Knee-deep in mud

 Leah Barona-Cruz   |  

irri pic

Rice research has helped many countries feed their people, but its successes account for only a small part of the rich rice production toolbox that the International Rice Research Institute has helped put together.

Achim Dobermann, IRRI’s head of research, has always wondered the following about the methods and technologies developed by scientists: Why don’t rice farmers use these more? This question influences the direction rice research might take in the future, and Achim needed an answer urgently. So, instead of poring over journals and talking with yet more experts, he decided to go on a quest to satisfy his curiosity. He took this challenge to the field.

Achim enlisted the help of a young rice farmer from Australia, Leigh Vial. Leigh currently heads the Experiment Station at International Rice Research Institute (IRRI). Together, they attempted to produce a rice crop using IRRI’s recommended best practices and tools for the prevailing field conditions and climate.The two set aside a 25 × 100-meter field—a quarter of a hectare—on IRRI’s Experiment Station and, in January 2012, started preparing the land for a dry-season crop in a 4-month experiment they called the IRRI Agronomy Challenge.

Land preparation

Before planting starts, the soil needs to be prepared. Dry soil tillage was no longer possible because of early rains, so the field had to be plowed as farmers normally do—with standing water in the field.To level the land, Achim and Leigh opted to use a tractor equipped with a laser leveler instead of maneuvering a carabao (water buffalo) and a wooden plank around. Laser technology is supposed to help the level the land in the most precise way possible, all in less than half an hour.It did, or at least they thought it did.After closer inspection, the two found that the soil was still uneven and needed a tiny bit of rework, and so they had to use the laser-leveling equipment a second time. It becomes a suspicion, at this point, that there are no shortcuts to an even field.It was important for the land to be evenly flat, so that water is equally deep at all points. This helps the rice plants root out well to get a firm grip on the soil and mature at the same pace. When rice plants mature uniformly, weeds have much less chance to grow.

Which variety to plant?

(Photo: Isagani Serrano)

(Photo: Isagani Serrano)

For their little experiment, Achim and Leigh decided to use the IRRI-bred variety IRRI 154, which was released in 2010 in the Philippines as NSIC Rc 222 or Tubigan 18.

IRRI 154 is recommended primarily for irrigated lowland areas, but has also performed very well in rainfed areas in the Philippines.

Achim and Leigh intended to use direct seeding (as opposed to transplanting) with a drum seeder, a device with holes through which rice seeds fall when it rolls over the surface of the soil.

When they started, however, they found after a few attempts that they could not use a drum seeder on the plot they made. They ended up broadcast seeding, which Leigh claims is an art that they had previously admired only from a distance. Broadcast seeding is a method of planting in which seeds are released by hand with a quick flick of the wrist so that they land in an even sprinkling over the surface of the soil.

New isn’t always best

A tractor guided by a laser leveler was used to even out the land and prepare it for planting. It did a quick job, but not better than a buffalo and wooden plank might have. (Photo: Chris Quintana)

A tractor guided by a laser leveler was used to even out the land and prepare it for planting. It did a quick job, but not better than a buffalo and wooden plank might have. (Photo: Chris Quintana)

A Few days after seeding, Leigh was dismayed to find an uneven field: there were well-germinated seeds on 50–60% of the area, where water drained well; poorly germinated seeds where water failed to drain; and bare spots, where seeds died because it was too wet. This, despite laser-leveling technology!

The dead spots were seeded again almost a week later. “Rice has a habit of catching up when it comes to flowering and harvesting, so this should be okay,” assured Leigh, who admitted that they were “seduced by technology” when it came to preparing the field.

“We looked to the laser-guided equipment, when, in hindsight, I think the smaller equipment invented here in the Philippines would have given us more level fields,” he added. “High-tech isn’t always better.”

Nutrients and water

Leigh brought smiley cards to grade good seedling growth, partial growth, and bald spots on the field.

Leigh brought smiley cards to grade good seedling growth, partial growth, and bald spots on the field. (Photo: Isagani Serrano)

As a soil scientist, Achim knew that the soil on the paddy field was rich in organic matter (about 4%) and had good potassium content. Using the recommendations of Nutrient Manager (a site-specific nutrient management tool on the Web, mobile phones, and on smartphones). and his own assessment of the soil, he decided to apply NPK (14-14-14) about 2 weeks after sowing, and urea twice, at about 4 and 6 weeks after sowing.

Achim applied NPK, despite sufficient potassium in the soil, because this fertilizer usually comes only in a 14-14-14 package in the Philippines and doing so will be a closer simulation of what most Filipino farmers do.

After fertilizer application, the field needed to have some water on it to help the rice plants take up nutrients better.

There’s a sticky part to water use, though: although a good layer of water will enhance nutrient uptake and prevent weeds from growing, it also provides a “highway” for golden apple snails to move across the field. These snails could cut off the young seedlings, and so a fine balance in water use was crucial.

An IRRI-recommended best practice, alternate wetting and drying (AWD), was used. With AWD, the field is irrigated with less water (so that snails can’t move around so much) but more frequently (so that weeds don’t thrive). This strategy also cuts water use by 15–30%. “But it does increase the risk of weed re-infestation,” said Leigh. “No such thing as free lunch.”



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