International Journal of Recycling of Organic Waste in Agriculture
Volume:11 Issue: 4, Autumn 2022

The decreasing number of peatlands has driven the search for new cultivation substrates. The aim of this study was to evaluate the use of different composts as growing media in the production of vegetable seedlings (pepper and tomato).

Composts were produced from: discarded carrots (ZC), fats (FC), and biosolids (BC) from the dairy industry. They were used as peat substitutes in different doses depending on the germinating species: control (CS-commercial substrate) and three growing media prepared with perlite: 25, 35, and 45% of ZC, FC, and BC for pepper seedlings and 40, 55 and 70% of ZC, FC, and BC for tomato seedlings. When the plants were ready for transplantation they were harvested and the data were collected to assess the development of the seedlings in the different growth media.

The obtained results suggest the possibility of total substitution of the CS by ZC, FC, and BC to produce pepper and tomato plants in commercial nurseries. The plants cultivated with composts presented higher concentrations of total dry matter compared to the controls. Photosynthetic pigments were affected by the presence of FC and BC, whereas TSP concentration was favored by BC.

Ours results suggest that it is feasible to perform a total substitution of commercial substrates with composts of different origins and compositions for the production of pepper and tomato plants in commercial nurseries.

Nematode diseases are major constraints in tomato production. Screenhouse and field experiments were conducted to assess the efficacy of Effective Microorganisms-Fermented Plant Extract (EM-FPE) and compost manure singly and in combination on Meloidogyne incognita infecting tomatoes.

Screenhouse and field experiments were designed respectively as 2×5 and 2×4 factorial fitted into a completely randomized design (CRD) in the screenhouse and randomized complete block design (RCBD) on the field. For single treatments, 100 ml of EM-FPE or 200 g of compost was used per plant while 50 ml of EM-FPE and 100 g of compost were combined and used per plant for treatment combination. Pots that did not receive any treatment served as control. Data were collected on growth parameters, fruit production, galling, and soil nematode population. The data collected was subjected to analysis of variance (ANOVA) where significant differences in means were separated using Fisher’s Least Significance Difference (LSD) Test at P = 0.05.

In both trials, treated plants performed significantly better. No significant difference was recorded among the three treatments for soil nematode population and root galling on the field. But in the screenhouse trial, plants treated with the combination of EM-FPE and compost recorded higher soil nematode population (150) and root galling (7) at harvest but the plants performed well. Among the treatments, compost manure applied singly gave the best result with respect to vegetative growth, flower formation, and yield of the tomatoes.

This study reveals that both treatments, EM-FPE, and compost manure could be relied on for effective control of Meloidogyne incognita in tomatoes.

Fertigation plays an important role in the so-called circular economy since it relies on the reuse of water and nutrients; therefore, this method is fundamental for production in areas with scarce resources. This study aimed to evaluate the effects of fertigation of soil plots with sewage on soil attributes, germination of seeds, and growth of bean and corn.

Due to the low concentrations of macronutrients in the sewage, the applied dose was calculated based on the water deficit. Three plots cultivated with maize and three plots cultivated with beans were fertigated, while the same number of plots received irrigation and mineral fertilization in amounts equivalent to the dose of nitrogen administered in the sewage for comparison.

There was an increase in the cation exchange capacity (74.6%), nitrogen (10.4%), available phosphorus (190.5%), and organic matter (44.9%) contents in the fertigated soil compared to those in the soil of the plots that received chemical fertilization, resulting in greater germination and corn and bean growth. Analyses indicated that the coliform count in beans is below the detection limit of the technique used.

Based on the results obtained, there are indications that fertigation can provide improvements in soil attributes at values higher than those provided by chemical fertilization, reducing the need to apply these macronutrients and irrigation water to the soil. Furthermore, fertigation can be sanitary and safe, since the count of microorganisms in the beans was not higher than that recommended by the World Health Organization (WHO).

Chicken eggshell (ES) is a global biowaste product of poultry industry and an enriched source of calcium required for plant growth. Therefore, the present study has been carried out to assess the potentiality of the combination of ES with vermicompost (VC) and chicken feather protein hydrolysate (CFPH) on growth and yield improvement of Capsicum plants.

A field study was conducted through randomized block design (RBD) with eight treatments having three replicates for each. Principle Component Analysis (PCA) have performed to analyze the yield related parameters of plant. Nutritional components of VC and ES were also analyzed.

The PCA analysis of the  field experiment data has indicated that the combination of ES, CFPH and VC (in a ratio of 100:10:3) remarkably increased the agronomic parameters of capsicum plant about four folds as compared to its chemical counterpart and control, while together VC and ES strongly influences the characteristics of fruits. The first two dimensions of first and second PCA analysis showed 88.39 and 66.91 percent of the overall dataset inertia respectively, explaining 88.39 and 66.91 percent of the total variability. These two values are higher than their respective reference values of 36.32 and 46.76 percent indicating substantial variability.

The co-application of ES, CFPH with VC could enhance the yield parameters of crops by enriching the soil with both micro and macronutrients. It also serves as a source of organic compost with concomitant reduction in the use of chemical fertilizers.

Chicken eggshell as a byproduct of the egg product industry makes serious problems to the environment. The aim of this study was to evaluate the effect of eggshell as a potential option in supplementing of the organic matter and improvement of soil conditions in the pot culture and the area. 

Two pot experiments were carried out to estimate the effects of CD and CDES vermicomposts provided from cow dung and cow dung + eggshell’s powder, respectively, on symbiotic relationships of Serendipita indica with wheat and soil enzyme activities tested under sterilized and non-sterilized soil conditions, respectively. Two in vitro experiments were also conducted to test the effects of eggshell extract and humic and fulvic acids extracted from CD vermicompost on S. indica growth.

CDES vermicompost improved soil enzyme activities of urease, phosphatase and invertase. Root colonization of wheat with multiple species of mycorrhiza and facultative symbiont S. indica was improved by CDES. S. indica growth was induced by eggshell extract. Humic and fulvic acids increased in S. indica mycelia mats dry yield. Results revealed when cow dung was amended with eggshell powder provided a better condition for earthworm growth and enhancing the colonization percentage of wheat root with indigenous mycorrhizal fungi. CDES vermicompost caused the increase in soil basal respiration and soil enzymatic activities.

Eggshell powder growth promoting effect can be attributed to the biologically active compound that exists in eggshell extract.

This study aimed to produce a value-added product by co-composting sawdust with food waste using a small-scale composter.

The composting experiment was carried out using 60L composting bins with a hole of 3 mm and 10 cm apart drilled on its side. Three experimental trials 1, 2 and 3 were adopted in this study with mixture of sawdust and food waste (Trial 1= 80% sawdust + 20% food waste, Trial 2 = 70% sawdust + 30% food waste, Trial 3 = 60% sawdust + 40% food waste). The composting process lasted for 90 days. Parameters examined throughout the composting process include temperature, moisture content, pH, electrical conductivity, organic matter content, and organic matter losses.

The results indicated that all the compost trials exhibit good development of composting process, with the highest solid organic degradation reached in a shorter period in compost trial 3. The temperature profile of the three trials are the same and above 60 0C after 30 days of composting. The compost samples had a pH ranging from 5.9 to 9.4. The electrical conductivity of the three composting trials was following the recommended value. The best compost trial that produces quality compost is compost trial 3.

The results showed that all composts obtained were stable and matured. In brief, recycling sawdust through the composting process to obtain valuable end products is adequate but in the presence of nitrogen-rich waste, such as waste food materials.

Due to the urgent need for sustainable agro-industrial waste management, a field experiment was conducted to evaluate the application of biosolids as organic fertilizer in a corn cultivation crop. In addition, to achieve food security, the study aimed to assess metals concentrations in soil and maize plants and enrichment factors (EF) for soils and plants.

Four sites with a biosolids application were studied and  compared against a control. Physicochemical properties of soils and heavy metal contents were evaluated after one year of application of biosolids. Metal concentrations, average kernel yield and biomass were measured in corn plants.

The results demonstrated that the biosolids increased the content of organic matter, nitrogen, phosphorus, and exchangeable bases in the soil. In addition, the concentration of heavy metals in soils with biosolids was higher than in soils without treatment, and the concentration of heavy metals in the corn kernels did not exceed the maximum recommended limits. However, EF values showed a considerable contamination grade due to the accumulation of metals.

Some of the physical and chemical characteristics of soil were improved by incorporating biosolids, but the metal content in the soil increased. Also, the application of biosolids increased the plant height  and corn yield. Therefore, biosolids can be used as organic fertilizer sources; however, it is necessary to carry out periodic evaluations to ensure low levels of enrichment in crops and soil, thus guaranteeing the safety of biosolids as soil fertilizers.

The study assessed the quality of compost produced by the Black Soldier Fly Larvae (BSFL) in terms of the compost nutrient level, microbial activities, and the bioaccumulation of possible heavy metals in the organic solid waste.

The study used the pre-experimental study design, one-group pretest-posttest to obtain the data. Five experimental units were used for the study, which include the daily feeding rate for the five different groups of larvae. The experiments were replicated three times. The nutrient level, heavy metal content and presence of microbes were analyzed before and after the decomposition process.

The study discovered that the Nitrogen, Phosphorus and Potassium (NPK)content   increased in the compost produced. Cross-contamination of Total Coliform from feed to the prepupae were significant while regrowth of Total Coliform in compost were insignificant. After the composting process most heavy metals like Fe had insignificantly increased in the compost .

It can be concluded that larval composting enhance the regrowth of pathogens since the process is entirely mesophilic. Bioaccumulation of most heavy metals was minimum, increasing the level of these heavy metals in the compost. The nutrients were extremely high in the compost to the extent that can cause phyto-toxicity. Post-treatment of the compost is needed to make BSFL compost viable for the market.

This field study evaluated the interactive effects of biochar (BC) and sewage sludge (SS) on P bioavailability and spinach yields for two seasons.

Treatments were combinations of biochar (0, 2.5 and 5 Mg ha-1) and sewage sludge (0, 6 and 12 Mg ha-1), or mineral fertilizer (200, 28, and 18.9 kg ha-1), amended in a randomized complete block design to Luvisol and Cambisol.

Significant (p < 0.05) yield increase of 53 and 65%, respectively occurred with increasing sole biochar doses on the Luvisol. Both applied alone and in combination with BC, the high rate of SS increased (p < 0.05) yields on the Luvisol over two seasons. Complimentary effects of 6SS+5BC on the Luvisol showed the highest yield increase for the study period. Co-application of amendments on the Cambisol decreased (p > 0.05) yields compared to sole amendments. Mehlich – 3 extractable P (M3-P) in control plots (CONT) increased between seasons, presumably due to P inputs from the irrigation water. Co-amendments on the Cambisol resulted in higher M3-P increase over mineral fertilizer than on the Luvisol in both seasons. Accumulation of M3-P in control plots confounded correlations between crop yields and available P. Higher P under BC compared to SS amended soils emphasize biochar capacity to capture P from irrigation water.

The results suggest that combined low rates of SS and BC can have significant effects on P availability and crop yields. Biochar enhanced plant P uptake, but decrease in yields with simultaneous increase in M3-P between seasons warrants further research.

The aim of this work was to study the effect of adding sugar beet molasses on the biochemical properties, microbial flora, fermentation quality, and aerobic stability of prickly pear cactus (Opuntia ficus-indica) waste silage.

Molasses (0%, 2%, 4%, 6%, 8% and 10%, w/w) was mixed with the cactus fruit scraps, straw and wheat bran.

The dry matter content, pH, total and reducing sugars of the pre-ensiling material increased after adding different percentages of the beet molasses (P < 0.05). During fermentation, we observed substantial protein and sugar degradation. All silage treatments reached stable pH values (pH 4.3-4.6). Among all the concentrations, the 10% beet molasses treatment underwent the highest lactic acid fermentation. Accordingly, the pH drop was higher in the 10% concentration (1.13 units) compared to lower beet molasses concertation  (1.03 units). Also, the 10% concentration has the highest number of lactic acid bacteria. The number of yeast and total aerobic mesophiles decreased continuously during silage. Moreover, during post-fermentation testing, the yeast multiplied little for the 10% concentration of beet molasses.

The results show that the addition of molasses has a significant effect on silage characteristics of prickly pear cactus.