Millet Stalks Research Articles

CO2 absorption performance of biogas slurry enhanced by biochar as a potential solvent in once-through CO2 chemical absorption process

Carbon capture, utilization, and storage (CCUS), offers a promising avenue for mitigating CO2 emissions, in which the big challenge is the high CO2 capture cost. A novel CCUS technology called once-through CO2 chemical absorption using biogas slurry, could potentially reduce the CO2 capture cost through decreasing the energy consumption greatly during CO2 capture. This technology, however, is constrained by the CO2 absorption capacity of biogas slurry. To enhance the CO2 capture capacity of this innovative technology, we proposed a method to enhance CO2 absorption by integrating biochar into biogas slurry. Results indicated that the CO2 absorption capacity of biogas slurry improved by biochar varied with the type of biochar adopted. Among all the investigated biochar, the wood biochar like sea buckthorn and sand willow exhibited the lowest CO2 capture enhancement, with 0.82±0.19 mmol/g and 0.81±0.30 mmol/g, respectively. Biochar from C4 plants like corn stalks and cobs demonstrated the highest enhancement, with 2.11±0.24 mmol/g and 2.47±0.86 mmol/g, respectively. The enhancement driven by C3 plant biochar like millet stalks and shells was intermediate, with 1.62±0.47 mmol/g and 1.62±0.46 mmol/g, respectively. The primary factor for promoting CO2 absorption in the biochar-based biogas slurry was the increase in pH of biogas slurry. The total pore volume of biochar was the principal material property that enhanced CO2 absorption, followed by the EC and BET surface areas of biochar. Increasing the carbonization temperature of biochar could also enhance the CO2 absorption capacity by biogas slurry. In CO2-rich biochar-based biogas slurry, CO2 primarily existed as HCO3− and carbamate. However, for the influence of the biochar's pore structure, CO2 in the CO2-rich biochar-based biogas slurry was more stable than that in CO2-rich biogas slurry.

Activation kinetics of biochars from peanut shells, cashew nut shells, and millet stalks under isothermal conditions in CO2 atmosphere

This study investigates the reactivity kinetics of biochar from biomass. The biochars were obtained by pyrolyzing peanut shells (PNS_800), cashew nut shells (CNS_800), and millet stalks (MS_800) at 800 °C in a fixed bed reactor. The chemical composition of the biochar samples shows that silicon (Si), potassium (K), and magnesium (Mg) are the major elements in the biochar of peanut shells (PNS_800) while potassium and magnesium are the major elements in the biochar of cashew nut shells (CNS_800) and millet stalks (MS_800). The biochars were activated in a CO2 (200 Nml/min) atmosphere at temperatures 1123 K, 1173 K, and 1223 K under atmospheric pressure. The random pore model (RPM) and a modified random pore model (MRPM) were used to correlate the reactivity profiles versus carbon conversion and to determine the kinetic parameters. It was observed that biochar reactivity increases as the temperature increases, attaining at least three times at 1173 K than those corresponding to 1123 K. Furthermore, the increase in reactivity is more pronounced with the biochar MS_800. It was observed that the RPM model cannot follow the kinetic of the experimental reactivity of all biochar samples. However, a better fitting of the reactivity is obtained when using the MRPM model. The activation energies (Ea) are distributed in the range of 98.11–148.46 kJ/mol while the pre-exponential factors (k0) are in the range of 19.31–249.53 s-1. It was observed that for the MRPM model, the lower activation energy and the lower pre-exponential factor were obtained by the biochar CNS_800. However, Ea et k0 are well evaluated for PNS_800 and MS_800 with a coefficient of determination of 99.76%. The proposed modified random pore model could be used to describe the reactivity of biochar from biomass as well as the reactivity of coal.

BIOCHARS FROM SLOW PYROLYSIS OF PEANUT SHELLS, CASHEW NUT SHELLS, AND MILLET STALKS AS VALUE-ADDED PRODUCTS FOR BRIQUETTE PRODUCTION

Biomass is nowadays used for producing biochar briquettes through slow pyrolysis technologies namely for cooking purposes in developing countries. This article investigated some properties of biochar obtained from tropical biomasses like peanut shells, cashew nut shells, and millet stalks, pyrolyzed at 400 °C and 800 °C. Firstly the mass yield and energy yield of the biochar were determined. The main properties investigated were obtained by conducting proximate and ultimate analysis, determination of calorific value, FTIR (Fourier-transform infrared) analysis, and thermogravimetric analysis. The results showed that depending on the biomass and the pyrolysis temperature, the biochar yields varied from 20.26 % to 42.79 % while the energy yields varied from 24.24 % to 60.71 %. The highest yields are obtained with the lowest temperature and are all more important with peanut shells. All the biochars had fixed carbon contents greater than 60%, except biochar obtained at 400°C with millet stalks. The millet stalks biochar obtained at 400 °C was the one with the highest ash content (21.41%) and the lowest fixed carbon content (59.31%). It was observed that the more the pyrolysis temperature increased, the more the carbon content increased. The lower heating value of raw biomasses and biochars varied respectively between 18.36 and 22.51 MJ/kg and between 23.83 and 30.85 MJ/kg. FTIR analysis results showed that the O-H and C-O bonds disappeared in the case of biochars obtained at 800 °C. The reactivity of biochars towards O2 showed that for all biochars, ignition temperatures (Ti) were up to 317 °C and the temperatures at maximum mass loss rate were between 438 °C and 501 °C.

Adaptation and Performance Evaluation Closed Drum Type Carbonizer for Waste Biomass

A nation’s development is frequently driven by its energy industry. It is alarming that firewood is still frequently utilized as the main source of energy for cooking in many nations, especially those that see a decline in forest cover. For the carbonization of biomass waste, a drum-type carbonizer adaptation was created. The potential for obtaining a biomass carbonization process is the subject of this research. Various agricultural waste products (such as sawdust, coffee husks, peanut shells, and millet stalks) have been heated up in a device called a carbonizer. These two residues’ biomass carbonization yields were calculated and found to be 37.5% and 60.98%, respectively, for sawdust and coffee husk.

Effect of Irrigation on the Content of Cellulose in Proso Millet Stalk (Panicum miliaceum L.) in Aydın/Turkey Conditions

Proso millet stalks are an under-utilized material that remains after the harvest. Given the share of large proso millet stalks in total production in Turkey, more than 8% of stalks could be easily available as a raw material in the fabrication of fuels. Unlike corn, proso millet stalks are not used as green fodder or silage due to the higher cellulose content and smaller green leaves for animal feeding. In this study, the usability of proso millet plant as a biofuel material due to this feature was tested in terms of the chemical parameters such as cellulose, lignin and some other nutritional elements. The impact on the plants grown and harvested materials parameters by applying control (non-irrigated) and four irrigation levels (50%, 75%, 100% and 125%) was investigated. Results of the study show that the highest values were obtained for 125% irrigation level.

Effect of Millet Stalks and Shea Nut Shells on Biogas Production

Biogas production undergoes decomposition of organic compounds under anaerobic condition. This present work investigated the yield of biogas production from Shea nut shell and millet stalk and their blends with sheep dung. It was revealed that sheep dung (control) had the highest yield with an average production of 187.8 ml of gas for 102 days followed by sheanut shell - sheep dung blends which had 123.3 ml of gas for 102 days. Millet stalk - sheep dung blends recorded 75.9 ml of gas for 79 days. Shea nut shell and millet stalk presented 31.5 ml of gas for 81 days and 7.1 ml of gas for 48 days respectively while the pH for production ranged from 10.1 to 4.6. The moisture contents recorded for millet stalk, Shea nut shell and sheep dung before and after production were 40%, 45%, 65% and 80%, 65%, 85 respectively, and also the recorded ash contents before and after production were, 35%, 45%, 40% and 85%, 75%, 65%, respectively. It was observed that the blending of Shea nut shell and sheep dung greatly improves biogas yield while Millet stalks alone are good material for biogas production at a reasonable pH and moisture content values.

Soap Production Using Locally Available Alkaline Extract from Millet Stalks: A Study on Chemical and Physical Properties of Soap

An agricultural by-product namely millet stalks were examined for their potential as an alternative source of potash for soap production. The alkaline extract was used in the preparation of soap using the traditional method. These materials were ashed and the sample was subjected to hot aqueous extraction. Extract from the crushed samples was characterized by its inorganic elements calcium, sodium, potassium, and magnesium. The resulting soap was subjected to physicochemical test; saponification value, iodine value, acid value, ash content, color, texture and the results were; 74mg/KOH/g, 31.72g/100g, 5.64mg/KOH, 1%, white, hard and rough, respectively. This showed that the white color of soap was a result of bleaching of the oil sample and the hardness of the soap was due to the presence of high concentration of K+ ions in the prepared soap. Also, emulsification test was performed and the result was positive. White soluble precipitate was formed with KCl, NaCl, and NH4Cl solution while with CaCl2, MgCl2, and FeCl3 solution white gelatinous precipitate was formed which gave the insoluble complex with water. This research showed that some agricultural by-products such as millet stalks can be utilized for the traditional soap production.

Characterization of Pearl Millet (Pennisetum glaucum) waste

Environmental considerations in recent times have led to increasing interest in naturally occurring lignocellulosic materials as they are abundant and biodegradable. Pearl Millet (PM) stalks are currently discarded in North India and add to agrowaste generation. In this study, raw stalk of PM was characterized for physicochemical properties such as composition, moisture content, water absorbency and thermal behaviour. Morphology and crystallinity were studied using scanning electron microscope and X-ray diffraction respectively. Pure cellulose, extracted from the stalk using an optimised process, was characterised similarly. XRD patterns indicate the presence of cellulose type I structure with crystallinity index of 32% for raw stalk and 55% for the purified material. Water absorbency was 10 g/g for raw and 13 g/g for extracted cellulose. Material was thermally stable up to 200 °C. These findings indicate that PM stalks may be used as an indigenous source of cellulose for the absorbent layer in hygiene products.

English

In this study, carbonized peanut shells, cashew shells and millet stalks were used as raw materials to produce coal briquettes. Clay and arabic gum were applied as binders during briquetting by use of manual press. Physicochemical and mechanical tests of the obtained briquettes were conducted. The results show that the lower heating values of coal briquettes remain higher to that of wood; however, their ash contents are very high compared to wood. Combustion of coal briquettes samples show also that coal briquettes of peanut shells, cashew shells, and millet stalks ignite respectively at 312, 202.5 and 150.5°C. Bulk densities of these briquettes are respectively 543, 765 and 579 kg/m3. Briquette made with arabic gum presents mechanical compressive strength above 1 MPa.   Key words: Coal briquettes, binders, heating value, bulk density, compressive strength.

Analysis of crop residues availability for animal feed in Kebbi State, Nigeria

This study analyzed the use of crop residues in animal feeding in Kebbi state, Nigeria. Data for the study was generated through the use of structured questionnaire and three points Likert rating scale and data obtained was analyzed using descriptive statistics. Results of the study revealed that all (100%) the respondents were male, active and productive in ages (18-47 years) with majority having non - formal education (Qur’anic education) and common mode of land acquisition being through inheritance (70%). Findings of the study further revealed that the common crop residue utilized by the respondents was groundnut haulm (40%) and both cowpea haulm and millet stalks (20%) that were mostly (89%) sourced from their farms, stored and preserved through baling (71%). Majority (90%) of the respondents infer that large proportion of the metabolizable energy is wasted during eating and digestion of low quality crop residues. The study concluded that groundnut haulms and sorghum stalks were the common crop residues utilized for feeding animals, mostly stored and preserved locally with the use of silos and drums. The study recommends that government and the respondents should come up with modern storage and preservation methods of crop residues in order to improve its nutrient value and avoid spoilage.

Sudanese Agro-residue as a Novel Furnish for Pulp and Paper Manufacturing

Sudan has rich sources of lignocellulose materials from agricultural waste that have potential to be used as a papermaking furnish following adequate chemical compositions, elemental analysis, fibre dimensions, and morphology of millet stalks and date palm leaves. Paper sheet properties from the various pulps made were investigated, and it was found that there was no difference in the polysaccharide (cellulose and hemicelluloses) content between millet stalks and date palm leaves, although millet stalks had a high lignin content of 18.20% relative to date palm leaves’ content of 15.34%. Moreover, millet stalks showed a high pulp yield (42.04%) with a viscosity of 665 mL/g compared to that (34.43%, 551 mL/g) and (38.50% and 534 mL/g) of date palm leaves and the blend, respectively. Papers produced from date palm leaves and millet stalk blends showed better physical properties compared to that of pure millet stalks and date palm leaves. The Scanning Electron Microscopy (SEM) analysis showed that fibres in the blend were more closely packed than that of the pure millet stalks and date palm leaves fibers. Based on their physical and chemical composition properties, millet stalks and date palm leaves have a high potential as a furnish for pulp and papermaking.

Sustainable conversion of agriculture wastes into activated carbons: energy balance and arsenic removal from water

ABSTRACTThe aims of this study are to investigate the production of activated carbons (AC) from Senegal agricultural wastes such as cashew shells, millet stalks and rice husks and to implement them in adsorption processes devoted to arsenic (V) removal. AC were produced by a direct physical activation with water steam without other chemicals. This production of AC has also led to co-products (gas and bio-oil) which have been characterized in terms of physical, chemical and thermodynamical properties for energy recovery. Considering the arsenic adsorption results and the energy balance for the three studied biomasses, the first results have shown that the millet stalks seem to be more interesting for arsenate removal from natural water and an energy recovery with a GEEelec of 18.9%. Cashew shells, which have shown the best energy recovery (34.3%), are not suitable for arsenate removal. This global approach is original and contributes to a recycling of biowastes with a joint recovery of energy and material.

Sustainable Conversion of Agriculture and Food Waste into Activated Carbons Devoted to Fluoride Removal from Drinking Water in Senegal

<p>The objective of this study was to investigate the production of activated carbons (AC) from cashew shells, and millet stalks and their efficiency in fluoride retention. These agricultural residues are collected from Senegal. It is known that some regions of Sénégal, commonly called the groundnut basin, are affected by a public health problem caused by an excess of fluoride in drinking water used by these populations. The activated carbons were produced by a combined pyrolysis and activation with water steam; no other chemical compounds were added. Then, activated carbonaceous materials obtained from cashew shells and millet stalks were called CS-H<sub>2</sub>O and MS-H<sub>2</sub>O respectively. CS-H<sub>2</sub>O and MS-H<sub>2</sub>O show very good adsorbent features, and present carbon content ranges between 71 % and 86 %. The BET surface areas are 942 m² g<sup>-1</sup> and 1234 m².g<sup>-1</sup> for CS-H<sub>2</sub>O and MS-H<sub>2</sub>O respectively. A third activated carbon produced from food wastes and coagulation-flocculation sludge (FW/CFS-H<sub>2</sub>O) was produced in the same conditions. Carbon and calcium content of FW/CFS-H<sub>2</sub>O are 32.6 and 39.3 % respectively. The kinetics sorption were performed with all these activated carbons, then the pseudo-first equation was used to describe the kinetics sorption. Fluoride adsorption isotherms were performed with synthetic and natural water with the best activated carbon from kinetics sorption, Langmuir and Freundlich models were used to describe the experimental data. The results showed that carbonaceous materials obtained from CS-H<sub>2</sub>O and MS-H<sub>2</sub>O were weakly efficient for fluoride removal. With FW/CFS-H<sub>2</sub>O, the adsorption capacity is 28.48 mg.g<sup>-1 </sup>with r² = 0.99 with synthetic water.</p>

Contribution to the Design of a Pottery Kiln Using as Fuel a Mixture of Cellulosic and Plastic Materials: Influence of the Proportion of Plastic on the Emissions of NO, CO<sub>2</sub>, O<sub>2</sub>

This paper concerns the study of the influence of the proportion of plastic from polyethylene, on the yields of gas emissions during the combustion of the mixture of “millet stalks and polyethylene plastic bags”, in a prototype of kiln of potters. During these investigations, we looked at the rate of residual oxygen (O2) and emissions of carbon dioxide (CO2) and nitrogen monoxide (NO), as a function of primary air flow (Q1) and secondary airflow (Q2). The potter’s kilns are considered those fueled by natural air flow. The primary air flows ranging from 45 to 85 Nm3?h 1 and secondary air flows from 20 to 60 Nm3?h 1. To conduct this numerical study, the model used is “reactor” based on the code CHEMKIN II. The modeled area is composed into a multitude of perfectly stirred reactors (PSR) and the kinetic model has 893 species and 113 reversible chemical reactions. The results show that in our test conditions, the increasing of the rate of plastic in the mixture produces a decrease of the residual oxygen content, due to higher oxygen consumption regardless of the airflow. The CO2 emissions are an increasing function of the rate of plastic (polyethylene) in the fuel mixture. Finally, NO emissions are increasing functions of the mass of plastic for a proportions less than or equal to 20%, and are essentially controlled by the temperature of the reactional medium.

Thermal Degradation of Polyethylene Bags and Millet Stalks: Influence of the Temperature and the Local Concentration of Oxygen on the Conversion Rate of Carbon

This paper concerns the influence of temperature and local concentration of oxygen on the conversion efficiency of carbon into CO, CO2, CH4, C3H8, C2H4, C2H2, C2H6, C6H6, during the thermal degradation of plastic bags and millet stalks. The experimental device used is the tubular kiln, coupled to an analyzer Fourier Transform Infrared (FTIR) and a Non Dispersive Infrared analyzer (NDIR). Temperatures are considered between 800 and 1000°C. Local concentrations of oxygen during thermal degradation are 0%, 10% and 21%. On the one hand results obtained on the influence of temperature show that for each type of thermal degradation and whatever the temperature of the combustion, the rate of conversion of carbon remains substantially the same. In the case of plastic bags, the rate of carbon converted during pyrolysis is about 90% of carbon converted during reductive combustion. On the other hand, with millet stalks, the carbon converted represents only 60% of the rate of carbon converted during combustion to 10% oxygen. 1 to 2% of carbon not analyzed is in the form of aromatic compounds that are found most often in the soot and/or tar from this combustion system. Moreover, whatever the temperature, the overall efficiency of carbon conversion increases linearly with the local concentration of oxygen. During the thermal degradation of plastic bags, we see that the reducer environment has fostered the conversion of 7% of carbon more while the presence of oxygen in double proportion promotes the conversion of 27% carbon. Regarding the influence of the local content of oxygen, it is clear that for plastic bags, the reactions of oxidation of CO into CO2 tend to be favored for the benefit of those of hydrocarbons into CO. The formation of CO and CO2 by oxidation of light hydrocarbons is primarily from gaseous compounds CH4 and C2H4. At 950°C, we have also acetylene (C2H2) which is involved in the production of carbon oxides. At 1000°C, benzene (C6H6) heavily involved in the formation of CO and CO2. However, with millet stalks, more the local content of oxygen increases, more combustion is better, that is to say that the oxidation reactions producing CO2 are faster than the oxidation reactions of hydrocarbons into CO. The rate of carbon converted into CO and CO2 is higher for millet stalks than for plastic bags, due to this oxygen levels higher in millet stalks than in plastic bags. Similarly, for the millet stalks, from pyrolysis to combustion (at 10 and 21% oxygen), there is practically no hydrocarbon emitted.

Comparing changes in air pollutant concentration before and after cook-stove replacement in rural Ghana

Background and Aims: Using novel, low cost, real-time air quality monitors,we performed a pilot study to analyze the impact of transitioning from open flame cooking to efficient, low emission cookstoves (Envirofit) in a region of Northern Ghana where studies of meningitis epidemics and climate are currently underway. These emissions are important since exposure to air pollution may be a contributing factor towards meningitis transmission and susceptibility. Methods: Monitors were equipped with sensors to measure concentration of total volatile organic compounds (VOCs), ozone, carbon monoxide (CO), and carbon dioxide (CO2). Typical cooking takes place in a enclosed room with an open doorway and burns dried millet stalks between three rocks on which a pot sits. The monitors were placed inside the enclosed cooking areas at 6 sites. Results: Cooking resulted in elevated concentrations of CO, CO2, and total VOCs. These three pollutants were positively correlated during cooking with correlation coefficients ranging from 0.34 to 0.88. The cookstoves emit between 1/5 and 1/18 of the combusted carbon as CO. During cooking events, concentrations of those three pollutants, which are products of combustion, were negatively correlated with ozone concentrations, as expected since emissions of nitrogen oxides from the cookstoves consume ambient ozone. After installing the cookstoves, CO2 concentrations decreased, but VOCs and CO increased slightly. Conclusions: Low cost portable monitors are robust and effective at analyzing variations of concentrations over time. We applied these monitors to evaluate the emissions and air quality in kitchens of rural Ghana before and after new cookstoves were put into use. It is yet unclear whether the long-term use of Envirofit stoves will lead to reduced exposure to various air pollutants within kitchens.

Impact of very low crop residues cover on wind erosion in the Sahel

In the Sahel, with average annual precipitation in the order of 500 mm yr − 1 , wind erosion occurs mainly on cultivated millet fields whose surfaces are only partially covered by crop residues. The impact of these residues on wind erosion was not clearly established. The objective of this study is thus to quantify the actual amount of crop residues in traditional Sahelian fields and to determine their impacts on wind erosion by reference to a bare surface throughout the seasonal cycle over several years. At the beginning of the year during dry season, Sahelian farmers use to “clean” their fields, i.e. cut and lay flat on the soil surface any millet stalks still standing and yearly sprouts of shrubs. After this clearing, the crop residues cover (CRC) regularly decreases passing from 12% to less than 2% four months later. On traditional cultivated plot, crop residues efficiently prevent soil losses by wind erosion during the dry season and considerably reduce erosion fluxes at the beginning of the rainy season. However, for CRC lower than 2%, wind velocities were sufficient to produce important erosion even during dry season. A minimal cover rate of about 2% (100 kg ha − 1 ) thus appears as critical to reduce wind erosion. This reduction is driven by the higher aerodynamic roughness length which increases the wind erosion threshold velocity. If field clearing is made in January, as currently done, the CRC just after clearing should be about 800 kg ha − 1 to maintain CRC above 2% at beginning of the rainy season when wind velocities are the highest and wind erosion the most intense. Our results also demonstrate that during the second part of rainy season wind erosion is reduced, not so much due to vegetation development but rather to a decrease in the number and the intensity of high winds events. ► Below a threshold of 2% of crop residues cover, Z0 decreases dramatically fields. ► Crop residues cover of 2% corresponds to a residues density of 100 kg ha − 1 . ► Above this threshold, potential wind erosion is reduced by at least a factor of 3. ► Meteorological changes explain the end of erosion by mid July in the Sahel.

Experimental characterization of gaseous species emitted by the fast pyrolysis of biomass and polyethylene

This study aims to experimentally characterize the carbonaceous and nitrogenous species, from the flash pyrolysis of millet stalks and polyethylene plastic bags, using the device of the tubular kiln, coupled to two gas analyzers: Analyzer Fourier Transform Infrared (FTIR) and an analyzer Infrared Non-Dispersive (IRND). Gaseous products analyzed are: CH 4, C 2H 2, C 2H 4, C 3H 8, C 6H 6, CO, CO 2, NO 2, NO, N 2O, HCN and NH 3. Whatever the temperature of thermal degradation, the pyrolysis shows us that in terms of mass: • For the millet stalks, the gaseous compounds are formed mainly CO and CO 2 to the carbonaceous species, HCN and NH 3, for the nitrogenous species analyzed; • As regards the polyethylene bags, hydrocarbons for carbonaceous species and HCN, NH 3 and NO 2 for the nitrogenous species, are most abundant. In addition, the results suppose that in our experimental conditions, the hydrocarbon which is involved primarily in the formation of CO is ethylene C 2H 4. At the end of this characterization, we determined the rate of carbon and nitrogen found in the volatile gas. With millet stalks we have about 45% of volatile carbon and 15% of the nitrogen of fuel that are found in gaseous products. The results obtained with the plastic bags give 68% carbon and 15% nitrogen found in the nitrogenous species analyzed.

Decomposition of organic amendment and nutrient release under the zai technique in the Sahel

In the West African Sahel, farmers use the zai technique to reclaim degraded cropland. Although the nutrients released by the decomposition of the amendments are central to the success of the technique, little is known regarding the impact of the zai pits on the decomposition process and whether the nutrient release is synchronized with plant requirements. The decomposition of millet stalks and cattle manure applied in zai pits or at the soil surface was studied in Niger using litterbags, under controlled irrigation on-station in 1999 and on-farm in 1999 and 2000 at two locations (Damari and Kakassi) with contrasting soils. In addition, a satellite trial was conducted in 2000 on-farm at the same locations to study the relative contribution of termites to manure decomposition. Only at Damari did termite presence enhance manure decomposition, by a factor three for surface placement compared to the zai pits. At Damari, zai pits enhanced the decomposition when termite activity was suppressed. Whereas manure decomposition proceeded two to three times faster than that of millet stalks at Damari, the type of amendment had no effect on decomposition rate at Kakassi. Nutrient release followed the trend of organic amendment decomposition except for K. When applied prior to the rainy season, nutrient release rate of organic amendments strongly exceeded plant nutrient uptake, which could lead to important leaching losses during the first 4–6 weeks after sowing, especially for N and to a lesser extent for K. However, at harvest, total nutrient absorption by plants was generally higher than the total amount released. The results indicate a highly site-specific response of amendment decomposition to zai and the need for a better timing of amendment application to reduce potential leaching losses, possibly through a split application.

Niger: A famine foretold

The seasonal rains returned to southern Niger in June, coaxing the green millet stalks from the dry earth and signalling an end, hopefully, to a food shortage that has left some 2.4 million Nigeriens — including 800,000 children — vulnerable to malnutrition. International relief workers have also started to arrive to distribute the emergency rations needed until the harvest is in.