International Journal of Recycling of Organic Waste in Agriculture
Volume:10 Issue: 1, Winter 2021

Purpose The objective was to evaluate the effects of mineral fertilizers and swine manure fertilization on soil aggregation indexes and on chemical and physical attributes of aggregates in Typic Hapludult managed under minimum tillage system. Method Experiment was implemented in 2013, in southern Brazil. The treatments were control, mineral fertilization (MF), swine manure compost + MF (SMC+MF); pig slurry + MF (PS+MF); PS to supply N for maize and black oat (PS100). In May 2015 and 2016, undisturbed soil samples were collected to obtain soil aggregates. Aggregates stability was evaluated through the mean weight diameter (MWD) and mean geometric diameter (MGD) indexes and aggregate distribution by diameter classes. In macroaggregates, total organic carbon (TOC), total nitrogen (TN), clay flocculation degree (CF%) and ∆pH were evaluated. Results The use of swine manure, associated or not to MF, increases TOC and TN contents in soil aggregates in 67.02 and 125.87%, respectively, for SMC+MF treatment. However, it was not efficient in improving soil physical attributes, reducing soil aggregation indexes, mainly in the 5-10 cm layer, by the decreased values of MWD and MGD. This result corroborates with the increase in microaggregates in all treatments. This was a result of the negative ∆pH values and the increased CF%. Conclusion Despite the increase in organic matter contents observed in this study, this was not enough to guarantee an improvement in soil physical attributes over 4 years. These results show that management must be supported by several conservationist techniques in order to have soil quality.

Purpose The solubility of silica is a key parameter affecting its suitability as a rice fertilizer. Therefore, this study determined the effect of calcination temperature and duration on the physical composition of silica derived from rice husk ash. Method Rice husks were calcined at 100–900 °C for 15–120 min in an electric furnace. The solubility and physical composition of the samples were measured, and the appearance of the calcined rice husk ash was determined via visual observations. Results The appearance of the rice husk ash changed drastically at a calcination temperature of 300 °C. The husk exhibited the whitest color at 500 °C and 120 min of calcination. The solubility of silica in the rice husk ash increased up to a calcination temperature of 500 °C and then started to decrease. The silica in the rice husk ash exhibited a gray zone between the amorphous and crystalline structures. Conclusion For actual field applications of silica derived from rice husk ash as a fertilizer, calcination conditions of 400–800 °C and 15 min are proposed to improve solubility. The optimal calcination temperature should be determined based on the heat recovery efficiency.

Purpose Chicken feather protein hydrolysate (CFPH) has drawn a significant attention as a component/type of biofertilizer in recent years, because of the beneficial impact on the growth of the plant. The current study aims to evaluate the potential influence of the combination of CFPH with vermicompost (VC) on growth-promotion and yield improvement in tomato plants. Method Feather degrading bacteria were isolated and characterized using 16s-rDNA sequencing, and assessed for biochemical reactions, growth-promoting attributes and keratinase activity. The medium used for feather degradation studies consisted of 0.75% (w/v) of raw feather, with 1% (v/v) of inoculum at 37°C, pH 7.5 and at 120 rpm. A field study was done by randomized block design (RBD) with five treatments in tomato. Results Keratinolytic and feather degrading bacteria isolated and used in this study were identified as Bacillus cereus PKID1 with accession number MT158702. The bacterium gave the highest keratinase activity of 80±0.28 U/ml. The CFPH showed the potential to promote remarkably the germination % of tomato (84.13), rice (87.24), onion (84.13), chilli (84.13), chickpea (73.24) seeds ; field experiment significantly increased plant growth and yield compared with control. Conclusion The principal component analysis of the field experiment as a result of tomato plant-growth, the order of best treatment efficacy for improvement of parameter estimates was as follows: CFPH and VC > CFPH > VC > recommended dose of fertilizers (RDF) > control. Thus, the application of CFPH with VC could improve the productivity of crops and decrease the use of chemical fertilizers.

Purpose Soil salinity and sodicity are two of the causes of soil degradation, especially in arid and semi-arid regions of the world. The use of modifiers, including organic matter, can often be an appropriate strategy to improve fertility of saline-sodic soils. Methods In this study, saline-sodic control soil was collected from Karaj and mixed with three levels of 1%, 3% and 5% of cow manure, vermicompost and Azolla. Treatments were then incubated for 5 months at 20°C and field capacity moisture. The physical and the chemical properties of the treatments were evaluated before and after incubation. Results After the incubation period, 5% Azolla and vermicompost treatments were at the lowest salinity level. The highest amplitude of changes in sodium absorption ratio was related to 5% cow manure treatment. There was little difference between the amounts of moisture in a given suction in different treatments. After the incubation period, salinity decreased and sodium absorption increased in most treatments. Subsequently, we observed a decrease in the saturation dehydration coefficient in the treatments, indicating a disruption of soil structure and conversion of large pores to fine grains, which is one of the effects of adding these organic substances. Conclusion According to the findings, cow manure at 1% level had almost no effect on soil properties and at higher levels caused a decrease in the quality and conditions of saline-sodium soil in terms of physical and chemical properties. Whereas, Azolla fertilizer and vermicompost fertilizer at 5% level can be suitable for correcting saline-sodic soil.

Purpose The upsurge of vegetable oil production in Nigeria and the equally increasing concern for the environment which arises due to indiscriminate disposal of phytotoxic vegetable oil mill effluent in a less regulated country like Nigeria makes the re-use of the effluent for fertigation a suitable strategy for its disposal if the appropriate treatment technique is adopted. Method  A laboratory experiment was set up to study how the detoxification of soybean oil mill effluent (SOME) under different anaerobic digestion time (0, 20 and 40 days) and application rates (0, 50 and 100 m3/ha) will influence the suitability of the effluent for fertigation. Results SOME has a pH of 8.3, which decreased steadily to 7.4 as digestion time increased to 40 days. EC and potassium levels also decreased as digestion time increased, from 0.37 dS/m and 120.6 g/l to 0.28 dS/m and 70.1 g/l, respectively. However, levels of organic carbon, nitrogen and phosphorus did not change significantly. The effluent impacted negatively on germination after a one-time application, with the germination index going as low as 22% for untreated SOME and gradually increasing to 66% as digestion time increased. Continuous application of the untreated effluent also affected soil microbial activity negatively when compared to the treated effluent. Conclusion Anaerobic digestion detoxifies SOME and the efficiency of the treatment increased with increasing digestion time. The effluent also contains low to moderate amounts of NPK and therefore has a potential for fertigation.

Purpose Reuse of landfill leachate is an effective alternative for their nutrients to mitigate decrease in freshwater. On the other hand, the growth of vegetation in the final disposal areas provides many benefits such as improving the visual impact, controlling of hydric erosion, etc. The purpose of this work was to evaluate landfill leachate as irrigation water and source of nutrients for growth of Tagetes erecta L., an ornamental plant with phytoremediation capacities. Method Vegetal growth, physiological responses and mineral elements uptake of the ornamental plant Tagetes erecta L. were studied with different levels of landfill leachate irrigation. The landfill leachate was provided by the municipal waste treatment. Experimental period covered 34 days of daily watering between the beginning and end of the flowering stage. Three different irrigation treatments were used: T1: 10% leachate; T2: 25% leachate; T3: 50% leachate. Hoagland's solution served as the control treatment. Results The irrigation treatment with a dose of 50% leachate causes a clear deterioration in the plant and its flowers. In lower doses, the plant responds favorably to both the production of flowers and the main features of them. Also, the water-use efficiency (WUE) is diminished in those plants irrigated with the major dose of leachate. Conclusion Maintaining controlled doses, landfill leachates can be used as an alternative source of water and nutrients. Irrigation with leachates of these characteristics should be done in dosages not higher than 25% to avoid possible damage of Tagetes erecta L. growth.

Purpose :

Bangladesh is an agriculture-based country, where about 3 million ha is covered by groundwater sources for irrigation, but a significant portion of irrigation water is Arsenic contaminated. To produce Potato under Arsenic contaminated soil, an experiment was conducted to find out the effect of sawdust as an adsorbent to decontaminate Arsenic toxicity in soil.

Method :

The research was conducted in pot experiment. It consisted of two factors. Factor A: Arsenic levels (4) viz., As0: control (0 mg/kgsoil), As1: 25 mg/kg soil, As2: 50 mg/kg soil, and As3: 75 mg/kg soil. Factor B: Sawdust levels (4) viz., S0: control (0 g/kg soil), S1: 10 g/kg soil, S2: 50 g/kg soil, and S3: 100 g/kg soil.

Results:

 Arsenic content in Potato tuber peel and flesh gradually increased with the increase of Arsenic levels. As3 was found for the highest accumulation of Arsenic in tuber peel (3.867 mg/kgfresh weight) and flesh (0.6236 mg/kgfresh weight). Arsenic content in both peel and flesh of Potato tuber decreased with increasing sawdust levels. The soil treated with S3 reduced 86.41% and 51.44% Arsenic accumulation from tuber peel and flesh, respectively, compared to control (S0). Potato produced from the treatment As1S1 accumulated a lower amount of Arsenic (0.15 mg/kgfresh weight) in Potato flesh compared to those of other treatments.

Conclusion:

 Therefore, Potato growers can produce Potato in 25 mg/kg Arsenic contaminated soil treated with 10 g sawdust/kg soil, which contains a minimum than the critical level of Arsenic for human consumption.

Purpose:

 Anaerobic digestion produces renewable energy, biogas, from organic residues, but also digestate, a valuable organic fertiliser. Previous studies have indicated that digestate contains ample plant available nitrogen (N), but there are also concerns about greenhouse gas (GHG) emissions after application of digestates to soil. The aim of this study was to compare digestate and undigested feedstock for fertiliser effect as well as greenhouse gas emissions during the next season.

Methods:

 Digestate and its feedstock, manure, were compared as N fertilisers for wheat. Mixing digestate with biochar before application was also tested. After harvest, soil samples were frozen and dried. Then GHG emissions immediately after a re-wetting of dry soil and after thawing of frozen soil were measured to determine emissions after a non-growing season (dry or cold).

Results:

 All N in digestate was plant available, while there was no significant N fertiliser effect of the undigested manure. N2O emissions were higher after a dry season than after freezing, but the undigested manure showed higher emissions during thawing than those detected during thawing of soils from any of the other treatments.

Conclusion:

 Anaerobic digestion makes N available to plants, and when residues with much N that is not plant available the first season are used, the risk of N2O emission next spring is high.