Sabtu, 26 November 2011

Traditional agriculture's

In comparison to foraging, traditional farming nearly always required higher inputs of human energy (and later also of animal labor), but it could support higher population densities and provide a more reliable food supply. Whereas foraging (except for maritime hunting) could support no more than a few people per 100 hectares (ha) of territory used for gathering and hunting, early traditional agricultures managed to support at least one person/ha of arable land (Fig. 3.1). By the end of the 19th century China’s nationwide mean was above five people/ha, and double cropping of rice and wheat in the most fertile areas could yield enough to feed 12–15 people/ha (Smil, 1994).
                                                                    Modern farming
                                                   Traditional farming
                                    Shifting farming
0.0001 0.001 0.01 0.1 1 10
Population density (people/ha)
Figure 3.1
Comparison of carrying capacities of the principal modes of human food production showing that farming can support 10–10 more people than foraging (based on Smil, 2000). 
The need for higher energy inputs explains why so many foraging societies kept delaying adoption of permanent cultivation and why shifting farming – a less intensive method of cultivation alternating short (1–3 years) cropping periods with much longer (a decade or more) fallow spells – was practiced so extensively. In spite of many regional and local differences there were many fundamental similarities that persisted across the millennia of traditional farming. Above all, these agricultures were entirely renewable; photosynthetic conversion of solar radiation produced food for people, feed for animals, recyclable wastes for the replenishment of soil fertility, as well as wood (often turned into charcoal) for smelting metals needed to make simple farm tools. But the renewability of traditional farming was no guarantee of its sustainability. In many regions poor agronomic practices gradually depleted soil fertility or caused excessive soil erosion or desertification. These changes brought lower yields or even the abandonment of cultivation. But in most regions traditional farming progressed from extensive to relatively, or even highly, intensive modes of cultivation.
 Except for small-scale cultivation of tubers (above all cassava) in the tropics and the Inca’s reliance on potatoes, all of the Old World’s traditional agricultures, as well as plowless Mesoamerican societies, shared their dependence on cereal grains. Cereal cultivation was supplemented by legumes, tubers and oil, fiber and, in some agricultures, also feed crops. After the domestication of draft animals the traditional crop cycles always started with plowing. Primitive wooden implements were used for millennia before the introduction of metal moldboard plows, 2000 years ago in China, but only some 17 centuries later in Europe. Plowing was followed by harrowing and by manual seeding. Harvesting also remained manual (sickles, scythes) until the introduction of grain reapers before the middle of the 19th century. Wheat cultivars had diffused worldwide from the Near East, rice from Southeast Asia, corn from Mesoamerica and millets from China.
Continuous primacy of grains in crop cultivation is due to the combination of their relatively high yields (two or three times higher than legume harvests), good nutritional value (high in filling, easily digestible carbohydrates, moderately rich in proteins), relatively high energy density at maturity (at 13–15 MJ/kg roughly five times higher than for tubers), and low moisture content ( 14%) suitable for long-term storage. Dominance of a particular species has been largely a matter of environmental conditions and taste preferences. Without understanding the nutritional rationale for their actions all traditional agricultures combined the cultivation of cereal and legume grains thus assuring complete amino acid supply in largely vegetarian diets. The Chinese planted soybeans, beans, peas, and peanuts to supplement millets, wheat and rice. In India protein from lentils, peas, and chickpeas enriched wheat and rice. In Europe the preferred combinations included peas and beans with wheats, barley, oats, and rye, in West Africa peanuts and cowpeas with millets, and in the New World corn and beans.
The principal means of agricultural intensification included more widespread and more efficient use of draft animals, increasing fertilization and regular crop rotations, more frequent irrigation in arid regions, and multicropping in the places where cli-mate could support more than a single crop per year. The use of draft animals (horses, mules, oxen, water buffaloes, camels, donkeys) eliminated the most exhaustive field work and it also sped up considerably many farmyard tasks (threshing, oil pressing), improved the quality of plowing (and later also of seeding), allowed for drawing of water from deeper wells for irrigation. The introduction of collar harness, invented in China about two millennia ago, iron horseshoes, and heavier animal breeds made field work more efficient (Smil, 1994). Feeding larger numbers of these animals eventually required further intensification to produce requisite feed crops.
Irrigation and fertilization moderated, if not altogether removed, the two key constraints on crop productivity, shortages of water and nutrients. Unaided gravity irrigation could not work on plains and in river valleys with minimal stream gradients; the invention and introduction of a variety of simple mechanical, animal- and people-driven water-lifting devices (mostly in the Middle East and China) solved this challenge (Molenaar, 1956). Fertilization involved recycling of crop residues and increasingly intensive applications of animal and human wastes. Extensive practices used no manure, whereas peak manuring rates in the 19th century Netherlands and in the most productive provinces in China surpassed 20 t/ha. Green manuring, cultivation of leguminous cover crops (clovers, vetches) which were then plowed under, was widely used in Europe ever since ancient Greece and Rome, and it has also been widely employed in east Asia (Smil, 2001). Even so, nutrient deficiencies commonly limited traditional crop productivity.
Growing of a greater variety of crops lowered the risk of total harvest failure, discouraged the establishment of persistent pests, reduced erosion, and maintained better soil properties. Crop rotations were chosen to fit climatic and soil conditions and dietary preferences. In poor societies they could substantially improve food self-sufficiency and food security at the local level. Traditional varieties of crops and their rotation schemes were enormous. For example, Buck’s (1937) survey of Chinese farming counted nearly 550 different cropping systems in 168 localities. The adoption of new crops – most notably the post-1500 introductions of such New World staple as corn and potatoes and such versatile vegetables as tomatoes and peppers – had an enormous impact on food production throughout the world. In spite of these innovations preindustrial agricultures brought only very limited improvements in average harvests. For example, European wheat yields, except in the Netherlands and the UK, did not begin to rise decisively before the last decade of the 19th century (Smil, 1994).
Traditional farming also provided no more than basic subsistence diets for most of the people. Even during fairly prosperous times typical peasant diets, although more than adequate in terms of total food energy, were highly monotonous and not very palatable. In large parts of Europe bread (mostly dark, and in northern regions with little or no wheat  our), coarse grains (oats, barley, buckwheat), turnips, cabbage, and later potatoes, were the everyday staples. Typical rural Asian diets were, if anything, even more dominated by rice or coarse grain (millet, buckwheat). In many cases traditional peasant diets also contained less animal protein than did the earlier intakes with higher consumption of wild animals, birds, and aquatic species. This qualitative decline was not offset by a more equitable availability of basic foodstuffs: major consumption inequalities, both regional and socioeconomic, persisted until the 19th century. The majority of people in all traditional farming society had to live on food supplies that were below the level required for a healthy and vigorous life and different kinds of malnutrition were common.
Documentary and anthropometric evidence does not demonstrate any consistent upward trend in per capita food supply across the millennia of traditional farming. Regardless of the historical period, environmental setting and prevailing mode of cropping and intensification, no traditional agriculture could consistently produce enough food to eliminate extensive malnutrition. More importantly, no preindustrial agriculture could prevent recurrent famines. Droughts and  oods were the most common natural triggers, and as a recent study demonstrates these natural disasters often represented the worst imaginable climatic teleconnections arising from the El NiƱo-Southern Oscillation (ENSO) whose effects are felt far beyond the Pacific realm (Davis, 2001). The combined (and never to be accurately quantified) toll of large-scale famines that repeatedly swept late 19th century India and China, and that also severely affected parts of Africa and Brazil, amounted to tens of millions of casualties.
In China in the 1920s peasants recalled an average of three crop failures brought by such disasters within their lifetime that were serious enough to cause famines (Buck, 1937). Some famines were so devastating that they remained in collective memory for generations and led to major social, economic and agronomic changes: the famous collapse of Phytophthora-infested Irish potato crops between 1845 and 1852, or the great Indian drought-induced famine of 1876–79. The world’s most devastating famine, in China between 1958 and 1961, was only secondarily a matter of drought; the primary causes lie in the delusionary Maoist policies (Smil, 1999a).


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