The nutrient buffer power concept for sustainable agriculture
by K P Prabhakaran Nair on 08 May 2018 4 Comments

More than a century ago, in one of the early editions of Advances in Agronomy, the magnum opus of agricultural science, popularly known as the “Bible of Agricultural Science”, Roy W. Simonson, a distinguished soil scientist, writing a chapter entitled “Concept of Soil”, noted “Someone has said that the fabric of human life is woven on earthen looms – it everywhere smells of the clay”.


A century later, agronomists and soil scientists, the world over, have come very far in their understanding of the “fabric of human life woven on earthen looms which everywhere smells of the clay”.


That the “fabric of human life”, which is so very intimately linked to soil, has dramatically changed is beyond dispute. Yet, there is no denying the fact that this “fabric of human life” will always be linked to soil, which is the pragmatic, the reality, the entity that dictates much of what societies can do. Soil, in my opinion, is that invaluable gift of God to life on planet earth, and can aptly be termed the “Soul Of Infinite Life”, as this author had defined it at the World Congress on Soil Science, Hamburg, Germany, August 1986.


The Difficult Indian Scenario


For more than half a century past, the “green revolution” has become a household term. It is time one reflects what it has done to Indian soils, so varied from the once fertile Indo-Gangetic plains to the degraded coast of Kanyakumari, in Kerala. Are these soils in the same state of productive capacity as they were half a century ago, at the start of the green revolution? If not, what is the reason?


Why can’t the once fertile soils of Punjab, known as the “cradle of green revolution”, grow a blade of rice or wheat in hundreds of acres, except with such low yields? Why Kuttanad, in southern Kerala, known as the “granary of Keralites”, has soils whose pH (an electro-chemical parameter, depicting the hydrogen ion acidity, and, indirectly the native soil fertility) is as low as 1 from the original 6.5 to 7 (the most conducive for plant growth)?  


Why has the native carbon, an index of inherent soil fertility, of Punjab soils gone down so low that yields of both rice and wheat have been plateauing since over the last two decades, in many cases even nose diving, despite application of the “recommended” rates of chemical fertilisers, namely nitrogenous, phosphatic and potassic?


Has something gone terribly wrong with the so-called green revolution? Or, more pertinently, have the powers that be at the helm of the agricultural hierarchy, from the start of the green revolution, given enough thought and attention for sustainable and sensible soil management? The answer to this vexed question is an emphatic no. 


The term “green revolution” was first used in a March 8, 1968 speech by Dr William S. Gaud, Director, US Aid for International Development (USAID), in which both the Ford and Rockefeller Foundations were very heavily involved. That the green revolution has failed to live up to its promise of ending hunger, employment and poverty, in Pakistan, has been forcefully argued by Dr Tarique Niazi, who teaches Sociology at the University of Wisconsin, USA, in an article (World Bank, 2002). An analysis of the time series of the past four decades points to worsening inequalities in income and asset distribution, contributing to poverty of one in every three Pakistanis. The Indian situation is no better, as has been argued in the books “Violence of the Green Revolution” and “Stolen Harvest: The Hijacking of the Global Food Security”, by Dr Vandana Shiva, a physicist turned environmental activist.  


This piece will focus on what happened to Indian, other Asian or African soils during the green revolution period, and why Indian agriculture is in the pathetic ecological and environmental situation that it is in, and what can be done to redeem this. The worst fallout of the green revolution in India has primarily been the degraded soils, the polluted ground water (due to unbridled use of chemical fertilisers and pesticides), making water non-potable, as can be widely observed in Punjab State, and environmental warming, a consequence of unbridled use of urea fertilizer, which many, even within the agricultural fraternity, are inadequately aware of.


Of the 328.73 mha of geographical area in India, as much as 120.40 mha has degraded soils. In other words, one in every three farmers is investing his scarce resources in a patch of soil which has lost its productive capacity.


The green revolution stands on three pillars - the “miracle dwarf” varieties of rice and wheat, copious use of chemical fertilisers, pesticides, and water. That the miracle dwarf rice and wheat varieties have lost their initial vigour, succumbing to many dreadful diseases such as rust in wheat, and blast in rice, wiping out thousands of acres of these crops is now an established fact. The “newer” varieties are nothing but clones of the earlier ones, with a yield differential of ±5 percent. Thus, one zeroes in on the critical pillar - fertiliser application.


And here is the question one must ask: Are the “recommended” rates of chemical fertilisers the optimum to tap the yield potential of the crop in question to the fullest? If it is sub-optimum or over-optimum, it is high time we looked at this serious issue, because both have serious consequences for crop production. Invariably, it is over-optimum, the prime cause for soil degradation.


South Asian and Central Asian example


Two very glaring instances, one from South Asian (Indian) and another from Central Asian (Turkey) agriculture illustrate how skewed current fertiliser recommendations can be. Black pepper (Piper nigrum) is the economic mainstay of Kerala farmers, as wheat (Triticum aestivum) is of the Central Asian (Anatolia in Turkey) farmers. Both crops need ample quantities of the important micronutrient zinc to produce optimum yield.


Soil scientists of the Indian Council of Agricultural Research (ICAR), New Delhi, have “recommended” a blanket application of 25 kg zinc sulphate per ha (which supplies the important micronutrient zinc), a very expensive fertiliser compared to urea, to black pepper, while their counterparts in Turkey have recommended 100 kg per hectare for wheat. It turns out that both recommendations are wide off the mark.


This has been proved by precisely quantifying the “Zinc Buffer Power”, by appropriate chemical methods developed by the author. In fact, in Kerala soils, zinc buffer power can vary almost three-fold from one soil to another. In other words, for a soil which has a high zinc buffer power, it is unwarranted to apply 25kg zinc sulphate per ha, as a blanket rate. It can be reduced to just 5kg per ha. And, in Turkey a 100 kg application is decidedly insane, making a big hole in the farmers’ purse. This author’s extensive research there proved that zinc application can be cut by more than 75 per cent if one were to accurately determine the soils’ “Zinc Buffer Power”.


Both in Kerala and Turkey, the official “recommendations” for zinc application is based on “text book” knowledge – extraction of the soil sample by a chemical Diethyl Triamine Penta Acetic Acid (DTPA), which underestimates the native zinc supplying power of these soils, warranting needless excess application of the fertilizer. One can well imagine the scientific absurdity of these “recommendations”, and what their consequences would be on soil degradation and ground water pollution with this heavy metal, adversely affecting human health, not to speak of the economic strain on the farmers.      


Researching on 20,000 ha of cardamom, a heavy feeder of potassium (K), spread over Kerala and Karnataka states, the author concluded that K fertilizer applications should be calibrated based on “K Buffer Power” of the soils, and not the routinely employed Ammonium Acetate extraction as is currently done in Indian laboratories. Soil samples tested from Idukki and Coorg districts, two very large cardamom growing regions in Kerala and Karnataka, respectively, showed, through precise experimentation, that Coorg soils were twice better K buffered than Idukki soils.


The practical implication of this important finding is that the routinely employed laboratory technique with Ammonium Acetate and K fertilizer recommendation based on this will lead to enormous economic loss to Idukki farmers. This finding will have very large economic implications for both states, as it will lead to enormous saving in K fertilizer usage, a highly expensive one, and thereby controlling soil degradation due to excessive K usage. The Department of Agriculture, Government of Kerala, has been accordingly advised.    


The African example: Project background


The African project was located in the Republic of Cameroon, which has very acidic soils, and the country, though politically free, is still functioning as a former French colony. The country has no fertiliser manufacturing capability and huge quantities of highly acidifying fertiliser like Ammonium sulphate is imported at enormous cost to the national exchequer and indiscriminately used, aggravating the already acidic soils, leading to much soil degradation.


The country has no national soil testing programme like India and agronomists arbitrarily recommend use of this highly expensive fertiliser to farmers. The investigation focused on two principal plant nutrients, phosphorus (P) – the most problematic – and potassium (K), and, the test crop selected was white clover (Trifolum repens), a highly nutritious fodder crop catering the country’s upcoming dairy industry.


It was unequivocally demonstrated that response of the test crop was highly correlated to the “P Buffer Power” and “K Buffer Power” of the soils and not the routinely employed Olsen’s test for P (recommended by the US) and the Ammonium Acetate extraction, for K, as explained above. Part of the research project formed the Master’s thesis of one of the author’s students, which was selected for a prestigious award of 400,000 CFA (Central African Currency) equivalent to US $1000 instituted by the Organisation for the Advancement of Science on the African Continent, which was given by the Minister of Higher Education and Scientific Research, on behalf of President Paul Biya. The event was nationally celebrated. 


Foot Note:

European Origin for the “Buffer Power Concept”

The foundation for the now globally famous “Buffer Power Concept” was laid when this author held Senior Fellowship at the world renowned Alexander von Humboldt Research Foundation, The Federal Republic of Germany, and affiliated to the prestigious Institute of Plant Nutrition, Justus von Liebig University, Giessen, the seat of world chemistry. The contents of this article are extracted from two chapters the author was invited to contribute to ADVANCES IN AGRONOMY, the magnum opus of agricultural science.


“The Nutrient Buffer Power Concept” was the only short-listed project from Asia, from over 3,500 nominations worldwide, for the prestigious US $1 million Rolex Awards For Enterprise of The Rolex Foundation, Geneva, in 2012, and currently nominated for the Right Livelihood Award (Alternative Nobel) of The Royal Swedish Academy of Sciences, Stockholm, for showing the right path to farming in Africa, Asia and Latin America. The research project, spread over three continents, Europe, Africa and Asia, is detailed in the book “The Nutrient Buffer Power Concept For Sustainable Agriculture”, Notion Press.

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