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EDITORS V.P.Abrol Fonner Head Division of Plant Physiology Indian Agricultural Research Institute New Delhi

N. Raghuram Reader School of Biotechnology Guru Gobind Singh Indraprastha University New Delhi M.S. Sachdev Principal Scientist Indian Agricultural Research Institute New Delhi

ik I.K. International Publishing House Pvt. Ltd. New Delhi





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13 Nitrogen from Industrial Wastes as Soil Amendment in Agriculture Deepak Pant1 and Alok Adholeya1,2 ICentre of Bioresources and Biotechnology, TERI School of Advanced Studies, DS Block, India Habitat Centre, Lodhi Road, New Delhi-110 003. 2Biotechnology and Management of Bioresources Division, The Energy and Resources Institute, New Delhi-110 003. II

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AgriculturalNitrogen Use & Its Environmental Implications Editors:Y.P.Abrol, N. Raghuram, M.S. Sachdev @2007 I.K. International Publishing House Pvt. Ltd., New Delhi, pp 263-278



Agricultural Nitrogen Use & Its Environmental Implications

including marine eutrophication, global warming, groundwater contamination, and stratospheric ozone destruction. However, very few studies in this regard have been carried out either in India or elsewhere. In this chapter, we attempt to summarize the present status of N rich industrial waste utilization,. the practices being fo.llowed while being utilized as sojlamendment and the implicatiolJ$ ofit.lh tha!pngtuh, Weal$O try>tb undetstandthe Nfertilizatpatterrtin India and how much of it can be replaced with N use from industrial Wastes. Also, as there are indications there might be some deleterious effects on such soils when applied for a long period. The role of biological N fixation has also been discussed.

1. INTRODUCTION Fertilizers are the chemicals that supply essential plant nutrients, mostly N, P and K, which are removed by crop plants in the largest quantities (Prasad, 1999). The provision of plant-available N through synthetic fertilizer in the 20thand 21stcenturies has contributed substantially to feeding and clothing for an ever-increasing human population. During the green revolution, N fertilizers contributed to the increase and sustainability of high yields across different agroecosystems. The intensive use of chemical fertilizers has not only polluted the soil, water, and the environment causing their slow degradation, but also affected the human beings. The increased use of N fertilizer has not come without cost to the environment, as its use, along with other human activities, has caused major changes in the cycling of N at a range of scales, from the very local to the global. Information on the components of the N cycle has accumulated rapidly in the past decade, particularly with regard to the processes of its transfer in different terrestrial, aquatic, and atmospheric environments. Hence, there is need to optimize the use of N and assess the impacts of continuing the supply of additional N to the natural and agricultural ecosystems. The information generated would help in seeking alternative resources and develop strategies for optimizing the use of nitrogen and reducing its environmental problems. Industries that generate nitrates in their manufacturing processes such as from distilleries and pulp and paper industries in the form of effluents and sludge are highly rich in nitrogen. This leaches into underground aquifers and contaminates the adjoining water reservoirs. There are relatively few studies that have directly studied the various industrial wastes as a nitrogen fertilizer-based system. Limited evidence suggests that wastewaters from distilleries and pulp and paper mills are rich in nitrogen and can be used as a source of nitrogenous fertilizers.

2. NITROGEN IN SOIL 2.1. Forms of Soil Nitrogen The provision of plant-available N through synthetic fertilizer in the 20th and 2pt centuries has contributed substantially to feeding and clothing an ever-increasing human population. However, the increased use of N fertilizer has not come without cost to the environment, as its use, along with other human activities, has caused major changes in the cycling of N at a range of scales, from the very local to the global. The availability of cheap nitrogen fertilizer and the complete freedom farmers and farm businesses have to use that nitrogen, leads to buildup of nitrate in the environment. The N not removed by the crop is incorporated into soil organic matter or is lost to the environment (atmosphere and water

Nitrogen from Industrial Wastes as Soil Amendment in Agriculture


bodies) by leaching, runoff, erosion, ammonia volatilization, and denitrification. But the quantities lost via individual pathways are highly uncertain and are very much situation dependent. If the soil is ponded and anaerobic conditions develop, significant amounts of N03 can also be lost by denitrification or conversion to N2. This denitrification process can generate emissions of trace gases. Soil N is subjected to chemical and biogeochemical transformations, and its dynamic is affected by several factors. This dynamic can change the chemical form of organic N compounds in a relatively quick amount of time, such as changing the proteins in crop residues to N03 and then to the gaseous N2 form. In this soil dynamic, the soil N can be a part of the microbial biomass, roots, or other components of the system (Delgado, 2000). There are other new technologies that can contribute to managing the rate of N transformations in the soil system. It has been reported that nitrification inhibitors (NI), slow-release fertilizers, and controlled-release fertilizers (CRF) can be used to increase NUE (Engelsjord et ai., 1997; Detrick, 1996). 2.2. Nitrogen Cycle Nitrogen, constituting 79% of the air, is one of the elements threatening the global environment (Vitousek et ai., 1997, Moffat, 1998). Nitrogen cycles, by biological and chemical processes from organic forms to ammonia may be volatilized to the atmosphere as ammonia or oxidized by soil bacteria to nitrate, the most water soluble and mobile form of inorganic nitrogen. Nitrate may be taken up by plants, leached, or converted by biological processes to nitrous oxide and elemental dinitrogen gas (N2)-a process called denitrification. This collection of reactions where nitrogen weaves in and out of various forms and moves through various parts of the environment is known as "nitrogen cycle". Nitrogen is a mobile nutrient present in both plants and soils. It is today an important issue in soil quality, carbon sequestration, water quality and virtually all components of the ecosystem. In its reduced form as ammonia and amides, it is a critical component of life's building blocks-the amino acids and proteins. Plants need nitrogen for growth: a typical cornfield might tie up 150 to 200 pounds of nitrogen an acre in the fodder and harvested grain. This is more nitrogen than most soils can supply in an available form during the short growing season of a corn crop, even though a fertile soil might have 3,000 pounds or more of nitrogen per acre incorporated in the organic matter (Keeney and Muller, 2000). Nitrogen can have several impacts on the environment. Inadequate N supply can limit plant growth, which can result in increased soil loss. This affects water quality through increased sedimentation and the release of Nand P, causing excessive growth of aquatic plants in Nand P limiting situations. Inputs of soil and fertilizer N from agricultural land can contribute to N-induced eutrophication in estuaries. The excessive growth of algae and the resulting depletion of oxygen, and the production of a range of substance toxic to fish, cattle, and humans, can be a major pollution problem. N cycling attracts worldwide attention because of its importance for food production and its effects on the environment. In the form of fertilizer, N exerts the most important effects on food production. As a result, human activities have significantly altered the natural N cycling, causing reactive N compounds (for example, NOx, N20, N03' NH3' NH4) to enter the atmosphere and water bodies at increasing rates. Increased N20 emissions to the atmosphere not only enhance the greenhouse effect, but also disturb the ozone layer. N03' N02 and NH4 entering the water bodies can negatively affect the quality of drinking water and may cause eutrophication. The dry/wet N depositions containing NH3 and NOx can alter the normal function of the forest ecosystems and also intensify the eutrophication of water bodies in these ecosystems.


Agricultural Nitrogen Use & Its Environmental Implications

2.3. Biological Nitrogen Fixation Nitrogen is one of the five major chemical elements that are necessary for life. While nitrogen is the most abundant of these, more than 99% of it occurs as molecular nitrogen or N2' which cannot be used by most organisms. This is because breaking the triple bond holding the two nitrogen atoms together requires a large amount of energy, which can be mustered only through high temperature processes or by a small number of nitrogen-fixing microbes. Prior to the introduction of chemical fertilizers by human beings, the primary source of nitrogen in plants, soils and waters was biological nitrogen fixation (conversion of atmospheric nitrogen by legumes and free-living bacteria to ammonia and organic nitrogen) and lightning. However, the change of mankind's activity towards agriculture changed that forever, and according to some estimates, the known human sources of nitrogen (fertilizers, legumes, and the nitrogen emitted by internal combustion engines and power plants), is equal to the nitrogen that is produced by natural sources before civilization (Jordan and Weller, 1996; Vitousek et al., 1997). Nitrogen-fixing trees are often deep-rooted, which allows them to gain access to nutrients in subsoil layers. Their constant leaf drop nourishes soil life, which in turn can support more plant life. The extensive root system stabilizes soil, while constantly growing and atrophying, adding organic matter to the soil while creating channels for aeration. Biologically fixed N is much more readily available to plants than the native soil organic N. Nevertheless, a part of it is also subject to loss. Working with a group of bacteria called Rhizobia, legumes are able to pull nitrogen out of the air and accumulate it biologically. The bacteria, which are normally free-living in the soil in the native range of a particular legume, infect (inoculate) the root hairs of the plant and are housed in small root structures called nodules. Energy is provided by the plant to feed the bacteria and fuel the nitrogen fixation process. In return, the plant receives nitrogen for growth (Elevitch and Wilkinson, 1998). 3. RECYCLING OF WASTE IN AGRICULTURE Rapid economic growth and development has taken place at the cost of unbalanced growth of urbanization and industrialization, which resulted into various environmental problems due to the production of large amounts of pollutants. Hazardous waste generation and industrial effluent and other wastes adversely affect the fauna and flora and degrade the natural resource system. The underground water and soil pollution from chlor-alkali sludge (with high complexity of brine and mercury), fly ash (with a presence of heavy metals), spent wash of distilleries effluents (with a presence of complex organic carbon and electrical conductivity), and tannery effluent (with problem of high chromium) makes the soil ecosystem miserable and unmanageable. This is due to the fact that in the undiluted effluent, concentration of nutrients is so high so as to become toxic, resulting in stunted plant growth. However, it has been observed that the use of effluent for irrigation after diluting with normal water is beneficial for crop growth and yield than the normal water. This way, the inorganic/organic contents of effluent can be utilized as substitute of chemical fertilizer for enhancing plant growth (Kumar et al., 2003). 4. NITROGEN FROM INDUSTRIAL WASTES Nitrogen pollution comes from a variety of sources; however, agriculture is a significant contributor in many areas. This contribution can be greatly reduced by establishing or improving nutrient

Nitrogen from Industrial Wastes as Soil Amendmentin Agriculture 267 management. According to international nitrogen initiative, there are two major problems with nitrogen: some regions of the world do not have enough reactive nitrogen to sustain human life, resulting in hunger and malnutrition, while other regions have too much nitrogen (due mainly to the burning of fossil fuel and inefficient incorporation of nitrogen into food products) resulting in a large number of major human health and ecological effects. The rate of change of the problem is tremendous, probably greater than that for any other major ecological problem. There are major tradeoffs in agricultural and environmental policies while determining N fertilizer use in a given country, and the effect that N fertilizer use has on food production and the environment. The impacts of N fertilizer determine whether priority should be given to increasing N fertilizer use to enhance food production and rural livelihoods, or whether environmental and health issues drive the agenda and lead to a reduction in N fertilizer use. 4.1. Solid Industrial


Treatment of both municipal and industrial wastewater produces sludge, which must be disposed of properly. Among the many methods developed for sludge disposal, incineration, solidification, and deep well injection are expensive and generally preferred for hazardous and toxic chemicals (Dolgen et aZ., 2004). Land application is the practice of applying treatment plant sludge for agricultural purposes, such as plant growing, soil conditioning, foresting, etc. Due to the possibility of recycling of valuable components such as organic matter, nitrogen, phosphorus, and other plant nutrients like boron, manganese, copper, molybdenum and zinc, there is an increasing interest in the agricultural use of treatment plant sludge (USEPA, 1983). Application of industrial wastewater treatment plant sludge for agriculture has not been a common practice due to heavy metals and their likely negative environmental and health impacts. These facts have significantly discouraged the application of industrial wastewater treatment plant sludge for agriculture. 4.2. Liquid Industrial


The national water policy of India has pointed out that by promoting wastewater reuse in agriculture, the water resources could be protected from pollution as well as provide an alternative source of water for crop irrigation (Kumar et ai., 2003). A huge amount of wastewater generated from distillery and paper industries has an important role to play in the context of scarcity of fresh water resources for irrigating agricultural land. Besides being a useful source of plant nutrients (N, P, K, S etc.), these effluents often contain high amounts of various organic and inorganic materials as well as toxic trace elements, which might accumulate in the soils in excessive quantities in long term use (Chhonkar et aZ., 2000). Generally, the effects of effluent quality upon the receiving soil may range from behaving as a clean water input to that causing serious sodicity/salinity levels in soil or clogging the soil micropores with solids, and that decisions about monitoring are based upon a clear understanding of the interaction between the effluent and the soil (Pattern, 1999). Chemical compounds introduced into soils can be adsorbed by soil constituents, transformed by soil organisms, taken up by plants, washed out by rain or irrigation water, or evaporated in gaseous form (Grover, 1975; Walker and Smith, 1979; Herzel and Schmitt, 1979; Roseberg and Alexander, 1980). Yeop and Poon (1983) observed that land application of palm oil mill effluent improves soil fertility and has no adverse effect on the


Agricultural Nitrogen Use & Its Environmental Implications

environment. Sugar factory effluent applied to soil in Cuba, taking into account the general deficiency in humic matter of Cuba soils, increased the soil organic matter content by 1% (Valdes et al., 1996), while cassava mill effluent applied to the soil increased the nitrate content as reported by Vieities and Brinkoli (1998). The growth of various crops has been reported to be influenced by different types of effluents. The soils treated with tannery effluent are rich in Mg, Mn, Fe, Na, and K ions. Tannery effluent caused an increase in leaf area, biomass, chlorophyll content and total protein of Gossypium hirstum, Vigna mungo, Vigna unguiculata and Lycopersicum esculentus over control as observed by Karunyal et al. (1993). Treated effluent of chemical industry was found to be effective in promoting germination, growth, chlorophyll and protein content of Mungo (Chidaunbalam et al., 1996). Rajni and Chanchan (1996) using tannery effluent, and Dutta and Boissya (1997) using paper mill effluent, however, observed a significant reduction in germination percentage, root length and total biomass in almost all varieties of Hordeum vulgare and Oryza sativa, respectively. 5. NITROGEN FERTILIZATION PATTERN IN INDIA Nitrogen (N) is one of the most important nutrients used worldwide to increase and maintain crop production. Consumption of chemical fertilizers has increased tremendously in recent years. Nitrogen, phosphorous and potassium are the primary fertilizers nutrients, which are widely used in our country. The N fertilizer consumption has increased many folds in recent years as shown in Table 3. In the recent past, increased anthropogenic activities have resulted in several environmental problems that have considerable implications for the food systems. Producing enough food for the increasing population against the background of reducing resources in an adverse environmentally changed scenario, while minimizing further the environmental degradation, is, therefore, the primary task of agriculture in the coming years. Nevertheless, we must learn lessons from the ill effects of overuse of chemical fertilizers and underground contamination of nutritionally rich wastes, generated from various industries, on soil, environment, and human health. There are a number of potential sources other than fertilizers, responsible for the environmental degradation. These include livestock and human excrement in the rural areas and leaking septic systems, sewage, combustion of fossil fuels in motorcars and other vehicles in the urban areas. Industries that generate nitrates in their manufacturing processes, such as from distilleries, pulp and paper industries and tanneries in the form of effluents and sludge are highly rich in nitrogen and leaches underground and contaminates the adjoining water reservoirs. In intensively cultivated areas of India, a high annual productivity of wheat results in removal of nutrients in substantial amounts that often exceed replenishment through fertilizers and manures ultimately leading to deterioration of soil health. Yield decline and decreasing factor productivity have been reported in wheat and farmers have started to use higher doses of N (up to 180 kg/ha), to maintain the higher yield levels. Such emerging trends of indiscriminate use of fertilizer N without using organic sources of nutrients and balance fertilization aggravated the problems. Hence the use efficiency of applied fertilizers needs to be enhanced to sustain the productivity of wheat. Nutrient schedule along with balanced fertilization using organic manures like farmyard manures is considered as promising agro-technique to sustain yield, increase fertilizeruse efficiency and to restore soil fertility (Singh and Agarwal, 2005). In Meghalaya, Majumdar et al. (2005) studied the effect of split application of N on yield attributes, yield alld nutrient uptake by rice (Oryza sativa L.) in a valley land under rainfed condition. The grain and straw yields, N, P and K uptake by rice increased significantly at each level of N application when applied as 1/2 basal + 1/2 at panicle initiation over only basal application.

Nitrogen from Industrial Wastes as Soil Amendment in Agriculture


6. SPECIFIC CASES 6.1. Distilleries Distilleries are one of the 17 major polluting industries in India (identified by the Central Pollution Control Board), as 88% of their raw materials end up as wastes. The effluent of distillery industries known as spent wash is a major cause of soil as well as water pollution. Distilleries are considered to be among the most polluting industries, as their effluents, if discharged into the water bodies, defile the natural ecosystem. There were 285 distilleries in India in 1999, producing 2.7 x 109 L of alcohol and generating 4 x 1010 L of wastewater each year (Joshi, 1999), the number of which has increased to 319 at present, producing 3.25 x 109 L of alcohol and generating 40.4 x 1010 L of wastewater annually (Uppal, 2004). Most of these are concentrated in the states of Maharashtra, UP, Andhra Pradesh, Madhya Pradesh, Tamil Nadu, and Karnataka. The proportion of wastewater, generally known as spent wash, is nearly 15 times the total alcohol production. This massive quantity, approximately, 40 billion litres of effluent, if disposed untreated can cause a considerable stress on the watercourses leading to widespread damage to aquatic life. In nearly all distilleries, the bath fennentation mode is adopted with about 12 to 15 L of spent wash being generated per litre of alcohol produced. An average molasses based distillery generates 15 L of spent wash/l of alcohol produced (Joshi 1999). The effluent is characterized by its colour, high temperature, low pH, high ash content, and high percentage of dissolved organic and inorganic matter. Characteristics of postanaerobically treated distillery effluent from a distillery are given in Table 1. Raw spent wash (waste water) generated from the distillation of fermenter wash is deep brown in colour, acidic in nature, with high concentration of organic material and suspended solid. Table 1: Characteristics of post-anaerobically treated distillery effluent Parameter Electrical conductivity pH BOD5 (ppm)* COD (ppm) Sodium (ppm)

Anaerobically treated effluent (released in field) 33.16 8.50 5000.00 25000.00 500.00

Potassium (ppm)


Manganese (ppm)


Magnesium (ppm)


Zinc (ppm)


Copper (ppm)


Total dissolved solids (TDS) Total sugar (%) Reducing sugar (%) *Parts per mill Source: Pant et aZ., 2006.

21255.56 2.8 0.227



Nitrogen Use & Its Environmental


Table 2: Annual bioenergy and plant nutrient potential of distillery effluent in various states of India * State

Andhra Pradesh

No. Total installed of capacity distilleries (million litre/year

Total effiuent generated million litre/year

Biogas (million m2)

Total nitrogen (tonnes)

Total potassium (tonnes)

Biomass potential (tdm in tonnes)**
























Goa, Daman and Diu
























*Joshi 1999; **total dry mass.

Conventionally, spentwash is treated through biomethanation. The total effluent generated by all the distilleries in a year amounts to nearly 40 billion litres, which has a potential of producing 1100 million cubic meters of biogas annually. This biogas normally contains 60% methane gas, which is a well-recognized fuel gas with minimum air pollution potential. If this source of energy is tapped, it will fetch additional energy units worth 5 trillion kilocalories annually. Besides, PME (post-methanation effluent) can provide 244000 tonnes of K, 12200 tonnes of N, and 2000 tonnes of P annually (Table 2). Therefore, the manurial potential of the effluent can meet the potassium requirement of 1.5 million hectare land, nitrogen requirement of 0.12 million-hectare land, and phosphorus requirement of 0.02 million-hectare land if two crops are taken in a year. This is very significant in Indian context for which more and more distilleries are adopting this technology. Out of all the distilleries, 129 have completed the construction of biomethanation digester for the primary treatment of the effluent; 49 are under construction, and the remaining are under planning stage. The volume of the effluents is enormous. Land application of distillery effluent has become a common practice these days because proper treatment of the nutrient rich waste involves large expenditure to bring down the high levels of BOD from about 50,000 mgll to the permissible limits of 30 mgll (CPCB, 1998). The minimum prescribed limits for wastewater from distilleries is given in Table 4. For a distillery with 30 kid (kiloliters per day), alcohol production capacity not less than 270 hectares of land is required. In future, such a large area may not be available for distilleries, and if possible, would be difficult to manage. In such cases, by using TERI's technology one can minimize up to three-fourth of the total 270 hectares area required to run 30 kId alcohol production. Under such conditions, plantation of higher transpiration rate plants with suitable microbes on ridges may transform the effluent into a nitrogen-rich bi~fertilizer, which would be costly but a highly demanded technology for agriculture, yet reduce contamination due to spent wash and nitrogen contamination in water and soil, and also check losses due to leaching. Opinion is divided among researchers over positive and negative impacts of distillery wastes when used as a fertilizer. It is speculated that very high BOD and COD are likely to have an adverse effect on soil health by increasing pC02 and temperature and forming several organic acids that lead to immobilization of plant nutrients (Chhonkar et at., 2000).


Nitrogen from Industrial Wastes as Soil Amendmentin Agriculture 271 Table 3: All India consumption of N in million tons Year






























Source: Fertilizer News, November' 1999.

Effluent application will reduce the nutrient requirement through fertilizers. Irrigation with distillery effluent increased the pH, EC, OC, SAR, PAR, exchangeable Na and K, and available nutrients such as N, P and K of the soils under sugarcane than with normal water at the same level of fertilizer application indicating that potassium fertilizer could be withdrawn from fertilizer schedule (Jadhav and Savant, 1975; Deverajan et at., 1994; Zalawadia and Raman, 1994). It was further concluded by Deverajan et al. (1994) that distillery wastewater can be safely used as liquid manure at the rate of 125 to 250 t ha-l. Significant higher yields of sugarcane and an increase in available N content of soil was observed with 200 kg N per ha supplied through spentwash, however, both yield and available N decreased when 300 kg N per ha was applied (Bajpai and Dua, 1972). However, high salt load, mainly potassium and sulfur, into the soil system may hamper the sustained crop yields due to continued long-term application of effluents. Therefore, the effects on soil and crop Table 4: Environmental standards for wastewater discharge from fermentation industry (Distilleries, Maltries, and Breweries) Parameter pH Colour and odour

Concentration in the effluent not to exceed, mgll (except for pH, colour and odour) 5.5 to 9.0 Absent

Suspended solids


BOD (27°C, 3 days) - Disposal into inland surface water/river/streams Disposal on land or for irrigation

30 100

Source: CPCB, 1996.


Agricultural Nitrogen Use & Its Environmental Implications

productivity have to be visualized on long term and sustainable basis. Identification of suitable cropping system, agronomic practices, irrigation scheduling and water management with distillery effluent has to be done for implementing such irrigation, ensuring minimum damage caused to the soil, crop, and ground water. High amount of nitrogen in distillery wastewater has been reported by Uzal et al. (2003). Nashikar (1993) reported that irrigation with high BOD wastewaters had no adverse impact on the nitrification activity in soils. Earlier, Adhikari and Sahu (1985) observed that effluent at low concentrations (1-10% v/v) and at pH levels of 7.0-8.0 increased the growth and Nfixing abilities of Anabaena, a blue-green algae. Spentwash has been classified as a dilute liquid organic fertilizer with high K, and whose N, mostly in colloidal form, behaves as a slow release fertilizer better than most inorganic N sources (Kulkarni et ai., 1987). The percentage utilization of applied N, P and K through fertilizer is more in distillery wastewater irrigation with 75% fertilizer dose than with normal irrigation with 100% fertilizer dose (Chhonkar et ai., 2000). Recently, a very comprehensive study was done by Kaushik et ai. (2005) on impact of long and short-term irrigation of sodic soil with distillery effluent in combination with bioamendments. It was found that significant increase in TOC and TKN took place due to effluent irrigation, which is attributed to high organic load (BOD) of the effluent. Similarly, a highly significant increase was in exchangeable K and phosphorus, which improved by 10 and 4.5 times, respectively. This shows that the requirement of N, P, and K and organic carbon in the soil can be met by irrigating the soil with PME for a long time. Long-term irrigation with distillery effluents remarkably improves all these nutrients in the soil showing statistically significant (p < 0.01) increase in these parameters. It was concluded that longterm irrigation with PME in sodic soil would improve soil organic carbon, nitrogen, soil dehydrogenase, and invertase activities, potassium and phosphorus in the soil, all of which are favorable for plant growth. However, it can gradually lead to Na build up in the soil that may increase the salinity and marginally the sodicity problem. In another study, Robert et al. (2005) studied the effect of brewery effluent on some soil chemical properties and growth of maize. The values of organic carbon, N, P, Na and Mg were reduced, whereas K, Ca, exchangeable acidity and soil pH increased. The growth of maize and chlorophyll content were enhanced. Outside India, in France, concentrated beet vinasse is used as fertilizers by all the distilleries (Deco lux et ai., 2002). Stillage is classified as a NPK fertilizer by the AFNOR NF U 42-001 (AFNOR, 1981). These fertilizers must contain more than 10% of (N + P2°5 + ~O) with a minimum of 3% nitrogen and 6% potash (K2O) and not more than 2% of chlorine. According to a study conducted by SNPAA (1994), the nitrogen of stillage is almost totally in organic form-amino acids, glutamic acid salts, betaine (2-4%). The average quantity of concentrated stillage applied to the land is 3 t/ha, which is 225 kg/ha of ~O and 90 kg/ha of total nitrogen (50-60% of which are available in the first year of application). Fertilising sugar beet with concentrated stillage improves the yield per hectare by 2-2.5 t/ha. Molasses vinasse enjoys a particular status, since it is a natural fertilizer produced on a large scale and whose quality is acknowledged unanimously. Concentrated vinasse can also be used in organic farming in conformity with the European directive CEE 2092/91. 6.2. Pulp and Paper Mills The Indian paper industry is more than 100-years-old. The first paper mill was established in India in 1812 in the West Bengal. While, at the time of independence, there were less than 20 mills in India with the total annual capacity of 100,000 tons, today there are about 406 pulp and paper

Nitrogen from Industrial Wastes as Soil Amendment in Agriculture


industries with an annual installed capacity of 6.2 million tons. The pulp and paper mills are further classified as large scale, medium scale and small-scale industry based on the installed capacity (Nemade et aI., 2003). Like distillery, the pulp and paper industry has also been brought under the list of 17 most polluting sectors as identified by the central pollution control board. Except a few exceptions of the new modernized mills, most of the mills are based on obsolete process technologies. The effluent from these industries is dark brown in colour due to high content of oxidized and partially degraded lignin. The black liquor containing lignin along with pulping chemicals is difficult to treat in the ETP (effluent treatment plants), as the lignin is not easily biodegradable. It also carries toxic compounds such as chlorinated phenols, chlorinated dibenzo-pdioxin, dibenzofuran, and AOX (adsorbable organic halides). Color is an indirect measurement of the amount of lignin compounds in the effluent. The greater the amount of lignin compounds, the darker the effluent and greater the tendency to produce foam. Due to the presence of various dissolved inorganic and organic chemicals like dyes, heavy metals, detergents, starch, etc., the effluent contains normally high COD, heavy metals, and high alkalinity. Each ton of paper produced in small paper mills (without chemical recovery using pulping) generates 2.60 times the pollution load discharged from a large paper mill with chemical (Kulkarni et ai., 1997). The pulp and paper industry generates vast quantities of residuals, particularly residues resulting from the treatment of paper mill process watt-rs. Wastewater treatment usually consists of primary treatment (settling) followed by secondary (biological) treatment. Due to the raw effluent treatment process, the treated paper mill effluent consisted of an increased amount of nutrients like N, P, K, Ca and Mg when compared to the untreated effluent. In the case of other nutrients, the sodium content in the treated effluent was found to be low. The treated effluent contains increased amount of N, P and K considerably due to the addition of nutrients in the treatment process. The land application of the treated effluent provides an effective and environmentally acceptable option for waste disposal, which not only recycles valuable nutrients into the soil-plant system, but also improves the soil quality (Suriyanarayanan, 2005). The minimum prescribed limits for wastewater from small-scale pulp and paper mills is given in Table 5. Irrigation of sugarcane crop with combined pulp and paper mill effluents has been found to increase pH, OC, N, P and K status of soils (Kannan and Oblisami, 1990). Pulp and paper sludge generally ends up in landfill sites, where it can constitute a major portion of the waste volumes received. The combined sludge of primary and secondary treatment contains nitrogen and phosphorus, because these two elements are necessary for the biological treatment. Table 5: Environmental Standards for wastewater discharge from small-scale pulp and paper industry Mode of disposal Inland surface water


Source: CPCB, 1996.


Concentration not to exceed, mg/I (except for pH and sodium absorption ratio)

pH Suspended solids BOD at 27°C, 3 days

5.5 to 9.0 100 30

pH Supended solids BOD at 27°C, 3 days Sodium absorption ratio

5.5 to 9.0 100 100 26


Agricultural Nitrogen Use & Its Environmental Implications

Pulp and paper sludge is rich in organic matter, and in the case of combined sludge, nitrogen and phosphorus as well. As such, it constitutes an excellent amendment that can improve the physical and chemical properties of soil. The use of combined sludge from pulp and paper mills in agriculture allows the farmers to reduce their fertilizer costs. Paper mill sludge appears to have a promising future as an efficient and cost effective means to replenish depleted farmlands, and to rehabilitate degraded soil. The use of combined sludge to rehabilitate degraded soil should be studied closely to limit the risk of nitrogen loss. To this end, a mixture combining other sludge containing higher C:N ratios should be considered (Sylvestre et at., 1999). 6.3. Industrial

and Municipal Sewage

Sludge is the final product of any wastewater treatment process and generally considered as a matter that should be disposed properly. Since sludge contains certain elements that are useful for the agricultural production and reflects no detrimental character, it may deserve particular interest especially for agro-based industries. Soft drink industries generate waste products in the form of sludge that is left unused and discarded. Since the sludge is high in organic matter and substantial quantities of nutrients such as N, P, K and low in toxic metals, the sludge therefore can be used in sustainable plant production. The sludge generated from purification process adopted in breweries industries can be used in an environmental friendly manner through land application to improve the soil properties. However, sustainable utilization of this sludge is possible only if the sludge does not contain pollutants in excess of the prescribed standards. Based on the risk assessment of a series of exposure pathways, the US Environment Protection agency has laid down certain standards for toxic pollutants, such as for metal concentrations in sludge, and the amounts of various metals that may be added to soil as a result of land application of this waste. Studies conducted by Dolgen et at. (2004) demonstrate that sludge taken from an agro-industry (vegetable processing factory) can be used as a partial substitute for chemical fertilizer and as a soil conditioner. Another important factor in determining the acceptability of sludge for land application is the nutrient content. Nitrogen and phosphorus are essential nutrients for plant growth, and they are required in relatively large quantities by plants. Any deficiency of these components in the sludge may be overcome by adding compost. In a study by Saravanane et at. (2004), the feasibility of integrated biomethanation process for joint treatment of sugar industry waste and municipal sewage plant was investigated. High yield of biogas with methane content of 65% was observed through integrated biomethanation process as compared to that of conventional biomethanation of press mud alone. The nitrogen content in the digested sludge was found to be 2.32%, and hence it can be recommended for agricultural use as fertilizer.

7. NITROGEN BIOFERTILIZERS VIS A VIS CHEMICAL FERTILIZATION Synthetic N fertilizers are the single most energy expensive input to modem agricultural production, accounting for approximately 68% of on-farm commercial energy use in less developed countries and 40% in more developed nations (Mudahar and Hignett, 1987). Continuous use of inorganic fertilizers mainly containing major nutrients, NPK, in large quantities and neglecting organic and biofertilizers paved the way for deterioration of soil health and in turn ill effects on plants, human beings and cattle. Nitrogen is applied to the soil as urea (which is readily


Nitrogen from Industrial Wastes as Soil Amendment in Agriculture


hydrolyzed to ammonium), ammonium nitrate or a combination of ammonium and nitrate. About 40-60% of applied nitrogen is lost by volatilization runoff, denitrification and leaching. The nitrate that is leached causes a lot of visible and invisible hazardous effects. Excessive application of chemical fertilizers lead to malnutrition due to degradation of carbohydrates and proteins, both qualitatively and quantitatively, besides affecting the physical properties of soil such as infiltration, soil aeration, soil structure and bulk density etc. Enrichment of surface water bodies with nutrients, addition of plant nutrients particularly P and N to surface water bodies such as lakes, reservoirs, and streams result in intense proliferation and accumulation of algae and higher aquatic plants in excessive quantities, which can result in detrimental changes in water quality. Already, legume rotations have progressively become less common, as farmers in most countries of the world have increased their reliance upon synthetic N fertilizers. Accounts of N inputs in farming systems estimate that while as much as 50% of all available N may have originated from biological N2 fixation by leguminous food, forage and green manure crops in the 1950's, this value dropped to around 20% by the mid1990's (Smil, 2002). On the other hand, organic farming systems rely on large scale application of animal or FYM, compost, crop rotations, cooperative residues, green manuring, vermicompost, biofertilizers, biopesticides and biological control. In India the use of organic manures in subsistence farming is an age-old practice. Organic manures improve physical, chemical and biological properties of the soil. Addition of organic manure improves structure aeration, water-holding capacity of soils, reduces phosphorus fixation in acidic soil, forms chelates with metallic ions and reduces their toxicity in crops. Biofertilizers are living cells of different microorganisms with an ability to mobilize nutritionally important elements from non-usable to usable form. They influence the availability of major nutrients like nitrogen, phosphorus, potassium and sulphur to the plants. Rhizobium, Azotobacter, Azospirillum, blue-green algae, Azolla, mycorrhizae, phosphate-solubilizing bacteria (PSB) and plant growth promoting rhizobacteria (PGPR) can be used as biofertilizers to increase the crop production. These microorganisms require organic matter for their growth and activity in the soil, and provide valuable nutrients to the plants in the soil. In a recent review, Crews and Peoples (2004) reviewed the sustainability of obtaining N from legume versus industrial sources in terms of ecological integrity, energetics and food security. These authors concluded that obtaining N from legumes is potentially more sustainable than from industrial sources. It was also suggested that while some countries are fundamentally dependent on synthetic N for food production, many countries have the capacity to greatly reduce or eliminate the dependence on synthetic N through adoption of less meat-intensive diets and reduction of food waste. 8. CONCLUSION



Based on the limited data available for estimating nitrogen availability from industrial wastes, it can be suggested that a portion of chemical fertilizers can be definitely replaced with industrial wastewaters and sludges. The utilization of industrial wastes for agricultural purposes also provides a solution to the disposal problems. The best strategy for utilization of distillery effluent (spent wash) is its use as source of fertilizers for growing agriculture crops. The application of distillery wastewater in agriculture has emerged as a potential area; the distilleries, pollution control agencies, farmers and research organizations have realized the potential of this wastewater in improving plant growth. Such an application also supports the positive environmental activities of the industries and facilitates


Agricultural Nitrogen Use & Its Environmental Implications

their efforts towards having some environmental or green standards. The soil nutrition value of the effluent as a source of manure has recently been recognized by TERI, New Delhi, in one of their pilot-scale testing programme being carried out in two states, Madhya Pradesh and Chhattisgarh, where distillery effluent and paper mill waste water was channelized in between rows of plants where plants utilized waste water as a source of nutrients, specially N and organic carbon, yet economizing the area required for effluent load. The volume of the effluent is enormous. For a distillery with 30-k litre/day alcohol production capacity, not less than 270 ha of land are required. In future, managing such a large area for a distillery would be difficult and may not be available for the distilleries. In such cases, by using TERI's technology one can minimize up to three-fourth of the total 270 ha area required to run 30-k litre/day alcohol production. Under such conditions, the effluent can be transformed into a nitrogen rich biofertilizer, which would be costly but would be a highly demanding technology for agriculture, yet reducing N contamination in water and soil and also check losses due to leaching. Identification of a suitable cropping system, agronomic practices, irrigation scheduling, and water management with distillery effluent has already been done by TERI for implementing as a policy for distilleries. Emphasis should be laid on exploring the possibilities of utilizing the wastewater for its organic matter and nutrients, which could be useful for growing crops or vegetables. To boost up the yield of the crop on sustainable basis without affecting environment, liberal application of organic manure, in addition to need based application of inorganic fertilizers, along with judicious application of chemical pesticides is essential.

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Agricultural Nitrogen Use & Its Environmental Implications

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. Agricultural Nitrogen Use & Its Environmental Implications Agricultural Nitrogen Use& Its Environmental Implications providesa comprehensive, interdisciplinary description of problems related to the efficient use of nitrogen in agriculture, in the overall context of the nitrogen cycle,its environmental and human health implications, as well as various approaches to improve Nuse efficiency. The book has been divided into six sections and targets graduates, postgraduates, research scholars and policy makers in Agricultural and Environmental Sciences.

Y.P. Abro~ former Head of the Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi. Professor Abrol has worked as Emeritus Scientist (CSIR), Senior Scientist (Indian National Science Academy), and is presently Adjunct Professor and Honorary Scientist at the Indian National Science Academy. He has published research/review articles in International and National Journals, besides editing a number of books! proceedings. He is a Fellow of the Indian National Science Academy; Indian Academy of Sciences; National Academy of Sciences; and National Academy of Agricultural Science. Professor Abrol has received several awards ..,

notably Dr. R.D.AsanaAward, Sukumar Basu Award, VASVIKand FICCIAward. N. Raghuramis currently Reader in the School of Biotechnology, Guru Gobind Singh Indraprastha University, Delhi. His areas of specialization are plant molecular biology and functional genomics. Besides writing books, he has written over 25 research articles, reviews and commentaries published in journals of national and international repute. He is an Editor of "Physiology and Molecular Biology of Plants", an international journal of functional plant biology. M.S. Sacbdev, Principal Scientist, Indian Agricultural Research Institute, New Delhi. He has published more than 140 scientific articles. His work on soil fertility, fertilizer and water use research has been recognized nationally and internationally and has received many prestigious awards from Fertilizer Association of India

and ICAR. Dr. Sachdev is the Fellow ofIndian Society for Nuclear Techniques in Agriculture and Biology (FNAS)



and the National Academy of Agricultural Sciences (FNAAS),and currently (2006-07) heJ-sthe SectionalPresident

ofAgricultureand ForestrySciencesofthe Indian.ScienceCongress.