Composting as a Cleaner Production Strategy for the Soil Resource of Potato Crops in Choconta, Colombia

Abstract

Choconta is the municipality in Colombia with the greatest prevalence of potato planting, representing 70.90% of the total territory. However, this crop has been affected by the presence of pests, diseases, and chemical contaminants from pesticides and chemical fertilizers that deteriorate the soil and, therefore, the quality of the final product. Compost (organic waste with specific characteristics and made from waste generated in Choconta) was studied as a sustainable production strategy to increase soil quality and thereby the quality of the local potato crop. For this purpose, a 3 × 2 experiment design was implemented with three treatments (0%, 25%, and 50% compost) and two variables (young potato and mature potato) in duplicate for 4 months. In this experiment, the use of compost led to an improved final product, which went from a floury texture to a dense and creamy texture. The use of compost also reduced the levels of heavy metals, such as lead, with a higher removal in treatment 3 (50% composting). The estimated direct cost of the composting process was USD 280.85, slightly lower than that of the application of fertilizers at USD 294.48. The use of fertilizers has a higher environmental impact due to the use of chemical products that have environmental and health implications. Using compost did not influence tuber harvest time but had a positive impact on tuber texture quality and on soil resources through the reduction in heavy metals, especially lead (16.40–18.03 ppm for treatment 1, 17.96–18.49 ppm for treatment 2, and 15.67–17.88 ppm for treatment 3). Using compost could be environmentally and economically beneficial for local farmers, and it promotes the circular economy and sustainable communities.

1. Introduction

The potato is a fundamental food in the Colombian economy and diet with a per capita consumption of 57 kg per year [1]. With an annual production of 21.5 million tons, the potato is grown principally in nine departments, the most important of which are Cundinamarca, Boyaca, Nariño, and Antioquia. In the case of Cundinamarca, 88,238 hectares are suitable for potato cultivation, especially within the municipalities of Villapinzon, Choconta, Tausa, and Subachoque. In these areas, residents mainly plant Pastusa potato (Solanum tuberosum subspecies andígena) during the months of February–May (30%), June–August (30%), and September–December (20%) [2].

Potato cultivation is an agricultural activity of great commercial interest to Colombia, but it is affected by various issues that threaten production and harvest quality. Gout disease, produced by the fungus Phytophthora infestans through poor manufacturing practices and environmental contamination, affects not only the potato itself, but also local soil quality [3,4]. In addition, soil contaminants, such as pesticides, which are generally extremely toxic substances for living beings, can affect crops and cause serious health problems for consumers [5,6]. Likewise, the presence of heavy metals (such as copper, lead, zinc, and cadmium) from industrial activities (mining, smelting, metallurgical industries that manufacture iron and steel, domestic waste, and electricity generation), can provide a high degree of toxicity due to their stability and dispersion for the formation of chelates [7,8,9]. Finally, the consequences of climate change and global warming directly affect agriculture and soil through the depletion of carbon and energy sources for crop development, leading to the deterioration of health and food security of the population of the affected area [10,11].

Two previous studies informed the development of this research. In the first, the conditions of potato cultivation and soil resources in Choconta were analyzed. The productivity of the municipality has been diminished by the use of chemical fertilizers that diminish favorable physicochemical soil properties, diseases, such as gout, and environmental pollution due to climate change and global warming. This environmental damage has led to a decrease in the quality of local agricultural products and, therefore, alterations in the food chain and human health.

In view of the aforementioned problems, more sustainable production strategies are being implemented to protect and recover agricultural crops, such as waste valorization, organic fertilizers, remediation, and the use of microorganisms, which help to enhance crop growth, and, thus, consequently reduce associated risks [12,13,14,15]. The second study that informed this research used a selection matrix for each of the above-mentioned strategies and established that composting is the most effective tool for waste valorization and soil potentiation in agricultural crops, as it has a lower production cost, high effectiveness within a shorter time, long-term benefits, and results in a long-term increase in nutrients in crops and bio-actives present in the soil. This strategy provides a possible alternative production strategy to implement in Choconta to solve the current issues associated with potato cultivation.

This research seeks to implement and evaluate the effectiveness of composting as a more sustainable production strategy for potato crops in Choconta, potentially providing an innovative solution to reuse agricultural waste and minimize social, environmental, and economic problems as a consequence of climate change, global warming, and poor manufacturing practices. From the present research, the reuse of agricultural waste products in soil resources for potato cultivation in Chocontá should be developed and promoted. This can also be externalized to other places where potatoes are grown, where using compost could reduce the presence of heavy metals in the soil and increase the quality of the final product, ensuring food safety and reducing environmental pollution.

2. Materials and Methods

2.1. Study Location

Choconta is located in the department of Cundinamarca in Colombia, approximately 75 km from Bogotá D.C., which provides the region with agricultural economic growth opportunities for the variety of fruits, vegetables, and tubers that are offered there. Choconta is part of the Northern Sabana bordering Suesca, Sesquile, Guatavita, Manta, Tibirita, Villapinzon, and Macheta, forming the province of the Almeydas shown in Figure 1 [16].

2.2. Soil Collection

The first step of the research was to collect soil, specifically soil from Choconta used for potato cultivation. The protocol used for soil collection was based on the integrated management of potato cultivation from the Colombian Agricultural Research Corporation (Corpoica) Technical Manual [16]. The site selected for the soil sample was cleared to eliminate vegetation cover, and the organic matter and soil that favors potato cultivation (black soil) was identified and extracted with a shovel.

A total of 62 kg of soil was extracted for planting the tuber selected for this study, the Pastusa potato (S. tuberosum subspecies andígena). The soil was transferred to Bogotá in sacks, which were sealed to avoid cross-contamination. The ideal humidity (~83%) and temperature (12–18 °C) conditions for cultivation [2] were simulated using a homemade greenhouse, and the tubers were planted at a depth of 6 cm in the soil brought from Choconta.

2.3. Soil Physicochemical Characterization

The soil from Choconta was analyzed in the laboratory to identify physicochemical properties, such as texture, granulometry, density, mineralogy, and organic matter content. This analysis was necessary to establish the soil type and identify its potential influence on the development and growth of the tuber crop.

2.3.1. Determination of Minerals in the Soil (Mineralogy)

The mineral composition of the soil was studied using a reaction with hydrogen peroxide (effervescence) and a microscope test [17] in which 3 g of finely sieved soil were added to a 600 mL beaker, along with 20 mL of distilled water to eliminate organic matter through oxidation. Oxygenated water was added to the soil, and the beaker was heated for 5 min, until no more effervescence was present. Once the soil sample was dry, it was deposited on a watch glass and passed through a magnet to study the presence of magnetite. The sample was then examined under the microscope for observation of mineral presence in the soil (quartz, feldspars, micas, calcite, hornblende, and pyroxenes).

2.3.2. Determination of Organic Matter

The determination of organic matter was performed by the calcination or loss on ignition method [18]. For this, the muffle was heated to a temperature of 600 °C, the crucible was removed from the desiccator, and its empty weight was determined (A). Subsequently, 2 g of soil sample were deposited and the weight was recorded (B). Finally, the crucible was placed in the muffle for 1 h and the weight of the crucible with the soil sample was recorded at the end of the process (C). The organic matter content was calculated using Equation (1), and the organic carbon content was calculated with Equation (2) using the conventional Van Bemmelen factor, as follows [19]:

$$\%\mathrm{organic}\mathrm{matter}={\displaystyle \frac{\left(\mathrm{B}-\mathrm{A}\right)-\left(\mathrm{C}-\mathrm{A}\right)}{(\mathrm{B}-\mathrm{A})}}$$

(1)

$$\%\mathrm{organic}\mathrm{carbon}=\%\mathrm{organic}\mathrm{matter}\times 1.7240$$

(2)

The levels of organic matter found in the soil of the municipality of Choconta were compared with the percentages of organic matter present in non-volcanic soils established by the United Nations Food and Agriculture Organization (FAO) [20].

2.3.3. Soil Texture Determination

To determine soil texture, the soil texture classification algorithm established by the United States Department of Agriculture (USDA) for the calculation of soil moisture by feel and appearance was followed [21].

2.3.4. Soil Granulometric Analysis

The sieving process from the United States Department of Agriculture (USDA) [21] was used to determine the sand, silt, and clay contents of the soil sample.

2.4. Tuber Selection

The tuber used for the research project is the pastusa potato (S. tuberosum subspecies andígena), which is the most commonly produced potato in Choconta. The potato is cultivated on 850 hectares within the municipality, with a production of 15–20 tons per hectare [22]. The tuber sample used for the project was purchased at the Paloquemao Market Place in Bogotá, D.C. For this study, two variables were evaluated in relation to maturation time: a young potato (sprouting stage) and a mature potato (presenting root and seed).

2.5. Selection of Compost

The compost was purchased at the Mercado Nacional de Plantas in Bogotá and contained vegetable residues, bovine rumen, cellulose, and food industry residues from Choconta.

Table 1. Compost properties.

Physicochemical Properties	Composition
Total phosphorus (P2O5) (%)	3.50
Total calcium (CaO) (%)	25.80
Total iron (Fe) (%)	1.10
Total silicon (SiO2) (%)	23.80
Total sodium (Na) (%)	0.86
Total oxidizable organic carbon (%)	11.40
Maximum humidity (%)	15.00
pH	7.78
Density (g/cm3)	0.84
Electrical conductivity (dS/m)	9.62
Salmonella	Absent/25 g
Total coliforms (NMP/g)	5.90

shows the properties of the compost according to ICA registration No. 12000 in the name of Biocarbono S.A.S ESP [23].

2.6. Experimental Design

The following 3 × 2 experimental design was implemented using two qualitative independent variables, namely tuber maturation (young potato and mature potato) and compost concentration (0%, 25%, and 50%), to analyze the use of compost as a sustainable production strategy for potato crops. The first treatment did not include compost for use as a control to demonstrate the effectiveness of the strategy proposed in this research. Each treatment was carried out in duplicate.

Subsequently, the initial hypothesis was stipulated in relation to the tuber harvest time, which is less than 4 months. A 3 × 2 experimental design analyzed by means of ANOVA was used to verify and validate the initial hypothesis.

For the experimental design, the following hypothesis was proposed:

Ho: Tuber harvest time < 4 months.

Ha: Tuber harvest time > 4 months.

Variables:

Potato maturity time—Variable A (independent):

• Young potato (sprouting stage).
• Mature potato (presence of root and seed).

Compost concentration—Variable B (independent):

• 0% compost (0 kg).
• 25% compost (2 kg).
• 50% compost (4 kg).

2.7. Method for Potato Cultivation

To plant the potatoes, 12 black sacks of 10 kg capacity were filled according to the compost proportion described in the experimental design (0%, 25%, 50%) [24]. The percentages were taken in relation to the total of 8 kg of soil contained in each bag. Figure 2 shows the setup for potato cultivation implemented in this research. The greenhouse where the potatoes were grown simulated the humidity (~83%), pH (5.5–7), and temperature (12–18 °C) conditions of Choconta.

Humidity, pH, and temperature were measured at the beginning, midway, and end points of the experiment to monitor conditions. The crops were watered weekly. Bromatological analyses were conducted, measuring the carbon/nitrogen ratio (C/N), the total nitrogen from the Kjeldahl method with the comparison of organic nitrogen with ammoniacal nitrogen from compost [25], and the organic matter from the calcination or loss on ignition method [18] and the Dumas or dry combustion method [26], using the Van Bemmelen factor [19]. These analyses were performed at the beginning of the experiment to determine initial soil conditions and later at the midway and end points. Similarly, during the process, a mineral characterization of the soil was performed using a portable X-Ray fluorescence (XRF) device [27].

After 4 months, the quality of the final product was evaluated in relation to organoleptic properties, tuber length and diameter, and yield per treatment.

2.8. Overall Estimated Project Cost

Estimated costs of the use of compost as a sustainable production method for potato cultivation in Choconta were compared with the estimated costs of using chemical fertilizers. Parameters, such as raw material, labor, and packaging, were evaluated.

3. Results

3.1. Quantitative Physicochemical Characterization of the Soil

The results of the initial quantitative soil analyses for density, porosity, organic matter, organic carbon, and temperature are shown in

Table 2. Quantitative soil analysis results.

Physicochemical Properties	Composition
Soil particle density (g/mL)	2.63
Bulk density (g/mL)	4.14
Actual density (g/mL)	1.56
Soil porosity (%)	62.32
Organic matter (%)	1.85
Organic carbon (%)	3.19
Temperature (°C)	20.40

.

3.2. Qualitative Physicochemical Characterization of the Soil

3.2.1. Determination of Soil Minerals

During the mineral characterization, passing a magnet over the soil revealed the presence of magnetite. Additionally, the presence of quartz (irregular, similar to broken glass), feldspars (orange colors), hornblende, and pyroxenes (dark green fibers) were identified using a 10× microscope, as shown in Figure 3.

3.2.2. Texture and Particle Size Analysis

The analysis of the physical characterization of the soil in relation to texture and granulometric analysis was performed, which resulted in the classification of the soil as silty clay based on the soil texture classification algorithm [20].

Table 3. Soil granulometric analysis.

Mesh	Sample Weight (g)
2 mm	56.40
710 µm	51.60
425 µm	23.80
180 µm	52.80
75 µm	13.20
38 µm	0.22

shows the granulometric analysis, with 198.02 g of total soil sample acquired from the sieving process. The sand fraction was 66.22% and the silty-clay soil fraction was 33.78%, which corroborates that the sample corresponds to clayey soil, suitable for potato cultivation.

$$Sandfraction=198.02\mathrm{g}-131.80\mathrm{g}=66.22\%$$

(3)

$$Clay-loamfraction=100\%-66.22\%=33.78\%$$

(4)

3.3. Characterization of the Tuber

Six young and six mature potatoes (shown in Figure 4) were selected for evaluation, comparing length, diameter, and organoleptic characteristics at the beginning and end of the process. The characteristics of the potatoes are detailed in

Table 4. Characterization of young and mature potatoes at the initial and final measurements.

Treatment	Physical Characteristics	Young Potato		Mature Potato
		Initial	Final	Initial	Final
1	Length (cm)	52.94	21.17	46.18	14.80
	Diameter (cm)	16.85	6.74	14.70	4.71
	Average weight (g)	125.02	100.17	45.63	25.32
	Odor	Toilet	Toilet	Toilet	Toilet
	Color	Cream pink	Cream pink	Cream pink	Cream pink
	Taste	Sweet and earthy	Sweet and earthy	Sweet and earthy	Sweet and earthy
	Texture	Floury	Floury	Floury	Floury
2	Length (cm)	57.16	25.70	46.50	15.17
	Diameter (cm)	18.20	8.18	14.80	4.83
	Average weight (g)	125.32	100.21	45.56	25.73
	Odor	Toilet	Toilet	Toilet	Toilet
	Color	Cream pink	Cream pink	Cream pink	Cream pink
	Taste	Sweet and earthy	Sweet and earthy	Sweet and earthy	Sweet and earthy
	Texture	Floury	Dense and creamy	Floury	Dense and creamy
3	Length (cm)	55.61	23.97	42.41	11.56
	Diameter (cm)	17.70	7.63	13.50	3.68
	Average weight (g)	125.23	100.12	45.32	25.42
	Odor	Toilet	Toilet	Toilet	Toilet
	Color	Cream pink	Cream pink	Cream pink	Cream pink
	Taste	Sweet and earthy	Sweet and earthy	Sweet and earthy	Sweet and earthy
	Texture	Floury	Dense and creamy	Floury	Dense and creamy

.

3.4. Potato Cultivation Process

Initial, midway, and final soil analyses were conducted to determine the physicochemical properties of the tuber during the planting, growing, and harvesting stages. The properties evaluated (shown in

Table 5. Initial, midway, and final measurements.

Physicochemical Characterization of the Soil
Treatment	Physicochemical Properties	Initial	Midway	Final
1	Organic matter (%)	1.85	1.80	1.73
	Organic carbon (%)	3.19	3.10	2.98
	Temperature (°C)	18.00	19.00	18.00
	pH	6.85	6.88	6.78
	Humidity (%)	71.74	66.25	70.05
	Fe (ppm)	9104.35 +/− 218.25	9169.20 +/− 304.88	9132.05 +/− 304.50
	Zn (ppm)	101.68 +/− 11.09	70.34 +/− 7.70	70.06 +/− 7.64
	Sr (ppm)	181.54 +/− 6.10	171.20 +/− 5.65	172.55 +/− 5.70
	Zr (ppm)	102.19 +/− 6.06	128.75 +/− 6.85	129.95 +/− 8.65
	Mn (ppm)	211.72 +/− 51.02	170.25 +/− 43.35	171.75 +/− 43.25
	Rb (ppm)	12.43 +/− 1.95	10.65 +/− 1.71	10.74 +/− 1.70
	Pb (ppm)	18.03 +/− 4.25	16.44 +/− 4.00	16.40 +/− 4.00
	Cu (ppm)	36.16 +/− 9.10	26.13 +/− 6.63	26.21 +/− 6.75
	Ti (ppm)	1839.14 +/− 370.90	1766.21 +/− 358.73	1768.51 +/− 358.66
2	Organic matter (%)	2.45	2.40	2.34
	Organic carbon (%)	4.22	4.14	4.03
	Temperature (°C)	18.00	19.00	18.00
	pH	6.63	6.88	6.60
	Humidity (%)	68.48	63.44	71.54
	Fe (ppm)	9103.35 +/− 218.22	6952.03 +/− 121.65	9500.63 +/− 163.37
	Zn (ppm)	70.45 +/− 8.0	72.95 +/− 7.65	73.60 +/− 7.60
	Sr (ppm)	186.05 +/− 4.8	173.65 +/− 4.25	174.75 +/− 4.30
	Zr (ppm)	137.15 +/− 5.05	128.30 +/− 5.00	129.30 +/− 4.95
	Mn (ppm)	170.63 +/− 44.88	161.13 +/− 43.13	161.13 +/− 43.00
	Rb (ppm)	12.50 +/− 1.78	11.99 +/− 1.73	12.02 +/− 1.74
	Pb (ppm)	18.49 +/− 4.50	18.29 +/− 4.15	17.96 +/− 4.06
	Cu (ppm)	30.13 +/− 9.25	35.50 +/− 9.00	36.27 +/− 9.13
	Ti (ppm)	1950.20 +/− 378.40	1861.30 +/− 364.60	1868.03 +/− 364.80
3	Organic matter (%)	3.68	3.52	3.45
	Organic carbon (%)	6.34	6.07	5.95
	Temperature (°C)	18.00	19.00	18.00
	pH	6.83	6.73	6.72
	Humidity (%)	68.03	64.40	70.05
	Fe (ppm)	9345.56 +/− 167.51	8511.29 +/− 153.93	8520.29 +/− 154.13
	Zn (ppm)	102.55 +/− 8.85	85.35 +/− 8.20	85.20 +/− 8.15
	Sr (ppm)	188.20 +/− 4.70	176.15 +/− 4.30	176.05 +/− 4.35
	Zr (ppm)	134.58 +/− 5.10	116.15 +/− 5.05	123.45 +/− 5.00
	Mn (ppm)	174.63 +/− 45.50	160.66 +/− 44.18	167.16 +/− 44.17
	Rb (ppm)	10.09 +/− 1.35	14.85 +/− 1.72	10.36 +/− 1.71
	Pb (ppm)	17.88 +/− 4.03	16.94 +/− 4.00	15.67 +/− 4.00
	Cu (ppm)	36.98 +/− 9.33	37.19 +/− 9.15	38.71 +/− 9.21
	Ti (ppm)	1635.38 +/− 367.96	1300.15 +/− 336.00	1369.15 +/− 336.35

) were organic matter, organic carbon, temperature, pH, humidity, and heavy metal levels. The carbon/nitrogen (C/N) ratio and total nitrogen were evaluated in a previous investigation.

4. Discussion

4.1. Quantitative Physicochemical Characterization of the Soil

The organic matter content of the soil from Choconta, ranging from 1.81–2.40%, can be considered to be of medium quality. The decreased organic matter content may be due to the deterioration of vegetation cover in the area and the arrival of intensive agriculture, which may have caused the deterioration of the soil’s phytochemical properties and a reduction in the nutrients necessary for crop development [28].

To improve soil quality in terms of organic matter content, this research evaluated the addition of compost with high nitrogen and carbon content. Compost allows for the sequestration of nutrients during the thermophilic phase and increases the transformation time of manure into humus. Compost previously processed from local livestock and agricultural residues is recommended in order to reuse this resource. Likewise, the addition of compost to crops represents an important source of nutrients for plants and a source of energy for soil microorganisms, improving natural fertility by releasing nutrients during decomposition and increasing cation exchange capacity and the formation of organic compounds and minerals that favor plant nutrients [29].

The use of compost for agriculture has positive effects on soil physical properties by forming aggregates, which increases the structural stability through the formation of exchange complexes in clay soils, increasing water penetration and retention, decreasing erosion, and favoring gas exchange [30,31].

4.2. Soil Physicochemical Characterization

4.2.1. Determination of Soil Minerals

Magnetite is a mineral consisting of Fe(ll) and Fe(lll) found naturally in the lithosphere or formed by biogenic processes. Magnetite is considered a promising adsorbent for the removal or immobilization of heavy metals and other contaminants in soils and water due to its large adsorption surface and high reactivity. The application of magnetite nanoparticles in soil could help remove metals from soils, decreasing contamination from heavy metals, such as lead, arsenic, cobalt, and copper. However, due to the high resistance in the removal of heavy metals, soils with this type of mineral have low fertility in crop development [32,33].

Quartz was also identified in the soil sample. This mineral is rich in fertilizing materials, and although it resists chemical alteration, it is easily reduced to microscopic particles due to its fragility. However, quartz is not considered an important mineral for agriculture, because its decomposition is extremely slow even in tropical climates, and it is difficult to cultivate crops in soils with quartz, since yields drop rapidly after a few good harvests due to nutrient reduction and poor soil composition [34,35].

Feldspars were also identified in the soil sample. Feldspars provide a large proportion of potassium, sodium, and calcium to agricultural soils, elements that are indispensable for plant life. Likewise, hornblende and pyroxene provide high fertility in agricultural soils due to their richness in calcium and magnesium. On the other hand, iron minerals in the soil can cause decreased fertility [34,36].

Due to the presence of minerals, such as quartz, it is necessary to add a source of carbon and nitrogen content, such as compost, which provides fertility and essential components for the development and effective growth of crops. Compost is an effective alternative not only to enhance the physicochemical properties of the soil but also to reuse local agricultural and livestock waste. More sustainable production strategies, such as composting, have the potential to increase food security in Choconta.

4.2.2. Texture and Particle Size Analysis

The soil sample was characterized as clay–loam soil, a great advantage in agriculture, since these soils have the capacity to retain more water than sandy soils and, therefore, do not require constant irrigation. Additionally, these soils are capable of retaining nutrients for plant growth, fundamental for good soil quality, which helps to decompose organic matter from compost, binding soil particles for the formation of soil aggregates. Physicochemical and biological control and monitoring are necessary to avoid cross-contamination and the growth of organisms that can cause diseases and tuber deterioration [37].

4.3. Characterization of the Tuber

At the end of the potato harvest, the final production time of the young potato and the mature potato differed by 15 days, due to the presence of sprouts from the mature potato, which makes it feasible for local growers to plant this type of tuber. However, adding compost did not modify the harvesting time of the tuber, which remained at 4 months.

An average potato production of 6 for treatment 1, 6 for treatment 2, and 7 for treatment 3 was observed, indicating that adding compost did not influence the number of potatoes produced. However, the size and planting space are determinants for the harvest of large tubers or with dimensions similar to the mother seedling, being one of the factors to be improved in future research. The length, diameter, and average weight of the young potato was 21.17 cm, 6.74 cm, and 100.17 g, respectively, for treatment 1; 25.70 cm, 8.18 cm, and 100.21 g for treatment 2, respectively; and 23.97 cm, 7.63 cm, and 100.12 g for treatment 3, respectively. Similarly, in the mature potato, the length, diameter, and average weight was 14.80 cm, 4.71 cm, and 25.32 g, respectively, for treatment 1; 15.17 cm, 4.83 cm, and 25.73 g for treatment 2, respectively; and 11.56 cm, 3.68 cm, and 25.42 g for treatment 3, respectively.

Adding compost was not a determinant for harvest time nor the amount of tuber produced. Additionally, the organoleptic properties (odor, color, and flavor) were the same for all treatments (odorless, creamy pink, and sweet and earthy, respectively). The significant difference was in the texture of the potato, with a floury texture at the end of the process in treatment 1 (0% compost) and a dense and creamy texture in treatments 2 and 3 (25% and 50% compost, respectively). The application of compost at the beginning of the production process improved the final texture quality of the tuber.

4.4. Potato Cultivation Process

The total nitrogen and C/N ratios of the compost used in this research were determined at 1.60% and 15.1/1, respectively [38]. Carbon is an essential biological component for the formation of crop and microorganism structures. Nitrogen influences the synthesis of the protein used for the development and growth of the final product. The C/N ratio was within the range established by Bioagro [39] at below 15.50/1, indicating that the compost used for in this research provides the necessary nutrients for the fertilization and productivity of the final product [40,41].

The physicochemical analyses conducted on the soil revealed that in all treatments the temperature and pH remained within the optimum range for potato growth and development. For treatment 1, the pH and temperature were between 6.78–6.85 and 18–19 °C, respectively; for treatment 2, they were between 6.60–6.88 and 18–19 °C, respectively; and for treatment 3, they were between 6.72–6.83 and 18–19 °C, respectively. Control and monitoring of both soil temperature and pH are important to establish ideal conditions for the potato crop. However, the control and monitoring of humidity (83% max) during this study were complex because of meteorological conditions in Bogotá during March–July 2024 due to the El Niño phenomenon. Although a homemade greenhouse was made which simulated the climatic conditions of Choconta, the El Niño phenomenon altered the humidity levels, which caused the soil to dry quickly in the first weeks. The humidity was 66.25–71.74% in treatment 1, 63.44–71.54% in treatment 2, and 64.40–70.05% in treatment 3.

The organic matter and organic carbon content were measured at 1.73–1.85% and 2.98–3.19%, respectively, for treatment 1; 2.34–2.45% and 4.03–4.22%, respectively, for treatment 2; and 3.45–3.68% and 5.95–6.34%, respectively, for treatment 3. Organic matter has a considerable influence on soil quality and, therefore, on the quality of the final product by providing the crop with carbon, nitrogen, and other nutrients essential for development and growth. By combining the silty-clay soil of Choconta with compost, the organic matter content and overall soil quality was improved, with medium soil for treatment 1 (no compost), moderately rich soil for treatment 2 (25% compost), and rich soil for treatment 3 (50% compost). The presence of compost in the soil for potato cultivation may improve potato quality by reducing soil contaminants and diseases that can affect the development of the tuber, which provides a great opportunity to promote food security and the reuse of organic matter from agricultural residues in Choconta.

The presence of micronutrients, such as iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu), in soil are essential for crop nutrition. As can be seen in Table 5, the iron levels were 9104.35–9169 ppm in treatment 1, 6952.03–9500 ppm in treatment 2, and 8511.29–9345.56 ppm in treatment 3. Zinc levels were 70.06–101.68 ppm in treatment 1, 70.45–73.60 ppm in treatment 2, and 85.20–102.55 ppm in treatment 3. Manganese levels were 170.25–211.72 ppm in treatment 1, 161.13–170.63 ppm in treatment 2, and 160.66–174.63 ppm in treatment 3. Finally, copper levels were 26.13–36.16 ppm in treatment 1, 30.13–36.27 ppm in treatment 2, and 36.98–38.71 ppm in treatment 3.

The presence of iron in soil is essential for the physiological development of plants, as iron is important for the formation of chlorophyll pigment, photosynthesis, and respiration; the absence of this nutrient can cause crop loss and damage [42]. Zinc is an essential element for plant structure and functionality, carbohydrate synthesis during photosynthesis, transformation of sugars into starch, and plant tolerance to pathogens; its absence reduces crop yields by twenty percent [43]. Manganese is involved in chlorophyll synthesis, nitrate assimilation, vitamin synthesis, ATP synthesis, lignin, hormone activation, and cell division [44]. Copper helps in the formation of lignin in cell walls, which is essential for maintaining the vertical position, seed formation, and stress resistance of the plants.

As can be seen in Table 5, strontium (Sr) levels were 171.20–181.54 ppm in treatment 1, 173.65–186.05 ppm in treatment 2, and 176.05–188.20 ppm in treatment 3. Zirconium levels were 102.19–129.95 ppm in treatment 1, 128.30–137.15 ppm in treatment 2, and 116.15–134.58 ppm in treatment 3. Finally, titanium levels were 1766.21–1839.14 ppm in treatment 1, 1861.30–1950.20 ppm in treatment 2, and 1300.15–1635.38 ppm in treatment 3. Strontium acts similarly to calcium, accumulating in plant walls in a stable manner [45]. Zirconium is important for plant water absorption. Titanium is needed for plant physiological processes, plant resistance to disease or pests, crop yield and quality, and tuber root development and regeneration [46].

Rubidium (Rb) levels were 10.65–12.45 ppm in treatment 1, 11.99–12.50 ppm in treatment 2, and 10.09–14.85 ppm in treatment 3. Lead (Pb) levels were 16.40–18.03 ppm in treatment 1, 17.96–18.49 ppm in treatment 2, and 15.67–17.88 ppm in treatment 3. Rubidium and especially lead are highly reactive metals and are toxic to plant cells, negatively affecting natural cycles and, therefore, the germination, development, and growth of plants [47]. Lead can accumulate in the soil causing serious damage to tuber structure and final tuber quality. However, when using compost as organic fertilizer for the plant at the beginning of the production process, lead levels decreased specifically in treatment 3 (50% compost), demonstratign that compost can be a tool to improve soil quality by reducing and mitigating damage caused by heavy metals through reducing their levels.

4.5. Design of Experiments

Using the experimental design, the null hypothesis of the project (harvest time < 4 months) was taken as a reference. The results obtained in duplicate for each of the treatments (0%, 25%, and 50%) were taken for the two variables evaluated: young and mature potatoes. The harvest time of the crop was determined from the tuber size (diameter), resulting in a probability < 1 and a significant difference in the treatments in relation to the critical value of F (5.14–5.99). Therefore, the null hypothesis was rejected, accepting that the potato harvest time is greater than 4 months.

Based on study results, adding compost did not seem to have an effect on the time to harvest of the final product (4 months), but it did seem to improve final product quality and contribute to the removal of and reduction in chemical contaminants, such as rubidium and lead. The higher the portion of compost in the experiment, the greater the removal of lead and the better the quality of the tuber. The potatoes in treatment 3 had a better texture, perhaps due to the change in the physicochemical properties of the soil. It should be clarified that if larger tubers are desired, the planting space should be expanded, using larger bags so that the roots of the tuber have a larger area of growth and development for the production of the final product.

4.6. Sustainability Analysis

The social impact of the use of compost as organic fertilizer for potato cultivation in Choconta could be positive due to the increase in the employment of growers and the reduction in operational costs by avoiding the use of chemical fertilizers that affect the quality of the final product. Similarly, a long-term cooperative alliance between growers and waste collectors through a circular economy could be possible, in which sustainable production strategies, such as composting, can be implemented and scaled by reusing agricultural wastes generated on local farms, which would reduce costs in the production of compost in greater quantities. This has the potential to strengthen agricultural productivity not only in Choconta but also in Cundinamarca as a whole, contributing to sustainable communities [48].

The economic impact of using compost was evaluated and found to be positive, especially in the reduction in costs needed for the purchase and transportation of chemical fertilizers. The increase in the use of organic compost in agriculture would lead to an increase in the supply and demand of the product. The use of compost would allow growers to obtain a higher quality tuber with reduced damage to the environment or human health [49].

Finally, the environmental impact was evaluated. The use of compost could be an environmentally friendly strategy to increase crop quality through a reduction in erosion and heavy metal contamination. Compost use contributes to the reuse of agricultural wastes, an improvement in tuber quality, the promotion of more sustainable production strategies in agricultural crops, increased protection of natural resources, and increased food security. Among the benefits are an increase in soil exchange capacity, increased nutrients necessary for plant life, and increased action of minerals important for fertilization and the absorption of the cell membrane. Finally, the use of compost leads to increased organic matter, which has benefits for biological properties through the process of mineralization, the development of plant cover, and the stimulation of plant growth.

The synthetic matrix of the sustainable development analysis was used to examine the factors of biodiversity, resilience, low carbon, economy, governance, gender, and social (Figure 5) as they relate to this research. The study aims to structurally improve the state of biodiversity and/or ensure the ecological quality and sustainability of natural resources. This research contributes structurally to the country’s low-carbon trajectory, reducing climate risks through actions to strengthen chains, sectors, and territories for the improved stewardship of natural resources and agricultural crops. The findings in this research contribute significantly to the transition towards a more sustainable and resilient economy with the capacity to react to challenges and governance through decision making. In the social field, the project has as a secondary objective to contribute to the empowerment of women, a reduction in gender inequalities, and a reduction in multidimensional inequalities of greater inclusion.

4.7. Overall Project Cost Estimate

In the investigation cost estimation, the direct costs of potato cultivation with compost application were compared in

Table 6. Direct costs of potato cultivation with compost application.

Description	Unit	Quantity	Unit Price (USD)	Total Price (USD)
Raw Materials
Vegetable waste	Kg	250.00	0.00	0.00
Cattle rumen	Kg	50.00	0.20	10.00
Cellulose	Kg	5.00	0.69	3.45
Tricholeb microorganism	Kg	0.50	62.00	31.00
Agricultural wastes	Kg	185	0.00	0.00
Rice husk	Kg	10.00	0.30	3.00
Tuber	Kg	13.00	0.60	7.80
Water	m3	9.00	0.40	3.60
Labor
Cleaning and irrigation	hour	95.00	1.50	142.50
Chopping, mixing, watering	hour	24.00	1.50	36.00
Post-harvest	hour	24.00	1.50	36.00
Packaging
Polyethylene sleeves	-	150.00	0.05	7.50
Total Direct Costs			USD 280.85

and with chemical fertilizer application in

Table 7. Direct costs of potato cultivation with the application of chemical fertilizers.

Description	Unit	Quantity	Unit Price (USD)	Total Price (USD)
Raw Materials
Vitavax	kg	0.25	5.20	1.30
Terraclor	kg	0.20	4.10	0.82
Carbofuran	kg	0.20	4.30	0.86
Nitrofoska blue	kg	2.00	5.30	10.60
Hakapos 13-40-13	kg	20.00	3.30	66.00
Urea 46-0-0	kg	6.00	1.50	9.00
Potassium sulfate 0-0-50	kg	5.00	1.70	8.50
Tuber	kg	13.00	0.60	7.80
Water	m3	9.00	0.40	3.60
Labor
Cleaning and irrigation	hour	95.00	1.50	142.50
Post-harvest	hour	24.00	1.50	36.00
Packaging
Polyethylene sleeves	-	150.00	0.05	7.50
Total Direct Costs			USD 294.48

. The economic estimate was made on a medium scale for a 60 m².

The total direct cost of potato cultivation with compost application was USD 280.85, while the total direct cost with chemical fertilizer application was USD 294.48. This reduction in cost could entail a great competitive advantage for the average farmer in Choconta.

It should be clarified that this financial analysis is general, because it was used to determine the cost of compost application for potato farmers in Choconta.

5. Conclusions

The use of compost as an organic fertilizer for potato crops was effective in reducing heavy metals in the soil and improving the texture of the final product in treatment 3 (50% compost). The addition of compost did not modify the harvest time of the potato crop but did help to improve physicochemical properties of the soil through the presence of iron, zinc, manganese, copper, titanium, and zirconium.

The space and size of the production process site should be increased so that the roots and the plant in general can develop effectively and, thus, obtain tubers of larger dimensions than those obtained in the research. Operating conditions should be monitored and controlled throughout the process, especially temperature, pH, humidity, and organic matter, to avoid the release of unpleasant odors and the presence of microorganisms and crop diseases.

Composting is a beneficial activity for the environment because it reduces the chemical contaminants in the soil. In this research, a reduction was seen particularly in lead levels (16.40–18.03 ppm for treatment 1, 17.96–18.49 ppm for treatment 2, and 15.67–17.88 ppm for treatment 3). Composting represents a competitive advantage in reducing soil contaminants, improving soil structure, and providing necessary nutrients for the improvement of crop quality. This is ultimately beneficial for local farmers and promotes the circular economy and sustainable communities. Using compost is viable economically when developed in situ in Choconta, with a direct cost of USD 280.85 compared to the application of chemical fertilizers at USD 294.48, resulting in a more sustainable agricultural strategy that benefits the community and reuses waste products.