Soil Chemical Analysis

Economic growth and rising food consumption in the world have led to increased production of organic wastes due to an important intensification of the agricultural production systems. The analysis of macro elements (nitrogen [N], phosphorus [P], and potassium [K]) in organic wastes reveals that the economic loss is significant with the intensification of the agricultural system. The good management of those wastes would be an effective means of organic matter restoration through carbon restitution to the depleted soils through organic amendments. Composting is a type of waste processing that has gained increasing acceptance over the years. As a rule, the process consists of the natural biological decomposition of organic waste components and involves diverse species of microorganisms. Those organic residues could reconstitute soils and be an important fertilization backup. Composts prepared from different organic wastes differ in their quality and stability, which further depends upon the composition of raw material used for the compost production. Compost quality is closely related to its stability and maturity. The wide variety of chemical and biological variations that occur during composting, and the range of methods suggested in literature, has made it difficult to agree on methods for the practical assessment of maturity. A literature review of the main start-up, monitoring and maturity parameters are discussed concerning different raw materials used and different composting methods practiced.

Composting parameters and compost quality: a literature review

Soil salinity under climate change: Challenges for sustainable agriculture and food security.

Agricultural waste recycling in horticultural intensive farming systems by on-farm composting and compost-based tea application improves soil quality and plant health: A review under the perspective of a circular economy.

Composting has become a preferable option to treat organic wastes to obtain a final stable sanitized product that can be used as an organic amendment. From home composting to big municipal waste treatment plants, composting is one of the few technologies that can be practically implemented at any scale. This review explores some of the essential issues in the field of composting/compost research: on one hand, the main parameters related to composting performance are compiled, with especial emphasis on the maturity and stability of compost; on the other hand, the main rules of applying compost on crops and other applications are explored in detail, including all the effects that compost can have on agricultural land. Especial attention is paid to aspects such as the improvement of the fertility of soils once compost is applied, the suppressor effect of compost and some negative experiences of massive compost application.

https://www.mdpi.com/2073-4395/10/11/1838/pdf

Recycling of Organic Wastes through Composting: Process Performance and Compost Application in Agriculture

Synchronic and diachronic studies were carried out in order to examine the change of certain soil parameters with time after applying organic (green waste and sugarcane composts) and inorganic (gypsum at two rates) amendments on three soils with different salinity levels using ryegrass as the test crop during a 180-day incubation. The diachronic analysis involved the evaluation of the electrical conductivity dynamics over time. Maximum level of salinization has been observed when applying gypsum (both rates) for the non-saline soil, low gypsum rate (3.8 mg.g−1) for the saline soil, and sugarcane compost for the extremely saline soil. The maximum decrease in salinity was recorded at 120 days for non-saline soil and at 20 days for both saline and extremely saline soils. The synchronic study evaluated at the end of the incubation, showed a relative increase in electrical conductivity (EC) when applying gypsum (all rates) for non-saline soil, after applying green waste compost for the saline soil, and by applying high gypsum rate for extremely saline soil. This analysis also showed an increase in alkalinity and a decrease in organic matter, calcium, and magnesium. However, gypsum application showed, with regard to the other treatments, its effectiveness as a good mineralizer, pH neutralizer, and reservoir of Ca2+ when measured overtime. Maximum potassium uptake by ryegrass at the expense of sodium was obtained at day 60 of incubation, whereas, the highest absorption was not related as expected to the lowest EC whilst, optimum uptake levels were reached in the non-amended soil in the case of non-saline soil, high rate gypsum-amended soil for saline soil and low rate gypsum-amended soil for extremely saline soil.

Organic and inorganic remediation of soils affected by salinity in the Sebkha of Sed El Mesjoune – Marrakech (Morocco)

Purpose
The region of Souss-Massa generates huge quantities of organic horticultural wastes estimated up to 1,307,465 tons·year−1. Fruit and vegetable producers are asked to process the organic wastes because of the GlobalGAP certification requirements. As a result, there is a need to assess the existing composting plants at regional scale, to improve their efficiency, produce a high-quality soil amendment, free from any pathogens, and weed seeds.

/pdf/agro-environmental-assessment-of-composting-plants-in-3u0osxiekx.pdf

Agro-environmental assessment of composting plants in Southwestern of Morocco (Souss-Massa Region)

More than 1 million tons of fresh organic wastes is produced in the Souss-Massa region in Morocco. Tomato organic residues represent more than 25% of the total organic wastes and are deposited in uncontrolled landfills. Thus, composting can represent a valuable and pertinent solution to this environmental problem. The objectives of this experiment are to identify the potential functional groups responsible for compost phytotoxicity and to determine the optimum initial carbon to nitrogen ratio (C/N) for maximum recovery of tomato residues. The experiment consisted of the variation of the initial C/N ratios (25, 30, 35, and 40) using mixtures of different raw materials (tomato residues, melon residues, olive mill pomace, and sheep manure). Physicochemical parameters (pH, electrical conductivity, C/N ratio, and humic acid/fulvic acid ratio) were determined and spectroscopic analyses (UV-vis and NMR-13C) were performed during the composting process along with quality parameters (germination and phytotoxicity tests) at the end. The results showed that the compost with the initial C/N ratio of 35 is the most humified with the least phytotoxic effect. The germination and phytotoxicity tests were negatively correlated with the methoxyl/N-alkyl-C ratio and O-alkyl-C. These two functional groups are probably the origin of phytotoxicity expression in compost quality tests. Thus, a simple and precise quality test could be performed to evaluate directly the phytotoxicity and maturity of compost.

/pdf/elucidation-of-functional-chemical-groups-responsible-of-4ia59m1coc.pdf

Elucidation of functional chemical groups responsible of compost phytotoxicity using solid-state 13C NMR spectroscopy under different initial C/N ratios

Different organic wastes (waste of tomato leaves and stems, sheep manure, olive mill waste and melon waste) were mixed with different proportions for different C/N ratio to make better use of tomato waste as it constitutes the majority of horticultural waste in the Souss-Massa region (south-western of Morocco). The objective of this study was to evaluate the effect of C/N ratio on the physicochemical parameters during aerobic composting process (temperature, relative humidity, pH, EC...), and the quality of the compost. The effect of each produced compost was also tested by its incorporation at different rates into sandy soil. The four studied C/N ratios (treatments) were: C/N=25; C/N=30; C/N=35 and C/N=40. Results revealed that the treatment C/N=35 has resulted in the highest oxygen consumption and also, the longest thermophilic phase. Treatments C/N=25 and C/N=35 have reached optimal C/N ratios at the end of the process (respectively 11.88 and 14.71), while treatments C/N=30 and C/N=40 stood higher than 15 (respectively 17.93 and 18.84). Fulvic acid evolution remained constant for all treatments, whereas humic acid content has reached highest levels with C/N=25 and C/N=35 treatments. The effect of compost on seed germination test and phytotoxicity test showed that treatment C/N=35 has produced the most mature compost with the lowest phytotoxicity effect. The amendment of compost has reduced the pH, increased the EC, and enriched soil with organic matter as far as the rate of the amendment is increasing (10; 20 and 30Tonnes.ha-1). Compost of treatment C/N=40 has recorded the highest soil total organic matter content poorly decomposed during composting. However compost of treatment C/N=35 has resulted in the lowest soil total organic matter content, this is mainly due to the intense degradation of the compost during the composting process. The quality of the produced compost depends largely on the level of C/N startup ratio and also the quality of its constituents within the mixture.

/pdf/dynamic-composting-optimization-through-c-n-ratio-variation-2cliu0jh37.pdf

Khalid Azim

Papers

Composting parameters and compost quality: a literature review

Organic and inorganic remediation of soils affected by salinity in the Sebkha of Sed El Mesjoune – Marrakech (Morocco)

Agro-environmental assessment of composting plants in Southwestern of Morocco (Souss-Massa Region)

Elucidation of functional chemical groups responsible of compost phytotoxicity using solid-state 13C NMR spectroscopy under different initial C/N ratios

Dynamic composting optimization through C/N ratio variation as a startup parameter