In flood-prone areas, why not floating gardens?

SCIENCE CITY OF Muñoz–Don’t despair if your home is swallowed by floods or marshlands when the monsoon rains set in. You can still produce the food you need by constructing easy-to-make floating gardens that have thrived well in countries such as Indonesia and Bangladesh.

These gardens thrive on 4 x 1 meter-long bamboo rafts where people can produce leafy vegetables, such as mustard, pechay, upland “kangkong” (swamp cabbage) bush “sitaw” (beans), and even rice, said Dr. Eduardo Jimmy Quilang, deputy executive director for development of the Philippine Rice Research Institute (PhilRice) in the Science City of Muñoz in Nueva Ecija.

Quilang heads a team, composed of researchers Vicky Dimaano, Rizal Corales, Jesusa Rivera, Artemio Corpuz and Elmer Alosnos, which had been commissioned to study the impact of floating gardens, using funds provided by PhilRice and the Department of Agriculture.

Now on its third season, the study has been evaluating the efficiency of locally available materials for the floating gardens and the adaptability of certain crops for growing and production under those conditions. In Muñoz, the progress of nine floating gardens at a big pond near Philrice’s crop science building is being observed.

Very promising

The technology appears very promising in a Philippine setting based on initial results, according to Quilang. “The modification of traditional cultivation methods is [necessary] to [help farmers] adapt to the effects of climate change… A floating garden is one possible alternative to conventional farming to reduce impact of [a changing weather],” he said.

Basic to the construction of the garden is the raft, which is made of bamboo poles fastened together. The frame is matted with sacks piled on top of each other until the layering is solid enough to hold a 15-centimeter thick spread of garden soil, organic fertilizer and carbonized rice hull.

PhilRice tested several materials for floaters to weigh the raft down and stabilize it. These included weighted bamboo, matured coconuts, empty plastic bottles and a pile of water hyacinth.

Pechay, kangkong and mustard were planted in the test gardens during last year’s long drought and rainy period, and again during this year’s monsoon season. No commercial fertilizers, pesticides or insecticides were applied.

Harvests from the garden that floated on 1.5-liter plastic bottles turned out to be superior. The researchers concluded that the bottles provided better buoyancy compared to coconuts or piles of hyacinth.

Buoyancy

“The productivity of floating gardens appeared dependent on the buoyancy,” the study said.

The garden tested under a monsoon produced 592 grams per square meter of pechay, 842 grams per sq m of kangkong, and 642 grams per sq m of mustard under a monsoon. But the yields improved under tests made during the dry spell, producing 1.70 grams per sq m of pechay and 1.63 grams per sq m of kangkong.

Quality harvests were also produced in the garden that floated on water hyacinth, but the raft sank when the hyacinth decomposed.

When rice was planted in the garden using weighed-down bamboo poles, it yielded 21.4 grams per sq m of grains.

Matured coconuts turned out to be poor choices for floaters because the gardens they supported on the water had the lowest vegetable yield.

“We will try using bigger floaters like plastic drums. They are sure to provide greater buoyancy,” Dimaano said.

The team constructed a floating garden in San Antonio town, a catch basin for floodwaters, but it was carried away by the spate of floods that occurred following the onslaught of two typhoons recently. “It should have been provided with stronger anchor,” Dimaano said.

The team will also conduct a field trial of the floating garden in the marshlands of Agusan del Sur. “There is a floating village there where 26 families reside. The floating garden can provide them additional source of food in just a short time. They can harvest leafy vegetables in just 24 days after sowing,” Dimaano said.

Some residents near the Pantabangan Dam reservoir in Nueva Ecija are now eager to set up their gardens, she said.

The team will introduce the technology to fishpond owners. “The underside of the floating garden can serve as refuge for the fish during hot weather. It can help prevent fishkill,” Dimaano said.