Soil and Water Conservation Engineering in the Dominican Republic

Written by F2F volunteer, John Tiedeman, April 15-29, 2018

Farmers are practical people wherever you find them in the world. Challenges in the Dominican Republic were to identify opportunities for soil and water conservation in the fertile Cibao Valley and surrounding mountains.

Week 1 focused on a 160 acre ranch where goals include preservation of a remaining cacao plantation, plus demonstration of sustainable organic production methods. Most acreage in the area of La Vega has been converted to intensive cultivation of cassava/yuca and bananas using synthetic fertilizers and pesticides.

Adequate drainage and water supply are essential to healthy plant growth, whether in the humid climate of the D.R. or in the dry summer climate where I live in northern California. For surface drainage, the starting point is to ensure an unobstructed outlet. Although landowner Altair Rodriquez had installed hand-dug surface drains in her cacao plantation, the downstream outlet was completely plugged by a failed concrete culvert under a paved highway. Flow over the highway has failed the highway shoulder and presents a risk to traffic safety. In collaboration with neighbors and local road department officials, repairing the culvert will improve farm drainage and remove a transportation safety hazard.      

                               Plugged culvert outlet                                                                                     Highway shoulder failure                                                 

On the water management side, we field tested drip irrigation to demonstrate the uniform applications available under low head (pressure). In a one acre test planting of green pepper (spice), a thousand and more plants are being watered by hand (picture below).

Pimienta verde (green pepper spice) with support trees (“pinon Cubano”  Gliricidia sepium). The support trees have other beneficial properties, including nitrogen fixation, livestock forage, and that they respond well to coppicing (opportunity for use of wood products).

Aside from the labor requirement for hand irrigation, it is difficult to deliver a uniform application of water to each plant. With the clay soil, a drip irrigation system was proposed (single one gal/hr emitter per plant) using ½” poly tubing for 80 meter long rows. Once the hand-dug well pump is restored, benefits will include (1) labor savings, (2) uniform application to each plant, and (3) water conservation.

Week 2 was spent in with rural farmer groups in three different regions, focusing on soil conservation, soil health, and supplemental (drip) irrigation.

    (1)  Manuel Bueno, west of Mao, near the Haitian border. Soils tend to be shallow, and rainfall is limiting. We discussed maintaining cover over soil (reduced tillage, lower grazing pressure) as well a living terraces (perennial grass contour strips) to protect soil from erosion and dissipate erosive energy of runoff.

A family scale drip irrigation system was installed to demonstrate improved water conservation and vegetable production.

(2) North of Santiago. In this mountainous area, the family must haul water up a hillside to reach their garden area. Under these conditions every drop counts due to the difficulty of obtaining and applying water. 

    (3)  La Vega area. This area receives more abundant rainfall, and also experiences flooding when the capacity of drains and canals is exceeded. For this reason supplemental irrigation is important for harvesting vegetable crops during windows in the dry season. In addition to individual drip emitters, small micro-sprinklers were found to operate under low head and be well suited to dense plantings such as spinach, lettuce, and radishes. 

The two weeks in the Dominican Republic were productive time well-spent.   The Farmer-to-Farmer staff in the Dominican Republic are well-organized to ensure efficient use of time at the right pace. It was a privilege to participate with the staff and farming communities.

Recommendations for future F2F volunteers:

    1). Ask questions and attempt to understand existing constraints before offering solutions.

    2). Provide training and materials to F2F staff and communities leaders, such that they can continue implementation after you’ve returned home.

    3). Be flexible and enjoy the cultural experience. The Dominicans are warm and friendly people, eager to learn new skills that will enhance their food security and well-being.