Water, fortunately, has not been a difficult resource to manage on our farm. We rely on boreholes for most of the year, and these allow us to irrigate our crops through all the seasons.
A year of farming in Yangon is generally divided between the monsoon season (June to November) and the dry season (December to May). In the monsoon season, torrential rains batter Yangon, blowing trees and plants down and causing floods. In the dry season, temperatures rise and drought can become an issue.
The challenge for us is not a lack of water, but rather the problems caused by the high humidity and heavy rainfall during the monsoon season. Our priority is to..
Our irrigation setup
We water our vegetables every day of the year without fail. Water is drawn up from the borehole at a rate of 20 gallons per minute using a 2-horsepower electric pump.
We use a hose for watering and it takes us one hour to water the eight roofed vegetable beds and another hour to water the plots of herbs, chilis, and other kitchen vegetables, making it a total of two hours per watering session. We use about 2,400 gallons of water per 2-hour watering session.
Our daily watering regimen
During the dry season, we water once in the morning around 8am and again in the late afternoon around 4pm. Moisture from the soil evaporates rapidly at this time of the year because we do not have many large trees on the farm to provide shade. The soil also heats up a considerable amount, but the compost and straw mulch we have layered on top of the beds slow the rate of evaporation.
The monsoons begin suddenly around June and give us near daily bouts of heavy rainfall with occasional thunderstorms until November. We water our roofed vegetable beds only once a day in the late afternoon since the soil is already moist from roof runoff and the previous day’s watering.
While the rainfall is great for our tropical region vegetables and fruits like chilis, coconuts, and eggplants, the high humidity that follows increases the risk of root rot and water-borne bacterial diseases spreading among our dinosaur kale and Italian basil, which come from the Mediterranean region and are not adapted to high-humidity climates. During the 2020 monsoons, we lost nearly 75% of our curly kale, dinosaur kale, and Italian basil crops to these diseases.
Water security for the future
As temperatures continue to rise, drought is becoming a reality for more and more farmers in Southeast Asia.
Relying on groundwater alone exposes us to risks and reduces our resiliency towards climate change. We do not have enough data on how quickly and adequately the groundwater recharges. We know that our neighbours also use the same groundwater we use, and this is probably the case for most of the farms and households in our area. If our collective use is more than the amount that is replenished, sinkholes could form in the near future. Harvesting rainwater seems to be a more reliable and sustainable alternative.
The next phase of our farm development will include upgrading our irrigation system to rely more on rainwater harvested on the farm. We have plans to install water reservoirs to harvest rainwater and drip feed them to our crops during the drier months.
We have already begun experimenting with different irrigation systems. In March 2020, we installed drip lines on four of our beds. Our tests using drip irrigation for mass planted beds of gazun and roselle have produced mixed results. Each nozzle watered an area not larger than six inches in diameter to a depth of about five inches after 3 hours of operation. We expected a better performance but the dense planting and high evaporation rates were possible limiting factors. Brown patches appeared in several areas in the beds, which have led us to think that a drip irrigation system might be better for larger single plants like kale and chilis.
Overhead sprinklers are another option. But with the high incidence of mould and moisture-loving bacteria that we saw infect our amaranth beds, they may cause more harm than good.