3rd b 2 historical development in soil fertility and plant nutrition

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  • Historical development in soil fertility and plant nutrition

  • The period in the development of the human raceduring which man began the cultivation of plantsmarks the dawn of agricultureThe exact time is not known, but it was certainly several thousands of years BCUntil then, man was nomadic in his habits

  • In all ages the growth of plants has interestedthoughtful manThe mystery of the change of an apparentlylifeless seed to a vigorous growing plant neverloses its freshness, and constitutes, indeed, nosmall part of the charm of gardeningThe economic problems are of vitalimportance, and become more and moreurgent as time goes on and populationincreases and their needs become morecomplex

  • We know now the facts about the needs ofessential nutrients and other factors of plantgrowthThese facts are the result of a few hundredyears of thinking and researchWe thus need to know how this subjectdeveloped historically

  • Ancient RecordsAgriculture started when man became more of a settler than of a wanderer. Families, clans, and villages developed and the skill of agriculture developed.Mesopotamia situated between Tigris and Euphrates in Iraq- very early civilizationWritings dating back to 2500 BC mention the fertility of the landIt is recorded that the yield of Barley was 86x 300x, i.e., for every unit of seed planted the harvested units were 86 to 300


  • Some 2000 years later (500 BC) Herodotus, the Greek historian- mentions the phenomenal yields obtained by the inhabitants of his landWell developed irrigation system and soils of high fertilityAround 300 BC- Theophrastus richness of the Tigris alluvium and stated that the water was allowed to remain on the land as long as possible so that large amount of silt may be depositedIn time man learned that certain soils would fail to produce satisfactory yield when cropped continuouslyThe practice of adding animal and vegetable manures to the soil to restore fertility probably developed from such observations but how and when is not known

  • Augeus a egendary king of Elis, had 3000 oxen in his stable which was not cleaned for 30 years.Augeus contracted Hercules to clean the stable out and agreed to give him 10% of the cattle in returnHercules is said to have accepted the task by turning the river Alpheus through the stable This carried away the accumulated filth and presumably deposited it on the adjacent land thus enriching the land.In the Greek epic poem The Odyssey (Homer ,900-700 BC) the manuring of vineyards by the father of Odysseus is mentioned.The manure heap, which would suggest its systematic collection that manuring was an agricultural practice in Greece during the 9 centuries BC

  • Xenophon (434-355 BC) observed that the estate has gone to ruin because someone didnt know it well to manure the land. And again . there is nothing so good as manureTheoprhastus (372-287 BC) recommended abundant manuring of thin soils but suggested that rich soils be manured sparingly.Bedding in the stall to absorb more of the urine and bulk and conserve it humus value of the manure would be increasedHe suggested that plants with high nutrient requirements also had a high water requirementThe truck gardens and olive groves around Athens were enriched by sewage from the cityA canal system was used, and there is evidence of device for regulating the flowIt is believed that sewage was sold to farmers.

  • The ancients also fertilized their vineyards and groves with water that contained dissolved manuresManures were classified according to their richness or concentration.Theophrastus listed the manures in the following order of decreasing value:

    human> swine > goat > sheep > cow > oxen > horseLater, Varro, an early writer on Roman Agriculture, developed a similar list but rated bird and fowl manure as superior to human excrement:

    bird + fowl > human>swine>goat>sheep>cow>oxen>horseArchilocus (ca. 700 BC) mentioned about the effect that dead bodies had on increasing the growth of crops.In Old Testament; in Omar Khayyam etc.

  • The value of green manuring crops, particularly legumes, was also soon recognised.Theophrastus noted that a bean crop (Vicia faba) was plowed under by the farmers of Thessaly and MacedoniaHe observed that even when thickly sown and large amounts of seeds were produced, the crop enriched the soilXenophon (ca. 400 BC) recommended spring ploughing because the land is more friable then and the grass turned up is long enough at that season to serve as manureCato (234-149 BC) suggested that poor vineyard land be interplanted with a crop of acimum. This crop was not allowed to go to seed and ir was turned under.He also said that the best leguminous plant for enriching the soil were field beans, lupines and vetch


  • Lupine was quite popular with the ancientsColumella listed numerous legume crops, including lupines, vetch, lentils, chick peas, clover, and alfalfa that were satisfactory for soil improvementVirgil (70-19 BC) advocated the application of legumesThe use of what might now be called mineral fertilizers or soil amendments was not entirely unknown to the ancientsTheophrastus suggested the mixing of different soils as means of remedying defects and adding heart to the soilThis practice may have been beneficial from several standpointsThe addition of fertile soils to infertile soil could lead to increased fertility, and the practice of mixing one soil with another may have provided better inoculation of legume seed in some fields

  • Again, the mixing of coarse textured soils with those of fine textured or vice versa may have caused an improvement in the water and air relations in the soils o0f the fields so treatedThe value of marl was also recognised. The early dwellers of Aegina dug up marl nd applied it to their landThe Romans even classified the various liming materials and recommended that one type be applied to grain and another type to meadowPliny (62-113): lime should be spread thinly on the ground and that one treatment was sufficient for many years, though not 50Columella also recommended the spreading of marl on a gravely soil and mixing of gravel with a dense calcareous soilThe value of wood ashes is recorded in the BibleBoth Xenophon and Virgil: burning of stubble to clear fields and destroy weeds

  • Cato: advice to the vine keeper to burn prunings on the spot and to plough in the ashes to enrich the soilPliny: use of lime from lime kilns was excellent for olive grovesColumella: suggested the spreading of ashes or lime on lowland soils to destroy acidityTheophrastus and Pliny: saltpetre (KNO3) as useful for fertilizing plantsTheophrastus reported the use of brine for palm treesEven as soil scientists of modern times have been searching for methods of predicting the fitness of soil for production of crops, so did the minds of the early agricultural philosophers and writers turn to such methodsVirgil: believed that soil that was blackish and fat under the deep pressed share, and whose mold is loose and crumbling is generally best for corn. He also wrote about soil characteristics now known as bulk density

  • Columella: measure the degree of acidity and salinity of soilsPliny: bitterness of soils might be detected by the presence of black and underground herbsMany of the early writers believed that the color of the soil was a criterion of its fertilityThe general idea was that black soils were fertile and light or grey soils infertileColumella disagreed with this view point: black marsh land soil infertile; light colored soil from desert area highly fertileHe felt that such factors as structure, texture and acidity were for better guides to an estimation of soil fertility

  • Much of the early writings regarding soil fertility consisted largely of descriptions of farm practicesThere seems to be little evidence of an experimental approach to farm problems, but many of these manuscripts do reflect a rather keen comprehension of certain of factors now known to affect plant growth.

  • Soil fertility during the 1st eighteenth century ADAfter the decline of Rome there were few contributions to the development of agriculture until the publication of Opus ruralium commodorum, a collection of local agricultural practices, by Pietro de Crescenzi (1230-1307) De crescenzi is referred to by some as the founder of modern agronomyHe suggested an increase in the rate of manuring over that is use at the timePalissy (1563) made the observation that ash content of plants represented the material they had removed from the soil

  • Around the beginning of the 17th century Francis Bacon (1561-1624) suggested that the principal nourishment of plants was water, the main purpose of the soil was to keep the plants erect and to protect them from heat and cold and that each plant drew from soil a substance unique for its own particular nourishmentBacon also maintained that continued production of the same type of plant on a soil would impoverish it for that particular species

  • Jan Baptiste van Helmont (1577-1644) a Flemish physician and chemist, reported the results of an experiment which he believed proved that water was the sole source of nutrient of plants200 lb soil + water; shielded soil to prevent dust and only rain or d.w was used. A willow shoot weighing 5lb was planted. The plant was grown for 5 years. After 5 years the tree that grew weighed 169 lbs 3 ozs. He could account for all but 2 ozs of the 200 lbs of soilAs he added only water so was the sole source of nutrientThe 2 ozs was attributed to experimental error.The work was done when nothing was known about mineral nutrition and photosynthesis

  • Van Helmonts work was repeated several years later by Robert Boyle (1627-1691) of England.He confirmed the findings of van Helmont plus one step furtherHe did the chemical analyses of plant samples and stated that plants contained salts, spirits, earth and oil, all of which were formed from water.About this time, J.R. Glauber (1604-1668), a German chemist, suggested that saltpetre and not water was the principle of vegetationHe collected the salt from soil under the pens of cattle and argued that it must have come from the droppings of these animals.He further stated that as the animals ate forage, the saltpetre must have come originally from the plants

  • When he applied this salt to plants and observe the large increases in growth it produced, he was convinced that soil fertility and the value of manure were due entirely to saltpetreJohn Mayow (1643-1679), an English chemist, supported the viewpoint of Glauber.He estimated the quantities of niter in the soil at various times during the year and found it in its greatest concentration in the springFailing to find any during the summer, he concluded that the saltpetre had been absorbed, or sucked up, by the plants during its rapid growth.About 1700, an Englishman John Woodward, grew spearmint in samples of water he had obtained from various sources: rain water, river water, sewage water, and sewage water plus garden moldHe carefully recorded the weight of the plants at the beginning and at the end of the experiment


  • Growth of the spearmint amount of impurities in the waterHis conclusion: terrestrial matter, or earth, rather than water, was the principle of vegetation Jethro Tull (1674-1741): Englishman, Oxford educated, ill health Soil should be finely pulverised soil particles were actually ingested through openings in the plant roots the pressure cased by the swelling of the growing roots was thought to force this finely divided soil into the lacteal mouths of the roots after which it entered the circulating system of the plantAround 1762, John Wynn Baker, established an experimental farm in EnglandThe purpose of this was the public exhibition of the results of experiments in agriculture

  • Arthur Young (1741-1820): did pot tests to find those substances that would improve the yield of cropsHe grew Barley in sand and used the following materials

    charcoal, train oil, poultry dung, spirits of wine, niter, gunpowder, pitch, oyster shells and numerous other materialsSome produced plant growth, others did not. He published his findings in Annals of Agriculture in 46 volumes. Many of the agricultural writings of the 17th and 18th centuries reflected the idea that plants were composed of one substance and most workers during this period were searching this principle of vegetation


  • Around 1775 Francis Home said that there was not only one principle but probably manyHe included among them air, water, earth, salts, oil, and fire in a fixed stateHe felt that the problem of agriculture were essentially those of nutrition of plantsHe carried out pot experiments to measure the effects of different substances on plant growth and made chemical analyses of plant materialsThe idea that plats contained fire in a fixed state lingered in the minds of man for many years. There was also the belief that organic materials or humus was taken directly by plants and that it constituted their principal nutrientThis idea persisted down through the years. It was difficult to dispel because the results of chemical analyses had shown that plants and humus contained essentially the same elements

  • Between 1770 and 1800 work was done on the effects of vegetation on air that was destined to revolutionise the ideas of the function of plants in the economy of natureJoseph Pristley (1775) said that sprigs of mint purified air plants, instead of affecting the air in the same manner with animal respiration, reverse the effects of breathing, and tends to keep the atmosphere pure and wholesome.He had not yet discovered O2, so he could not give precision to his discoveryLater on, when he discovered O2 and learned how to estimate it, he unfortunately failed to confirm his earlier results as he overlooked the necessity of light He was therefore unable to answer Scheele, who had insisted that plants, like animals, vitiate the air

  • Jan Ingenhousz (1730-1799) said that purification of air goes on in light only, while vitiation takes place in the darkness Jean Senebier (1742-1809), a Swiss natural philosopher and historian, had also arrived at the same resultHe also studied the converse problem the effect of air on plantsIn 1782 he stated that the increased weight in the van Helmonts willow tree was the result of fixed air

  • Progress during the 19th centuryTheodore de Saussure (1804) attacked two problems of Senebier the effect of air on plants and the origin of salts in plantsHe grew plants in air or in known mixtures of air and CO2 and measured the gas changes and the changes in the plant De Saussure was able to demonstrate that plants absorbed O2 and liberated CO2In addition, he found that plants would absorb CO2 with the release of O2 in the presence of lightIf, however, plants were kept in an environment free of CO2, they diedDe Saussure concluded that the soil furnishes only a small fraction of the nutrients needed by plants, but he demonstrated that it does supply both ash and nitrogen

  • De Saussure effectively dispelled the idea that potash is spontaneously generated by plants and stated further that the plant roots do not behave as a mere filter. Rather the membranes are relatively permeable, allowing for a more rapid entrance of water than of saltsHe also showed the differential absorption of salts and the inconsistency of plant composition, which varies with the nature of the soil and the age of the plantDe Saussures conclusion that the C contained by plants was derived from the air did not meet with immediate acceptance by his colleaguesSir Humphrey Davy in 1813, stated that some plants may have received their C from the air but major portion of it was taken through the rootsHe recommended oil as fertilizer because of its high C and H content


  • The middle of the 19th to the beginning of the 20th century was a time during which much progress was made in the understanding of plant nutrition and crop fertilizationFamous among the people during this period was Jean Baptiste Boussingault (1802-1882) a widely travelled French chemistEstablished a farm in Alsace on which he carried out field plot experimentsHe employed the careful techniques of de Saussure in weighing and analyzing the manures he added to his plots and the crops he harvestedHe maintained a balance sheet that showed how much of the various plant nutrient element came from rain, soil, and airHe analyzed the composition of his crop during various stages of growthHe determined that he best rotation was that which produced the largest amound of O.M. in addition to that added in the manure

  • Boussingault is considered by some as the father of the field-plot method of experimentationMany of the agricultural scientists of this period recognised the value of de Saussures observationsHowever, there were many adherents to the old humus theoryIt was such a natural theory that it was difficult to dispelMany must have felt then, as some do today, that the decay of plant and animal materials give rise to products that are best suited for the nutrition of growing plantsThe humus myth was very effectively disposed of by the German chemist Justus von Leibig (1803-1873).Since then, only a few scientists have dared to suggest that the C contained in plants comes from any source other than CO2. Leibig made the following statement:

  • Most of the carbon in plants comes from the CO2 of the atmosphereH2 and O2 comes from H2OThe alkaline metals are needed for the neutralization of acids formed by plants as a result of their metabolic activitiesPhosphates are necessary for seed formationPlants absorb anything indiscriminately from the soil but excrete from their roots those materials that are nonessentialAcetic acid is excreted by rootsNH4+ form of N is the one absorbed and plants might obtain this compound from soil, manure, or airNot all of Leibigs ideas were of course not correctLeibig firmly believed that by analysing the plant and studying the elements contained one could formulate a set of fertilizer recommendations based on these analyses

  • It was also his opinion that the growth of plants was proportional to the amount of mineral substances available in the fertilizerHe eventually developed the law of the minimum ; the growth of plants is limited by the plant nutrient element present in the smallest quantity, all others being present in adequate amountsLeibig manufactured a fertilizer on his ideas of plant nutritionThe formulation of the mixture was perfectly soundHowever, he made the mistake of fusing the phosphate and potash salts with lime, as result the fgertilizer was a complete failureLeibig is considerd as the father of agricuktural chemistry

  • J.B.Lawes and J.H.Gibert established in 1843 n agricultural esperiment station at Rothamsted, Herpenden, Herts, EnglandWork here was carried out along the same line as tht carried out earlier by Boussingault in FranceLawes and Gilbert did not believe that all of the maxims set down by Leibig were correct12 years after the founding of the station they settled the folowing points:

    Crops require both P and K, but the composition of the plant ash is no measurement of the amounts of these constituents required by the plantNonlegume crops require a supply of nitrogen. Without this element, no growth will be obtained, regardless of the quantities of P and K presentNitrate and ammonium salts being lmost equally good. The amount of ammonium nitrogen obtainable from atmosphere is insufficient for the needs of crops

  • 4. Leguminous crops behave abnormally5. Soil fertility could be maintained for some years by means of chemical fertilizers6. The beneficial effect of fallow lies in the increase in the availabilityof N compounds in soilThe water cultures of Knop (1861) and other plant physiologists showed conclusively that K, Mg, Ca, Fe, P, along with S, C, H, N and O are all necessary for plant lifeFor a long time, farmers were reluctant to believe that fertility could be maintained by the use of chemical fertilizers aloneThe early work at Rothamsted proved conclusively that it could be done

  • In 1852, Thomas Way in England first demonstrated the phenomenon of cation exchange from the observation that a Yorkshire farmer was able to reduce ammonia loss from manure by the addition of soil. However, its tremendous significance was not immediately recognised.George Ville (during 1867 and 1874-75)- a Frenchman of Viencennes, recognised the value of some of the early results from the Rothamsted experimentsHe maintained that the use of chemical fertilizers was the only method of supporting soil fertilityHe made recommendations for the fertilization of crops based on the results of field trials He drew up a simple scheme of plot tests that could be used by farmers to determine for themselves just what fertilizers were needed for their cropsVilles view that chemical fertilizers were always better and cheaper than dung is too narrow and did not survive

  • The problem of soil and plant nitrogen remained unsolvedSeveral workers had observed the unusual behaviour of legumesIn some instances they grew well in the absence of added N, whereas in others no growth was obtainedNonlegumes, on the other hand always failed to grow when there was insufficient nitrogen in the soilIn 1878 some light was thrown on the confusion by two French bacteriologists Thodore Schloessing and Alfred MntzThey purified sewage water by passing it through a filter made of sand and liume stone analysed the filtrate periodically for 28 daysOnly NH4 N was detected during this periodAt the end of this time NO3 began to appear in the filtrateThey observed that the production of NO3 could be stopped by adding chloroform and that it could be started again by adding a little fresh sewage waterThey concluded that nitrification was the result of bacterial action

  • Robert Warrington during 1878-1891, applied the results of these experiments to soil processesHe showed that nitrification could be stopped by CS2 and chloroform and that it could be started again by adding a small amount of unsterilized soilHe also demonstrated that the reaction was a two step phenomenon, the NH3 first being converted to NO2 and then to NO3He, however, failed to isolate the organisms by using gelatin methodThe organism was later isolated by S. Winogradsky in 1890 on silica gel plateAs to the erratic behaviour of legumes with respect to N, the two Germans, Hellriegel and Wifarth in 1866 concluded that bacteria must be present in the roots of legume roots

  • These organisms were believed to assimilate gaseous N from the atmosphere and to convert it to form that could be used by higher plantsThe organism was isolated by M.W. Beijerinck (1890) and named it Bacillus radicicola, later named as rhizobium and now known as BradyrhizobiumThe general conclusion that bacteria are the real makers of plant food in soil, and are, therefore, essential to the growth of all plants, was developed by E. Wollny and M. Berthelott (1884) It was supposed to be proved by E.Laurents (1886) experimentFurther investigation of soil problems has shown that they are more complex than was first supposedSoils can no longer satisfactorily be divided into a few simple groups: sands, clays, loams etc., according to their particle size; nor an alteration be confined to the surface layer

  • It is necessary to take their historySoil properties as enunciated by the Russian investigator V V Dokuchaev (1883) are dependent on factors like climate, vegetation besides parent materials.This ushered the study of soil as a living entity and other aspects of soil usesThus we study any soil on pedologic and edaphologic aspectsThe advancement soil studies in the 20th and 21st centuries have been tremendousSoil chemical processes, physical processes, biochemical and microbiological are now studied in both destructive as well as non-destructive methodsSoils are now classed as per their suitability to specificcrop production or other uses







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