Food security

How do the various soil types in Puerto Rico support different crops?

Puerto Rico, where I am from, is the main island of an archipelago in the Caribbean. The smaller islands are Caja de Muertos, Culebra, Desecheo, Mona, Monito, and Vieques. Our history is rich in music, art, tourism. But agriculture is an important historical industry too.

About 23% of our land is well-suited to agriculture. The land on the islands varies quite a bit. All these territories formed from underwater volcanic activity. They emerged from the ocean’s surface at different geological periods and environmental conditions such as temperature and pressure.

The cropping process of pineapples step-by-step. Credit: Agro. Henry Córdova

One of the most notable geologic formations is the central mountain chain that crosses Puerto Rico from east to west. The landscape position of the mountains plays a very important role differentiating climate conditions from northern to southern regions on our island.

Soil scientists use a method called “soil mapping” to keep track of soil types in various areas. Maps give valuable information about soil conditions for agricultural use. For example, the map in Figure 1 is the visual representation of the soil orders distribution in Puerto Rico. (To learn more about Soil Orders click here). As you can see in the soil map I created, we have 10 of the 12 soil orders established in USA and territories. The soils of Puerto Rico are quite diverse, depending on the region where they developed.

Colored map of puerto rico soils
Figure 1: A map of the Soils Orders of Puerto Rico. Credit: B. Alvarez Torres

The green, yellow, pink and red bands on the map that run through the center of Puerto Rico are areas of mountains and rivers. The soils there are Inceptisols, Ultisols, Alfisols, and Oxisols. This area supports cultivars of pasture, citrus, coffee, pineapples, starchy crops, plantain, and bananas. The area also contains woodland, part of El Yunque National Forest.

The northern plains of Puerto Rico contain Alfisols and Oxisols, which are great for grazing and pasture land. The southern plains have mostly Vertisols. However, there are areas with carbon-rich Mollisols (much like the soil found in the US Midwest). These are good for growing plantain, vegetable and fruits, such as pineapple.

cattle on hill with trees
Cattle grazing in the pasture lands of the Lajas Valley, in the south of Puerto Rico. Soils here don’t support the growth of crops, so they are used for pasture and hay production. Credit: B. Alvarez Torres

In southwest and central south Puerto, the low rates of rain favored the formation of Aridisols, as you can see in the Guánica Dry Forest Reserve. Many of these “marginal” soils cannot support the growth of food crops, so are used more efficiently for pasture and hay production. Entisols and Histosols are commonly found in coasts and wetlands.

The diversity of crops that grows in Puerto Rico is a proof that soils vary across the country. They vary in nutrient content, texture, and water retention capacity by location, all important factors for plants. If you are interested to explore more about Puerto Rico and its agricultural resources in an interactive way, please press this ArcGIS web link.

Answered by Beverly Alvarez Torres, University of Puerto Rico

To learn more about soils in Puerto Rico by this author, please visit this link: https://www.instagram.com/beverlyalvareztorres/

To read about the importance of seed banks to an area like Puerto Rico, read here.

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.

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