The University of Michigan has an ongoing collaborative translation project for the Encycopedia of Diderot & d'Alembert
The Encyclopédie (link is external), ou dictionnaire raisonné des sciences, des arts et des métiers (English: Encyclopaedia, or a Systematic Dictionary of the Sciences, Arts, and Crafts) was a general encyclopedia published in France between 1751 and 1772.
The Encyclopédie's aim was "to change the way people think", and represents the enlightenment roots of the open source and agrarian movements.
"The goal of an encyclopedia is to assemble all the knowledge scattered on the surface of the earth, to demonstrate the general system to the people with whom we live, & to transmit it to the people who will come after us, so that the works of centuries past is not useless to the centuries which follow, that our descendants, by becoming more learned, may become more virtuous & happier, & that we do not die without having merited being part of the human race." (Denis Diderot)
The Farm Hack Encyclopedia of Practical Farm Knowledge (link is external) is a direct descendent of this earlier work, which captures many of the complexities and context for resilient and diversified agriculture with significant contributions from one of the first innovators in agricultural technology, inventor of the seed drill Jethro Tull (link is external). This entry provides a prototype to discussions of rotations, enterprise plans, and innovation in equipment and sharing of knowledge begun over two hundred years ago, and provides the historic context and symbolic role that participating in agriculture had in the Chinese Empire, the Roman Republic that frames the symbolism of the contemporary White House garden within longer historic context.
The text has been digitized and an English translation project initiated by the University of Michigan Library. The translated articles can be searched here (link is external)
The following text (link is external) from the university of Michigan Library was translated by Ann-Marie Thornton [Bilkent University, Ankara, Turkey]
Agriculture, as the term implies, is the art of tilling the soil.  It is the first, most useful, most widespread, and perhaps most essential of all the arts. The Egyptians attributed its invention to Osiris,  the Greeks to Ceres and her son Triptolemus,  the Italians to Saturn or their king, Janus, whom they deified in gratitude for this godsend. Agriculture was the sole occupation of the patriarchs, the worthiest of men by their simplicity of manner, goodness of soul, and elevation of sentiment. It was the delight of great men among other ancient peoples. Cyrus the Younger planted most of the trees in his garden and deigned to cultivate them: on seeing them, Lysander of Lacedaemon, a leader of the republic, cried out: ‘Prince! All men must think you blessed for having known thus how to combine virtue with so much grandeur and dignity!’  Lysander uses the word ‘virtue’ as if it were thought at this time that a monarch who practised agriculture could not fail to be virtuous, and must at least have a taste for useful things and innocent occupations.  Hieron of Syracuse, Attalus, Philopator of Pergamum, Archelaus of Macedon, and countless others are praised for their love of the fields and of agricultural work by Pliny and Xenophon, who were not their subjects and did not praise in ignorance.  Cultivation was the primary objective of the Roman legislator, and in order to instil in his subjects the high opinion in which he held it, he ensured that the function of the first priests he appointed was to offer the first fruits of the earth to the gods and ask them for abundant harvests. There were twelve of these priests: they were called arvals, from ‘arva’, meaning fields or ploughable land.  When one of them died, Romulus took his place and subsequently this honour was accorded only to those who could claim an illustrious birth.  In these primitive times, everyone exploited and subsisted on the domains which they were bequeathed. The consuls inherited and retained this custom.  The entire Roman countryside was cultivated by the subjugators of the regions. For several centuries, the most celebrated Romans came from the countryside to assume the primary functions of the republic, and, what is infinitely more noteworthy, returned from these functions to engage in country pursuits. This was not through indolence, a distaste for grandeur, or a desire to retire from public affairs, for illustrious farmers, always ready to defend the fatherland, reappeared in order to attend to the needs of the state. Serranus was sowing his field when he was called upon to lead the Roman army.  Quinctius Cincinnatus was ploughing land which he held on the other side of the Tiber when he was appointed dictator. He abandoned this restful exercise, took command of the armies, vanquished the enemy, put his captives under his yoke, received the honours of war, and was back in his field after sixteen days.  Everything in the early days of the republic and the finest days of Rome reflected the consideration in which agriculture was held: the wealthy, ‘locupletes’, were none other than those whom we would now call husbandmen and rich tenant farmers. The first coin, ‘pecunia à pecu’, carried the imprint of a sheep or ox as the main symbols of wealth.  The registers of the quaestors and censors were called ‘pascua’.  In the Roman hierarchy, the primary and most numerous citizens were those forming the rustic tribes, ‘rusticæ tribus’, and it was a great ignominy to be reduced, for lack of good and wise management of one’s fields, to the number of urban dwellers and their tribe, ‘in tribu urbana’.  The town of Carthage was taken by storm: all the books in the libraries were given as gifts to princes who were allies of Rome; only Captain Mago’s twenty-eight books on agriculture were retained. Decius Syllanus was given the task of translating them and the original along with the translation were kept with great care.  Cato the Elder studied and wrote about the art of cultivation and Cicero recommended it to his son with the words: ‘Omnium rerum, ex quibus aliquid exquisitur, nihil est agriculturâ melius, nihil uberius, nihil dulcius, nihil homine libero dignius’, which means, ‘Of all which may be undertaken or pursued, nothing in the world is better, more useful, more enjoyable, in short, more worthy of a free man than agriculture’.  But this eulogy is still not as powerful as that of Xenophon. Agriculture was born with the law and society: it accompanied the division of land.  The earth’s fruits were man’s first riches: he knew of none other while he was more content to increase his happiness in the corner of land which he occupied than to resettle in different places and learn of the happiness or misery of others. However, as soon as the spirit of conquest enlarged societies, engendering luxury, trade, and every other dazzling symbol of grandeur and wickedness, metal became the mark of wealth, agriculture lost something of its first glory, and farm work, abandoned to subalterns, preserved its former dignity only in the songs of poets. In the centuries of decadence, authors, finding nothing in the city which would lend itself to imagery or painting, took flights of fancy into the countryside and delighted in portraying ancient customs which offered a cruel satire on those of their day. However, the land seemed to take revenge on this scorn for cultivation. ‘In bygone days’, Pliny records, ‘she offered us her fruits in abundance: she seemed to take pleasure in being cultivated with ploughs pulled by triumphant hands, and, to match this honour, she increased her yield with all her might. Today, this is no longer the case: we have abandoned her to mercenaries; we get slaves or convicts to cultivate her, and one is tempted to think that she has felt this affront.’  I am not informed of the current state of agriculture in China, but père Du Halde relates that in order to inspire a taste for it in his subjects, the emperor puts his own hand to the plough once a year to plough a few furrows, and his most distinguished courtiers then follow him in turn. 
Those involved in land cultivation are included under the terms ‘ploughmen’, ‘husbandmen’, ‘sequestrators’, ‘stewards’, each of which may designate any nobleman who exploits his land and cultivates his fields with his own hands.  They each enjoy the prerogatives granted from time immemorial to those engaged in land cultivation. They are subject to the same laws, which have always been weighed in their favour and have at times even been extended to those animals which share farm work with men. It was forbidden by an Athenian law to kill the ox which pulled the plough, or even to offer it in sacrifice: ‘He who commits this offence or steals agricultural tools will be punished with death.’ A young Roman who was accused and convicted of killing an ox in order to satisfy the whim of a friend was banished as though he had killed his own sharecropper, Pliny adds.
But it was not enough to protect ploughing implements by law, it was also necessary to ensure the tranquility and safety of the ploughman and his belongings. It was for this reason that Constantine the Great forbade all creditors to seize slaves, oxen, and ploughing tools for the payment of civil debts: ‘If creditors, bondsmen, or even judges infringe this law they will serve an arbitrary sentence to which they will be condemned by a higher judge.’ The same prince extended this prohibition by another law and enjoined his tax collectors on pain of death to leave the indigent ploughman in peace. He held the view that any obstacles posed to agriculture would hamper the production of goods and trade, and indirectly the extent of his rights.  At one time, country dwellers were obliged to furnish post horses for messengers and oxen for public coaches. Constantine took care to exempt draught horses and oxen from these corvées: ‘You must’, this prince said to his law enforcers, ‘severely punish whoever contravenes my law. If a man’s rank prevents you from acting ruthlessly, denounce him to me, and I will take charge of the matter: if there are no horses or oxen save those working on the land, make the carriages and dispatches wait.’  The Illyrian countryside was laid waste by small village landlords who called on the services of ploughmen, setting them corvées which were harmful to land cultivation: the emperors Valens and Valentinian were informed of these disorders, and put a stop to them by a law imposing perpetual exile and confiscation of all property on those who dared to exercise such tyranny in the future. 
But the laws protecting land, ploughmen, and oxen have enabled the ploughman to carry out his duty. The emperor Pertinax wanted fallow land to belong to those who were willing to cultivate it and those charged with clearing land for cultivation to be exempt from taxation for ten years, and, if they were slaves, to be set free.  Aurelius ordered town magistrates to urge citizens to cultivate abandoned land in their dominions and gave three years’ immunity to those who agreed to do so.  A law of Valentinian, Theodosius, and Arcadius put the first occupant in charge of abandoned land and in full possession if it were not reclaimed within two years. 
The edicts of our kings are no less favourable to agriculture than the laws of the Romans: Henri III, Charles IX, and Henri IV delighted in favouring country dwellers through their regulations. They prohibited the seizure of the ploughman’s furniture, harnesses, implements, and livestock. Louis XIII and Louis XIV reinforced these regulations. This article would never end if we were to mention every edict relating to grain preservation from sowing to harvest, but they are all just: who would be willing to incur the fatigue and expense necessary to agriculture, and scatter his grain over the earth, if he did not expect the reward of a good harvest? God’s law set the example: ‘If a man damages a field or vineyard by letting his beast roam in it, he must repair the damage with his best property. If a thorn bush catches fire and the fire spreads to a pile of wheat, whoever lit the fire must sustain the loss.’  The law of man added: ‘If a night thief plunders another man’s field, he shall be hung if he is over fourteen, and if he is younger he shall be birched and given to the landowner as his slave until he has repaired the damage to the assessor’s satisfaction. Whoever sets fire to a pile of wheat shall be flogged and burnt at the stake. If it catches fire through negligence, he will either repair the damage or be birched, at the assessor’s discretion.’ Our princes have been no more tolerant of damage caused to fields, maintaining that it should be repaired if it is accidental, and repaired and punished if it is premeditated: ‘If livestock wander through the wheat fields, they are to be seized and the shepherd punished.’ It is forbidden, even for gentlemen, to hunt in vineyards, wheat fields, or sown land: see Edit de Henri IV c Follembray, 12 January 1599, and the edicts of Louis XIV (August 1689; 20 May 1704). These kings have favoured the harvest further by allowing it to take place even on feast days, but the reader may refer to article ‘Grain’ and other articles for all which relates to the harvest, sale, trade, transportation, and policing of grain, and we shall move on to land cultivation. 
In order to cultivate land profitably, it is important to identify the soil type, since different soils require different methods of tilling and sorts of grain. The general points covering this subject may be found in articles ‘Land’ and ‘Soil’, while the articles on particular plants detail the type of soil and cultivation which they each require. Here, we are concerned only with the general principles of agriculture and ploughing.
Adjust your livestock and implements, the number, depth, and form of the ploughings, and the ploughing and fallow seasons to the soil condition and climate.
If your domain is quite extensive, divide it into three roughly equal parts. This is referred to as dividing one’s land into breaks.  Sow one of these three parts with wheat, another with oats and spring wheat which is called les mars, and leave the third to lie fallow. 
The following year, sow the fallow land with wheat, the wheat land with oats, and let the part sown with oats lie fallow.
This arrangement will make the yield, respite, and labour of the land more or less even if the soil is equally fertile over the whole surface area. However, the wise ploughman who wishes to leave nothing to chance will pay more heed to the quality of the land than the difficulty of cultivating it, and the fear of dearth will prompt him to exhaust one year by cultivating a large stretch of barren land in order to receive a regular income from it in subsequent years, rather than risk receiving an irregular income by ploughing at an even pace, and will give himself the smallest possible grounds for saying ‘my wheat land is strong or weak this year’.
Do not despoil your land because it is forbidden, and because you will gain nothing from making it yield more than its use and good ploughing permit.
You are robbing your master if as a tenant farmer you work land which should lie fallow against both his will and the terms of your lease. See ‘Décompoter’. 
Wheat land: till the wheat land three times while it is lying fallow before sowing it with wheat, wheat and rye, and rye. The first tillage should take place before the Feast of Saint Martin or before Easter after sowing the spring wheat, though tilling in autumn is more usual and beneficial.  It involves breaking up the land and destroying the weeds, and is called to give the first tillage or ploughing, to fallow, or to plough, break, or turn up fallow land. This first ploughing is usually to a depth of four digits in tight furrows, though in some provinces it is thought beneficial to deep plough.  By this means, the stubble from the previous crop is ploughed back into the land, unless it is thought preferable to burn it, in which case the ash is ploughed over. Otherwise, the stubble is either uprooted, ricked, and put to various uses, or ploughed back by lightly grazing the land. In this last case, the stubble is given time to rot, and in December the plough is brought back into the field and the land receives the first of the three real ploughings: this ploughing is deep and is called ‘plant ploughing’. It is followed by clod breaking, using a clod breaker or, more frequently, a strong harrow set with strong, iron teeth. One must also remove stones and stumps, and clear brambles, thorns, etc.
The second ploughing is called harrowing: if the first tillage has been completed before winter harrowing takes place at the end of winter, but if it has been given in spring the land is harrowed six weeks or a month later. The ploughing is brought forward or postponed according to the air temperature or strength of the soil and must be deep.
The third ploughing is called ploughing for the third time or harrowing for the second time. Before ploughing, the land is manured if it has not been worked on earlier. When there are only three ploughings, the third must be deep and should be given when the grass has started to bolt and the fallow land is ready to be sown, and no sooner than a week or a fortnight beforehand.
Since there should always be one ploughing before sowing, many lands require more than three ploughings: heavy soil may take up to four or five ploughings while the grass is coming up. When sowing is preceded by a fourth ploughing, it should be light: this is called ‘to cross-plough’. Land which is low-lying, deep, or difficult to drain is not cross-ploughed. When more than three ploughings are given, one rarely gives more than two or three complete ones: two in winter and one before sowing; strictly speaking, the others are only half-ploughings, using only the ploughshare without the coulter and mould- boards.
Spring wheat land: this land is left to lie fallow from July or August when the wheat has been harvested, to March when it is sown with spring wheat. It receives only one or two ploughings, before winter and before the sowing season. Those who wish to enrich this land leave or burn the stubble, and give the first ploughing before the Feast of Saint Martin and the second before March.
In France, only horses or oxen are used. Oxen plough more deeply, start earlier and finish later, are healthier, cheaper to feed and harness, and may be sold when aged. They must be coupled together closely so that they pull evenly. In Italy buffalos are used, and in Sicily donkeys: these animals should be taken young, fat, strong, etc.
Do not go down to the fields if you do not know the terrain, if your animals are not on form, or without sharp tools. The soil should be eighteen inches deep.
Choose a suitable time: do not plough too early or late in the year: the first ploughing will determine the success of the others with regard to the land.
Do not plough when the ground is too dry: you will either merely scratch the surface by a light ploughing or disperse the soil by ploughing deeply. Ploughing in midsummer heat should be followed by a half-ploughing before sowing.
If one were to plough in sultry weather, the wet soil would turn to mortar instead of loosening and the seeds would not thrive. Allow time for the land to lighten after rain or fog.
Start ploughing again when the grass begins to prick through the soil and give the last ploughing shortly before sowing.
Plough rich, damp, heavy, newly broken soil deeply and sandy, stony, dry, light, poorly-manured soil lightly.
Do not plough your furrows out too far or your beast will have too much to pull in one draught. It is thought beneficial to divide the land into strips of no more than 40 perches long for horses and 150 feet long for oxen: let the animals rest only at the end of the furrow. 
If you are ploughing on a hill, plough across rather than down.
Give smooth, flat ploughings in regions where the land needs rainwater. Plough damp, low-lying land in slopes, humpbacks, and high furrows. In this last case, leave a large furrow on each side of the field to receive and drain off excess water.
Make your furrows tighter, less smooth, and deeper in damp land. If the furrows are narrow, only 14-15 inches wide by 13-14 inches high, plough from south to north, so that your grain is exposed to the sun on both sides. This detail is less important if your furrows are flat. If you are ploughing damp soil on a level and in lands, do not forget to make a deeper furrow in the centre for drainage. Some soil may be ploughed smoothly without furrows or lands, in which case it suffices to tip all of the furrows to the same side, using only the mould- board to pick up the soil so that after the ploughing no large furrows are visible, following which a turning-handle plough is used.
Water furrows are permitted only when they are strictly necessary and do not offend one’s neighbours.
When you are ploughing for the third time, cross-plough so that your land, broken up in every direction, may be more easily cleared of stones and can soak up rainwater more readily.
Always make your last ploughing deeper than the previous one. Plough your furrows tightly and change the ploughshare infrequently. Do not sow the same crop for two consecutive years and avoid using hired labour for ploughing: if you must do so, make sure that the work is done well.
Have a good plough: see under article Plough a clod-breaker, harrow, pickaxes, etc. 
Here is a calendar of your year’s labour. 
In January: pick the large vegetables. Turn over the fallow land. Prepare the hemp and flax. Clean and repair your carts and tipcart, and prepare some stakes and osiers. Fell the willows and poplars. Rebuild the ditches and shape the hedges. Turn over the vineyards. Manure the fruit trees which are languid and prune the rest. Clear the meadows. Thresh the grain. Turn over the manure. Plough the light, sandy soil which was not ploughed at the Feast of Saint Martin. When it is mild, resume planting in the valleys. Graft the early trees and bushes. Plant the corms, kernels, nuts, etc. Have the hemp scutched and begin to spin. Make bundles of firewood and sticks. Let those hens which are ready start brooding. Brand the lambs you wish to keep. Salt the pork. If you are in a hot country, break up the fallow land, prepare it for the March sowing, etc.
In February: continue the previous tasks. Plant vines, and clear, cut back, and stake the planted vines. Manure the trees, fields, meadows, gardens, and beds. Trim the meadows. Prune the trees, clear them of dead leaves, worms, moss, dirt, etc. Till the ground to be sown in March, especially if it is hilly. If you take heed of the proverb, sow the oats. Sow the lentils, chick peas, hemp, flax, and woad. Prepare the sainfoin land. Inspect your vines if they are tender. Plant the woods, coppices, and slips. Clean the dovecote, henhouse, etc. Repopulate the rabbit warrens. Repair the burrows. Buy hives and honey bees. Manure the tree bases. If your climate is hot, tie the vines to the stakes. Give the boars to the sows, unless you prefer to wait.
In March: sow the oats and barley, flax, oats, and spring wheat. Finish pruning and staking the vine. Give the first full ploughing. Make firewood from the bine. Decant the wine. Give the second tilling to the fallow land. Hoe the wheat. Sow the olives and other stone-fruit trees. Trim the trees in the tree nurseries. Graft the trees before they bud. Tidy your gardens. Sow olive sediment on languid olive trees. Clear the meadows. Buy oxen, calves, heifers, foals, bulls, etc.
In April: continue to sow the spring wheat and sainfoin. Plough the vineyards and lands which have not yet been ploughed. Graft the fruit trees. Plant new olives and graft the others. Prune the new vines. Feed the pigeons, as they will no longer be able to find any food. Give the stallion to the mares, she-asses, and ewes. Feed the cows which normally calve during this period. Buy honey bees, and hunt for some in the woods. Clean the hives and go butterfly hunting.
In May: sow the flax, hemp, turnips, rape, millet, and panic grass if you are in a cold country. Plant the saffron. Plough the fallow land. Hoe the wheat. Give the second tilling and tend to the vineyards. Remove the fruitless vine branches and shoots. Cut the oaks and alders so that they may be barked. Prune and graft the olive trees. Tend to the honey bees and especially the silkworms. Shear the ewes. Make butter and cheese. Stock up with wine. Geld your calves. Look for young foliage for your livestock in the forest.
In June: continue the ploughing and sowing of the previous months. Debud and tie the vines. Continue to tend to the honey bees and geld the calves. Stock up with butter and cheese. If you are in a cold country, shear your ewes. Give the second tilling to your fallow land. Cart the manure and marl. Prepare and clean the threshing floor of the barn. Clear out the excess honey bees. Keep the hives clean. Fork the meadows and other green fields. Ted the hay. Pick the ripe vegetables. Towards the end of the month, reap your barley squares. In Italy begin harvesting your wheat, and in every country prepare for the harvest. Thresh some wheat for sowing. Pick the cherries. Collect some riddles and pen in the livestock.
In July: finish hoeing the fallow land. Continue carting the manure. Pick the early barley, turnips, rape, flax, silkworms, crops, and summer vegetables, and store the winter ones. Give the third ploughing to the vine. Remove the couch grass. Level the land to preserve the roots. Rid the apple and pear trees of rotten and superfluous fruit. Collect those which have been blown down by the wind and make early cider from them. Serve your cows. Visit your herds. Cut the hay. Empty and clean out your barns. Employ some reapers. In a hot climate, buy rams for your ewes and cover exposed tree roots.
In August: finish the harvest, uproot the hemp, and make the verjuice. In cold countries thin the leaves of the late vinestocks, and in hot countries put the vinestocks in the shade. Begin the third ploughing of the fallow land. Thresh the rye for the next sowing. Continue manuring the land. Where necessary, look for springs: if you find some in August you will have water all year round. Go wasp hunting. Set fire to the pasture in order to kill the weeds. Prepare your wine presses, vats, barrels, and other equipment needed for the wine harvest.
In September: finish picking the grain and hemp, and ploughing the fallow land. Manure the soil and turn over the manure. Fork the second section of meadow. Pick the hops, mustard, apples, pears, nuts, and other autumn fruits. Gather stubble for covering your cowsheds, and begin sowing the rye, wheat and rye, and even the wheat. Reap the rice and millet. Pick and prepare the woad and madder. Towards the end of the month, begin the grape harvest. In hot countries, sow the peas, vetch, mustard, buckwheat, etc. Break up the land for the sainfoin. Prepare new meadows and revive old ones. Sow the lupins and other similar seeds, and assemble a large number of skinny pigs for the acorn harvest.
In October: finish the grape harvest, wine making, and wheat sowing. Collect the honey and wax, and clean the hives. Finish the saffron harvest. Store the orange trees. Sow the lupins, barley square, peas, horsebeans, and winter fodder. Make cider and retsina. Plant olives and expose the roots of those which are planted. Preserve the white olives. Towards the end of the month, begin to layer the vine, raising the earth against it if that is your practice.  Attend to the new wine. Begin felling the woods, marling, and planting. In hot countries, sow oats and barley, bearded wheat, and even flax, which we plant only in spring, from 10-23 October.
In November: continue making the cider. Fell the woods. Plant and layer the vine, and expose the roots. Gather the olives when they begin to change colour and extract the first oil from them. Plant new olives and prune those which are planted. Sow new plants. Harvest the sweet chestnuts, madder, and osiers. Store the autumn and winter fruits. Gather acorns for the pigs. Store the rape. Gather and dry some grass for the livestock. Cart the manure and marl. Tie the vines. Bring in and store the stakes. Cut the willow shoots and strip or split them. Make nut oil. Begin pruning the vines, and cut the trees back. Chop wood for building and fuel. Clean the hives and visit your greenhouses and fruit and vegetable stores. In hot climates, sheep are kept from this month, the billy goat is released to the goat, and the short bearded wheat, barley, broad beans, and flax are sown. In cold and temperate zones, this sowing takes place only in March.
In December: clear the woods and chop some wood for building and fuel. Manure and marl your land. Thresh your wheat. Make stakes, rush and wicker baskets, rakes, and shafts. Prepare your tools and repair your harnesses and implements. Kill and salt the pork. Manure the tree bases and vegetables which you wish to keep until spring. Visit your land. Head back your poplars and other trees if you want them to grow well in the spring. Set snares and traps, and begin your year again. For the detail of each operation, see the relevant article.
Such is the year, labour, and work methods of our ploughmen. However, an English author has proposed a new system of agriculture, which we will explain using M. Duhamel’s translation of the English work enriched by his own findings. 
Mr Tull divides roots into taproots which sink vertically into the soil and support large trees such as oaks and walnuts, and spreading roots which extend parallel to the earth’s surface. He claims that the latter are far more suited to collecting nutritive sap than the former. He then demonstrates that leaves are vital to plant health (we will explain this experiment in article ‘Leaf’), from which he concludes that it damages lucernes and sainfoins to allow livestock to graze on them too frequently, and that it may be less beneficial than previously thought to put cattle in wheat fields when the animals are too strong. 
Having examined the vital organs of plants, that is, the roots and leaves, Mr Tull proceeds to consider plant food: he believes it to be simply a fine powder, which is neither implausible nor unproblematic, for the integral substances of the earth would then need to be soluble, which, as M. Duhamel observes, does not appear to be the case.  Mr Tull then puts a difficult question: he wonders whether all plants nourish themselves with the same sap. He believes this to be the case, but several authors disagree and accurately observe that a particular soil may be sterile for one plant but not for another, that trees planted in the same soil for a sustained period do not spring up as quickly as new trees, that since the sap with which barley is nourished resembles that of wheat, barley exhausts the soil more easily than oats, as a consequence of which wheat should follow oats in a field rather than barley, all else being equal. Whatever the intricacies of this question, on which botanists may still ponder, M. Duhamel proves that one of the main advantages of not sowing land during the fallow year is that it allows more time to increase the number of ploughings needed to destroy weeds, break up and turn over the earth, and prepare it to receive the most precious and delicate grain of all, that of wheat. Consequently, it is futile to multiply the ploughings in one piece of land without leaving a sufficient lapse of time between them, since this would not be to the soil’s advantage. Once the stubble and grass have been turned over, they should be left to rot and the earth to absorb goodness from the elements, otherwise one risks returning the earth to its original state through hurried ploughing. It is therefore necessary to both increase the number of ploughings without which the roots will put out with difficulty and draw little sap from the soil, and leave a sufficient interval between the ploughings without which the soil will not be renewed. In addition, the weeds must be destroyed by frequent ploughing, and the correct balance obtained between the number of plants and the soil’s ability to nourish them.
The aim of frequent ploughing is to separate the earth’s particles, multiply its pores, and bring more food closer to plants. This separation may also be obtained through calcination and manure, but manure always alters the quality of produce to some extent and one does not always have manure of the desired quantity and quality, while the number of ploughings may be increased to a certain point without altering the quality of the produce. Manure may give substance to soil, but repeated ploughings successively expose different parts of the soil to the influence of the air, sun, and rain, rendering it suitable for vegetation.
However, precautions must be taken when ploughing land which has not been sown for a long period, which may be dispensed with when dealing with land which has been cultivated continuously. Mr Tull divides such land into four classes: 1. wooded land; 2. moors; 3. fallow land; 4. wet land.
Mr Tull observes that if the scarcity of wood had not put a stop to the practice of setting fire to wooded land in order to convert it to ploughable land, it would have to have been abandoned, because scouring the land for stumps is an excellent form of tillage and the fertilization of soil by ashes is, if not illusory, then at least not greatly effective.
The poor produce of moors must, he argues, be burnt towards the end of summer when the grass has dried out and ploughed frequently.
With fallow land, which includes sainfoin, lucernes, clover, and meadows, along with a few pieces of land which are only ploughed every eight or ten years, one ploughing does not suffice with regard to the meadows: one must begin by breaking the earth into huge clods using a strong plough equipped with a mould-board, then wait for the autumn rains to break up the clods and for winter to finish destroying them before giving a second ploughing, a third, etc. In short, this land should be sown with wheat only when it has been sufficiently refined by ploughing. Land which is ploughed only once a decade is burnt in the following manner: the entire surface is cut into equal pieces of 8-10 inches squared by 2-3 digits deep, as in a a a (Fig. 1); they are then stacked against each other as in b b b (Fig. 2).  Three days suffice to dry them out in fine weather. They are then made into kilns. In order to form these kilns, a small cylindrical tower is first erected of one foot in diameter, a f b (Fig. 3). As the wall of the small tower is made from sods of turf, its thickness is determined by theirs: care must be taken to put grass inside and make a door one foot wide on the windward side. A large piece of wood serving as a lintel is placed above this door. The top of the tower is filled with dry wood mixed with straw and the furnace is completed with the same sods in the form of a dome, as in e d (Fig. 4). Before the vault is entirely closed, the wood is set alight, then the door, d, is closed very quickly, sods of turf also being used to close the crevices through which excess smoke escapes.
The kilns are watched over until the earth seems to be on fire. If any apertures appear, the fire is put out with sods of turf and the kiln is rebuilt. After 24-28 hours, the fire will die out and the sods of turf will have turned to powder, apart from those at the top which sometimes remain uncooked if the fire has not reached them. In order to avoid this drawback, the kilns are made small. After rainfall, the cooked earth is spread as evenly as possible, except over those areas formerly occupied by the kilns. A light ploughing is given immediately but subsequent ploughings are heavier. If it proves possible to give the first ploughing in June and if rain should follow, immediate profit may be drawn from the land by sowing millet, rape, etc., which will not prevent the sowing of rye or wheat the following autumn. Some people spread their burnt earth only immediately before the last ploughing, but Mr Tull condemns this method in spite of the pains taken to ensure its success, because it is beneficial to mix the burnt earth well in with the soil.
Damp land is drained by a deep furrow running along each side of the land or cutting through it. Mr Tull describes the different modes of ploughing, which do not differ from those outlined above, but his system differs markedly from traditional methods in the following manner: I suggest, Mr Tull states, ploughing the land while the annuals are growing, and as the vine and other perennials are cultivated. Begin with a ploughing of 8-10 inches deep using a plough with four coulters and a wide ploughshare: when your land is well prepared, begin to sow, but instead of scattering the seeds randomly by hand, distribute it in rows spaced at sufficient intervals using my seed drill (this instrument will be described in article ‘Seeder’).  As the crops grow, plough between the rows using a light plough. For a description of this type of plough, see article Plough.  Mr Tull wonders whether more grain is needed in rich than in poor soil and concludes that less grain is needed in areas where the plants are more robust.
With regard to the choice of grain, Mr Tull prefers new wheat to old. Our tenant farmers soak their wheat in lime water: we must await new experiments, which M. Duhamel has promised us, in order to test the validity of this practice. It is thought beneficial to alternate the grain from time to time and experiments have confirmed this. Other authors claim that wheat produced in rich soil should be sown in poor soil and vice versa, whereas Mr Tull thinks that all wheat should be drawn from the best soil, an opinion which according to M. Duhamel is advanced but not proved in Mr Tull’s book. It is erroneous to think, as some do, that grain can change to the point where wheat becomes rye or rye grass. Such are the general principles of agriculture advanced by Mr Tull, which differ from other methods in the manner of sowing, the number of ploughings, and the ploughings between plants. We will describe their effects in articles ‘Corn’, ‘Wheat’, ‘Sainfoin’, etc. Here, we will merely report M. Duhamel’s judgement of them, which, given his powers of observation, may be relied upon.
One should not consider, states M. Duhamel, whether wheat produces more grain when sown according to Mr Tull’s principles, as this comparison would be too favourable to him. Neither should one merely seek to establish whether an acre of land cultivated according to his methods produces more grain than an acre cultivated by traditional methods, for when seen from this perspective the new form of cultivation may fare little better than the old.
What should be examined is: 1. whether the entire farmland cultivated according to Mr Tull’s principles would produce more grain than when cultivated according to traditional methods; 2. whether the new form of cultivation would require a greater outlay than the old and whether an increase in profit would exceed any increase in expenditure; 3. whether by following the new method rather than the old there would be less risk of those accidents which thwart the ploughman’s endeavours.
To the first question, Mr Tull replies that one acre of land will yield more grain when cultivated according to his principles.  Distribute the wheat stalks which are on the lands along the entire length of the borders, he says, and the whole surface area will be as covered as usual, but the ears will be longer, the grain bigger, and my harvest better.
It is hard to believe that three rows of wheat placed in the centre of an area six foot wide can make up in fertility for all that is in the open ground, and perhaps, M. Duhamel remarks, Mr Tull is exaggerating. However, it must be remembered that usually one third of the land lies fallow, one third is sown with spring wheat, and one third with wheat, whereas in the new method all of the land is sown with wheat. However, since from a width of six feet only two are used, then here also only one third of the land is taken up with wheat. It remains to be seen whether the rows of wheat are sufficiently robust and yield sufficient grain, not only to compensate for the oat harvest, valued in farm rent at one third of the wheat harvest, but also to increase the ploughman’s profits.
To the second question, Mr Tull replies that his land costs less to cultivate, and this is true when one compares each method using the same land area, but since following the new method the entire surface area needs to be cultivated, whereas according to the old method one third is left to lie fallow, only one tillage is given to the third sown with oats, and only one third is sown with wheat which requires a whole tillage, it is impossible to conclude in Mr Tull’s favour. It therefore remains to be seen whether any increase in profit may compensate for the additional outlay.
With regard to the third question, Mr Tull replies that of all the accidents which may befall wheat there are some which cannot be averted, such as hail, wind, rain and excessive frost, certain accidental frosts, dry mist, etc., but that his method obviates those conditions which make the wheat small and shrunken, spiky, etc.
Let us be more precise: let us suppose that there are two farms of 300 acres each cultivated by a different method. The tenant who follows traditional methods will divide his land into three breaks and have 100 acres of wheat, 100 acres of barley, oats, peas, etc., and 100 acres of fallow land. 
He will give one or two ploughings to the plot of spring wheat, three or four to the fallow land, and the remainder, taken up with wheat, will not be ploughed. The two exploited plots therefore work out at six ploughings for 200 acres or, which comes down to the same thing, his work amounts to ploughing 400 or 600 acres once a year.
It usually costs six francs to have one acre ploughed: hence, depending on the required number of ploughings, the tenant farmer will spend 2,400 or 3,600 pounds. 
At least 2½ minas of wheat (a measure devised by Petiviers, one mina weighing eighty pounds) are required to sow an acre. When the wheat is second rate, it expands and weighs three minas, which is why it is said that one sows three minas an acre.  We will assume this to be the case, because since seed wheat is the finest and most expensive wheat there is an offset. Without distinguishing between the cost of harvest wheat and seed wheat, we will estimate that both cost four pounds a mina: 100 acres will therefore cost 1,200 pounds.
There is no outlay for sowing and harrowing because the ploughman who has been paid for the tillage sows the wheat without charge.
Cutting and carting the wheat into the barn costs six pounds an acre, which totals 600 pounds for 100 acres.
The cost of weeding the grass or hoeing varies each year: it may be valued at one pound and ten shillings an acre, which comes to 150 pounds.
One needs as much oats or barley as wheat to sow the spring wheat plot, but since they are cheaper tenant farmers value them at only one third of the price of wheat: 400 pounds.
The cost of sowing is limited to rolling, which is paid at the rate of ten shillings an acre: fifty pounds.
The cost of harvesting comes to 200 pounds, which is one third of the cost of the wheat harvest: 200 pounds.
We will disregard manure because: 1. tenant farmers do not buy manure but make do with the produce of their kilns; 2. manure is used in both methods, with the single difference that in the new method twice as much land is manured.
Farm rent and taxation cost the same in each case: hence the expenditure of the tenant farmer who cultivates 300 acres of land following traditional methods amounts to 5,000 pounds if he gives only three tillages to his wheat and one to his oats, or 6,200 pounds if he gives four tillages to his wheat and two to his oats. 
Let us estimate his yield: good land will produce about five times the weight of the seed; he will therefore have 1,500 minas, worth 6,000 pounds.
The oat harvest being one third of the wheat harvest, it will give him 2,000 pounds.
His total harvest will be worth 8,000 pounds: deduct 5,000 pounds for expenses and he will be left with 3,000 pounds, from which a further 1,200 pounds would need to be deducted if he had given more than four tillages to his land.
In the following calculation, it is assumed that the land has been cultivated for several years following Mr Tull’s method. One good ploughing should be given to the borders after the harvest, one light ploughing before sowing, one ploughing in winter, one in spring, one when the wheat stems grow, and finally one when it is in the ear, which makes six ploughings to be given to 300 acres of land. The 300 acres must be cultivated and sown with wheat, which would make 1,800 acres to plough once a year. But since in each ploughing one third of the land is not turned over, these 1,800 acres will be reduced to 1,200 or 1,000, which will cost, at the rate of six pounds an acre, 6,000 or 7,200 pounds.
Only one third of the wheat used is consumed: hence this expense will be the same for 300 acres as for the 100 acres of the preceding calculation: 1,200 pounds.
Let us suppose that the cost of sowing and harvesting is the same per acre as in the preceding hypothesis, which is the maximum possible amount: for 300 acres that would be 1,800 pounds.
The hoeing per acre will differ from the above, so for 300 acres we will put 150 pounds.
The figure totals 10,350 pounds which the tenant will need to spend and this expense exceeds the preceding estimated outlay by 5,350 pounds.
I have assumed, contrary to Mr Tull’s testimony, that one acre will produce the same amount of wheat whichever method is followed. I have estimated fifteen minas an acre, that is, 4,500 minas for 300 acres at the rate of four pounds a mina: 18,000 pounds. But if from this 18,000 pounds one deducts the outlay of 10,350 pounds, the new method will surpass the old by 4,650 pounds.
Whence it follows, that if two acres cultivated according to Mr Tull’s principles produced only the same as one acre following traditional methods, the new form of cultivation would still give 1,650 pounds more than the old one over 300 acres. But one advantage which has not been taken into consideration and is quite significant is that in the first method the harvest is more reliable.
We have dwelt on this subject because it is of great importance to mankind. We invite those whose wealth permits them to undertake costly experiments with no guarantee of success, yet without incurring any financial hardship, to add the weight of experiment to the parallels and conjectures made by M. Duhamel. This skillful academician wisely judged that one small example would have more impact than reasonings which, though sound, would not be understood by most men or trusted by those who might have difficulty in following them. He too had a rectangular plot of land ploughed, half of which he had sown according to traditional methods and the rest at intervals of six inches in rows four feet apart. This small field was sown towards the end of December. In March, M. Duhamel had the land between the rows dug over with a spade: when the wheat began to spring up in the rows, he gave a second ploughing and finally a third ploughing before it flowered. When the wheat was full grown, the seeds from the centre of the area cultivated along traditional methods had produced only 1, 2, 3, 4, sometimes 5, and rarely 6 stalks, whereas those in the rows had produced from 18-40 stalks, and the ears were longer and contained more grain. But unfortunately, M. Duhamel adds, birds ate the grain before it was ripe and the produce could not be compared. 
1. ‘Agriculture’ is derived from the Latin ‘agricultura’, meaning ‘culture of a field’ (Skeat, 1994, pp. 6, 89).
2. Osiris, who was incarnated in the sacred bull Apis, was a nature god of fertility (Howatson and Chilvers, 1996, p. 387).
3. Ceres, identified with the Greek Demeter and worshipped by Greek merchants on the Aventine Hill in Rome, was a goddess of nature’s creative power. Triptolemus was chosen by Demeter to teach men the skills of agriculture (ibid., pp. 116, 553).
4. Saturn may have been a blight or seed god: he was identified by the Romans with the Greek Cronus. Janus was traditionally an early king of Latium (ibid., pp. 295, 482).
5. Sparta was an oligarchy rather than a republic. Cyrus the Younger (d. 401 BC ) was the second son of Darius II, king of Persia from 424-405 BC. Cyrus was a friend of the Spartan naval commander, Lysander of Lacedaemon (d. 395 BC ). In Oeconomicus (‘Household management’) the Athenian historian Xenophon ( c. 428- c. 354 BC ), who fought in Cyrus’ mercenary army, describes how Cyrus showed Lysander round his garden at Sardis. Lysander was said to have admired the regularity of the tree planting, which he erroneously attributed to Cyrus’ agent, before being corrected by Cyrus (ibid., pp. 157, 326; Sackville-West, 1989, pp. 260-61; Adams, 1991, p. 23).
6. On Diderot’s association of agriculture with virtue, see below, n. 34.
7. These rulers are: Hieron I, tyrant of Syracuse (478-467 BC ); Attalus I of Pergamum (269-197 BC ); Attalus III, Philometor Euergetes, who bequeathed Pergamum to Rome (133 BC ); and Archelaus, king of Macedon (413-399 BC ). Xenophon’s Hieron is a dialogue between the tyrant and a citizen, Simonides. Pliny the Elder ( AD 23/4-79) was celebrated for his Naturalis Historia in thirty-seven books (Howatson and Chilvers, 1996).
8. The arval priests or brothers formed the oldest college of priests in Rome. They offered sacrifices in public for the productivity of the land, their main ceremony taking place in May for the agricultural divinity Dea Dia (ibid., p. 64).
9. The mythical Romulus is said to have founded Rome, which he is named after, in 753 BC (ibid., pp. 473-4).
10. The consuls were the primary civil and military magistrates of Rome in the republic. They were elected annually by the people from among the senators (ibid., p. 144).
11. A surname of Marcus Atilius Regulus, who was twice Roman consul, a commander in the First Punic War, and leader of the Roman expedition to Africa (ibid., p. 465).
12. The mythical Roman hero Lucius Quinctius Cincinnatus was supposedly summoned from his fields to be dictator in 458 BC, when the army was blockaded by the Italian Aequi tribe on Mount Algidus (ibid., p. 128).
13. ‘Pecunia’: property, wealth; ‘pecus’: cattle, sheep.
14. The quaestors were two Roman magistrates who were elected by the consuls in order to help them dispense justice. The two censors, who were also magistrates, were elected in order to take the census; they purged the senate of unlawful and immoral senators (Howatson and Chilvers, 1996, pp. 115, 463). ‘Pascua’ means ‘a pasture’.
15. There were at first three tribes or administrative units founded on kinship. Under Servius Tullius, they were replaced by four urban tribes intended to include aliens. In time, ‘rustic’ tribes were added for country dwellers (ibid., p. 552).
16. Carthage, the seat of a great empire enriched by trade and agriculture, was destroyed at the end of the Third Punic War in 146 BC. The Carthaginian writer Mago’s agricultural encyclopaedia, mentioned in Varro’s De Re Rustica (book I, ch. 1) of 37 BC, was probably based on Hellenistic agricultural literature, and may have been composed after the peace treaty concluding the Second Punic War, when Punic landowners introduced more intensive farming methods (ibid., p. 109; Cary and Scullard, 1979, p. 147 and n. 9).
17. The De Agri Cultura of Marcus Porcius Cato ‘the Censor’ (234-149 BC ) treated the intensive cultivation of vines, olives, fruit, etc., on a mixed farm of 66-220 acres, and is the oldest extant piece of sustained Latin prose. Marcus Tullius Cicero, 106-43 BC, wrote his last philosophical work De Officiis (44 BC ), for the improvement of his son Marcus, who was studying philosophy at Athens (Howatson and Chilvers, 1996, pp. 112-13, 124, 160, 173; Cary and Scullard, 1979, p. 188).
18. In his Oeconomicus.
19. Jean-Jacques Rousseau develops this point in his Discours sur l’inégalité. Diderot’s article ‘Agriculture’, appearing two years after the composition of Rousseau’s Discours sur les sciences et les arts in 1749, and two years before that of the Discours sur l’inégalité in 1753, forms part of the intellectual exchange between the two friends at this time.
20. Pliny the Elder was a critic of contemporary Rome, of its taste for luxury and Greek influence. Eighteenth-century thinkers referred to such critics as an indirect warning to their own monarchs, attributing the decadence of Rome to the progress of commerce and luxury at the expense of noble pursuits such as agriculture. In the first part of the Discours sur les sciences et les arts, Rousseau refers to a Rome ‘founded by a herdsman, and made famous by ploughmen’, which, from being a ‘temple of virtue’, had become a ‘theatre of crime’. Diderot also adopts an ethical stance, seeking to promote the view of agriculture as a virtuous occupation, as does the physiocrat François Quesnay (1694-1774) in article ‘Fermiers (Economie Politique)’, Encyclopédie, vi.528.
21. See Jean-Baptiste Du Halde, 1735 (ii.70) which inspired the physiocrats, whom Diderot frequented and who saw China’s fostering of agriculture at government level as a model for Europe. Emperor Yontchin’s ‘k’eng-chi’ spring ritual was one of the most potent symbols of China in eighteenth-century France. François-Marie-Arouet de Voltaire’s description, derived from Du Halde, ends with the flourish: ‘What must our European sovereigns do upon learning of such examples? Admire and blush, but above all imitate’ (article ‘Agriculture’: ‘De la grande protection dûe à l’agriculture’, Voltaire, 1768). The future Louis XVI, ‘the ploughing dauphin’, did imitate the ritual by following a plough in a sowing ceremony on 15 June 1769. Diderot refers to the ‘k’eng-chi’ ritual in article ‘Philosophie de la Chine’ (Guy, 1963, pp. 356-8).
22. A ‘gros laboureur’ is a husbandman, while a ‘laboureur’ is a ploughman, a term which included tenant farmers and sharecroppers, and was also used to refer more generally to the peasantry.
23. This is a thinly veiled recommendation to the French government. Constantine the Great, AD 285-337, sole emperor from 324, established a new residence at Byzantium, which in 330 was renamed Constantinople (Howatson and Chilvers, 1996, p. 143).
24. A critique of French feudalism is implied here: in the Encyclopédie (iv.280), the French corvée seigneuriale is defined as a service paid by a subject to his lord, including the duty of making his coaches and carts, and supplying oxen, horses, and other beasts of burden to pull them. The corvée, of which the ‘vée’ is an old Lyonnais dialect, signifies ‘suffering’ and ‘labour’, and originated in Roman law.
25. The brothers Valens and Valentinian partitioned the Roman empire in 364: Valens ruled the west and Italy, and Valentinian the east. (Cary and Scullard, 1979, p. 550).
26. Helvius Pertinax was Roman emperor from January to March AD 193. He was murdered by his own troops, perhaps as a consequence of his extensive domestic reforms (ibid., p. 490).
27. Marcus Aurelius ( AD 121-80) was Roman emperor from 161 (Howatson and Chilvers, 1996, p. 77).
28. Theodosius I, ‘the Great’ ( AD 347-95) was Roman emperor from 388-95. His son, Arcadius ( AD 378-408), succeeded him and ruled with his brother Honorius. Arcadius governed the two eastern prefectures, the Orient and Illyricum (ibid., p. 535; Cary and Scullard, 1979, p. 550).
29. It was customary for eighteenth-century authors to trace the history of civilization with infrequent reference to Scripture. Diderot’s allusions to antiquity are more numerous: he felt that a knowledge of Greek and Latin was necessary for educated men but that such knowledge should be reserved for an intellectual elite. He considered natural history a more useful general discipline (Grell, 1995, p. 71).
30. Articles: ‘Grain’, ‘Grains (Economie Politique)’; Encyclopédie, vii.812. The latter exposes in detail the problems besetting agriculture in eighteenth-century France.
31. Mettre ses terres en soles’ is now ‘assolement des cultures’. The term ‘crop rotation’ was not used until 1778. Obligatory crop rotation, or ‘contrainte de sole’, was abolished on 5 June 1791 (Jones, 1990, p. 292).
32. Spring wheat is called ‘blé de mars’ or ‘les mars’ because it is sown in March.
33. The article ‘Décompoter’, omitted from the Encyclopédie, may be found in the Dictionnaire universel français et latin (ii. 1849); the word signified changing the order of crop rotation and working land which should remain fallow. A ‘fermier’ was a tenant farmer who paid rent (‘fermage’) to a landlord in order to cultivate land, usually in addition to his own, and frequently according to rules fixed by the landlord. The other main form of cultivation, sharecropping or ‘métayage’, was based on payment in kind (Williams, 1984, pp. 214-15).
34. The Feast of Saint Martin is November 11.
35. In article ‘Mesure longue’, the English ‘digit’ is given as a translation of ‘doigt’: ‘digit signifie un travers de doigt’ ( Encyclopédie, x.417). A digit, or finger’s breadth, is about three-quarters of an inch.
36. The English perch measured 16½ English feet, while the French ‘perche’ measured eighteen French feet or ‘pieds’ in Paris. The French pied was slightly longer than an English foot: 150 pieds would have equalled just over 160 English feet.
37. See also Agriculture and Rustic Economy, Ploughing, plates I-IV, in Encyclopédie, Volume I of the plates (1762), and above, pp. 81, 85-6.
38. Diderot is here follows the precedent set by classical writers on agriculture: book I of Varro’s De Re Rustica offers a general overview of the agricultural year, and books II- XIII of Palladius’ De Re Rustica, composed in the fourth century AD in 14 books, detail the monthly calendar of a farm (Howatson and Chilvers, 1996, pp. 174, 392).
39. ‘Rueller’ means to make small paths or alleys by raising the earth on both sides against the vine stock.
40. On Tull, 1733, translated Duhamel du Monceau, 1750-61, see Appendix 2. The Parisian Henri-Louis Duhamel du Monceau (1700-82) wrote numerous books on agriculture and trade, and was elected to the Académie des Sciences in 1728. On the agricultural writer and farmer Jethro Tull (1674-1741), see above, pp. 85-6. In 1699, Tull began farming on his father’s land at Howberry, near Wallingford, where in about 1701 he invented and perfected his horse-drawn seed drill, and began experimenting with his new system of sowing in drills or rows, which were sufficiently wide to allow tillage using ploughs and hoes during most of the period of growth. This practice was more economical than the traditional method of scattering the seed, which was referred to as ‘broadcasting’ from 1767 ( Encyclopedia Britannica, 1995).
41. Article ‘Feuille’ ( Encyclopédie, vi.652).
42. Tull, and others, erroneously thought that earth particles were absorbed by plants for food, and that pulverization facilitated their absorption.
43. Agriculture and Rustic Economy, Ploughing, plate V: Method of…burning land, in Encyclopédie, volume I of the plates, and above, p. 86.
44. Article ‘Semoir’ ( Encyclopédie, xiv.947).
45. See also Agriculture and Rustic Economy, Ploughing, plate I (Fig. 3: ‘the plough of M. Tull’), above, pp. 85-6.
46. The French ‘arpent’ is defined in the Encyclopédie (i.702) as a stretch of land measuring 100 square perches (2,500 square metres), and an ‘acre’ (i.113), in England and Normandy, as 160 square perches, or 4,000 square metres.
47. A farm of this size would be owned by a rich tenant farmer or ‘fermier’, usually in possession of at least one plough with four horses. Members of the rural bourgeoisie, these farmers would need to make a considerable outlay, sometimes as much as 10,000 pounds, and twice as much if they owned two ploughs, two years in advance of their first harvests. Although such farmers were few in eighteenth-century France, Diderot xml:ids them deliberately: they were sufficiently educated to follow his reasoning, and, more importantly, could do most to revitalize agriculture by spending on their land, thereby increasing its yield and providing work for poor peasants, enabling them and their children to remain in the provinces rather than migrate to the capital.
48. The French franc was roughly equivalent to the livre, which it displaced as a unit of currency from the 1790s. The ‘livre’ or one pound in weight, is about half a kilogramme.
49. ‘Chotté’: a term used in Berry to mean second-rate wheat lands (Larousse, iv.197).
50. Farm rent was estimated at eight pounds, and taxation at four pounds, an acre. The principal taxes were the ‘taille’ and the ‘gabelle’: the former was a direct royal tax which dated from 1439. It was based either on movable wealth or land, neither of which were considered to be fair means of taxation by Quesnay. The ‘gabelle’, the dreaded salt-tax, was suppressed in 1790; Jones, 1990, p. 413; article ‘Fermier (Economie politique)’, Encyclopédie, vi.539.
51. This hazard, which is not mentioned above, provides a humorous antedote to the complicated equations of the article’s conclusion, reminding us, as these articles are often at pains to emphasize, that human experiments are at the mercy of nature.