prueba de Duncan (p&lt;0.05) mostró diferencias significativas en la abundancia de las especies (UFC/g de suelo) y la frecuencia de ocurrencia. La mayor población se encontró en El Saltito, Los Encinos y Las Pocitas con UFC de 2.1, 1.8 y 0.7 × 103 g-1 de suelo respectivamente. En el antagonismo <em>in vitro</em>,<em> T. koningii</em> inhibió significativamente el crecimiento de los hongos fitopatógenos comparado con el control comercial. La actividad antifúngica de las diversas especies de <em>Trichoderma</em> spp. pueden ser una alternativa para el biocontrol de enfermedades ocasionadas por hongos fitopatógenos de las especies analizadas.

A Contribution to Soil Fertility Assessment for Arid and Semi-Arid Lands

Soil fertility must be viewed as a dynamic concept that involves the constant cycling of nutrients between organic and inorganic forms. In this context, it refers also to supply adequate amounts of water and aeration for plant growth. Soil fertility under arid and semi-arid lands is constrained not only by limited water availability but also by small organic matter contents. Most fertility assessment systems are based on organic matter contents as the main parameter. However, crop experiments from various irrigated arid and semi-arid soils indicate that productivity is less- affected by organic matter contents than assumed. Therefore, we propose a new soil fertility system for dryland soils. It is a rule-based set of algorithms, mainly using additions and subtractions. Soil, climate, and landscape factors are integrated to calculate the numerical value of fertility for a given soil. We expect the system, which is focused on soil properties that keep or increase optimum soil moisture (such as texture), to be applicable in arid and semi-arid lands and to provide more realistic estimates of fertility regarding agricultural purposes. The manuscript will provide an outline of the main aspects of the system, illustrated by various case applications.

Geotechnical aspects of Alluvial soils at different depths under sodium chloride action, Najran region, Saudi Arabia: Field supported by laboratory tests

The present work is to investigated the effect of sodium chloride (NaCl) on the behavior of semi-arid soils in the Najran region of Saudi Arabia. An experiment work was carried out to investigate how the addition of (NaCl) "salt" to semi-arid soils collected from Najran region affects the Atterberg limits, compaction characteristics, California Bearing Ratio (CBR) and shear strength. All tests were performed on soils samples collected from different areas in Najran region at various depths of 1.5, 3, and 4.5 m along soil profiles. Soils samples were tested alone and then compared with the same soils samples mixed with sodium chloride (salt) at different percentages of 5, 10, and 20% respectively. Using advanced techniques, such as the scanning electron microscope (SEM), energy dispersive x-ray analysis (EDX) and X-ray diffraction analysis (XRD), the process of stabilization was examined. The results showed that salt has a major impact on the geotechnical characteristics of semi-arid soils. With the addition of sodium chloride, the maximum dry density increased and the optimal water content decreased with the increase in the added salt percentage. The liquid and plastic limits and, in turn, plasticity index reduced as the added percentage of sodium chloride increased. Furthermore, significant increase in CBR and shear strength parameters was noticed. It is therefore concluded that, the sodium chloride could be a good stabilizing agent, particularly at 20% and could be used as a sub-base material in road construction. Technical and economic advantages arise from the implementation of NaCl.

BIOLOGICAL NITROGEN FIXATION STABILITY OF COWPEA CULTIVARS WITH TROPICAL SEMI-ARID RHIZOBIAL STRAINS

ABSTRACT Cowpeas (Vigna unguiculata L. Walp) are an economically and socially important legume in northern and north-eastern Brazil and can establish effective symbiosis with nitrogen-fixing bacteria. We evaluated the symbiotic compatibility and efficiency of rhizobial strains from Pernambuco semi-arid soils and determined their symbiotic stability on the IPA-206, BR 17-Gurguéia, and BRS Novaera cultivars, selected for different environments. The experiment was conducted in a greenhouse to evaluate a 3 × 28 factorial arrangement (cultivars selected for different environments × inoculation with the currently recommended strain, uninoculated plants with or without mineral nitrogen, and 25 rhizobial strains from semi-arid soils) in a randomized block design with four replicates. We determined nodule number, shoot and root dry matter, nodule dry matter by nodule number, nitrogen accumulated in the shoot by nodule dry matter, nitrogen content and accumulation in the shoot, relative efficiency of the recommended strain based on nitrogen accumulation, and shoot dry matter. Overall, the cultivars responded differently to different strains and cultivar biological nitrogen fixation potential. Strains G7.85 and BR 3262 showed potential for biological nitrogen fixation. BR 3262 was confirmed to be adequate for inoculation of different cowpea cultivars.