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Dry rice system revives output for northern China

Chinese peasants are growing rice successfully in dry fields in areas where water is scarce.

The year 1984 saw 90 000 hectares of dry fields sown to rice along and north of the Yellow River, three times as much as in 1983, according to the Ministry of Agriculture, Animal Husbandry, and Fishery.

Despite natural setbacks, per-hectare output averaged 4.725 tons. Tongxian county outside Beijing, with 2 300 hectares of dry rice, managed 6.75 tons per hectare, and some areas actually achieved greater per-hectare output from dry rice than from wet.

By doing away with seedling beds and flooding, dry cultivation of rice uses less water, manure, and manpower. In practice, one-third as much water and two-thirds as much manure are needed as with traditional methods. This cuts costs by $60 per hectare and facilitates mechanized farming.

With less than 500 mm of rain annually, northern and northeastern China have had no water to spare for flooded fields, so wheat, maize, and sorghum have been the traditional crops. But with the new system an estimated one million hectares are suitable for dry rice.

Rice hectarage around Beijing, for instance, reduced several years running because of industrial water consumption, is now rising again with the new technique. In 1984, dry fields accounted for about a quarter of the city's rice hectarage.

"Growing rice dry is very like growing wheat," said Ling Pengzhi, an agronomist at the Agricultural Science Research Institute in Daxing county, a major Beijing rice producer.

After the spring ploughing, each hectare is spread with 45-75 cu.m. of farmyard manure and 450 kg of calcium super-phosphate, then level led and irrigated with 750 cu.m. of water.

Seeds are sun-dried for two or three days to increase germination percentage, then screened to remove foreign substances and tipped into a brine of 10 kg of salt per 50 litres. The salt may be replaced with 15 kg of clay. Only the seeds that sink are used.

These are steeped in fresh water for six or seven days to absorb all they can, then one day before sowing are fed in the shade and sprayed with a 100 ml per litre of water solution of the insecticide chlordane E.C. (50 per cent).

"All this is to maximize seedlings, one key to an ideal yield," says Ling. The seeds are sown two to three centimeters deep, slightly shallower than wheat. Weeds flourish on the unflooded land. "They must be kept down with chemicals," says Ling, "or a good harvest is impossible." The seedlings are not irrigated until four to six leaves appear, when 750 cu.m. of water are used per hectare.

The five to seven irrigation's of 600-750 cu.m. per hectare each during the growing period take 3750-4500 cu.m. per hectare, one-third that in flooded fields, though slightly more than for wheat.

Ling explains that rice, unlike lotus or reeds, has no root air cells and can survive drought like other land plants.

"Intermittent irrigation gives the root enough air and water," he says. "Only at critical moments do the plants need much water."

By "critical moments" Ling means tillering, booting, heading, and the milk stage. "Under normal circumstances," he adds, "if the plants are watered plentifully at these times, good harvest is as sure as posting a letter."

For an ideal harvest, says Ling, 50 kg of ammonium bicarbonate per hectare should be applied at tillering and again at booting.

Serious drought in 1971 and 1972 reduced Daxing's rice hectarage from 7 000 to 5 000 and forced Ling and his colleagues to seek a new way to insure output.

Helped by the Academy of Agricultural Science, their dry rice cultivation experiments succeeded in 1973, and one-third of the county's rice was dry-grown by 1984.

The national dry-grown rice hectarage will be enlarged to 260 000 in 1985 and one million by 1990, according to the ministry.