International Journal of Recycling of Organic Waste in Agriculture
Volume:7 Issue: 2, Spring 2018

Silicate rock powders have been appointed as possible nutrient alternative sources which might enhance the agricultural sector sustainability. However, the application of those materials directly in soil presents as main limitations the low content and solubility of the mineral nutrient sources. In this perspective, the aim of the present study was to evaluate, in a bioweathering perspective, the conjunct application potential of phonolite with organic composts over the nutrients release in soil, as well as the production and nutrition of brachiaria grass (Urochloa decumbens). In addition, it was sought to assess the composting process effectiveness in improving the nutrient release from this rock.

An experiment was conducted with five treatments (control; enriched compost with powder rock at 10%; mixed compost with powder rock at 10%; solely powder rock; solely compost) and four repetitions.

The alternative sources positively influenced the productivity, as well as the K and Si contents at the aerial part of the brachiaria grass and the nutrient release in soil. However, the conjunct applications of powder phonolite with organic composts were the source which the best promoted the total nutrient biorelease to soil.

Nevertheless, there was no evidence that the composting process promotes the phonolite bioweathering. On the other hand, the conjunct application of powder phonolite with organic composts, either as an initial component to the composting pile or additive to the stabilized composts, is a strategy which enhances the nutrient biorelease of the mineral source.

A study was conducted to characterize the ‘Madhyam culture’ (Excel Crop Care Limited.), an aerobic-composting microbial consortium culture, and understand composting dynamics, product quality and use in crop production vis-à-vis vermi-composting (using earthworms).

16S rDNA analysis was used to characterize aerobic-composting culture. Aerobic-composting and vermi-composting technologies were evaluated to decompose sorghum straw and dung biomass (80:20 ratio; primed with 0.5% urea and 4% rock phosphate) to study days to maturity and composting dynamics in terms of changes in temperature and microbial population. Compost quality was tested for macro-, micro-nutrients and C:N ratio, and evaluated for food production in on-farm trials.

16S rDNA analysis screened sixteen bacterial isolates—eight related to genus Bacillus, three to each Halobacillus and Staphylococcus, one to each Microbacterium and Streptomyces. The population of bacteria was 4.5 cfu ml−1 at 10−7 dilution. Aerobic- and vermi-composts matured in around 50 and 60 days, respectively. Aerobic-composting throughout recorded relatively higher bacterial population, and higher temperatures during the initial phase. Aerobic-compost tested for high nutrient (1.55% N, 0.93% P, 1.00% K) content and stable C:N ratio (10.3) compared to vermi-compost (1.11% N, 0.43% P, 0.96% K and C:N ratio of 11.7). Field evaluation of both composts showed yield benefit and saving of chemical fertilizers up to 25%.

Aerobic-composting (using microbial consortium culture), like vermi-composting, proved to be an effective technology with advantage of no requirement to maintain ambient living conditions in lean periods as is required for earthworms in vermi-composting, but needs more energy/labor for biomass turnings.

The objective of research was emphasized on the optimal conditions (initial pH and C/N ratio) for enhancing bioenergy from food waste by a two-stage fermentation process.

Bioenergy production from food waste was operated by mixed culture under thermophilic temperature in batch reactor. Thermophilic biohydrogen production was optimized in terms of initial pH (5.0–9.0) and then was optimized in terms of C/N ratio (10–50) in the first stage. After that, thermophilic biomethane production was optimized in terms of initial pH (6.0–10.0) in the second stage.

The results revealed that the thermophilic biohydrogen production from food waste at an initial pH 7.0 presented the maximum hydrogen yield of 176.10 mL H2/g COD. At this optimal initial pH, the maximum hydrogen yield of 214.88 mL H2/g COD was achieved at C/N ratio 30. Subsequently, the effluent from the first stage of thermophilic biohydrogen production from food waste under the optimal initial pH of 7.0 and the optimal C/N ratio of 30 was used as a substrate in the second stage of thermophilic biomethane production. Thermophilic biomethane production from hydrogen fermentation effluent provided the maximum methane yield of 310.77 mL CH4/g COD at initial pH 7.0. At these optimal conditions, COD removal was achieved at 70–90%.

Therefore, a two-stage thermophilic fermentation process could effectively enhance biohydrogen and biomethane production, including reduction of organic waste at the same time.

Improving the nutritional value of rice straw by microbial inoculants and some physical treatments for animal feeding during dry seasons.

Different microbial inoculants and some physical treatments were used to improve the nutritional value of rice straw. Rice straw was divided into moist straw, soaked straw for 24 h without pasteurization and soaked for 24 h and pasteurized at 100 °C/1 h, and all of them were inoculated with different microbial inoculants.

Moistened rice straw inoculated with Azotobacter chroococcum and Saccharomyces cerevisiae recorded the highest significant reduction in organic matter percent, 74.21%. The highest significant reductions in crude fiber, neutral detergent fiber, and acid detergent fiber percent were recorded in moistened rice straw inoculated with Azospirillum brasilense and Saccharomyces cerevisiae which gave 27.54, 55.39 and 42.47%, respectively. The highest significant increase in crude protein percent, 13.71%, was recorded in rice straw soaked for 24 h and inoculated with Azospirillum brasilense and Bacillus megaterium. The combined interaction between microbial treatments and physical pretreatments of rice straw gave a significant decrease in organic matter, crude fiber, neutral detergent fiber and acid detergent fiber %, as well as a significant increase in crude protein % compared to control. Addition of nitrogen fixers to rice straw improved its nitrogen contents.

This study showed the possibility of improving the nutritional value of rice straw using microbial inoculants and some physical treatments to produce safe and cheap animal feeds.

Depletion of soil fertility accounts for the low yield and quality of malting barley (Hordeum vulgare) in Ethiopia. Mineral fertilizers can counteract nutrient depletion but are unaffordable by low-input farmers. Organic amendments can contribute to correct soil degradation but are often unavailable in the required amounts. Therefore, this experiment was conducted to investigate the effects of combined use of organic and mineral amendments on the yield and quality of malting barley, and on selected soil chemical properties at Lemu-Bilbilo district in the southeastern highlands of Ethiopia.

Eight treatments were arranged in randomized complete block design with three replications to compare sole and integrated applications of organic and mineral nutrient sources on crop performance attributes and selected soil characteristics.

Application of 2.82 t ha−1 compost or 1.07 t ha−1 farmyard manure (FYM) along with 18–10 kg ha−1 N–P gave 4234–4443 kg ha−1 grain yield with 15–17 and 32–39% increase over sole organic amendments and control, respectively, and 757% economic benefit. Combining organic and mineral fertilizers also gave 7–17 and 1–6% increase in available soil P and total N content of the soil.

Combined application of 50% recommended compost (RC) or 50% recommended FYM (RFYM) + 50% recommended NP (RNP) or 33% RC + 33% RFYM + 33% RNP enhanced yield, grain quality, soil attributes and economic benefits. Therefore, integration of organic and mineral amendments is recommended as best agronomic and economic optimum soil fertility management options for sustainable malting barley production in the southeastern highlands of Ethiopia.

Olive oil industry is a growing industrial sector in Mediterranean countries. Unfortunately, about 30–35% of total olive weight is discarded as olive pomace (OP), a highly environmental-polluting solid waste. OP is mostly used for composting and production of animal feed; nevertheless, the high oil content, phenolic compounds and fiber contents in addition to its low protein content represent major obstacles for both applications. So, the present study was conducted to evaluate the role of solid state fermentation (SSF) in OP using Kluyveromyces marxianus NRRL Y-8281 yeast on the chemical composition and tannin content of OP in a trial for its bioconversion into a value-added animal feed.

Chemical composition, nutritive and energetic values, tannin and gallic acid contents of unfermented and fermented olive pomace were investigated.

The fermentation altered the chemical composition of OP, so that crude fiber was decreased by 8.56%, while crude protein, fat and carbohydrate contents were increased by 2.74, 2.63 and 3.57%, respectively. Moreover, the effect of fermentation on cell wall constituents, gross energy, digestible energy, total digestible nutrients and digestible crude protein was evaluated. Furthermore, HPLC analysis revealed that K. marxianus mediated fermentation of OP resulted in a sharp decrease in tannin content by 96.75% with 2.8 times increase in gallic acid concentration.

SSF of OP by K. marxianus does not only eliminate the environmental pollution resulting from its accumulation, but also presents a new eco-friendly valorization technique which leaves OP with an altered chemical composition allowing its use as animal feed or compost.

This research aimed to study the adsorption of ammonium and nitrate by simply modifying the surface of the rice husk using slow pyrolysis and surfactants modification.

Rice husk biochar was prepared by slowly pyrolyzing at 500 °C, 2 h. The rice husk and its biochar were modified by cetyltrimethylammonium bromide or sodium dodecylbenzenesulfonate. FTIR, BET and zeta potential measurements were used to characterize the obtained adsorbents.

Slow pyrolysis increased the specific surface area and decreased the surface charge of rice husk while surfactant clogged the pore but could change the charge of a surface. Adsorption of both ammonium and nitrate on rice husk, its biochar, and their modification with surfactants fitted Freundlich and Langmuir isotherms, indicating heterogeneity in adsorption. Slow pyrolysis gave the highest ammonium removal with maximum adsorption capacity of 44 mgN/g and it was a physical process. The cetyltrimethylammonium bromide modification gave a significant nitrate removal on both rice husk and its biochar with maximum adsorption of 278 and 213 mgN/g, respectively, which is higher than a commercial adsorbent.

These two modification techniques gave great adsorption enhancement with cost-effectiveness as compared to other reviewed methods which could use as a nitrogen-rich fertilizer and fertilizer retainment in crop production.

The long-term use of manure as a source of nutrients can promote phosphorus (P) leaching, especially in sandy soils. The aim was to evaluate P mobility from organic and mineral sources in columns, linked with the Dystric Xeropsamments adsorption characteristics with long-term organic fertilization regime.

The mineral, chemical, and physical properties of the samples were characterized, including Langmuir adsorption and desorption kinetics. The P mobility was determined in one leaching experiment, in 20 cm soil columns. The topsoil (0–10 cm) layer was treated with organic (cattle, swine, goat, and hen manure) and inorganic fertilizers. Leaching was corresponding to 10 pore volumes (PV), 1 PV day−1. Aliquots of the leachate were collected to analyze P concentrations. After the leaching, the columns were sliced into 5-cm sections for the analysis of water-extractable P (WEP).

The mineral source obtained higher leaching of P and between the organic sources the bovine and swine manure. The latter were the ones that had higher value of Pw in the soil after the leaching. Due to the increase of the adsorption capacity of P with depth, there was a reduction in the mobility of P, and an unbalance of Pw in the soil was found.

The mobility of P depends on the concentration of the soluble P soil or added material; moreover, the presence of Fe and Al oxides, even in small amounts, reduces the mobility of P in sandy soil.

This study conducted to assess the presence of pharmaceuticals in soils and crops irrigated with treated wastewater in Oman. The study was aimed to evaluate the potential of plant uptake of four commonly used pharmaceuticals in Oman: amoxicillin, sulfamethoxazole, trimethoprim and ibuprofen by radish (Raphanus raphanistrum subsp. sativius) in soil culture.

Radish (Raphanus raphanistrum) was selected as a test crop. Liquid chromatography mass spectrometry/mass spectrometry (LC–MS/MS) instrument was used to measure concentrations of pharmaceuticals. Groundwater and treated wastewater were used for irrigation. Additionally, there were two spiked treatments; high-spiked concentration (5 mg/l) and low-spiked concentration (1 mg/l).

Results of the study showed that trimethoprim and ibuprofen were not detected in any samples of soil and plant. Sulfamethoxazole accumulated in radish roots for low- and high-spiked treatments. Amoxicillin accumulated in roots with low-spiked- as well as high-spiked treatments. Radish showed the ability to translocate some of the selected pharmaceuticals from soil irrigated with treated wastewater if they are present in sufficient concentrations.

Radish showed positive uptake of some selected pharmaceuticals from soil irrigated with treated wastewater with spiked (both high and low) concentration of pharmaceuticals and has the ability to accumulate them in the roots. Pharmaceutical usage and disposal must be given attention to prevent their occurrences in the environment. Furthermore, treated wastewater must be given attention, as it is an important source of water in Oman, which suffers from water shortages.

To study the direct effect on the first mustard cropping and the residual effect of three kinds of vermicompost on the productivity of the second, third, fourth Pak-Coi mustard sequential cropping.

A field experiment was conducted for four sequential planting periods of mustard Pak-Coi in silty clay Inceptisol. The experiment used a factorial randomized block design with two factors. Factor I comprised three kinds of vermicompost with three types of bedding materials; V1—spent mushroom waste, V2—coconut husk, and V3—sugarcane trash, while factor II comprised four different application rates: 5, 10, 15, and 20 t ha−1. From these two factors, there were 12 treatments plus one control treatment (without vermicompost application).

Application of vermicompost increased soil NPK content. The highest nutrient uptake was also found in the residual effect for the second cropping. Nutrient uptake of the third and fourth mustard cropping had a decreasing trend. The highest yield on the first cropping was found in the application of vermicompost V2 and V1 with the application rates of 10–15 t ha−1. In the second cropping, the productivity increased, whereas the third and fourth sequential cropping decreased in the vermicompost V1 and V2, whereas in the vermicompost V3 the productivity of the third and fourth cropping was slightly increased.

The application of vermicompost to organic farming provides nutrient availability in four mustard subsequent planting periods. Differences in the dynamics of nutrient availability, nutrient uptake and crop yields are affected by the vermicompost materials used.