Changes in Arenosol Bio-Physicochemical Properties, Chickpea Nodulation, and Finger millet Grain Nutrition as Influenced by different Faidherbia albida tree stand ages

Abstract

Declining land productivity due to severe land degradation is a persistent issue in many farming systems in Tigray, Ethiopia. Soil nutrient depletion and physical property deterioration on smallholder farms are fundamental biophysical causes contributing to reduce per capita food production in Ethiopia. Consequently, farmers are trapped in a vicious cycle of ecological degradation and poverty. Addressing this challenge through nature-based solutions is imperative, with the harnessing of agroforestry plant species, such as Faidherbia albida hereafter F. albida, being among several ecological options. F. albida is a nitrogen-fixing tree species found in parkland and agro-ecosystems, renowned for its unique reversed leaf phenology (shedding foliage during the rainy season). This characteristic makes F. albida an ideal agroforestry species, distinct from other tree species that also enhance soil fertility. Several studies have highlighted F. albida's potential to improve soil fertility and productivity on marginal soils, although comprehensive studies are necessary for a thorough understanding. This study initiated to comprehensively understand the effects of varying stand ages of F. albida on selected soil bio-physicochemical properties, cereal crop growth and nutritional content, rhizobia population density, nodulation and growth of grain legumes in Arenosols. The research was conducted in Abraha-Atsbeha, a semi-arid village in Tigray, Ethiopia, where different stand ages of F. albida are prevalent but detailed knowledge on their impacts on soil attributes is lacking. Field and laboratory data were carefully collected and analyzed using advanced analytical techniques and statistical methods. Soil physicochemical properties were analysed using advanced instrumentation and analytical methods. Ultravialet visible spectroscopy (UV-VIS) spectroscopy for soil and plant nitrogen forms, available phosphorus, and soil organic carbonviii whereas Atomic Absorption Spectrophotometry (AAS) and flame photometer were used for determination of mineral concentrations in soil and plant samples (AAS for Ca, Mg, Fe, and Zn and flame photometer for K and Na). Biological parameters such as total microbial biomass, fungi-to bacteria ratios, nematode trophic composition and abundance, and rhizobia population density were also quantified using established methodologies. Normality, analysis of variance (ANOVA), and post Hock tests and comparisons were done using SPSS V 20 statistical software while canonical correspondence analysis (CANOCO) software was used to analysis and understand the relationships among all the soil physicochemical and biological variables.