Introduction

In 2015, the United Nations (UN) promoted action for the eradication of human poverty and sustainable development through the ‘Plan of action for people, planet, and prosperity for the next fifteen years’. Fostering sustainable agriculture plays a crucial role in ensuring food security in a world where agricultural productivity is threatened by climate change and resource depletion. Maintaining a healthy environment involves preventing soil erosion, maintaining fertility, efficiently using water resources, reducing water pollution, minimizing the use of chemical fertilizers and pesticides, and preserving biodiversity (United Nations, 2015; Carranza-Patiño et al., 2024; Mercedes et al., 2024).

In crop cultivation, organic mulching is an agricultural technique that covers the soil surface where crops are grown with various materials, such as straw, fallen leaves, and compost. This practice is distinct from synthetic mulching, which utilizes plastic film. Mulching has been reported to suppress weed growth, retain soil moisture, regulate soil temperature, prevent soil erosion, improve soil structure, and supply nutrients. These effects ultimately promote crop growth and significantly improve yield and quality. They can be particularly effective in areas experiencing water shortages due to climate change. However, active research is being conducted on the pros and cons of various mulching materials, such as polyethylene, straw, and biodegradable film, specifically regarding their impacts on weed suppression, thermal regulation and environmental issues like plastic waste (Quintarelli et al., 2022; Xu et al., 2023).

Digitaria eriantha, believed to be native to South Africa, is commonly known as digitgrass or pangola-grass and is a grass native to tropical and subtropical climates. It grows relatively well in a variety of soils, but especially in moist soils. It is drought and flood tolerant, suppresses weed growth, and grows relatively quickly after grazing. This grass is widely used as livestock feed for farmers in subtropical and tropical African regions and is also distributed as a high-quality feed with a crude protein content of 5 - 14% of dry matter in Southeast Asia and Central and South America, countries with similar climates. Since its introduction to Central and South America in the 1950s, it has been widely utilized as a key tropical pasture due to its rapid growth and adaptability to environmental conditions (Osbourn, 1969; Tikam et al., 2013; Jack et al., 2020).

Research on the use of dried plants as mulching materials in Central and South American agriculture is actively underway, with Pangola being one of them (Ramos et al., 2024). Therefore, this study aimed to examine the effectiveness of mulching using dried Pangola as a mulching material for sustainable potato production in the Constanza region. This mulching approach aims to improve agricultural system efficiency and overcome soil degradation and resource depletion.

Materials and Methods

Potato cultivation trials using dried Pangola harvested in La Vega province, Dominican Republic, as a mulching material were conducted in the field at the IDIAF Horticultural Experiment Station in Constanza located at 18°55′ north latitude and 70°44′ west longitude from January to May 2025. The experiment consisted of three treatments with mulch sources and six replications under a randomized complete block design: traditional plastic film (T1), a control (no film and dried plant material, T2) and dried Pangola residues (T3). The test field consisted of 18 blocks each block containing four beds or furrows. Each bed was 0.80 m wide, 4 m long and was divided with 0.25 m distance. 64 potato plants were grown in each treatment unit, and yields were evaluated from the central 28 plants to mitigate edge effects. Based on soil analysis, Horti-1 (14-5-16 + 4S) compound fertilizer was applied at a rate of 1,200 kg ha^-1 after 7 and 30 days after sowing.

The experimental soil samples were collected in a zigzag pattern at a depth of 0 to 15 cm from the soil surface before fertilization and after cultivation, dried in the shade, and prepared according to the National Institute of Agricultural Sciences and Technology (NIAST, 2000) guidelines. The chemical properties of the soil were analyzed according to Page et al. (1982). Soil pH and Electrical Conductivity (EC) were measured at a ratio of 1:2 by the potentiometric method, and organic matter was quantified by the Walkley and Black method after oxidation with potassium dichromate. Available phosphorus was measured by Mehlich III, and exchangeable cations and available silica were quantified after extraction with NH₄OAc and NaOAc, respectively. Trace elements such as iron, copper, manganese, and zinc were quantified by Atomic Absorption spectrophotometry (PinAAcle 900F, Perkin Elmer, U.S.A.) after decomposition with perchloric acid.

Potato yield, soil moisture retention capacity, and soil temperature for each treatment group were evaluated. The potato yield was measured by harvesting the middle furrow of the experimental soil, excluding 0.5 meters from the row ends to avoid edge effects. The weight per usable area per experimental unit was then measured and calculated in tons per hectare. Soil temperature and moisture were measured twice a week throughout the potato crop production cycle, with measurements taken at 10:00 a.m. and 3:00 p.m., depending on weather conditions. The measuring device used was an RF Sensor WT1000N. Fisher's analysis of variance (ANOVA) and Duncan’s test was used to analyze the data to identify significant differences between treatments using InfoStat software.

Economic Efficiency (EE) is calculated by considering the total costs incurred from land provision to harvest and the total revenue from sales for each treatment using the following formula, and a higher value indicates greater profitability. The formulas were:

Benefit=Yield×Saleprice

EconomicEfficiencyEE=Benefit-Costs/Costs

Results and Discussion

The experimental soil pH was 7.4, indicating slightly alkaline. This alkalinity is likely due to the high calcium content (15.8 cmol_c kg^-1), which is significantly higher than the recommended level for the Dominican Republic. This is closely related to the report that the average acidity of agricultural water in the Dominican Republic is 7.7 ± 0.02, and 94.4% of the water has a pH of 7.0 or higher (Cepeda, 2019). EC was measured to be 0.32 dS m^-1 which showed an appropriate level. Organic matter content was 57.3 g kg^-1 and available phosphorus was 69.9 mg kg^-1, indicating adequate for the Dominican Republic recommended level, but Mg content was found to be low (Table 1). In addition, the Dominican Republic uses the relative ratio of cations as an evaluation index, expressing the ratio of each cation in the total content of K, Ca, Mg, and Na cations as saturation (%) and setting the appropriate levels as 3 - 7%, 60 - 85%, 10 - 20%, and <5%, respectively. The results showed that the saturation of Ca was high at 63.2%, while the saturation of Mg was low at 2.9%, requiring appropriate management of Ca and Mg. This promotes the insolubilization of phosphorus by calcium, raising concerns about phosphorus deficiency in crops. (Table 1).

Table 2 shows the contents and ranges of available trace elements such as Fe²⁺, Mn²⁺, Cu²⁺, and Zn²⁺ in experimental soils. In general, the contents are higher than the guidance agency’s appropriate level, so no additional fertilization of trace elements is required.

Table 3 shows the total potato yield data in ton per hectare (Mg ha^-1) for each treatment evaluated in the field. T1 (Plastic film) showed wide variability, with yields ranging from 11.8 to 45.9 Mg ha^-1, indicating a possible influence of the specific conditions of each block. T3 (Dried pangola mulch) maintained high and consistent values ​​across all blocks, exceeding 27.0 Mg ha^-1, with an average yield higher than the other treatments, reaching an average of 46.0 Mg ha^-1. T2 (Conventional control) reached an average of 40.4 Mg ha^-1, ranking above T1 but below T3. There are significant differences in potato yield among the treatments evaluated with the results of a statistical analysis (Duncan test) comparing total potato yield (Mg ha^-1). T2 and T3 produced significantly higher yields than T1, but they did not differ significantly from each other. The highest numerical yield was obtained by T3. Both blocks and treatments showed statistically significant differences in total potato yield (p < 0.05). Regarding vegetative growth, a comparison of the number of stems per plant during the growing season according to treatment revealed that T3 had the lowest number of stems per plant, with an average of 3.98, followed by T1 with 4.57. Conversely, T2 had the highest number of stems per plant, with an average of 6.44. The effect of T3 was also confirmed in the diameter and length of harvested potatoes (data not shown).

Table 3 shows the results of a mean comparison (Duncan test) comparing soil moisture content for each treatment group. There were significant differences among the evaluated treatments. The analyzed data showed that T3 had the highest water retention capacity, while T1 and T2 had similar retention capacities. This finding is consistent with research showing that mulching with wheat and grass residues in a semi-arid region of Peru, where crop production suffers from water shortages, reduces soil moisture evaporation and increases yields in soybean cultivation (Solano Ramos et al., 2024). Flores et al. (2019) also found that using crushed wood chips from pruning fruit and ornamental trees as a mulch increased soil moisture content compared to inorganic mulches. These results suggest that plant residues play an important role in soil moisture conservation and fertility improvement.

Table 3 shows the results of the Duncan test comparing soil temperatures. T3 had a lower average soil temperature at 23.38°C, followed by T1 at 26.02°C, and T2 had a higher average soil temperature at 27.29°C. Numerous studies have reported the use of dried plant residues as mulching materials. Mulching with dried plant residues resulted in lower soil surface temperatures than conventional plastic film mulching or a control group without mulching, which is thought to be due to the fact that it blocks direct radiant heat from reaching the soil and reduces thermal conductivity due to the large amount of air contained between the residues (Sinkevičienė et al., 2009; Gomez, 2015). Table 3 also shows the analysis of variance (ANOVA) results for total potato yield, soil moisture content, and soil temperature changes for each mulch treatment. Statistically significant differences were observed between treatments, with p-values ​​less than 0.05. However, there were no statistically significant differences between replicates.

Economic analysis revealed that dried Pangola residues provide the highest financial return for potato production in the Dominican Republic (Table 4). The T3 treatment achieved a 36% yield increase over the traditional plastic film treatment, which resulted in a higher economic efficiency of 1.79 per peso invested, while the synthetic T1 treatment yielded a suboptimal ratio of 0.83. Since a ratio of 1.0 represents the break-even point where revenue equals costs, these results confirm that imported plastic film is not financially viable for local growers. This high profitability for T3 stems from the significant yield advantage combined with lower material costs compared to synthetic alternatives. Post-harvest soil analysis further showed that while potassium levels declined due to crop uptake, available phosphorus increased to 217.8 mg/kg in the T3 treatment (Table 5). Although the lack of plant tissue analysis limits a full nutrient balance comparison, these findings confirm that Pangola mulch maintains both economic viability and soil productivity.

Conclusion

Using dried Pangola residues as a mulch for potato crops is an effective strategy to improve the sustainability of production in the Dominican Republic. This study demonstrated that Pangola mulching (T3) achieves a 36% yield increase over traditional plastic film by maintaining a superior root-zone microclimate with an average soil temperature of 23.38°C. Beyond regulating moisture and suppressing weeds, this organic approach provides the highest economic efficiency at 1.79, offering a cost-effective solution for local growers. As the residues decompose, they contribute vital organic matter to the soil to improve long-term fertility and structure. These results confirmed that replacing synthetic mulches with local organic materials can increase crop productivity while enhancing environmental resilience in tropical agriculture.