Promoting Jatropha Agriculture for Sustainable Soil Capital Improvement: A Win-Win Technology for Rehabilitating Degraded Lands in Africa

A significant decline in soil quality has occurred across Sub-Saharan Africa (SSA) through adverse changes in soil properties causing serious challenge to regional food security. This paper presents the new Jatropha technology for soil quality improvement and its importance for meeting rural energy demand in SSA. The paper starts from the premise of Jatropha agriculture and its impact on soil quality improvement with reference to examples from the drylands of Nigeria and Mali. Having reviewed the sweeping claims on Jatropha’s role and ability as alternative energy source, its ‘alleged’ cheap domestication and rush for mega plantations of Jatropha, the paper weighs the controversies surrounding the sustainable production, land grabbing and consequent economics of Jatropha productivity in mega plantation settings. It suggests the need to focus Jatropha agriculture and research in SSA toward rehabilitation of degraded lands, wastelands and badlands while, promoting Jatropha hedge-row fencing for small-holder farming. In addition to technical availability in terms of soil improvement and seed yield, it is suggested that indiscriminate tree-felling for fuel wood in SSA can be checked through a shift from current petrochemical technologies to biodiesel alternatives. The main conclusion is that first, SSA must consider as germane, a natural resource improvement approach based on a new green and bioenergy revolution, and secondly that a regional, pro-active and strategic direction is required to promote Jatropha research for innovation to deliver solutions to addressing the hydra-head environmental challenge of declining soil quality and fuel wood scavenging in the region

Valorization of Pennisetum purpureum (Elephant grass) and piggery manure for energy generation

This study investigated the biogas production potential of Pennisetum purpureum (Elephant grass) (El-g) codigested with piggery manure (PM) under mesophilic condition in order to combat the menace of weed in cropping systems as well as pollution problems emanating from disposal of PM. Prior to anaerobic digestion (AD), El-g was subjected to a combination of mechanical, thermal and alkaline pretreatments. Using cattle rumen content as inoculum, the pretreated El-g was anaerobically co-digested with PM while the raw El-g was also codigested with PM and served as control experiment. The physicochemical characteristics of feedstock were evaluated before and after the digestion period using standard methods. The initial high concentrations of chemical oxygen demand (COD) reduced significantly after digestion indicating efficiency of the digestion process. Also, there were reductions in concentrations of calcium and other parameter needed for microbial growth after the digestion which indicated their utilization by microbes to generate biogas. Biogas production began on the 5th and 7th days and was progressive until 30th and 24th days in both digestions after which a decline was observed until the end of the experiment. For the digestion period of 37 days, the total biogas recorded from the pretreated and untreated experiments were 409.5 and 184.1 m3 CH4/kg VS with average of 11.07 and 4.98 m3 CH4/kg VS/day respectively. The study concluded that co-digestion with piggery dung enhanced the biogas producing capacity of El-g hence advocated

Efficient land water management practice and cropping system for increasing water and crop productivity in semi‐arid tropics

In Indian semi-arid tropics (SATs), low water and crop productivity in Vertisols and associated soils are mainly due to poor land management and erratic and low rainfall occurrence. This study was conducted from 2014 to 2016 at the ICRISAT in India to test the effect of broad bed furrows (BBF) as land water management against conventional flatbed planting for improving soil water content (SWC) and water and crop productivity of three cropping systems: sorghum [Sorghum bicolor (L.) Moench]–chickpea (Cicer arientinum L.) and maize (Zea mays)–groundnut (Arachis hypogaea L.) as sequential and pearl millet [Pennisetum glaucum (L.)] + pigeonpea [Cajanus cajan (L.) Millsp.] as intercropping, grown under different nutrients management involving macronutrients (N, P, and K) only and combined application of macro- and micronutrients. The results stated that the SWC in BBF was higher over flatbed by 9.35–10.44% in 0- to 0.3-m, 4.56–9.30% in 0.3- to 0.6-m and 3.85–5.26% in 0.6- to 1.05-m soil depths during the cropping season. Moreover, depletion of the soil water through plant uptake was higher in BBF than in flatbed. Among the cropping systems, sorghum–chickpea was the best in bringing highest system equivalent yield and water productivity with the combined application of macro- and micronutrients. The BBF minimized water stress at critical crop growth stages leading to increase crop yield and water productivity in SATs. Thus, BBF along with the application of macro- and micronutrients could be an adaptation strategy to mitigate erratic rainfall due to climate change in SATs

EFFECT OF ORGANIC AND INORGANIC SOIL AMENDMENTS ON SOIL PHYSICAL AND CHEMICAL PROPERTIES IN A WEST AFRICA SAVANNA AGROECOSYSTEM

Long-term agroecosystem productivity has stirred up the need to develop and implement nutrient management strategies that maintain and protect soil resources. In an attempt to address this, the current study involved the incorporation of residues of Centrosema pascuorum, Lablab purpureus and Parkia biglobosa. In addition, an inorganic fertilizer amended soil and, a maize/Lablab purpureus intercrop, along with the control (no amendment) was included. The treatments were replicated three times and the site had been under continuous cultivation for eight years in a savanna Alfisol. Soil quality (physical and chemical) indicators were examined for treatments effects. Dry macroaggregate turnover increased by 7% under C. pascuorum amended soils. This same treatment had more water-stable large microaggregates and a 40% increase in aggregated silt and clay content. Soil bulk density and saturated hydraulic conductivity reduced in nutrient management practices involving residue incorporation. However, soil organic carbon, total soil nitrogen, exchangeable Ca2+ and Mg2+ concentration were highest with soil receiving C. pascuorum. Crop residue management practices involving incorporation of C. pascuorum significantly improved soil physical and chemical properties of the study area