Can Organic Agriculture Feed The World?November 14, 2015, 6:16 pm
by Dr Parakrama Waidyanatha
There has been a live debate on organic versus conventional farming in the columns of The island during the last few weeks. Conventional agriculture is blamed as a major polluter of the environment and it is argued that we should return to organic or traditional agriculture, free from synthetic chemicals, for pollutant –free food and water. Is this feasible and is organic farming non-polluting? The writer’s endeavour is to provide a profile of the evidence on the subject for the reader to paint his/her own picture The quest for toxin- free food amongst people, especially the affluent, has boosted the production of organic food to some degree, though usually costlier than conventional food. Much has been said promoting organic agriculture, but realities rather than rhetoric and emotions should guide our thinking and actions.
Organic farming to Conventional farming - some history
Organic farming (OF) may be broadly defined as production of crops and animals without the use of synthetic agrochemicals and sewerage sludge. Natural minerals such as rock phosphate, potash and dolomite are allowed for use in OF, but not any synthetically altered products thereof such as superphosphate. Nitrogen is to be provided via organic matter, free-living nitrogen fixing bacteria (eg. Azatobacter), biological nitrogen fixing legume cover crops, green manures, crop rotations and relay cropping with legumes.
The transition from traditional agriculture where fertilizer comprised essentially farmyard manure(FYM) and green manures, to conventional agriculture(CF), as we know it today, took place in the mid 19th century with two ground breaking inventions : the synthesis of soluble (super) phosphate and chemical nitrogenous fertilizer by two great scientists cum entrepreneurs. One was John Lawes(1814 to 1900), an Englishman, who was later knighted. He was also the founder of the prestigious Rothamsted Experimental Station in England, regarded as the senior of all agricultural research institutions, which he set up in his own farm. The other was a German, Justus von Liebig(1803-1873- later, Professor of Chemistry). Lawes’ invention of soluble phosphate was considered as a one of the greatest inventions in agricultural chemistry. He commenced his soluble phosphate research in his bedroom mixing sulphuric acid and rock phosphate, but was fortunate to come out unscathed! Similarly, Liebig was an outstanding chemist and discovered nitrogen as a plant nutrient, apart from many other inventions such as chloroform. In 1909, another great German scientist, Fritz Haber successfully synthesised ammonia by combining atmospheric nitrogen and hydrogen which revolutionised the production of commercial nitrogenous fertilizers.
These inventions and the rapidly growing knowledge then in plant chemistry lead to the substitution of natural dung with chemical fertilizer. The third important element, potassium, was provided largely by potash, a substance that had been known from antiquity. It has been said that without these inventions, the industrial countries of Western Europe could not have supported the dense population growth of the 19th century. It is the same reason, rapid global population growth, that later led to the Green Revolution. A later Director of Rothamsted , Sir John Russell (1942), a reputed soil scientist, in an article titled British Agriculture states that: "it is difficult for us in this distance in time to recapture the feelings with which the farmers received the information that a powder made in a factory and applied out of a bag at the rate of only a few hundred weights per acre could possibly act as well as farmyard manure put on the land as dressings of tons per acre". This is ironically the fundamental question that we should ask. Is there adequate organic matter to meet the nutrient demands of crops, on a global scale today, if it was inadequate then?
In Britain, the introduction of chemical fertilizers and the consequent changes in farming practices that led to dramatic increases in crop productivity has been hailed as the British Agricultural Revolution comparable with the Green Revolution. Ideally, it should have been called the’ European Agricultural Revolution’, as it spread across the entire Western Europe or the first green revolution .
The green revolution
In the mid 20th century, one hundred years later, came the ‘Green Revolution’ where emphasis shifted from crop nutrition to crop breeding – the synthesis of high yielding, short- statured, fertilizer- responsive cereals, without which the world food demand could not have been met today. The pioneering efforts of breeders such as the Nobel Laureate Norman Borlaug, described as the father of the green revolution and ‘the man who saved a billion lives’ stand out in this regard. In Sri Lanka too rice breeding and other research took great strides increasing yields by over 7 fold and production by 14 fold from the 1940s to date, the increase in land extent under rice, especially from the Mahaweli project also contributing to production and eventual attainment of self sufficiency( Table 1). This achievement clearly would not have been possible without chemical fertilizers and pesticides. High productivity of these new varieties demanded large quantities of fertilizer which made the crops luscious, inviting pests and diseases and leading to the need for pesticides, without which the high yields could not have been achieved. Breeding for pest resistance in the new varieties followed. Resistance breeding , for example, in the new rice lines yielded many breakthroughs and greatly mitigated pesticide use in rice, but pesticides yet continue to be widely used in many crops. That traditional varieties are more pest and disease resistant than the new varieties is a myth! For example, some of our traditional rice varieties such as Murungakayan and Pachchaperumal have been susceptible to the main pests and diseases - Gall midge, Brown Plant Hopper and Blast. In the recent past there have been also claims of some traditional rice varieties yielding 80 bushels per acre (near the national average yield) under traditional farming (TF)methods, and this as justification for return to TF. The TF technology used here has not been defined but such yields may well be achievable in isolated, well managed plots. Large scale cultivation is a different matter! Ideally, there should also have been a comparison of performance with at least a few new varieties under similar crop management technologies
Conventional farming (CF) is blamed for environmental pollution, not that organic farming is innocent! Agricultural pollution, for example, is reported to cost the US, USD 12 billion in environmental and health care and USD 45 billion in soil erosion, annually. In Sri Lanka, an overwhelming issue is the indiscriminate and profligate use of agrochemicals, and the application of pesticides without the use of protective gear. The case of serious phosphate pollution of water bodies in the Rajarata, due to profligate and wonton use of phosphate fertilizer is a classic example. The vegetable farmers in the hill country are applying 5-10 times the recommended doze leading to serious P pollution of water bodies downstream in the Rajarata. The Department of Agriculture (DoA) research has revealed that over 70% of these farms soils have P levels in excess of the agronomic critical level (30 ppm) above which crops do not respond to further P applications, despite which the farmers continue to apply! In over 50% of the farms, the P levels exceed the environmental critical level (60 ppm) and some farm soils have even 350 ppm! . Excessive P in water bodies causes algal blooms which hinder the use of water apart from secreting toxins very harmful to health, and it has been reported that they may play a role in the chronic kidney disease that is seriously afflicting some farming populations in the dry zone. The government, to date, has not done anything effective to regulate phosphate application in the upcountry.
The DoA recommended rates of poultry dung, cow dung and compost applications for total organic farming ( without chemical fertilizer) are 20, 30 and 40 tons/ha respectively. Continuous application of such large quantities, in particular of poultry dung over long periods may lead to nutrient pollution, especially of heavy metals and P, the P content in poultry dung being generally high than in others and usually double that of cow dung. Irrespective of fertilizer regimes, it is critically important to monitor soil chemical properties regularly to maintain nutrient balance. This unfortunately hardly happens now in our country.
As regards pesticides, their Judicious use with appropriate safety measures should greatly mitigate pesticide pollution. Some programmes in Sweden, Canada and Indonesia have also demonstrated that pesticide use can often be reduced without loss of crop by as much as 50 to 60% ( In Pimental et at al , Bio Science , 55 (7), 573-581 :2005). Over the last half century, there has been a gradual shift from highly toxic pesticides to less toxic ones; and the process continues. There is also now wider recourse in bio-pesticides and integrated pest management. The problem, however, is that the pests mutate into more virulent forms faster than the invention of remedies.
There have also been reports of pesticides detected in alternative (fake) crop protectants ( so called herbal formulations) recommended for organic farming . Dr Naoki Motoyama (Tokyo University of Agriculture – 2012) has reported the detection of at least eight toxic pesticides including Abamectin (LD50 = 10mg/kg), an insecticide, in the herbal formulations!
Organic or inorganic fertilizer - crops have no preference!
Crops have no preference for one or the other type of fertilizer! Organic manures should breakdown in the soil through microbial action to provide the nutrients in the soluble (ionic)form for the crops to absorb. So should the inorganic fertilizers dissolve in the soil for crop uptake. The advantage with inorganic fertilizers is that the exacting requirements of individual nutrients to crops can be provided as individual chemicals or mixtures because crops differ in their nutrient requirements. For example, whereas cereals such as maize, rice and wheat require relatively more nitrogen that P or K, banana, coconut and manioc require twice or more of K than N or P. Although with adequate inputs of organics, crop yields comparable or higher than that with chemical fertilizers is achievable, providing exacting nutrient demands for specific crops is difficult with organic forms unless supplemented with chemical fertilizers. In the endeavour to supply the requisite crop nitrogen requirement, there is often the excessive addition of others which is wasteful and can lead to pollution. The greatest benefit of organic fertilizers as against chemical fertilizer, however, is the improvement of soil physical, chemical and biological properties which is important for soil health and sustained crop productivity.
Theoretical feasibility and economic viability
Organic matter availability need not always be a limitation in organic farming given the fact that mineral rock phosphate and potash can be used. The main limiting factor then is nitrogen. A team of scientists from the University of Michigan, USA (Catherine Badger et al, 2006: ‘Organic agriculture and global food supply’; Renewable Agriculture and Food Systems: 22 (2) 86-108) examined the theoretical feasibility of supplementing nitrogen by biological nitrogen fixation in legumes. They argue, using published data on legume nitrogen fixation rates that the entire nitrogen demand for global food production can be met by legumes, and the global food needs by organic agriculture. They apply yield ratios of crops from organic and conventional farms to current global food production values(FAO statistics) for 20 general food categories. Two models are used, one based on food production data for the developed world and the other for the developing world. According to the first model, the estimated conventionally and organically produced food supplies are comparable, whereas according to the second, the latter exceeds the former. This difference is explained on the basis that, in the developing world, yields from resource-poor conventional farms are lower than those from relatively better maintained organic farms. As said above, the assumption is that phosphorus and potassium are supplied as mineral fertilizers and nitrogen is provided by biological fixation in legumes through green manures, cover crops, crop rotations, intercropping and relay cropping with legumes. This may sound exciting to organic farmers, but practicality and economic feasibility in many farming situations are questionable. Nitrogen supply and weed management are considered the biggest constraints to organic farming. The economic feasibility of the reduction of food crop intensity to accommodate legume covers or green manures, especially in small farms of the third world countries, needs serious consideration. Would our farmers, for example, invest in a leguminous green manure or cover crop to provide nitrogen for the oncoming main crop? There is a need for far more research and new technologies in this regard for various farming systems.
There are then the questions of availability and costs of organic matter. An example should, ideally, illustrate this issue. The Ministry Agriculture some years back considered implementing a policy of reducing the chemical fertilizer for paddy by 25% and substituting it with of 5 tons of cow dung or 2 tons of poultry dung. Clearly it was neither practically feasible nor economically viable. At current market rates these quantities should cost around Rs 15, 000 and Rs11,000 respectively per hectare . Logistics and cost of application should be added. Given the present low rates of return to rice farming even with the massive chemical fertilizer subsidy, can rice farmers afford to apply organic fertilizer at these prices? More importantly, what about availability? A simple calculation based on statistics published by the Department of Census and Statistics on the numbers of animals in Sri Lanka and the dung produced, and that only 10% of cow dung and 50% poultry dung are collectable, at the recommended rates of application and assuming that all the available dung is applied to paddy (1.2 million ha), only 25% and 5% of the total paddy extent can be fertilized annually! Organic manure should primarily go to improve soil physical properties and should not be dumped into rice paddies in which soil structure is no consideration. Surely, the government should have considered the feasibility of implementing such a recommendation before it was made.
The Cuban example
The Cuban agriculture, as at present, has often been quoted as an example of the feasibility of switching over totally to organic farming. Cuba was in fact compelled to go organic! This was a consequence of the collapse of its economy following the disintegration of the Soviet Union in 1989 and its total suspension of aid to Cuba. Cuba was nearly totally dependent on USSR on its agrochemicals, fuel, agricultural machinery and equipment. Moreover, it had very favourable trade terms such as selling sugar to USSR at five times the world price! The collapse of the Cuban economy drove the Cuban peasantry to near starvation with the per capita calorie intake dropping from 2900 to 1200 calories. These circumstances saw the end of the high chemical input agriculture policy , and in the proceeding so called ‘special period’( 1991-1996),major revisions to the land policy leading much of the state-owned farms being distributed among the peasantry took place. Substantial emphasis was also placed on agro-ecological concepts of farming- organic agriculture, the use of nitrogen fixing microbial technologies, bio-fertilizers and crop rotations. These approaches to some degree mitigated the decline in crop productivity in the absence of chemical inputs. The concurrent development of urban agriculture where all cultivable lands in the cities and suburbs were farmed was unprecedented anywhere else in the world. The urban farms produced adequate fruits and vegetables for the cities. Perhaps the most admirable technology development was in biopesticides and other biological control methods of pests and diseases. Cuba now has over 200 centres (CREES) for the production of pest control microbial agents across the country, run largely by qualified children of farmers. Fidel Castro himself was promoting these activities. Sri Lanka should greatly benefit from learning these technologies from Cuba as our pesticide pollution problem is apparently more serious than that of the fertilizer.
Despite all these endeavours, it is evident from the data in Table 2 that the nutrient supply was inadequate to produce optimal yields. The yield of rice, for example, a major staple of the Cuban diet, was comparable with that of Sri Lanka during the green revolution period when chemical fertilizers were used. However, during the so called ‘Special Period’ when agroecological farming technologies were introduced and the ‘Reanimation Period’ ,when these technologies were in full operation and stabilized, the comparative rice yields were lower than in Sri Lanka. Similarly, yield of sugarcane, one of Cuba’s main export income earners, decreased considerably despite the new technology application and was 43% less in the 2008-2010 period as against the period of the green revolution when chemical fertilizers were liberally used. Cuba is nearly twice the size of Sri Lanka but has half its population, implying that its land-man ratio is four times ours. Of the total land mass, 30% is agricultural and 40% of the soils are highly fertile. These facts tell a lot as to how Cuba is surviving the crisis and managing to feed its people despite the lack of chemical inputs.
Organic agriculture- the global picture
‘The proof of the pudding is in the eating’! The total world extent under organic farming yet remains less than 1% (0.9% in 2012) of the total farm lands. Of this, two thirds are grasslands, only 19% arable crops and 8% horticultural crops. Organic farming is thus a minor phenomenon in many countries and is yet a long way from feeding the world. There are, however, 1.6 million producers in 84 countries ( ‘World Agriculture Statistics and Emerging Trends -2012’).Organic farming has expanded substantially especially in Europe( 10 million ha) and Oceania(12.1million ha), Latin America ( 8.4 million ha)at a growth rate of over 50% annually in recent times. On the other hand, extents in Asia (2.8 million ha) North America (2.7 million ha) and Africa (1.1 million ha) have remained relatively small and stagnant. There has been a slight decrease recently in the total world extent, due largely to marginal decreases in extents in India and China, some farmers reverting to conventional farming.
In conclusion, years of resource exploitive and polluting conventional agriculture has done substantial damage to the environment, affecting the health of man and animals, not that organic agriculture is totally free of pollution. Although theoretically, as explained above, it can be argued that the global food needs can be produced by organic technologies, far more research is needed to develop such technologies for specific farming situations that are both practically feasible and economically viable. Until then feeding the world by organic farming is a distant dream. What is immediately needed is to ensure judicious and safe use of agricultural inputs. This requires comprehensive farmer education and training, and regular monitoring of the environment for pollutants for corrective action. Is Sri Lanka equal to the task?
Last Updated Mar 24 2017 | 09:21 pm