International Journal of Recycling of Organic Waste in Agriculture
Volume:10 Issue: 3, Summer 2021

PurposeThe management of household wastes has been a real challenge for the capital city of Cameroon for some years now. In order to adopt ecological and sustainable strategies for better management of organic fraction of solid wastes, the present work was aimed to propose a sustainable alternative for the recycling of household organic waste through a vermicomposting process. Method A vermicomposting of household organic waste was carried out during 46 days, preceded by 23 days of pre-composting. Then, three treatments were established by mixing epigeic earthworms with different proportion of pre-composted waste. Maturation parameters such as pH, electrical conductivity (EC), C/N ratio, ammonium (N-NH4+) and total organic matter (TOM) were monitored about four weeks. The agronomic quality of the vermicompost was also determined at the end. Results During pre-composting, the temperature reached a maximum of 54.3±5.4°C suitable for the elimination of potential pathogen. The pH varied between 9.44 and 8.53 leading towards neutrality at the end of the vermicomposting process. The obtained mean values of C/N ratio and the TOM were respectively 11.04-11.68 and 25.82-27.19% in line with the AFNOR (NFU 44-051) guideline. The obtained vermicompost revealed high levels of nutrients such as N, P, K, Ca and Mg. The phytotoxicity test on lettuce showed germination rates above 50%, revealing the non-toxic nature of the vermicompost produced. Conclusion The vermicompost were rich in nutrients and exhibited the non-phytotoxicity. Thus, vermicomposting can be applied in the context of Cameroon to transform organic waste into organic fertiliser suitable for sustainable agriculture.

Purpose Intensive rice cultivation, non-addition of organic matter and indiscriminate use of inorganic fertilizers lead to soil fertility deterioration; on other side, farmers are burning huge quantities of rice residue causing severe air pollution warrants pragmatic disposal solution. In situ composting is considered as a potential alternative to destruction of crop residues. Moreover, fortification of crop residue with beneficial microbes and bio stimulants increase the availability of nutrients which constitutes an integral component in sustainable agriculture.The objective was to evaluate the effect of in situ rice residue compost fortification with PGPM consortia, humic acid and seaweed extract on the soil nutrient availability and uptake by rice. Method The experiment was conducted in a RBD at field condition. Rice was grown under 10 treatments comprising a control (100 % NPK) and nine treatments (in situ rice residue, fortified FYM, fortified in situ rice residue along with 100, 75 and 50 % NPK). Results In situ rice residue fortified with PGPM consortia, humic acid and seaweed extract significantly improved the soil carbon, nutrients' availability (macro and micro) and soil fertility. Combined application of fortified rice residue compost with 75% NPK resulted in significantly higher rice yields (grain 6.03 t ha-1 and straw 8.57 t ha-1) and nutrient uptake. Conclusion In situ rice residue composting provides promising straw disposal method as well as recoups lost share of organic matter and nutrients to soil. Farmers may adapt in situ compost to restore soil health without causing environmental hazard and also sustain crop productivity.

Purpose Management of sewage sludge generated from wastewater treatment plants is a big challenge for its potential reusage in agriculture. Most of the Lebanese local sludge is discarded in the water or in landfills (most wastewater plants are partially functional). The objective of this research was to assess the effect of the application of different sewage sludge rates on the wheat production as an alternative of chemical fertilizer. Method Field trials were conducted, for one-year study, in IAAT village in the Bekaa valley-Lebanon. The considered treatments of 4, 8 and 16 kg.m-2 rates were compared to a control treatment. Physicochemical and microbiological analysis were performed on sludge and soil samples (pre cultivation and post-harvest). The harvested wheat was also analyzed for several parameters as mineral content. Results Results presented significant differences between control and treatments. pH values decreased with biosolids additions; organic matter rose in the amended soils, macronutrients levels increased. Heavy metals outcome increased significantly after amendment, microbiological analysis didn’t show any contamination by Salmonella, E.Coli, Staphylococcus Aureus and Helminth eggs. As for wheat plants' evaluation, fiber and protein contents presented an increase similar to nitrogen and phosphorus. Conclusion These results are a key component that identifies the role of biosolids as pH regulator and soil conditioner which improves the physicochemical properties of soil without any risk of microbiological contamination. These results are promising and they encourage the use of biosolids as agriculture amendment.

Purpose Our study had considered some organic amendments to enhance nutrient level of marketed municipal solid waste (MSW) compost for its potential use as fertilizer for growing crops in alluvial soils. Method We prepared three types of amended compost by mixing 20% mustard oil cake (MOC), and 30% poultry manure (PM) or cowdung (CD) or sugarcane press mud (SPM) with 50% MSW compost. The nitrogen (N), phosphorus (P) and sulphur (S) mineralization study was done in soil treated with three amended and one unamended composts with three replications through an incubation experiment at a temperature of 25 ± 1°C for 82 days under aerobic (field capacity) and anaerobic (submerged) conditions. The mineralization data were fitted to the first-order kinetic model. Results The soil NO3--N content was 2-3 times higher in aerobic condition than in anaerobic condition, while the NH4+-N was higher in anaerobic soils. The kinetic model reveals that poultry manure and sugarcane press mud had higher capability to supply N for use by the crops. The P release was the highest at day 15 with three-time higher availability in anaerobic condition. The S mineralization in soil was higher in field capacity than in submerged condition. ConclusionThe compost mixture comprising MSW, MOC and SPM in a ratio of 5:2:3 demonstrated the highest cumulative N, P and S mineralization in both aerobic and anaerobic conditions. The N and S availability decreased while the P availability increased in submerged soils which result has fertilizer management implications for wet  land rice crop.

Purpose Application of Tithonia diversifolia leaves as organic fertilizer is common in most rural regions in Africa. There is usually time period for curing between preparation and application stage. However, this curing period leads to reduction in fertilizer efficiency. This study aimed at analyzing the change in functional groups, particle morphology, size and elemental composition from preparation and application stages of T. diversifolia leaves as organic fertilizer. Method The fertilizer was synthesized from T. diversifolia leaves. The synthesized fertilizer was stored at room temperature and pressure conditions for a grace period of 5 days; as is norm. Characterization of the samples at the two stages was done by FT-IR (functional groups), SEM (morphology), TEM (particle size) and EDS (elemental composition). Results The results indicated reduction or complete loss of amine groups and carboxylic groups over this period. The fertilizer particles agglomerated over the storage period. Particle size increased from 112 nm to 133 nm diameter. There was a significant variation in the elemental composition between preparation and application time of the fertilizer samples. Conclusion These findings prompt for better storage techniques to be used or reduction in curing and storage period of the fertilizers to minimize loss of plant nutrients.

Purpose Animal production wastes are promising for use in agricultural production as a plant nutrient or soil conditioner. However, if not properly managed, they can contaminate the soil and plants, resulting in public health risks. Considering that the composting technique is recommended to ensure compost hygiene and agronomic viability, the present study aimed to evaluate the microbiological and parasitic load during the composting of residues from conventional and organic animal productions. Method The presence of Salmonella sp. and/or helminth eggs and the quantification of thermotolerant coliforms were determined in horse bedding and organic and conventional poultry litter during the process of composting.  Results The initial load of thermotolerant coliforms was greater than 1017 MPN g-1 in the three raw materials. All of them showed a significant reduction in these bacteria at the end of the composting process, reaching 99.98%, 100.00%, and 99.80% in the horse bedding, organic poultry litter, and conventional poultry litter, respectively. All the fresh residues contained helminth eggs, with the horse bedding exhibiting the highest amount compared to the others. However, they all revealed an absence of helminth eggs at the end of the composting process. Salmonella sp. was absent in both the raw materials and the final compost. Conclusion Composting was effective in eliminating helminth eggs and reducing thermotolerant coliform levels. However, the final composts retained a higher pathogenic microbial load than that required by the current Brazilian legislation for use in agriculture.

The purpose of this research was to evaluate the effectiveness of compositions based on the strains of microorganisms and intended for cow dung processing.

Cow dung in an amount of 6 kg was placed into fermentation containers. To process the waste, we used microbial compositions. Sampling was performed on the 1st, 5th, 12th, 19th and 29th days. During the experiment, an analysis of microbiological, physicochemical and phytotoxic parameters was carried out.

The number of micromycetes in the compostable mixture decreased by half compared to the control sample on the 5th day. When treated with microbial compositions at a dose of 25 ml/kg, no Salmonella bacteria was detected in the compostable mixture on the 29th day. In the variants of the experiment with the introduction of microbial compositions, the temperature increased to 45-51°C in a month after the experiment, the humidity decreased to 69%, and the pH of the compostable mixture was set at a neutral level. It was shown that the amount of total nitrogen increased by 7.1-38% when treated with microbial compositions. After 29 days in almost all experimental samples with the introduction of a liquid bacterial culture, the rate of germination and seedling emergence exceeded the growth rate of the control sample.

The possibility is shown to use the given compositions with bacteria of various functional groups as a basis of biological products for the accelerated processing of organic waste, such as cow dung.

Organic waste is a serious concern across the globe contributed by human activity that can be managed by efficient process like vermicomposting which can reduce the waste that is dumped in landfills into useful product vermicompost. This research was conducted to study the bio-conversion of organic waste (fruit and vegetable waste) using Perionyx excavatus into quality vermicompost.

Three organic waste treatments were used for the vermicomposting process: FW [Fruit waste + Cow Dung], VW [Vegetable waste + Cow Dung], FVW [Fruit waste + Vegetable waste + Cow Dung]. A control group was set up without earthworms for each treatment. The compost was harvested after 38 days, weighed and the rate of production per day was calculated. The harvested compost was then subjected to physico-chemical analysis to determine the nutrient status.

The experimental group had a significant rate of production with higher quantity than the control groups. Vermicompost produced from vegetable waste was 515.45 g (51.55%) which was the highest among all the treatments. The lowest amount of compost was produced by the Fruit + Vegetable waste treatment in the control group (184.16 g). The nutrient status was within the acceptable range for the experimental groups.

Epigeic earthworm Perionyx excavatus is highly efficient in reducing organic waste (fruit and vegetable waste) into vermicompost enriched with nutrients necessary for plant growth.

The objective was to evaluate the agronomic performance of black wattle seedlings (Acacia mearnsii) grown on substrates with increasing proportions of biochar based on anaerobic sewage sludge (ASS-biochar). In addition, the present study proposed appropriate ranges for the main physical-hydraulic and chemical attributes of these substrates.

The evaluated substrates included ten substrates with increasing proportions of ASS-biochar, combined with a “standard” mixture (organic compost, carbonized rice husk and vermiculite), in addition to three commercial substrates (references). The experimental design was randomized blocks, with four replications and eight plants per repetition. The physical-hydraulic and chemical attributes evaluated in all substrate formulations were: wet and dry density, total porosity, aeration space, easily available water, buffering water, available water, remaining water, pH and electrical conductivity (EC). The agronomic performance of the black wattle seedlings was evaluated through plant height, length of the root system, neck diameter, dry mass of aerial parts, dry mass of roots and Dickson's quality index.

Biochar from anaerobic sewage sludge increased the chemical and physical-hydraulic quality of the substrates, particularly within the proportion of 45-50% of the substrate formulations, and thus positively affected the growth parameters of the black wattle plants.

The biochar produced from anaerobic sewage sludge is an efficient raw material to compose substrates for the production of seedlings. Transformation of anaerobic sewage sludge into biochar and its combination with other locally available raw materials can be considered a safe way of reusing this residue in agriculture.

Treated wastewaters are reused in agriculture to deal with the water deficit, especially in arid and semi-arid regions. However, they may contain contaminants such as heavy metals that can adversely affect the soil quality and life health. This work aimed to assess the degree of contamination of the soil and the turf leaves of a golf course irrigated in the long term (10 years) by treated wastewaters.

Analysis of eight heavy metals (Cd, Co, Cr, Cu, Ni, Mn, Fe and Zn) was carried out at two sites. The first was irrigated by sprinkling (site 1), the second by a drip system (site 2).

The results showed a generalized contamination of the soil at the two sites. Fe and Mn recorded the highest levels. Cd and Cr contents were significantly higher in the soil of site 1. However, all the heavy metals recorded values below the limits set by the FAO / WHO standards for soil. Turf leaves also exhibited high values of Fe and Mn contents in the two sites. Mn content was significantly higher in in the turf leaves from site 1. The results showed an accumulation of all the metals in turf leaves in which the Fe and Cd contents exceeded the FAO / WHO standards.

Long-term irrigation results in an accumulation of heavy metals in the soil and in turf leaves. Particular attention should be paid to Cd and Fe for the use of treated wastewater in agriculture. Drip irrigation system would minimize crop contamination.