The origin of the banana is located in Southeast Asia, the origin of plants from the Musaceae family. It is believed to have been introduced to the Americas (specifically to the Dominican Republic) from the Canary Islands during Spanish colonization. Although the word "banana" has its roots in Latin, the terms "banano" and "guineo" come from Africa (Rosales et al., 2010).

The radish (Raphanus sativus L.) is an annual plant from the Brassicaceae family, cultivated since ancient times in China. Its root, 3-5 cm in diameter and up to 30 cm in length, penetrates compacted soils, improving their structure. As a cover crop, it reduces soil compaction, lowers tillage costs, and contributes nutrients. Its roots absorb nitrogen at deeper levels, enhancing soil fertility. Additionally, it emits chemical substances that control pests like nematodes. In a research study with papaya in Isabela, Puerto Rico (Racancoj-Coyoy, A. J, 2018), it was demonstrated that radish provides high weed control (94% in live cover and 69% in dead cover), surpassing sesame cover (76%).

Cover crops have variable effects on the soil depending on the species, cover duration, and local conditions. Cover crops from the legume family play a crucial role in the nitrogen cycle, potentially supplying a large portion or all of the nitrogen needs for the subsequent crop (Martínez Mera et al., 2016). The study by Santos-Varga (2010) evaluated the effect of planting times and cutting dates on the biomass production and nitrogen accumulation of Sunn hemp (Crotalaria juncea L.) in Puerto Rico. It was found that planting in June and harvesting 121 days after sowing maximizes biomass and nitrogen production, offering potential as a cover crop and green manure in local agroecosystems.

Forage peanut, Arachis pintoi, acts as a cover crop that can reduce weeds by up to 70.5% in plantain plantations. This fast-growing legume has the ability to fix atmospheric nitrogen into the soil, improving its structure, reducing erosion, increasing water infiltration and retention, and enhancing soil health. Due to its low height, it does not interfere with the production of coffee or other tree crops, making it a beneficial option for improving soil quality and crop yield (USDA-Natural Resources Conservation Service, 2023).

Sorghum, belonging to the grass family, is used as a cover crop due to its rapid growth and ability to cover the soil. It is planted between main crops to suppress weeds, reduce soil erosion, and improve soil structure. Forage sorghum is notable for its adaptation to dry areas, making it optimal for silage in the first cut and subsequent regrowth for hay and grazing. Two experiments conducted at the Isabela Agricultural Experiment Station, UPR, evaluated legumes such as Crotalaria and sorghum in monoculture and association. Canavalia and Mucuna were also examined. The contribution of nitrogen in biomass and the release of inorganic nitrogen were analyzed. The combination of Crotalaria + sorghum resulted in the highest nitrogen contribution (Méndez Alicea, 2023).

In the humid tropics, research has highlighted the importance of earthworms as indicators of soil functioning. These studies analyzed soil macrofauna in terms of taxonomic richness, diversity, density, biomass, and functional composition, allowing for the evaluation of land-use intensity. Earthworms, in particular, are key to understanding soil health and its capacity to support various agricultural and forestry uses (Cabrera-Davila et al., 2017).

Fungi play an essential role in soil health by decomposing organic matter and recycling nutrients. A single gram of soil can contain up to 200 meters of fungal filaments, known as mycelium, which act as an underground network, connecting plants and facilitating nutrient exchange. This "web of life" not only enhances soil fertility but also protects plants against diseases and environmental stress.

Collembolans are tiny, abundant invertebrates, very similar to insects, that inhabit humid environments. These small arthropods, measuring only 1-2 mm, play a vital role in the decomposition of organic matter and nutrient cycling. By feeding on fungi and bacteria, they help maintain microbial balance in the soil. Moreover, their presence and diversity reflect healthy soil, as they thrive in soils rich in organic matter and well-structured environments.

Covering the soil is essential for soil health because it protects against erosion, retains moisture, and promotes biodiversity. Vegetative covers, such as mulch or cover crops, act as a natural barrier, reducing the impact of rain and wind. This helps prevent nutrient loss and improves soil structure. Additionally, these covers provide habitats for beneficial microorganisms and increase organic matter, which is vital for healthy soil.

Crop biodiversity in the tropics is crucial for soil health because it fosters a balanced and resilient ecosystem. Different crops contribute a variety of roots and organic residues, which improve soil structure and increase organic matter. This diversity also reduces pest and disease pressure by making their spread more difficult. Additionally, different plants can fix nutrients, such as nitrogen, enriching the soil and promoting its long-term fertility.

A single gram of soil can contain up to a billion beneficial bacteria, which are essential for soil health and, surprisingly, for human health as well. These bacteria break down organic matter, releasing nutrients that plants need to grow. Additionally, some soil bacteria, like Mycobacterium vaccae, have been shown to have positive effects on human mood, acting as natural antidepressants when we come into contact with the earth.

Protozoa, microscopic predators in the soil, are key to maintaining a balanced food chain. In PLFA (phospholipid fatty acid) analysis, their presence indicates a complex food web and healthy soil. By feeding on bacteria and other microorganisms, protozoa release essential nutrients that plants absorb. Their diversity and abundance in the soil reflect high biological activity and an increased capacity for the soil to support productivity and ecological resilience.

Not all nematodes are harmful; in fact, beneficial nematodes are essential for soil health. These tiny worms help control pests by parasitizing harmful insects, and they also decompose organic matter, releasing nutrients that plants can use. Additionally, nematodes contribute to improving soil structure by creating pores that facilitate air and water circulation. Their presence indicates a healthy and balanced soil ecosystem.

Root exudates, a gelatinous substance secreted by plants, are a feast for beneficial soil bacteria. These exudates not only nourish microorganisms but also promote the formation of stable soil aggregates, improving soil structure. These aggregates enhance water and nutrient retention, reduce erosion, and create a healthier environment for roots, all of which contribute to more fertile and resilient soil.

The balance of water in the soil's micropores is crucial for its health, as these pores retain water that is available to plants between irrigation or rainfall. Maintaining the right balance prevents waterlogging, which can suffocate roots, and drought, which limits growth. A good water balance in the micropores also promotes microbial activity and the decomposition of organic matter, improving soil structure and its ability to support healthy crops.

Centipedes, though feared for their sting, play an important role in soil health. They are natural predators that control insect and other invertebrate populations, maintaining ecological balance. By burrowing into the soil, they improve soil aeration and structure, facilitating water and root penetration. Additionally, their waste enriches the soil with nutrients, contributing to a more diverse and healthy underground ecosystem.

The presence of pollinators, such as bees and butterflies, indicates a healthy ecosystem and, consequently, healthy soil. These insects depend on flowering plants, which in turn require nutrient-rich and well-structured soils to thrive. Healthy soil supports diverse plant biodiversity, which attracts pollinators. Their presence reflects an ecological balance where the soil provides the necessary support for both plants and animals, creating a sustainable and productive life cycle.

Living roots are fundamental to soil health because they maintain continuous biological activity. Vetiver (Chrysopogon zizanioides) is an excellent example of a grass with extremely long roots, which can reach depths of up to 4 meters (around 13 feet) or more. These deep roots allow vetiver to firmly anchor the soil, preventing erosion and improving land stability in areas prone to landslides or floods. Additionally, vetiver roots help enhance water infiltration and nutrient absorption, promoting overall soil health.