“Time and tide wait for no man”, so they say. Rice farmers living in coastal areas of South Sumatra, and Central and East Kalimantan in Indonesia know this only too well. Their paddy fields are flooded by river water pushed back up the deltas by each incoming tide. Preparing the land is especially difficult. Not only do weeds grow incredibly vigorously under the swampy conditions, but plowing the land too deeply can result in crop failure. Although the high organic matter topsoil is fertile, below lies a yellow layer of toxic iron pyrite. This is phytotoxic to the rice if disturbed.
Farm labor is often difficult to find. Working in hot weather and high humidity in these tidal-swampy areas makes land preparation a time consuming and exhausting job. Traditionally, farmers slash the tall weeds with a long machete called a “tajak”. Weeds have been controlled this way for hundreds of years by tidal rice farmers. The cut weeds are collected and piled-up in heaps called “puntalan” and left to dry under the sun. The puntalans have to be turned frequently to assist drying and encourage decomposition of the biomass. When dry, farmers spread the remains of the vegetation evenly over the flooded paddies. After plowing, rice seedlings are transplanted a couple of weeks later. Establishing the rice crop in this traditional way usually takes one to two months and up to 100 man-days of labor per hectare.
After six months, rice crops will yield a maximum yield of 2.5 tonnes per hectare, barely enough to support a family. Traditional farming traps millions of tidal rice families in poverty.
However, more progressive farmers have been using paraquat and finding an easier and quicker way to prepare a paddy field.
Typically very dense weed populations are sprayed with paraquat and left for several days until fully desiccated. Only paraquat can act fast enough between tides to kill weeds because it is absorbed by leaves before it can be washed off – in just the same way that it is rainfast in less than half an hour.
The dead vegetation is then lightly incorporated into the paddy mud using a mechanical cultivator if available. Otherwise, a drum filled with water can be used to roll down the weed residues. Returning the decomposed weeds to the soil adds organic matter, important to maintaining fertility.
By controlling weeds with paraquat the land does not need to be plowed. Two or three days later rice seedlings can be transplanted.
Land preparation which previously took one to two months on a typical one hectare farm is reduced to only seven to ten days. A single farming household can now manage crops on two to four hectares. Using paraquat, farmers can harvest two crops of high yielding varieties each year. A paraquat-based system typically costs only 20% that of a plow-based system. Rice production can increase by 60% at each harvest or by 120% over one year. Ultimately, tidal rice farmers using paraquat can triple their income. Paraquat has enabled rice productivity in the coastal areas of Indonesia to increase substantially, contributing to the country’s success in feeding its fast growing population.