Rice: A Major Force in Japan's History--The Basic Mechanics--
Rice: A Major Force in Japan's History--The Basic Mechanics--It is difficult to overstate the importance of rice in human history. After humans had begun to acquire an understanding of agricultural technique some ten thousand years ago, but well before most had acquired writing systems, rice became the single most important foodstuff to the species' survival. And it has remained so down to today.
Rice, which probably was first cultivated several thousand years ago in the borderlands of present-day China-Thailand-Vietnam, came subsequently to be cultivated widely throughout Asia, from Japan southwestward across Korea, China, Southeast and South Asia, on into Africa, and eventually to all other major areas of human occupancy.
Rice is notable for its capacity to sustain large human populations. It can do so, moreover, in areas that seem relatively unfavorable to agriculture because of their mountainous or swampy character, Japan being a case in point. Furthermore, because the most productive techniques of rice cultivation demand much labor, social organization, and technical know-how, societies that practice it tend to be densely settled and complexly organized. One wonders: what is it about rice that has caused it to have these ramifications?
Rice: the Plant
When we think of rice cultivation, we commonly picture a crop growing in fields flooded with a few inches of water, and that image is appropriate. Properly speaking, however, rice (Oryza) is not an aquatic or swamp plant.1 Like wheat or barley, it is a genus of grass (Gramineae), a grain. However, because of their vascular structure, the few species of rice that are cultivated (Oryza sativa) flourish in wet soils as other grains do not. Conversely, most varieties are much less tolerant of drought than are other grains. When adequately watered, however, cultivated rice produces a much larger number of seeds per plant than do most grains. In consequence a crop yields a greater harvest per acre, and of that yield a much smaller proportion must be saved as seed-grain for the following year.2
Regarding those varieties of cultivated rice that can be grown as dryfield crops, they yield far less harvest per acre than does rice grown in flooded fields. Within two or three years, moreover, crops of dry-field rice can exhaust a field's fertility. Probably for those reasons rice appears, almost from its initial cultivation, to have been grown primarily in flooded fields. For all practical purposes, therefore, to speak of cultivated rice is to speak of rice grown in flooded fields --i.e., "wet rice" or paddy (from pacti, the Malay word for rice).
Nearly all wet rice is either of two sub-species: Oryza sativa indica or O. s. japonica, each of which now encompasses many thousands of varieties. Indica flourishes in tropical areas; japonica prefers the longer days of temperate-zone summers. Moreover, most varieties of japonica are more tolerant of cooler climates. So it is the predominant rice in Japan and has been since the crop's introduction there some 2,500 years ago.
Rice: Its Cultivation
The great productivity of wet-rice cultivation reflects, in part, the plant's large seed-count. But it also reflects the impact of irrigation. Unlike the rainfall that waters dry fields, the inflowing runoff-water that keeps paddy fields flooded carries organic matter, which feeds algae and microorganisms present in the water and topsoil. They convert the organic matter into nutrients that the paddy roots are capable of absorbing to sustain vigorous plant growth.
Moreover, because this inflow of nutrients occurs whenever paddy fields are kept flooded, those fields, unlike dry ones, can be used year after year without periodic fallowing. The upshot is that while paddy tillage can be a technically complex and labor-intensive form of cropping, it enables cultivators to harvest a substantially greater yield per-acre and to do so year in, year out, provided the water supply is not seriously disrupted.
Not all systems of paddy field cultivation are alike, however. A cultivator can simply clear the natural growth out of a swamp, work the topsoil into usable condition, broadcast rice seed onto the field, control water flow to prevent disruptive surges of flooding, control weeds where possible, and harvest the ripened heads of grain when they are mature.
That relatively simple technique yields only a moderately rich harvest, however. One problem is that from seed-sowing to harvest requires a rather long growing season and risks frost damage: Another problem is that weeding such a field is very difficult, forcing the rice to compete with other growth for both nutrients and sunlight. Yet another problem is that naturally flooded swampland is commonly impossible to drain, and as a consequence the field cannot be emptied of water when the crop is nearing maturity, which makes it more difficult for the plants to dry down and spur the seedhead to full ripening.
Paddy tillage works better if the cultivator can stop the inflow of water and dry out the field annually. Not only does that procedure produce a better harvest, it also produces a more efficient field. One way it does so is by enabling the tiller to grow a dry-field crop on it during the colder months, if climate permits. More importantly, however, periodic drying improves the field's efficiency as paddy land.
To explain, water in a wet field flows downward through the soil, carrying both nutrients and suspended soil particles, mainly fine clay, into subterranean waterways. When the field is dried down, however, water in the soil will flow upward due to capillary attraction, carrying its nutrients and soil particles back up toward the dry surface. That upward flow brings nutrients up to the level of plant roots and deposits clay in the field's subsoil. Such deposition of clay gradually creates a layer of hardpan, making the subsoil more watertight and thereby reducing downward loss of water and nutrients when the field is re-flooded for a subsequent crop.
When, therefore, a rice farmer establishes paddy fields high enough above the natural water table so that incoming water can be diverted and the maturing crop dried down, the fields gradually become more and more efficient in their processing of water, keeping a larger portion of waterborne nutrients available for the growing crop.
To achieve those gains in productivity, however, the farmer must clear land that likely is well wooded and then level irregular surfaces to achieve table-top flatness. Walls to hold the water must encircle the individual paddy fields, and an irrigation system must be established that not only can bring in water from a stream or other source but later shunt the flow elsewhere when the paddy is to be dried. These measures all entail more know-how and labor input and, as the scale of operation grows, more cooperation among members of the farming community.
Paddy farmers can also improve their land's productivity by utilizing seedbeds and row-planting. By sowing the seed densely in seedbeds, they can better control the water level for tender sprouts, shelter them from frost or other menaces, give their paddy fields more time to warm up in the spring before the seedlings are set out, and improve their work schedules by enabling the new crop to start growing even before they complete preparation of the paddy fields.
Then, when the seedlings are ready for transplanting, the farmer's work crew removes them from the seedbed, carries them to the field, and inserts their roots into the soil, aligning the seedlings in rows and spacing them for optimal growth. Such careful row-planting permits workers to move much more easily through the planted fields to replace failed seedlings, pull weeds, control other pests, add fertilizer materials, and harvest the crop. The use of seedbeds and row-planting thus requires much greater labor input. But it also boosts yields substantially and reduces the risk of crop failure due to frost.
Paddy farmers also developed ways to reduce the risk of frost by warming the irrigation water. Allowing it to set in unplanted paddy fields for several sunny days before transplanting seedlings was one such measure. Farmers also learned how to construct shallow ponds --so-called "saucer ponds" --at sunlit sites, warming water in them, and then using that warmed water to irrigate their seedbeds and fields during the early weeks of the crop season.
In addition to these changes in technique, paddy farmers also improved the productivity of their land and labor by utilizing metal tools and draft animals when those became available. And centuries later, during the 1900s, as industrialism spread across the globe, they adopted gasoline-powered equipment to facilitate plowing, setting out seedlings, irrigating, weeding, harvesting, threshing, bagging, and transporting the harvest.
As centuries passed, they also began supplementing the nutrient load of inflowing water by adding other fertilizer materials to their fields: manure and fodder as well as mulch collected from nearby woodlands. And during the twentieth century, they began using commercially produced fertilizers. Eventually, too, they learned how to apply pesticides to control some of the unwanted insects and micro-organisms.
As a whole the various pre-industrial technical improvements increased both the yield-per-acre and the labor requirements of paddy culture. Which is to say, they increased the human population density within walking (and, later, riding) distance of paddy land. And since rice-farming communities rely on surrounding terrain for many other necessities --including construction materials, fuel wood, fertilizer materials, feed for draft animals, space for buildings, work areas, cemeteries, etc., and dry land for growing other crops --the substantial population growth that paddy culture made possible translated into a substantially expanded human impact on the biosystem.
Moreover, as the scale of irrigation systems grew, the extent of required cooperation also grew. As long as that cooperation involved face to-face personal interactions among neighbors, it usually could be managed locally. But when it entailed severe conflicts of interest or the interaction of strangers, it could have broader social ramifications, fostering the standardization of language, development of writing and literacy, creation of regulations and mechanisms for their enforcement, and emergence of hierarchies of power and authority. And with those hierarchies came social stratification and, among the higher strata, more luxuries and the expressions of self-indulgence commonly known as "higher culture."
1On the biology of rice and rice cropping, see D. H. Crist, Rice (London: Longmans, Green and Co. Ltd., 1965),. pp. 56, 81, and passim. This is a multi-edition work that was first published in 1953.
2Francesca Bray, The Rice Economies: Technology and Development in Asian Societies (Oxford: Basil Blackwell, 1986), p. 15.