In this opportunity I wanted to share with the entire academic community of the #Hive platform, scientific content on the elaboration of bioproducts based on aquatic plant species, mainly the effect of the C/N ratio (carbon / nitrogen) on the physicochemical and chemical properties of compost based on Eichhornia crassipes.
Introduction
Any process of elaboration of solid bioproducts, where the aim is to obtain a quality product, with adequate physicochemical and chemical values, must guarantee the normal development of each one of the composting phases, mainly the microbiological activity.
In this sense, it is necessary to control the parameters that influence the development and microbiological activity, in order to guarantee the uniformity of the process, among the main factors that influence composting are: environmental parameters (temperature, moisture content, pH, aeration), and parameters related to the nature of the substrate (C/N ratio, particle size and nutrient content).
Therefore, considering that C/N ratios to a greater or lesser degree affect microbial growth and determine the speed and efficiency of the process, this manuscript aims to socialize experimental results on the effect of different carbon/nitrogen ratios in compost based on Eichhornia crassipes.
Conceptual Overview
Carbon/Nitrogen Ratio
The carbon/nitrogen C/N ratio of the mixtures to be composted is the parameter that most affects the biodegradation process, considering that carbon is used as an energy source by the microorganisms, while nitrogen is used for protein synthesis.
It is stated that the C/N ratio may vary from one substrate to another, but it has been established that a ratio of 25:1 to 30:1 is adequate for a good development of the composting process, under these values there are losses of nitrogen, by volatilization of ammonia, at higher ratios nitrogen becomes a limiting nutrient, causing a delay in the composting process.
Agro-morphological field study
Experimental aspects
Now, in order to answer the effect of the C/N ratio (carbon/nitrogen) on the physicochemical and chemical properties of compost based on Bora (Eichhornia crassipes), these would be the steps to follow experimentally to evaluate the effect of different ratios of carbon/nitrogen on the quality of these bioproducts.
Study area
The trial was carried out in the nursery facilities of the botanical garden of the Universidad Nacional Experimental Sur del Lago (UNESUR), located in Santa Bárbara, Zulia State, Venezuela. The average temperature of the area is 27°C and the relative humidity reaches an average value of 80%, with an altitude of 5 meters above sea leve.
Characterization of raw material
The fresh Bora samples were collected on the banks of the Escalante river, Colón municipality, Zulia state, Venezuela, and chopped into 2.5 cm pieces manually, the manure was obtained from the corrals of the U. P "La Chiquinquirá" of UNESUR, the palm nepe in the area of reception of corozos of the company San Simón C.A. and the soil from the areas adjacent to the botanical garden, 1 kg of each material was taken, which was placed in plastic bags with hermetic seal. Subsequently, they were taken to the Chemical Analysis Laboratory of UNESUR (LAQUNESUR), where they were tested in triplicate for % humidity (H), carbon (C), nitrogen (N) and C/N ratio.
Formulation of mixtures
Based on the characterization of the initial materials, three mixtures were formulated by means of a mass balance, determining the C/N ratio and the humidity of the materials to be composted, using the model of optimal mixtures proposed by [3] according to the following formula:
Where:
S = Kg. of waste A
C = carbon content
N = nitrogen content
Design of treatments
Three piles of 2 m2 and 1.5 m high each were formed, composed as follows:
Pile 1: (Compos 1):
40% Bora, 40% cattle manure, 10% soil and 10% palm kernel, with a C/N ratio of 20:1.
Pile 2: (Compos 2):
55% Bora, 20% cattle manure, 10% soil and 15% palm kernel, with a C/N ratio of 30:1.
Pile 3: (Compos 3):
40% Bora, 20% bovine manure, 20% soil and 20% palm kernel, with a C/N ratio of 35:1.
Once the piles were formed, they were arranged in an open system, stacked with turning every 2 d during the first 2 weeks of the process and without irrigation, every 8 d from week 3 to 8 with irrigation and every 15 d from week 9 to 12 with irrigation.
Sampling
At the end of the composting process, representative samples were taken from each pile, consisting of 3 simple random subsamples of the middle layer, mixed and homogenized, and then placed in 1 kg bags for analysis [1].
Physicochemical and chemical analysis
Physicochemical and chemical tests were performed in triplicate in order to determine the quality parameters of the compost obtained, and the physicochemical and chemical procedures and parameters established in the manual of compost analysis methods by [5] were used.
Agro-morphological results
Physicochemical properties of starting materials
The results of the physicochemical tests of the initial materials are shown in Table I., The highest carbon content was observed in NP, Bora, EB and T respectively, the highest amount of N was obtained in EB, followed by Bora, NP and soil, finally, it is observed that NP showed high values of C/N ratio, the variability of the materials analyzed allowed balancing the mixtures subject to study.
Physicochemical, chemical and microbiological analysis of Bora compost
A. Physicochemical properties
Differences were found in the moisture content of the composts, however, the three values are within the range of quality that according to Chilean Official Standard NCh2880, should range between 20 and 40%, similar results were obtained in pH, electrical conductivity (EC) and total organic matter (OM) (Table 2), compost 2 showed the highest values of pH, EC and OM and compost 3 showed slightly lower values, indicating that the C/N ratio affects the physicochemical quality of Bora.
Fig. 4 Abbreviations: Compost 1: 40% Bora, 40% cattle manure, 10% soil and 10% nepe palm, Compost 2: 55% Bora, 20% cattle manure, 10% soil and 15% nepe palm, Compost 3: 40% Bora, 20% cattle manure, 20% soil and 20% nepe palm. Values with equal letters indicate compost groups with no significant differences (Tukey test, p<0.05). Author:.
B. Chemical properties
The contents of N, P, K and total Ca among the composts showed differences, with C2 having the highest values, the percentage of total Mg showed no differences in the composts evaluated, with the highest values in C2 and C1 and the lowest in C3, as for the determinations of soluble N, K, Ca and Mg, differences were also found among the composts, with the highest values in C2 and C1 (Table 3); however, it is considered that the low values found in C3 are due to the excess of carbon, which could have caused the immobilization of nitrogen, generating a decrease in the microbial flora in the composting process.
Fig. 5 Abbreviations: C1: 40% Bora, 40% cattle manure, 10% soil and 10% nepe palm, with a C/N ratio of 20:1. C 2: 55% Bora, 20% cattle manure, 10% soil and 15% nepe palm, with a C/N ratio of 30:1. C3: 40% Bora, 20% cattle manure, 20% soil and 20% nepe palm, with a C/N ratio of 35:1. Values with equal letters indicate compost groups with no significant differences (Tukey test, p<0.05). Author:
CONTRIBUTIONS OF THIS PUBLICATION
- The contribution of this manuscript focused on socializing on the valuable tool C/N ratio as a technical factor to be considered in the elaboration of solid bioproducts (compost), starting from its determination and optimum range to be selected at the moment of balancing the raw materials, generally added in the composting process, with the purpose of guaranteeing the correct decomposition and mineralization of the organic matter, which provides a product of good physicochemical and chemical quality at the end of the process. Likewise, the article shows the physicochemical and chemical results, found in greater proportion, in the balanced bioproduct with a C/N ratio of 30:1, which placed this range, as the balanced between both elements, to positively affect the physicochemical and chemical values, of the composts elaborated based on the Aquatic Macrophyte, of the free floating group as Eichhornia crassipes.
BIBLIOGRAPHICAL REFERENCES CONSULTED AND CITED:
[1] TMECC US Department of Agriculture. Test methods for the examination of Composting and Compost. 2002. Article: Online access
[2] Norma Chilena Oficial NCh2880 Compost clasificación y registro. Instituto Nacional de Normalización. INN Chile. Primera Edición. 2004. Article: Online access
[3] Richard T., and Trautmann N Moisture and carbon/nitrogen ratio calculation. Cornell Waste Management Institute, Department of Agricultural and Biological Engineering, Ithaca, New York, USA. Article: Online access
[4] Rynk R On-Farm Composting Handbook - Natural Resource Agriculture and Engineering Service. 1992; 196. Article: Online access
[5] Sadzawka A., Carrasco M., Crez R. y Mora M Métodos de análisis de compost. Instituto de Investigaciones Agropecuarias. 2005; 3: 142. Article: Online access
[6] Soliva M, and Felipó M Organic wastes as a resource for Mediterranean soils. 2002. Article: Online access
[7] Sztern D., and Pravia M Manual para la elaboracion de compost bases conceptuales y procedimientos. Organización Panamericana de la Salud. URU. 2002. Article: Online access
[8] Tejinder P., Mangal S., Dhanda T., and Singh J Biochemical characterization of consortium compost of toxic weeds Parthenium hysterophorus and Eichhornia crassipe. Bioresource Technology. 2012; 123: 360–365. Article: Online access
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