The Science Behind Trees

By Christina A. Frediles

What could be more challenging than farming at the top of a mountain?

Some farms in Claveria, Misamis Oriental do just that. Farmers here tend plants on steep slopes with erodible and acidic soils; rainfall serves as their main source of water.

But these challenges did not stop them from farming. Their allies? The nearby trees, which are beneficial to rice and other crops.

Tree Myths 

Some farmers think that planting trees near rice is not a good practice. They say that rice plants will produce fewer grains as trees “block energy from the sun,” in reference to a misunderstanding of the process of photosynthesis, in which plants convert light energy into chemical energy, which fuels plant growth.

Dr. Agustin Mercado Jr., research manager of the World Agroforestry Centre, said trees and crops can complement each other. “In planting trees with rice, farmers should consider [the] economic, environmental, and social benefits,” he said, adding, “Trees maintain soil organic [matter] such as leaves and [decayed roots]. It also improves vegetable productivity due to windspeed reduction and increases relative humidity, and soil moisture at the surface.” Trees also help prevent soil erosion with their deep roots, which serve as contour hedges.

Dr. Mercado advised farmers to plant trees in 20-25 meters (m) apart between rows and 3 m apart between trees to avoid light energy competition.

Dr. Agustin Mercado Jr., research manager of the World Agroforestry Centre, shows the proper distancing of planting trees to avoid light energy competition with crops.

In a 2005 report to The World Bank, Dr. Roehlano M. Briones of the Philippine Institute for Development Studies reported that the agricultural area of the Philippines covers over 12.2 million hectares of sloping land, 17% of which is classified as “very steep slopes” and 66% of which is considered “steep slopes,” making them prone to erosion. Erosion causes the loss of nutrients in land, and makes the soil unable to hold water, which can affect flooding.

Landslides can be avoided with trees. Most of the upland areas experience more than 2,500 millimeters of rainfall per year, which is inevitable, but its effects can be lessened if trees were planted there.

Dr. Mercado encouraged farmers to plant trees that can be sold on the market for additional income.

Crops Plus Trees and Other Organisms

A study by Dr. Mercado’s team showed that the integration of rubber trees with upland rice normally yields the best results. While rubber trees help prevent soil erosion, upland rice is aerobic and does not emit methane gas. Flooded rice emits a significant amount of methane to the atmosphere, and this contributes to worsening global warming and climate change.

Planting trees and vegetables in the uplands helps diversify beneficial organisms. This concept is called “ecological engineering” and is grounded on cultural techniques to increase the population of beneficial insects. Trees and vegetables serve as a habitat and source of food for beneficial organisms. In return, beneficial insects such spiders, coccinellids (ladybugs/ ladybirds), damselflies, and others which attack 90% of rice pests.

“Integration of rice and rubber trees is a good option to increase rice production [and the] food and economic security of the country while mitigating climate change,” Dr. Mercado said.

On the other hand, Arachispintoi (mani-mani) planted underneath the trees is used as live mulch in the uplands, which maintains the moisture of the soil. The plant prevents weeds and controls erosion in the field. It can also be used as feeds for livestocks such as pigs, cattle, and goats.

For decades, Dr. Mercado has been working with World Agroforestry Centre. The centre is an international leader in agroforestry research and development. It aims to grow more food and lessen gas emissions by converting degraded grasslands into highly productive farmlands and sequestering more carbon in trees on farms.

Rainwater Harvest

Rainwater is the only source of irrigation in the hilly farming areas of Claveria. Dr. Mercado’s team put up ponds that serve as water storage. “With these ponds, we need not…worry during [a] dry spell or whenever it is time to irrigate. We also culture fish which can serve as food and nutrition or additional income for farmers. Fish also improves the nutrients in the water, making it beneficial to the growth of the crops it irrigates,” Dr. Mercado explained.

Undoubtedly, climate change adds to the ultimate challenge that upland farming presents to farmers. But with trees proving their importance to climate change adaptation and mitigation, the adoption of agriforestry practices should be strengthened to complement the needs of crops and animals. After all, farmers are expected to bring more food to their tables while staying resilient in the face of the changing climate.

This appeared in Agriculture Monthly’s September 2016 issue. 

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