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UK Organic Farming in PerspectiveAnthony Trewavas (Also see Appendix on No-Till Agriculture) Background to the situation Although the UK government has pushed through an organic action plan I have found considerable unease amongst scientists in these areas concerning the scientific justification for such policies. To quote one "organic has the image-but the reality is rather different, it is based on assertion". The Curry report (a UK government solicited report on UK agriculture and the apparent basis for the action plan) reflected no more than the balance of interests of which it was composed in the first place. Since the Curry committee included a member of the Soil Association (the most prominent organic association in the UK) it is hardly surprising that recommendations for organic farming formed part of the whole package. Behind all this discussion is the pressure from various groups about organic farming which represents in most cases no more than the desires of environmental groups to retreat from the present day, to express exaggerated fear about the future and to capitalise on the fear of new technologies. Such fears seem always to have been present in a segment of the population. Plato in the 6th century BC decried the erosion of soil in his native Attica. Tertullian in the 2nd century AD stated "the earth can no longer support us. Need we be astonished that plague, famine warfare and earthquake come to be regarded as remedies to trim and prune the superfluity of the population". There is no objection to those who wish to farm organically or to eat organic food; that is the choice given to anyone in a democratic society. But it is the claim that organic is superior or better that can be examined scientifically. So much depends on the comparator and my quarrel with the organic action plan, including its supposed but un-established benefits at the end of the document, is what you compare with what. If organic is better (using the comparators described by DEFRA, (government Department of Environment, Food and Rural Affairs) then integrated farm management (IFM) is its equal and no-till incorporating IFM is easily superior in the criteria used. But are there such action plans for these forms of farming? If not, why not? In attempting to examine the claims of organic agriculture it is necessary to establish suitable systems where the only difference is in the technology. The root difference between organic and other forms of agriculture are the rejection (supposedly) of soluble minerals and synthetic pesticides and herbicides(2). Natural pesticides are instead allowed where necessary; or at least this is the rhetoric. How far copper sulphate or soap (two organic pesticdes) should be regarded as natural is a debatable issue. The distinction between natural and synthetic has little meaning when as Leake(1) showed the synthetic version of copper (mancozeb) is superior to copper sulphate in every environmental aspect(1) or when synthetic pyrethroids can be shown to work at much lower concentrations and with less general environmental effect than pyrethrum itself(2). How natural is sulphur or oil (organic pesticides) really when they have to be mined, chemically modified or distilled before use? The only objection to synthetic pesticides that can reasonably be made is that they are not sufficiently selective to deal with just the pest. The advantage of using GM pest resistant crops therefore stands out as an obvious solution and it is illogical that GM is rejected despite its environmental benefits. Such rejection is however the revealing aspect that shows organic proponents really to be frightened of new technologies and presumably to wish some return to some supposedly golden past when the problems didn't exist. That is hardly a philosophy that should be encouraged in societies like ours with government-sponsored action plans, particularly as societies (again like ours) depend on new technologies and their development for their survival. However, much more to the point is the issue of management in farming. Managerial skill varies amongst farmers much as it does in any sphere of human activity. Thus in my view a farmer that uses an excess of pesticides, is wasting money; a mixed-farm farmer that fails to spread manure on his land is wasting money on fertiliser as well as failing to maintain desirable soil quality; farmers that treat animals poorly will suffer financial loss from worse yields, farmers that do not maintain hedgerows or margins experience more limited numbers of pest predators and thus use more pesticide etc. Such farmers are managerially poor and incompetent and it would be more sensible to consider licensing farmers to farm rather than allowing anyone owning a piece of land to farm it. Comparisons between well-managed and poorly-managed conventional farms however reveal the same differences that are supposedly unique to organic farms. In the UK the highest standards of farm management that I have come across are organised by LEAF (www.leafuk.org) the leading integrated farm management group but normally classed as conventional farming. The organic community emphasise comparisons with poorly-managed conventional farms to further their own cause and so far as I am concerned DEFRA has fallen into the same trap. Organic farming is recognisably more managerially-intense requiring by regulation greater care for hedgerows and field margins and documentation for example. An inspector system is a good idea that could be broadly improved for conventional farms (instead of limiting it to veterinary concerns) but it is preferable that farmers should police themselves. IFM (as organised by Leafuk.org) does in a sense precisely this. LEAF (linking environment and farming) requires the highest possible standards from the IFM farmer as well as a holistic approach to the farm but throws the responsibility onto the individual farmer. I discussed about a year ago at Rothamsted, the desirability of trying to introduce systems thinking such as posed by LEAF and as claimed by organic associations into farm practice. But I have found that good farmers are already natural systems (holistic) thinkers. But if a proper comparison between organic and other forms of farming is to be made then the issue of managerial skill has to be removed from the comparison. Is there real intrinsic benefit to organic methods of eliminating soluble minerals and synthetic pesticides so that all forms of farming should be organic? Or are there intrinsic dangers? If the difference is merely managerial skill then different legislation can be used to deal with those problems without the requirements of radically changing agriculture with the uncertainties that follow. The only way to make the comparison effective is to use the same qualified farmer on the same farm with carefully matched fields identical in all respects on soil quality and environmental history. At least in the UK with present day agriculture the 10 year study at Boarded Barns, Ongar, Essex(3) and the 7 year study at CWS farms at Stoughton(4) are the only two that really match up to these criteria. Other longer-term experiences at Broadbalk(5) and Woburn(6) are applicable. Otherwise to eliminate the farmer and farm variable would require comparison on hundreds of farms and even then we would be left with great uncertainty because the UK climate and soil structure is enormously variable between different parts of the UK. In this latter case the only possible means of comparison is to use best practice conventional, IFM and organic farming as indicators of possible advantages/disadvantages. This has not often been done! Current claims that organic is environmentally better seem largely to emanate from German measurements. However I have strong caveats about such observations because they fail to take account of improvements with time over pesticide development. The German climate is continental unlike the UK maritime climate. Thus I have relied heavily on the studies at Boarded Barns and CWS because of necessity. DEFRA have told me that they regard Boarded Barns as either an exception or unusual- to my mind it is the exception that proves the rule. It establishes clearly the environmental benefits that issue from good management. Organic is regarded by many farmers as risky and certainly whole crops can easily be lost to pests and disease. Only the most competent and managerially skilled farmers are likely to risk organic farming so that organic action plans will merely transfer skilled farmers from one kind of farming to another with no overall managerial improvement. So far as I am concerned the organic action plan is doomed before it started because the right questions were not asked by the Curry report. Instead like many committees it merely fudged the competing interests. There are a number of assertions made by organic proponents. I will deal with each briefly in turn providing references for those that wish to examine the validity of statements. Space has constrained discussion. Pesticide traces in conventional food damages public health The actual evidence indicates the complete contrary. Maroni and Fait(7) and at least 4 additional papers(8-11) survey the literature from 1975-1991 which detail cancer rates amongst pesticide users, manufacturers and farmers. If pesticides really do damage health these people are in the front-line. The total numbers of people surveyed were over 300,000. Only amongst farmers, exposed as they are to inhalation from pesticide sprays, handling dilutions for spraying and presumably eating their own produce, are cancer rates different. Farmers have general overall cancer rates at least one half a control segment of the population. The reasons why farming is so healthy are not known. In general terms cancer rates in the UK are in decline(12), there are no indications from detailed statistics of any relation of cancer frequency to the onset of pesticide use or its changing constituents and use over the last 50 years. The Governments Committee on Carcinogenicity(13) has concluded that breast cancer rates are completely unrelated to organo-chlorines eliminating claims by environmentalists of supposed endocrine problems with pesticide traces. And it is now known that organochlorines are formed in abundance in decaying plant material(13); exposure to such chemicals has been permanent for millions of years. Organochlorine traces (supposedly oestrogen mimicks) are about one millionth that currently consumed in the diet as genestein, another oestrogen mimic(13). According to Sir Richard Doll it is among the young and middle aged that anything untoward appears and these two groups show the greatest declines in cancer rates over the last 50 years(14). Cancer is a disease of old age- as we die less from heart failure inevitably we (in old age) die more from cancer. Life expectancy continues to increase unabated(15). Block et al 1992(16) summarise some 200 investigations on diet and cancer using cohort studies over the previous 20-30 years and indicated that for virtually all the major cancers, a diet high in fruit and vegetables cuts cancer rates approximately in half. These investigations involved very large numbers of people. These studies involved only western countries and those under investigation consumed western produce containing the inevitable pesticide traces. The fact that increased consumption of these supposedly damaging substances actually makes you healthier contradicts any logic behind the organic case. Furthermore we now know that fruits and vegetables contain an estimated 10,000 secondary products which when tested in exactly the same way as synthetic pesticides at the maximum tolerated dose are also carcinogens(17). These natural pesticides (so-called because they are synthesised to inhibit predation by insects and herbivores) will also be consumed in greater amounts with diets high in fruit and vegetables. The quantity on average consumed/day of natural pesticides outweighs synthetic pesticide residues by 20,000 to 118. These results indicate that the tests and assumptions, used to identify synthetic pesticide traces as damaging, are likewise meaningless. Hormesis is the paradoxical effect of toxic chemicals at low concentration(19-21). That is, chemicals that are toxic at high concentration (such as pesticides) turn out to be beneficial to health at low concentration. There is an enormous toxicological literature on this subject and Calabrese and Baldwin who refer to hormesis as a revolution in the toxicological paradigm are not off the mark(19). Hormesis is the rule rather than the exception and data from 5000 dose response measurements establish the claim clearly. The old method of assessing toxicity required a linear extrapolation from the effects of a chemical at the maximum tolerated dose but always on the assumption that toxic at high concentration meant less toxic at low. This model (for that was all it was) and formulated in the 1970's is now known to be incorrect; developments in our understanding of cancer has shown the basic elements that produced the model to be wrong. Hormesis results from the beneficial effects of mild chemical stress at low concentration potentiating the immune system. Well-established cases show that chemicals like cadmium or dioxins or anthracenes for example actually lower cancer rates below control levels. In other words if synthetic pesticide traces are at a level to have any effect at all, the effect is likely beneficial and those who demand removal (such as the organic community) are now actually arguing for a decline in the general health of the population and an unnecessary increase in premature death from cancer. The expected hormetic effect of natural pesticides in fruit and vegetables probably accounts for their beneficial action in reducing cancer. However organic food is more expensive because it uses land more wastefully. Only 25% of the UK and only 20% of US citizens actually eat the necessary two fruit and three vegetable portions/day recommended by the government to provide protection against cancer. Those numbers will not be increased by increasing the price of produce because it is known that price is a very strong determinant of consumption(22,23). For those on low incomes if organic food is purchased, less will be consumed with consequences in cancer rates decades later. The net summary of the information above suggests that if pesticide traces have any effect at all they will be beneficial. Because conventional food is also cheaper and increased consumption has improved the health of the UK population (stomach cancer rates have declined by 60% since 1950(24) an observation explained by the fact that conventional fruit and vegetable consumption has doubled during that period; the stomach would likely be the first port of call for any carcinogen) conventional food can be regarded as healthier than organic food. Furthermore the epidemic of allergy disorders including asthma in the UK is increasingly being suggested to result from too-clean environments and this will include removing beneficial chemical traces from food that potentiate and energise the immune system. As human hunter-gatherers, mechanisms like hormesis would have been essential to enable humans to eat the diversity of food in variable conditions but without long- term health damage. A low organic yield is more natural It is generally accepted that organic yields are lower, the extent depending on the crop. Leake at CWS4,(25) reported in direct comparison that wheat, beans and peas yields were 60-70% whereas oats were 85% conventional yields. Boarded Barns(3) routinely found organic wheat yields about 50%. Such yield differences indicates a waste of good farmland which could easily be more profitably employed in woodland, in willow plantations for biofuel or returning it to other natural conditions such as fenland. The considerations are much more important overseas where growing populations using inefficient organic agriculture (as recommended by Greenpeace amongst others) will simply cut down more tropical forest to feed the growing population. Currently for example Mexican peasants destroy 3 million acres of virgin tropic forest /year to slash-and-burn agriculture. No form of agriculture is natural (all rely on preventing forest succession) but the nearest to nature is no-till which mimics the annual cycle of the meadow or prairie. Agriculture tends in one sense to mimic the effects of individual tree loss in forests. When a mature tree falls over, light penetrates the forest floor, there is flush of nitrate and water in the soil and weed seeds which are light and nitrate sensitive germinate. Most crops are derived from weeds although their germination requirements for nitrate and light have been bred out. Agriculturalists mimic tree loss by clearing ground and the claim that nitrate is an unnatural fertiliser by organic acolytes is contradicted by this perfectly natural process. Soil structure and fertility are better on organic farms One of the mythologies that has developed over organic agriculture has been the supposed benefits of organic regulations to soil and soil structure. A series of reviews on organic soils constructed by organic and conventional researchers published in Soil Use and Management last September (volume 18 supplement) clarifies the situation. The concluding and summarising chapter(26) states that "Soil fertility is defined as an ability of a soil to provide the conditions required for plant growth". Plants interrogate the soil in which they live and respond accordingly. If conventional soils were poor from a plant point of view that would show in poor yields and clearly they do not. The chapter continues " Although nutrient management in organically managed soils is fundamentally different to soils managed conventionally, the underlying processes supporting soil fertility are not". I disagree with the statement in only one respect. Ploughing in of legume rotations in organic farming provides substantial amounts of soluble minerals since the vacuole of each cell of a mature plant contains mM concentrations of calcium, magnesium, phosphate and 2-300mM potassium. Therefore the underlying processes are not completely different. Another chapter(27) concludes " it is not the farming system per se that is important in promoting better physical conditions but the amount and quality of organic matter returned to the soil" "Comparing like with like organic farms had at least as good and sometimes better soil structure than conventionally managed farms". Note the word sometimes. Clear indication that management is the difference not the farming system per se. Farmers on mixed farms that do not use manure to offset costs of fertiliser are wasting money. In a further chapter(28) entitled "Does the supply of available nitrogen restrict organic productivity" the authors have to come to a very obvious conclusion. Canopy development in late spring (mainly leaf production) requires sudden heavy sources of nitrate (synchrony in N availability) to produce protein for chloroplasts and photosynthesis. A process that ploughs in material which is only slowly degraded over many months or even years cannot release minerals in a short intense burst as required for plant growth. This is the great benefit of applying soluble minerals-with care they can be applied precisely when needed. The evidence indicates that although organic soils may contain substantial levels of purported nitrogen, the plant acts as though only a fifth or thereabouts is actually available for growth. Further confusion follows from microbial measurements(29). It is hardly surprising that large amounts of organic material will be accompanied by higher microbial numbers. But the evidence here suggests that microbial mass was higher in IFM soils whereas fungal mass was higher in organic soils. But is there any observable benefit? Very large number of microbes are only required if organic material has to be broken down to provide minerals for plant growth. An inability to provide sufficient N at the time required suggests there are probably insufficient numbers. Earlier evidence indicates that no till agriculture provide eight fold higher levels of microbes than tilled agriculture(29). Conventional farms pollute nitrate, organic farms do not Measurement published from Rothamsted over a five year period comparing organic and conventional farms found the five year average of nitrate release into water ways to be identical(30). A further chapter in Soil Use and Management found that "nitrate losses following arable crops averaged 47 and 58 kgNha-1 for organic and conventional fields respectively with part of the difference being due to the greater proportion of non-cereal break crops in the latter"(31). These figures are no different to those described from Rothamsted with the difference accounted for by break crops. The nitrate loss figures are based on area measurement. If based, as I think they should be, on a yield basis measuring the actual efficiency of use of nitrate by the crop then the figures indicate that organic wastes 9.4 kgN.tonne-1ha-1 whilst conventional agriculture wastes 7.5kgN.tonne.ha-1. Soluble minerals damage the soil. Conventional agriculture is not sustainable The Broadbalk experiment has now lasted 160 years(5). In this experiment winter wheat has been grown continuously with no rotation on land either given only manure (35 tonnes.ha-1) or only minerals. This far-sighted experiment, now of direct relevance, has shown that the yields have remained identical and the only feature changing both yields in parallel was the introduction of new winter wheat varieties every two decades or so. It is quite clear from these data that within the confines of the experimental set-up, that conventional agriculture using minerals is as sustainable as organic agriculture using manure. 160 years is long enough to establish the point. The soil carbon content has increased in the manure-only field by two fold but this has not enabled a higher yield to be obtained(6.) The soil carbon has increased even in the minerals-only field, the result of leaving root material in the soil. Whether such equivalence would be obtained with other crops is not known but the experiment makes the critical point. But no current farmer would use a non-rotating system. Pests are better dealt with by rotating crop use. Nitrate run off has been measured and averaged for the whole of the 90's decade for Broadbalk. The manured field (35 tonnes/ha) showed higher run off of nitrate than the highest level of N fertiliser applied ( 244kg.ha-1). In other experiments the highest yields of wheat were obtained with a mixture of manure and minerals. The question of sustainability can also be answered with another long term 50 year experiment at Woburn that finished in 1925(6). This experimental set-up was similar to Broadbalk but only one kind of winter wheat was used. With allowances for changes in soil pH (the result of using ammonium sulphate as part fertiliser) slow declines in yield were observed in both field situations. The conclusion is that in those situations organic farming is no more sustainable than conventional agriculture. Mineral recycling on organic farms is sustainable A well grown crop of potatoes (60t/ha) for example if sold removes from the farm 29, 338,12, 4 and 5 kg/hectare of P, K, Mg, Ca, Na and micronutrients in the tubers which must be replaced otherwise the soil is mined. UKROPS (organic regulations) permit mined CaCO3, KCl, MgSO4, rock phosphate, trace elements and eight other renewable inorganic chemicals for a claimed chemical-free agriculture? There is concern over potential and likely organic food micro-nutrient deficiency such as in selenium which is not required for plant growth but is essential for human health. There are therefore no plant deficiency symptoms. When examined slow declines in mineral content of organic soils can be detected particularly in K and P2. Again measurements at Rothamsted indicate that 86% of organic soils analysed are deficient in phosphate whereas only 15% conventional soils are in this state(32). Recent detailed analyses of soil on a metre by metre basis indicate substantial variability in mineral content and yield of individual fields. Because dumping manure requires increased labour, than distributing minerals it has been found that fields farthest from manure heaps on organic farms are the least treated and experience most deficiency. What effect P deficiency will have on the quality of food is not known but changes in metabolism are surely inevitable towards a stress response (would this be oxidative stress leading to some accumulation of vitamin C?) . More crucial is that organic regulations constrain the numbers of animals on organic farms so that excess manure can neither be produced nor distributed. In that case organic farming becomes dependent on manure from other sources i.e conventional farms where it is produced with the aid of soluble minerals. To quote from reference 32 b, "The data presented here also suggest some cause for concern in relation to sustainability of organic dairy systems because of their dependence on imported feedstuffs and bedding for P and K and for N on the very variable fixation by legumes of imports of manures or composts". On its own then organic farming is not sustainable except as part of another form of agriculture on which it is actively dependent and which it opposes. Either that situation will occur or it will have to import minerals of one sort of another which due to slow breakdown will cause problems in matching requirements with yield as figures already indicate. In that case it will no longer be able to claim to be chemical free. The notion that organic farms can operate as small totally self-contained entities which was the original philosophy is a complete delusion. Organic is enviromentally superior This is a common assertion however it depends what is considered the most valuable criterion of environmental benefit and that is not easy to define. Nor do the actual results support any simplistic view. The Boarded Barns study reported that 80-85% of biodiversity on any farm (measured as small mammals, collembola, (mites that damage pests), micro and predatory arthropods, predatory beetles and birds) existed in the field margins and hedgerows; what was in the cropped area was of little overall significance(3,33). Small mammal activity (wood mouse, bank vole, common shrew) and based on trapping was identical with all three farming types. In Collembola the only significant change was a higher proportion of individuals on IFM soils, conventional and organic being the same; species richness was similar. Earthworm densities were highest in the IFM with organic second at about twice that of conventional fields. [But these differences were no where near those observed between no-till to till which are 6 fold particularly in the large Lumbricus terrestris whose burrows provide excellent drainage qualities to no-till soils; see supplement on no-till]. Species numbers were however similar. Micro-arthropods were five fold higher than organic or conventional fields on IFM fields(33). The numbers of predatory arthropods, in particular carabid beetles were however higher (about 25%) on organic soils but the crop in the field played a greater part in carabid variation than the mode of agriculture being 4 fold higher in bean crops than wheat. In these measurements organic wheat had only one half the numbers of carabids than conventional wheat. However similar results have been found by a number of investigations (see reference 34 and the six or so references included to other investigations). Here carabids (ground beetles) in numbers of individuals were higher (3 fold) in organic fields but almost all was due to very large numbers of one species of beetle, Pterostichus Melanarius, the common black beetle which eats earth worms. However numbers of staphylinids, winged predatory beetles, were substantially higher in conventional fields. Application of measures of biodiversity ( the Shannon-Weaver index for example) indicated highest beetle biodiversity on conventional fields. That should not be a surprise and appears to be common(34). As for bird territories, Boarded Barns examined 13 bird species and found slightly higher levels of birds over the organic fields although at the end of ten years, no difference in numbers was observed(33). In the most intensive study, 22 farms of organic status were compared with nearby conventional farms although no attempt was made to match managerial competence. While bird abundance exceeded that of conventional farms in 50 of 68 individual cases, significance was only established for two(35). Much of the variation was attributed to field boundary effects and to hedgerow height and width, aspects of the landscape which are not necessarily related to the mode of farming practiced. LEAF for example specifies equal treatment and maintenance of hedgerows because populations of pest predators are found in abundance there. Furthermore the benefits of organic farming to birds in terms of biodiversity and numbers were only present in one year out of three(35). There is a common trend for slightly higher numbers of birds to be present on organic farms during winter as in Boarded Barns but these ambiguous changes are not in anyway matched by comparisons of till with no-till where orders of magnitude difference were readily observed compared to tilled fields in winter months(33). Since IFM farms maintain hedgerows too, the assumptions that going organic is going to lead to substantive changes in bird population seems unwarranted; IFM would do as well. In conclusion it would be difficult to make a case for organic farming on any reasonable basis for environmental benefit. Hedgerows and field margins can be legislated on as the condition of set-aside. What is surprising is the received wisdom that organic must be better for the environment because it doesn't use synthetic pesticides simply does not stand up to rigorous investigation. Or perhaps we should not be surprised, the environment is complex its ecology is not well understood and frequently in these complex networked systems the results are often counter-intuitive. The data previously referred to in no-till indicated the easy superiority of this form of farming in environmental measures including lack of soil erosion and so on. An examination of management schemes to improve biodiversity in Holland found no improvement(36). Changing to organic would lower costs of agriculture Pretty et al (2000) (37) estimated the externality cost of UK agriculture.
The article makes no attempt to estimate the benefits of food security
from UK agriculture nor the improvement of life expectancy of which certainly
a portion has come from a reliable food supply. In one sense, the article
is therefore an attack on the costs of UK agriculture and particularly
its conventional version. Indeed one component, the supposed costs of
pesticide removal from river water, has been used by Jules Pretty, on
several occasions that I have heard, to audiences largely composed of
organic acolytes. However the costs estimated here and used by him are
according to Parliament grossly incorrect(38). Pretty et al.,(37) state
that the costs of removing pesticides from river water is about £120
million/year. However this figure seems to have been the cost of building
new water treatment plants to comply with EC regulations and was quoted
from 1997. A question in the House of Commons on 3 April 2000 showed that
this figure was correct for 1997 but had dropped to only £11 million
in 1999 and presumably to zero thereafter(38). The Minister involved (Mullin)
stated that no figure was actually available for purification running
costs, only building, and anyway water has to be purified full stop; one
cannot segregate purification requirements of any one chemical from another
natural or synthetic. Removing that error from the figures of Pretty et al., and using the gaseous losses from each of the main kinds of agriculture(39) I estimate the externality costs/ha/year as £154 for conventional agriculture. Equivalent costs for organic assuming all the UK was organic are £79 and £29 for no till. There are about 12 million ha of farmland in the UK and the population is about 60 million. On these figures each person therefore is environmentally costed £30/year for conventional agriculture, £16 for organic and £6 if it were no-till. Those bills should be set against the food costs/person/year of £1500 for conventional and no-till and on present costs £2100 for organic. Organic is healthier and more tasty Many taste assessments have been properly made. In these the individual is provided with three individual pieces of the same produce and asked to state which two are the same. Such tests have indicated that here is common confusion of freshness for organic produce and that the public cannot distinguish organic from conventional(40). Although the Soil Association has tried to state that organic is healthier food, the evidence is strongly against it. Most papers indicate that composition is not significantly different from conventional food(41-44). Summaries from nutritionists and others indicate that that occasionally there may be slight increases in vitamin C although the figures are not consistent and are strongly biased by two measurements by Schupan(45) many years ago in cabbage. However vitamin C may accumulate when oxidative stress is experienced, a consequence of disease, and perhaps no surprise that the content could be higher in organic produce as a result of disease. There is no indication that the UK public is in anyway short of vitamin C; in fact current dietary levels are close to the renal plasma clearance value(46). Organic uses less overall energy Bertillson(47) has provided figures for the use of energy in the production and transport and distribution of nitrate fertiliser. These figures are about 10KWh.kgN. No data is available for the mining and transport of phosphate fertiliser although it seems to be forgotten that organic farming ultimately depends on its use and other fertilisers. Reganold et al., (49) in a recent paper made this error of assuming that because chicken manure was purchased from a conventional farm it involved absolutely no energy use. Of course it did; the minerals incorporated in the manure required mineral and fertiliser production and those costs are now organic not conventional. Every gm of N in manure costs the same as every gm N in mineral fertiliser. Leake(48) at CWS farms measured every last drop of fuel used on organic conventional and integrated no- till agriculture and observed that organic used the most draft energy. Organic used three fold more than integrated farming and substantially more than conventional farming. Putting the Bertillson figures (for fertiliser and transport) with those of Leake on fossil fuel use on farms, the efficiency of conversion of fossil fuel use into seed energy can be estimated. The figures for organic in kWhr/tonne of yield are organic 200, integrated 132, conventional 140. The latter two forms of farming are more efficient in their conversion of energy into product. There are several caveats. Leake used 180kg N /ha. Other farmers may use more or less also dependent on manure use. Leake states his organic yields are substantially higher than the average organic yield. Bertillson assumed that intensive farming only uses 100kgN/ha. Thus I have programmed in a worst case scenario for conventional farming. Secondly I have not included any energy considerations for the mining and transport of phosphate rock or transport or packaging of minerals to organic farms. Taking account of these considerations places integrated no-till as about 2x as efficient as organic farming. Finally a study by ADAS used by DEFRA in their document on organic farming seems to have omitted actual measurements of draft fossil fuel use on farms. I believe their figures to be incorrect on this basis. Conclusions There is no basis for the assertions of organic farming once management is taken into account. Proper experimentation indicates that organic agriculture is just another form of agriculture with its own problems and difficulties and no better than other alternatives. If it is thought desirable that a variety of farming should take place in any country then there is case for organic just as there is for conventional with good practice and for integrated and for integrated no-till. If the environment is the issue then present data suggests that no-till is better but most of the data comes from the USA and there has been ludicrously small amounts of research in the UK to test these possibilities here. If it is thought that we overproduce in Europe then I would suggest just as English Nature has recently and sensibly done, purchase farmland and turned it back to fenland. Except that I would welcome the return of deciduous forests not from land which is currently used for spruce forests but from our supposed excess. References 37. Pretty JN, Brett C, Gee D, Hine RE, Mason CF, Morison JIL, Raven
H, Rayment MD, Van der Bijl G. An assessment of the total external costs
of UK agriculture. Agricultural systems 65, 113-136. "Had we not originally gone contrary to the laws of nature by plowing the land we would have avoided the problems as well as the time consuming efforts to solve them. We would have missed all of the erosion, the sour soils, the mounting floods, the lowering water table, the vanishing wildlife, the compact and impervious soil surface" Ed Faulkner, (1943) Plowmans Folly(1). All of Faulkner's claims have been established by measurement and indicate the benefits of no-till agriculture over organic and conventional ploughing technologies. Ploughing is the most damaging soil treatment and no-till agriculture is most easily introduced with Herbicide Tolerant (HT) crops to avoid weed problems. GM HT crops are the simplest way to introduce no-till agriculture. Organic farmers need to plough not only to remove weeds which accumulate in organic fields (weed seed density has been shown to be three fold higher) but to mineralise nitrate and possibly phosphate. No-till has not been greatly used in the UK. DEFRA have issued two booklets describing case histories and indicating that clay soils are best for no-till. (Booklets are "A Guide to Managing Crop Establishment" produced by the Soil Management Initiative and "A Guide to Better Soil Structure" by National Soil Resources Institute. This booklet contains maps that suggest much of southern and midland England are suitable for no-till. There have been experiments some 30 years ago in Scotland on no-till but cold soils may have been a problem in its introduction. Blackgrass was also a problem but that is now controllable with glyphosate. However this would seem to be an area for further research to be undertaken. My criticism of DEFRA is that they have not pushed no-till as they have pushed organic farming reflecting as far as I am concerned merely political pressure by groups who understand little about farming or think that retreat to previous forms of farming to solve supposed problems (largely elicited by themselves) is the only way forward. I have listed the No till benefits compared to till(2). The material
can be found in the listed references. I have only found a few investigations
to investigate environmental benefits to no-till in the UK. A few were
performed at CWS farms in Stoughton and others at Boarded Barns farm Ongar
in Essex. However the no-till only occupied 4 years and while differences
emerged in environmental measurements a four year period is insufficient
for a farming process that requires basically permanent commitment to
no-till. 1. Farm fossil fuel use 1/3rd that of a tilled field. 2. Erosion reduced to 5% ploughed field. Soil nutrition, structure and drainage vastly better. Flooding for example all but eliminated. 3. Preventing sediment losses from erosion greatly improves local aquatic habitat. Estimates suggest that erosion causes losses of 9 billion dollars in the US. I have not seen equivalent figures for the UK but I don't doubt they exist. Run-off is greatly diminished and consequently herbicides such as isoproturon are no longer detectable in soil drainage. Rain water drains through the soil and the longer residence of chemicals in the soil enables microbial action to break them down. Free oxidised nitrogen compounds such as nitrate are reduced to 1/20th that in tilled soil. 4.Pest predators (mainly carabids and staphlinids) and large earthworms both up 6 fold. The latter greatly improve drainage by leaving open channels in the soil. In ploughed soils only much smaller worms predominate. Pest predators hide under the vegetation on the surface. 5. Birds territories and bird nests increase anywhere from 3-100 fold.
Time requirements for young bird feeding reduced five fold. These figures
contrast quite strongly with the very minor and uncertain differences
observed between well-managed conventional farm and organic farms. 7. Soil carbon accumulates continuously in no-till soils and the contribution to global warming reductions can be substantial. However one pass of the plough leads to enormous losses of carbon dioxide. The input of oxygen into the soil enables large scale breakdown of organic material by microbes. And Robertson et al., (2000) showed that no-till has 1/3rd global warming potential of organic which in turn is about half that of large scale conventional farming in the USA. Intriguingly these authors also reported that methane and nitrous oxide losses from soil were similar amongst all farming modes. The difference is in carbon dioxide production. 8. No-till mimicks seasonal change in soil surface vegetation in both meadow and prairie. It needs to be stressed that no form of farming is natural. All rely on prevention of the Fenn-Carr succession which takes old fields through from annuals to shrubs to climax forest. However agriculture does mimic in part the loss of individual trees in mature forests. When such trees succumb to age or weather and fall over, there is a flush of nitrate in the soil, water loss increases, light penetrates to the soil surface and many annual seeds germinate in response to light and nitrate signals. Rejection of the use of nitrate in Organic regulations does not mimic natural conditions contrary to claims. References 1. Faulkner E. (1943), Plowmans Folly. Grosset and Dunlap, New York. A very readable book. A less full quotation from Faulkner is to be found in information from the "Conservation technology information center" www.ctic.purdue.edu. This source provides much information on no-till or conservation tillage. Note particularly the article on "Conservation tillage and Plant Biotechnology" by Fawcett R and Towery D. 2. Basore NS, Best LB, Wooley JB. ( 1986). Bird nesting in Iowa no tillage
and tilled cropland. J Wildlife Management 50, 19-28. |
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