Original Article

Obtaining compost from agricultural waste markets biotransformation

Clara García-Ramos^{1  *} 

Noel J. Arozarena-Daza² 

Francisco Martínez-Rodríguez¹ 

Marcela Hernández-Guillén¹ 

José Ángel Pascual-Amaro¹ 

David Santana-Gato³ 

¹Instituto de Suelos/Ministerio de la Agricultura. Autopista Costa-Costa, y Antigua Carretera de Vento, Km. 8½., Capdevila, Boyeros. La Habana, Cuba

²Instituto de Investigaciones Fundamentales en Agricultura Tropical “Alejandro de Humboldt” INIFAT/Ministerio de la Agricultura. Calle 188 No. 38754 entre 397 y Linderos, Santiago de las Vegas, Boyeros, La Habana, Cuba

³Unidad Provincial Presupuestada de Recogida y Disposición Final de Basura/Gobierno Provincial La Habana. Calle 100 y Línea del Ferrocarril. Marianao, La Habana, Cuba

ABSTRACT

The generation of solid urban waste in Havana city with more than two million habitants reaches 20,000 m³ per day and demands efficient alternatives for its management and treatment. A considerable fraction corresponds to agricultural products residues, derived from the operation of more than 300 existing public markets, which due to their chemical nature can become a source to obtain organic matter carriers for agriculture. The biotransformation of these wastes was evaluated as an alternative treatment to avoid unfavorable environmental impacts associated to their accumulation and decomposition; the urban solid waste from the markets was composted (of fruits, vegetables, roots and tubers). The biotransformed material was evaluated for pH, electrical conductivity and the contents of organic matter, phosphorus, potassium, calcium, magnesium, copper, zinc, cadmium and lead; the germination index, basal respiration and the presence of pathogenic microorganisms (total and fecal coliforms and Salmonella sp.) were also determined. The obtained compost serves to prepare substrates for agricultural use, in mixtures with acid reaction soils. Its use does not imply contaminations by pathogenic microorganisms nor by heavy metals, according to valid international norms, which validates the selected treatment route for these residues.

Key words: compost; waste; quality

INTRODUCTION

Urban solid waste (MSW) are waste materials (garbage, waste, sludge, etc.) of a heterogeneous nature, generated by uninterrupted, multiple and simultaneous activities, typical of population centers or their areas of influence and that must be collected or treated for lack of economic value, for sanitary reasons, to avoid the occupation of space and for aesthetic reasons ¹.

Its constant generation and accumulation constitute one of the main challenges facing the sustainability of human settlements, mainly because of the increase in the urban population, which in the Latin American context already represents more than 75 % of the total population ². It is important to remember that one of the indicators of sustainable development of urban settlements is precisely the percentage of recycled urban waste, with respect to the total daily generation volume of this type of waste.

An alternative to cope with this situation is the use or recycling of some components of urban waste: to that vision respond the actions of recovery of raw materials (plastic, glass, metal, paper, rubble, etc.) present in the RSU ³. Another common practice is the use of the biodegradable fraction of MSW, to obtain organic matter carriers for agricultural use ^4-6. In both cases, it is possible to reduce the amount of waste to be disposed of, which extends the useful life of the landfills, obtaining positive impacts for the environment and the economy ⁷.

Havana is no stranger to the problem described, to which the unsatisfied demand of carriers of organic matter, from the urban, suburban and family farming system, committed to the supply of condiments, fruits and vegetables to the population is added ⁸. However, the use of the organic fraction of the MSW, whether via vermiculture or composting, although it contributes to solving both problems, also implies the responsibility of guaranteeing the safety and quality of the food produced, as well as the environmental preservation. The aspects that have made the management and treatment practices of MSW very vulnerable and questioned, including its processing for agricultural use purposes ^9-11.

With the study carried out, it was intended to contribute technically based elements to the debate on the subject, based on the identification of aspects to be taken into account in the biotransformation through composting, of MSW generated in agricultural markets of Havana.

MATERIALS AND METHODS

Batches of 12000 ± 100 kg of solid waste from different agricultural markets were used to establish composting piles 3.00 m wide x 5.00 m long x 2.00 m high, in areas of the Provincial Budget Unit of Garbage Collection and Final Disposal, located in the Marianao municipality and belonging to the Directorate of Community Services of Havana.

It was established as a work scheme, the assembly of two treatments or variants, each with three repetitions arranged in an area of 50 m² indoor and with the irrigation and drainage conditions required by the work to be performed. Treatments: A) Stacks of 100 % v of waste from agricultural markets and treatment B) Stacks of 80 % v of waste from agricultural markets + 20 % v of partially decomposed cattle manure, as inoculant to accelerate biotransformation.

Each assembly was repeated twice in the year (February-May and September to December). To rule out effects of the variation in the composition of the starting material; both cattle manure (EV) and agricultural market waste (RMA) were homogenized in terms of size of the fractions between 5 cm and 10 cm in diameter ⁷. To ensure the greatest contact or interaction surface during the process of composting and at the same time prevent, compaction and anaerobiosis ^12,13; mechanized turning was available daily until the thermophilic phase and then weekly, until the compost maturation. Before each turn, the temperature was measured with a thermometer (°C; three repetitions/variant / date) at 0.20 m ^(14.15) and 0.60 m deep in the stacks ¹⁶. The water addition was carried out weekly in coincidence with the turn. Samples composed of 1 kg of mass, EV, RMA, stacks were taken and analyzed at the time of assembly and compost obtained in each case, with three repetitions for each material to be analyzed; the analytical determinations and the methods used are shown in Table 1 below.

Table 1 Analysis of samples of RMA, cattle manure, composting piles (with and without cattle manure) and the compost obtained; analytical methods used 

Analysis	Source of references
pH [in water]	^17
CE [ms cm^-1]
Organic matter [%]	^18
Sodium [%]	^19
Potassium [%]
Magnesium [%]	^20
Cupper [mgKg^-1]	^21
Zinc [mgKg^-1]
Lead [mgKg^-1]	^22
Cadmium [mgKg^-1]
Germination Rate [%]	^23
Basal respiration [mg CO2 g of sample]	^24
Total and faecal coliforms [NMP 100g of sample]	^25^,^26
Salmonella spp [Absence or presence]	^27

The results obtained in the two moments in which the study was carried out were determined by the average. The manure and temperature samples were processed for the calculation of average value and standard deviation; The data of the RMA samples, composting and compost piles, were processed to calculate the range, median and average of the following variables: pH, electrical conductivity and organic matter contents, phosphorus, potassium, magnesium, copper, zinc , cadmium and lead.

RESULTADS AND DISCUSSION

Temperature

The temperature record at the selected depths appears in Figure 1, for piles without cattle manure and with such inoculum. In both cases, the succession of the phases of the biochemical degradation of the fermentable organic matter, which took place during composting. It is shown; that trend was independent of the depth at which the corresponding data was taken. The measurement values at 0.20 m were lower because it is the most superficial area of the piles, an aspect that corroborates the importance of the turnaround, to guarantee the homogeneity of the biotransformation and the quality of its result ^28-30. In addition, it favors the activity of oxidases produced by decomposing microorganisms and achieving uniform temperatures in the mass in transformation, which is expressed in the quality and uniformity of the final product ³¹.

The differences between the two treatments are due to the fact that, although the organic matter to be transformed contains its own or natural load of microorganisms participating in biodegradation, it is also recognized that the use of other microorganism carriers contributes to increasing the microbial population and reducing the time of elaboration and maturation of composts ³¹.

The vertical lines correspond to the standard deviation

Figure 1 Temperature variation [T; ºC] during the composting of RMA and RMA + cattle manure, [ average data of six observations per date] 

Thus, the advance of the order of the ten days that was achieved with the mixture described as variant B, to reach the maturation of the composts, is explained by the increase in microbial activity, associated with the inclusion of manure in the process ³². After evaluating the composting of peanut residues, including chicken poultry ³¹, it reported reductions in decomposition time and advanced temperature increases during composting, in favor of manure treatments that are maintained even in the face of inoculation of residues with a biopreparation of B. cereus and T. longibrachiatum formulated to stimulate composting. It is worth mentioning that the incorporation of manure in the established proportion implied an improvement in the uniformity of the material arranged in the batteries: this is due to the greater proximity between the temperature values taken at each depth, for treatment B with respect to A.

In both treatments the thermophilic stage was reached, which guaranteed the sanitation or biological disinfection of the final product with respect to pathogenic microorganisms, as a result of the simultaneous incidence of high temperatures, the presence of chemical substances of antibiotic effect and the generation in situ of Vapors and toxic products caused by heating and chemical transformation ^33).

In Table 2 it is shown that during the first week of composting there were no significant differences between treatments, subsequently the temperature begins to increase due to the rapid transformation of soluble materials and high availability (sugars, amino acids) mediated by the action of populations of bacteria and mesophilic fungi ³⁴.

Table 2 Comparison analysis of temperature averages during composting of RMA and RMA + cattle manure  

Depth (m)	Treatment	Days
		7	14	21	28	35	42	49	56	63	70	77	84	91	98	105	112
0.2	without inoculum	33.0	39.6	51.3	60.0	62.3	61.6	59.6	60.0	64.3	61.3	62.0	62.0	59.0	44.3	40.3	38.6
		a	b	c	b					a		ab		a		ab	a
	with inoculum	37.0	56.6	59.3	66.0	68.0	68.3	66.6	64.0	61.6	59.0	57.6	56.0	47.6	42.3	37.0	37.3
		a		ab				a	ab	a		b			a	b	a
0.6	without inoculum	35.0	44.6	52.6	60.6	65.3	68.6	68.0	68.0	66.3	62.0	63.0	63.0	62.0	48.6	44.3	39.6
		a	b	bc	b	ab	a								b	a
	with inoculum	38.0	58.6	63.3	67.6	69.33	70.0	70.0	66.6	64.3	62.0	57.6	57.6	50.0	44.3	39.6	38.3
		a							ab	a		ab		b	a	ab	a
Tukey		6.6864

Different letters in column differ statistically according to Tukey (p <0.05)

From the 14 days of the composting process and until the 28^th, in the treatments where the cattle manure was incorporated, significant differences were observed with respect to the treatments where said inoculum was not incorporated, which can be attributed to the microbial load present in manure ³², which allows the temperature to rise. These results were different from those obtained by ³⁴ who obtained significant differences from the third week of composting in food waste and its inoculation with a commercial biopreparation and a biopreparation of B. cereus and T. longibraquiatum used as process accelerators of composting, attributing this behavior to the low height of the piles.

It can be seen that up to 49 days there is a higher temperature rise in the variants that are inoculated with manure. From that time there is a decrease in the temperature in all the variants, however, from day 63 to day 70 there are no significant differences between the treatments and later. It is observed that in the manure treatments they present lower temperatures which is it relates to the contribution of manure in a first stage of easily biodegradable carbon, which provides conditions for microbiological activity and therefore greater availability of energy until the carbon source is depleted so that the temperature begins to fall.

Initial analysis of manure samples and piles at the beginning of Chemical Chemical and physical-chemical characterization

Table 3 shows the results of the characterization of cattle manure. Most of the microorganisms involved in the process of decomposition of organic matter develop well in a slightly acidic or neutral environment and even better if it is slightly alkaline ⁷ which would indicate another advantage in favor of the use of manure in this case. If it is taken into account that its application represented 20% of the mass of the batteries. An equally coincident trend was obtained for the content of organic matter, which makes it possible to affirm that the manure used did not show deviations from these properties with respect to the results traditionally obtained for its characterization for agricultural use purposes, in the country ^35,36.

Table 3 Analysis of samples of cattle manure used as microbial inoculum in composting of solid waste from agricultural markets in Havana 

Indicator	pH water	MO	K	Na
Minimum value	8.0	66.0	1.5	0.2
Maximum value	9.0	72.0	2.2	0.4
Median	8.4	68.2	1.9	0.3
Mean	8.4	68.5	1.8	0.3
Standard deviation	0.4	2.2	0.2	0.1

Legend: pH; organic matter, K and Na: %; data from six samples composed of each determination

For the interpretation of potassium and sodium values, it was taken into account that manures are materials of very variable composition and dependent on factors as diverse as the quality and quantity of food supplied to animals, the age or stage of development in which they are the same, the seasonal time, among others ¹⁶. For these reasons it is that the manures are recognized more as amending, for their status as carriers of organic matter and their effects on the physical and biological properties of soils, which for its net contribution of nutrients.

Table 4 gives the results of the characterization of initial samples of RMA piles according to treatments A and B. The pH values at the beginning of the composting were alkaline, which is typical of these organic residuals ²⁹. The percentages of organic matter in the treatments reached similar values to those reported for residuals of the same origin ²⁹ and ratify the possibility of using the solid wastes used for composting, which represents an attractive option for their management and for the reduction of the increasing volume of waste materials that are sent daily to the city's landfills.

Regarding the electrical conductivity, the values were similar to those obtained by ²⁹, at the beginning of the composting of lots of waste from markets, respectively. These values do not have to be assumed as definitive, since during the composting there are numerous chemical transformations that also result in the formation of products and substances capable of influencing the magnitudes of this property.

It should be noted that the pH values, the percentage of organic matter and the electrical conductivity showed, from the statistical point of view, little variability. Regardless of the time of the year in which the study was carried out the maximum coefficient of variation between the analytical determinations made, did not exceed 9.6 % ~. For some authors it is associated with the fact that it was, generically, a unique type of residual and valid for the conditions of the Cuban capital, the option of collection or collection of solid urban waste, separately and based on its possible subsequent use.

Table 4 Analysis of initial samples during the composting of RMA and RMA + cattle manure 

Determinations	Treatments	Indicador
		Minimum value	Maximum value	Median	Mean	Standard deviation
pH in water	without inoculum	8.60	9.15	8.92	8.90	0.18
	with inoculum	8.37	9.10	8.41	8.60	0.33
C. E.	without inoculum	7.30	8.91	8.59	8.43	0.60
	with inoculum	6.46	8.15	7.73	7.60	0.61
M. O.	without inoculum	30.0	34.20	31.94	31.93	1.70
	with inoculum	32.46	36.98	33.49	33.94	1.68
Na	without inoculum	0.06	1.01	0.13	0.27	0.37
	with inoculum	0.03	0.19	0.07	0.09	0.07
K	without inoculum	3.00	5.57	3.33	3.76	0.98
	with inoculum	0.98	3.52	1.71	1.90	1.02
Mg	without inoculum	0.10	0.47	0.22	0.26	0.16
	with inoculum	0.10	0.44	0.10	0.19	0.15
Cu	without inoculum	20.90	27.80	27.40	25.37	3.87
	with inoculum	28.10	31.70	29.70	29.83	1.80
Zn	without inoculum	37.62	57.54	44.75	46.44	7.61
	with inoculum	39.68	54.45	41.63	43.97	5.72
Cd	without inoculum	0.10	1.54	1.00	0.84	0.61
	with inoculum	0.10	1.50	0.86	0.82	0.49
Pb	without inoculum	5.50	6.50	5.70	5.90	0.53
	with inoculum	3.70	5.20	4.00	4.30	0.79

Legend: pH; electrical conductivity: ms • cm-1; organic matter, Na, K and Mg:%; data from six samples composed of each determination

Notwithstanding the foregoing, the solid waste generated by the activity of agricultural markets cannot be considered as a material of homogeneous composition, due to its origin and due to the factors of various kinds that affect its generation, management and collection. This explains the variability expressed by the results of the chemical analysis for the sodium, potassium, magnesium and heavy metal contents. There are no published data on such studies in this type of RSU, so this information could serve as a reference for subsequent and necessary evaluations of them.

Studies carried out in Cuban soils, values of 8.2 mg kg^-1 and 28.6 mg para kg^-1 for Pb and Cu ³⁷, For this reason, the results indicate that the use of waste in the obtaining substrates for agricultural use, environmental pollution risks are not associated due to the presence of these elements. In this case, due to the way in which they were selected in situ and during the two seasonal seasons of the year and from the units or markets Generators ~ are representative of the chemical quality standard of this type of material. For Cd and Zn, the values were also remarkably low, as commented by this author in his study, on microelements in agriculture.

Due to the results obtained, the analysis of these elements in the composts was rejected; however, regular monitoring of the starting materials is recommended, to ensure the quality of use of the compost made. Similar results were reported when evaluating the contents of Cd, Pb, Ni, Cr, Zn and Cu in composts of crop residues and their mixture with cattle manure ³⁸.

Finally, although the previous discussion is consistent with the information shown in Table 4, it is not idle to comment that the differences between both treatments are due to the effect of adding manure to the RMA at the time of composting stacks, which apparently supposed a magnitude effect 20% of the total amount a dilution effect. It resulted in a decrease in the concentration of some chemical elements and with it, in the electrical conductivity.

Biological characterization

Pathogenic microorganisms

Table 5 shows the contents of pathogenic microorganisms corresponding to treatments A and B. The values for the determination of the presence of coliforms were significantly lower than the limit of less than 1000 NMP of individuals/g dry weight ⁷, as criteria of acceptable quality of use for this type of material; there was also total absence of Salmonella. This information indicates that the RSU used are not a contaminant or risk material due to the presence of these microorganisms, which adds to the fact that the route of their identification and collection makes them representative of the microbiological quality standard of this type of material.

This response pattern for microbiological analyzes, together with the pasteurizing character ³³, as an attribute of composting processes bases the decision not to perform similar analyzes on composts obtained in cases like this, although they are essential for materials input to the process

Table 5 Microbiological characterization of initial samples of RMA and RMA + cow manure piles 

Microorganism	Without inoculum	With inoculum
Total coliforms NMP/g (dry weight)	44.4	220
Thermotolerant coliforms NMP/g (dry weight)	≤0.2	≤0.2
Salmonella sp.	Absent	Absent

Legend: average data of six observations per date

Obviamente, la mayor cantidad de coliformes totales propia del tratamiento B, se debe a la inclusión del estiércol vacuno ³⁹, como parte del material presente en las pilas de compostaje.

Characterization of composts obtained from solid waste from agricultural markets in Havana

Chemical characterization

The results of the chemical analysis of the composts obtained according to treatments A and B in Table 6 are shown.

The pH values were similar when evaluating this parameter in agricultural waste composts with values of 8.85 ²⁹. Studies in the decomposition of organic waste under an open and closed composting system associated the increase in pH at the high temperatures that occurred during the thermophilic stage due to the metabolic action of some types of acids such as carboxylic and phenolic groups and the consequent mineralization of organic matter ⁴⁰.

Mature RSU composts have a neutral or slightly alkaline pH ³⁶; the deviations from this behavior would indicate a lack of completeness in the maturation of the compost and consequently, that they are not suitable for agricultural use. Because of this basic quality, the composters can be used as amendments to acid soils, where there is an increase in pH in them, even buffering the pH drops caused by some mineral fertilizers, both on neutral or alkaline soils. , the same procedure does not cause appreciable changes in pH ⁴¹.

Table 6 Analysis of samples of RMA and RMA + beef manure composts 

Determinations	Treatments	Indicador
		Minimum value	Maximum value	Median	Mean	Standard deviation
pH in water	without inoculum	8.92	9.10	8.95	8.99	0.09
	with inoculum	8.32	8.98	8.57	8.62	0.29
C. E.	without inoculum	7.70	8.94	7.86	8.02	0.46
	with inoculum	4.07	6.50	5.49	5.32	0.89
M. O.	without inoculum	21.82	32.36	23.63	25.79	4.32
	with inoculum	22.20	32.30	29.45	28.21	3.93
Na	without inoculum	0.03	0.13	0.12	0.10	0.04
	with inoculum	0.05	0.10	0.07	0.07	0.02
K	without inoculum	1.02	2.80	1.78	1.87	0.76
	with inoculum	1.01	1.56	1.30	1.31	0.21
Mg	without inoculum	0.10	0.30	0.17	0.17	0.08
	with inoculum	0.10	0.70	0.10	0.25	0.25

Legend: pH; electrical conductivity: ms • cm^-1; organic matter, Na, K and Mg:%; data from six samples composed by analytical determination

The electrical conductivity values were adequate to the range they propose for this indicator ³⁶. It recognizes relatively high salt concentrations in RSU composts and coincide with ^42,43 by pointing out that their application to the soil, especially at high doses may increase the salt content of this medium, which would have an adverse effect on the germination and development of species of agricultural interest. However, it is still encouraging that, because of the incorporation of manure into the process, the electrical conductivity decreased significantly in the order of 40 %, thus giving rise to a product of lesser impact on similar land ownership.

The percentages of organic matter, which in any case equal to not less than 85 % of the values of biotransformed materials, can be interpreted as efficiency indicators in the use of processed MSW. It is documented that during the composting, there are events of reduction of the amount of organic matter present, through mineralization processes that involve loss of carbon in the form of CO₂ and that can reduce mass by up to 20 % initial of the material undergoing biotransformation; Other authors ³¹ have described similar events from their respective experiences. However, they plan that the values of organic matter at the end of the composting process were adequate to be higher than 20 % ⁷.

The sodium, potassium and magnesium contents are lower than their corresponding initial values in Table 4, which is related, in addition to the reduction of the mass of material during composting, with the possible loss of both elements by leaching which occurs in the batteries, throughout the composting process; equal interpretation offer ²⁹.

Biological characterization

Phytotoxicity

An adequate process of composting organic waste and the achievement of a quality compost must guarantee its use in agriculture, without causing harmful effects on the soil or plants. However, it has been pointed out that there is no greater consensus regarding the determination of the moment or conditions of the composts ³¹.

Thus, the maturity of the composts can be established by germination tests, with species sensitive to phytotoxic substances. An unfinished composting material contains unstable chemical compounds such as organic acids that are toxic to seeds and plants ⁷ and that have been shown to have an inhibitory effect on the germination of seeds of certain species.

Regarding phytoxicity, Table 7 shows the results of the germination test conducted with Raphanus sativum L. Both composts (treatments A and B) presented moderate phytotoxicity, according to the gradation ²³, although the compost produced according to variant B, was characterized by a

better response, according to the range established by the authors for the evaluation and that admits values from 50 % to 80 % for that category of the indicator.

Table 7 Evaluation of the Germination Index of samples of RMA and RMA + cow manure composts 

Indicator	Treatments	Minimum value	Maximum value	Median	Mean	Standard deviation
Germination index	without inoculum	56.9	60.4	56.9	58.1	2.0
	with inoculum	68.5	70.0	69.2	69.1	0.8

Legend: Germination index:%

Some authors have related this affectation with the high concentration of salts attributed to

composts, because of the conductivity values that characterize them ⁴⁴. This property would not invalidate the use of composts obtained in this case, since the greater use value of organic matter carriers in Cuban agriculture is associated with their use as components of substrates prepared for the production of seedlings of various species of interest and for production under organopony conditions.

However, although the result does not limit the use of composting as an alternative for the management of these MSW, the best response obtained with the inclusion of manure as a microbial inoculant in several of the evaluations, also identifies demands for knowledge to be addressed in the Search for the best treatment option for these residuals.

Basal respiration

Table 8 shows the result of the basal respiration tests performed on the samples of the composts obtained in treatments A and B. This test was applied as an indicator or termination criterion of the biotransformation process where values <2 mg CO₂∙g of sample^-1 correspond to a notable reduction in microbial activity, associable to the cessation of composting and by extension, to the maturation or biological stabilization of compost ⁴⁵.

Table 8 Evaluation of Baseline Respiration of samples of RMA and RMA + cow manure composts 

Indicator	Treatments	Minimum value	Maximum value	Median	Mean	Estándar Deviation
Respiración basal	Sin inóculo	1,15	1,65	1,47	1,43	0,22
	Con inóculo	1,20	1,65	1,60	1,81	0,56

Legend: Basal respiration: mg CO₂ • g of sample^-1

Note how the values obtained meet the criteria of use of the indicator, for any of the composting variants put into practice. This result allows us to state that the composting process took place in 112 days, according to treatment A and in 105 days (one week less) with the addition of cattle manure, that is: according to variant B, as shown in Figure 1 in which the respective moments at which the ambient temperature was reached are shown.

CONCLUSIONS

• Composting is a viable alternative for the management of urban solid waste generated by agricultural markets and obtaining an organic fertilizer for possible agricultural use.

• The inclusion of cattle manure as a microbial inoculant in this process improves the efficiency of biotransformation and shortens its duration by ten days.

• The contents of heavy metals and the presence of pathogenic microorganisms in these waste materials do not offer risks of environmental contamination, associated with their collection and handling for composting purposes, or the agricultural use of the composts produced.

• The biotransformation process through the composting of this type of RSU allows the recovery in composts of a high percentage of the organic matter content initially present.

BIBLIOGRAFÍA

1. Arozarena N, González R, González A, González P, Pozo J, Ramos H, et al. Solid Urban Wastes as a source of organic substratum for agriculture: Minimum period of composting before use them as earthworm food. Revista Latinoamericana de Química 29(Suplemento Especial). 2001;125.

2. Habitat ONU. Estado de las ciudades de América Latina y el Caribe 2012. Rumbo a una nueva transición urbana. UN Habitat: Nairobi. 2012;196.

3. Reyes Curcio A, Pellegrini Blanco N, Gil R, E R. El reciclaje como alternativa de manejo de los residuos sólidos en el sector minas de Baruta, Estado Miranda, Venezuela. Revista de Investigación. 2015;39(86):157-70.

4. Muñoz JM, Muñoz JA, Rojas CM. Evaluación de abonos orgánicos utilizando como indicadores plantas de lechuga y repollo en Popayan, Cauca. Biotecnología en el Sector Agropecuario y Agroindustrial. 2015;13(1):73-82.

5. Castro G, Daza M, Marmolejo L. Evaluación de la adecuación de humedad en el compostaje de biorresiduos de origen municipal en la Planta de Manejo de Residuos Sólidos (PMRS) del Municipio de Versalles, Valle del Cauca. Gestión y Ambiente. 2016;19(1):179.

6. Bernui F, Rivero J. Obtención de abono orgánico (compost) a partir de desechos agroindustriales y su influencia en el rendimiento del cultivo Zea Mays. Revista CIENCIA Y TECNOLOGÍA. 2017;12(1):45-56.

7. Román P, Martínez MM, Pantoja A. Manual de compostaje del agricultor: Experiencias en América Latina. FAO; 2013.

8. MINAG. Lineamientos de la Agricultura Urbana, Suburbana y Familiar para el año 2018. Ministerio de la Agricultura, INIFAT, Grupo Nacional de Agricultura Urbana; 2018.

9. Morales-Maldonado ER, Casanova-Lugo F. Mezclas de Sustratos Orgánicos e Inorgánicos, Tamaño de Partícula y Proporción. Agronomía Mesoamericana. 2015;26(2):365-72. doi:10.15517/am.v26i2.19331

10. Reyes OES, Orozco MCA, Tenorio EB. Evaluación preliminar de residuos sólidos en la Plaza de Mercado del municipio de Puerto Tejada (Cauca). RIAA. 2018;9(2):4.

11. Cury K, Aguas Y, Martinez A, Olivero R, Ch LC. Residuos agroindustriales su impacto, manejo y aprovechamiento. Revista Colombiana de Ciencia Animal-RECIA. 2017;122-32.

12. Sánchez DMA, Parra ALR, Ortega FS, Acevedo GM. Producción de abono orgánico mediante el compostaje aerotérmico de residuos de poda. BISTUA REVISTA DE LA FACULTAD DE CIENCIAS BASICAS. 2019;16(1):156-62.

13. Bertolí M, Terry E, Ramos D. Producción y uso del abono orgánico tipo Bocashi. Una alternativa para la producción de los cultivos y la calidad de los suelos. Mayabeque, Cuba: Ediciones INCA; 2015. 50 p.

14. Azurduy S, Azero M, Ortuño N. Evaluación de activadores naturales para acelerar el proceso de compostaje de residuos orgánicos en el municipio de Quillacollo. Acta Nova. 2016;7(4):369-88.

15. Ballesteros Trujillo M, Hernández Berriel M del C, de la Rosa Gómez I, Mañón Salas M del C, Carreño de León M del C. Crecimiento microbiano en pilas de compostaje de residuos orgánicos y biosólidos después de la aireación. Centro Azúcar. 2018;45(1):1-10.

16. Hang S, Castán E, Negro G, Daghero A, Buffa E, Ringuelet A, et al. Compostaje de estiércol de feedlot con aserrín/viruta: características del proceso y del producto final. Agriscientia. 2015;32(1):55-65.

17. Norma Cubana. Humus de lombriz. Determinación de pH, Conductividad eléctrica, cloruro y sodio solubles. La Habana; 1019, 2014. p. 8.

18. Kalra Y. Handbook of reference methods for plant analysis. CRC press; 1997.

19. Norma Ramal. Tejido vegetal. Determinación de nitrógeno, fósforo y potasio. La Habana; 144, 2010. p. 13.

20. Norma Ramal. Tejido vegetal. Determinación de calcio y magnesio. La Habana; 145, 2010. p. 9.

21. Norma Ramal. Tejido vegetal. Determinación de elementos trazas (zinc, manganeso, hierro y cobre). La Habana; 146, 2009. p. 7.

22. Alvarez-Sánchez ME, Marin-Campos A. Manual de procedimientos analiticos de suelo y planta. Universidad Autónoma de Chapingo, Texcoco. 2011.

23. Zucconi F. Evaluating toxicity of immature compost. Biocycle. 1981;22(2):54-7.

24. Font-Vila L. Estimación de la calidad del suelo: criterios físicos, químicos y biológicos [Doctorado]. [Mayabeque, Cuba]: Instituto Nacional de Ciencias Agrícolas; 2007. 82 p.

25. Norma cubana. Determinación del número más probable de coliformes totales y fecales. La Habana; 93-01-128, 1988.

26. ISO 9308-2. Water quality-detection and enumeration of coliform organisms, thermotolerant coliform organisms and presumptive Escherichia coli-Part 2: Multiple tube (most probable number) method. 1990;

27. ISO 6340. Water Quality, Detection of Salmonella Species. International Organization for Standardization; 1995.

28. Bhadra A, Bhattacharjee D, Paul M, Singh A, Gade PR, Shrestha P, et al. The meat of the matter: a rule of thumb for scavenging dogs? Ethology Ecology & Evolution. 2016;28(4):427-40.

29. Hanníbal B, Rafaela V, Guevara L. Obtención de compost a partir de residuos sólidos orgánicos generados en el mercado mayorista del Cantón Riobamba. European Scientific Journal. 2016;12:76-94.

30. Jara M, Gaibor CS, Garcia Y, Garcia Y, Guerra YR, Chafla AL. Parámetros físico-químicos y contenido de coliformes de un compost obtenido a partir de residuos orgánicos del Camal Frigorífico Riobamba. Revista Amazónica Ciencia y Tecnología. 2016;5(3):252-63.

31. Guzmán-Cedeño AM. Comportamiento del compost de residuos agropecuarios con la inoculación de un preparado microbiano autóctono de Manabi, Ecuador. Tesis. Ph. D. Ciencias Agrícolas. Universidad de Matanzas. Matanzas. Cuba; 2015.

32. López GJC. ¿Cómo incrementar la materia orgánica del suelo en la actividad ganadera del trópico? Avances en Investigación Agropecuaria. 2018;22(3):37-44.

33. Trejo Vázquez R. Procesamiento de la basura urbana. 1a. ed. México: Trillas; 1994. 283 p.

34. Villacis ECA, Murillo RMA, García FHC, Delgado HEV. Uso de biopreparados en el compostaje de residuos orgánicos urbanos. Revista ESPAMCIENCIA ISSN 1390-8103. 2016;7(2):135-41.

35. González JES, Cuéllar EE, Cuéllar AE, de Almeida FM, Espinosa RR. Aplicación de abonos orgánicos en la producción de material de propagación en el cultivo del boniato (Ipomoea batatas (L.) Lam.). Agricultura Tropical. 2018;4(2).

36. Hugo V, Basantes C, Gavilanes I, Bustamante M, Paredes C. Co-compostaje de residuos vegetales y estiércol. Efecto del sistema de aireación y del tipo de estiércol en la evolución del proceso y en la calidad de los compost obtenidos. In Valencia, España: Instituto Valenciano de Investigaciones Agrarias; 2018 [cited 2019 Sep 9]. p. 133-9. Available from: https://www.researchgate.net/publication/331431276_Co-compostaje_de_residuos_vegetales_y_estiercol_Efecto_del_sistema_de_aireacion_y_del_tipo_de_estiercol_en_la_evolucion_del_proceso_y_en_la_calidad_de_los_compost_obtenidos

37. Muñiz O. Los microelementos en la agricultura. Agrinfor; 2008. 132 p.

38. Muñiz O, Rodríguez M, Álvarez A, Accioly A, Nascimento C. Ciencias Ambientales. Temáticas para el Desarrollo. In: Ruiz J, Castelán R, Tamariz V, Hernández M, editors. Criterios de contaminación por metales pesados en suelos y abonos orgánicos en Cuba. México: Universidad Autónoma de Puebla; 2014. p. 83-96.

39. Salcedo M del RJ, Romero LLL, Villalobos JAM, Viramontes UF. Dinámica de crecimiento microbiológico y su relación pon pH y la conductividad eléctrica en composta. Agrofaz: publicación semestral de investigación científica. 2016;16(2):17-26.

40. Villanueva DBC. Descomposición de la biomasa de residuos orgánicos bajo un sistema de compostaje abierto y cerrado. BioScience. 2015;2(1):21-30.

41. Gallardo-Lara F, Navarro A, Nogales R. Extractable sulphate in two soils of contrasting pH affected by applied town refuse compost and agricultural wastes. Biological wastes. 1990;33(1):39-51.

42. Huerta Muñoz E, Cruz Hernández J, Aguirre Álvarez L, Caballero Mata R, Pérez Hidalgo LF. Toxicidad de fertilizantes orgánicos estimada con bioensayo de germinación de lechuga. Terra Latinoamericana. 2015;33(2):179-85.

43. López Bravo E, Rivera A, Javier A, Herrera Suárez M, Gonzalez Cueto O, García de la Figal Costales A. Propiedades de un compost obtenido a partir de residuos de la producción de azúcar de caña. Centro Agrícola. 2017;44(3):49-55.

44. López-Clemente XA, Robles C, Velasco-Velasco VA, Luna JR, Valle JRE del, Ortiz GR. Propiedades físicas, químicas y biológicas de tres residuos agrícolas compostados. CIENCIA ergo-sum. 2015;22(2):145-52.

45. Bernal M, Hunce S, Clemente R. Repercusión de las propiedades del agente estructurante en la generación de energía durante el compostaje. In Valencia, España: Instituto Valenciano de Investigaciones Agrarias; 2018. p. 321-7.

Received: February 04, 2019; Accepted: May 13, 2019

^*Author for correspondence. [e-mail]