Decontamination of Heavy Metals Contaminated solid and Liquid Wastes through Biological Means

Low organic matter coupled with low native nutrient status in most arable soils of India, is responsible for low productivity and unsustainable production base. One of the most well known practices to recover and maintain the soil productivity is to add organic amendments. The availability of organic manure is not sufficient due to competitive use for dung and biomass as fuel. Therefore, other sources like municipal solid wastes (MSW) are gaining prominence. Urban wastes (MSW and sewage sludge) are increasingly being used as organic amendments after composting to reduce possible environmental and health problems. MSW have a high amount of inert materials and other non-biodegradable by-products of industrial origin and are laden with heavy metals. Most heavy metals are accumulated as micronutrients such as copper, zinc, manganese and non-nutrient metals like nickel, cadmium, tin, mercury, lead in high amount induc8ing toxicity towards soil microbiota. Long-term application of MSW or sewage water/ sewage-sludge slowly leads to accumulation of heavy metals in soil and inhibits the microbial activity. The application of metal contaminated wastes affects the soil microbial processes like carbon mineralization, ammonification, nitrification and nitrogen fixation.

Removal of heavy metals from metal bearing waste water effluents before discharging them into natural water bodies is accomplished by physico-chemical processes which include precipitation, coagulation, reduction, ion-exchange, membrane process (Such as ultra filtration, electro-dialysis and reversed osmosis) and adsorption. Adsorption on activated carbon is a recognizd method for removal of heavy metals from waste water. These methods are costly and there is a need to search a low cost and easily available adsorbent preferably of biological origin for metal removal.

Recent developments in the field of environmental biotechnology include the search for microorganisms as biosorbents for removal of heavy metals. Two methods of heavy metal toxicity elimination, by action of microorganisms are (a) bioleaching in which specific organisms reduce the toxicity of metals by complexation through acid production under aerobic condition in solution phase and (b) biosorption to improve biomass production.

Biosorption, using suspended non-living biomass, and flotation for consequent separation of the metal loaded biomass is needed for removal of toxic metals from dilute aqueous solutions. The activity of soil microorganisms and enzymatic activity decreases significantly as the solubility of the metal species increases and is dependent on soil type and environmental conditions. Many sorbents and ion-exchangers are often particulate in nature. Sorption with free mobile particles in suspension provides high surface area for binding sites, but their subsequent separation from decontaminated effluent may be problematic particularly in ultra fine range. Heavy metals are recognized as the most hazardous soil biological pollutants because they cannot be broken down and only change from one oxidation state to another. Heavy metals are forever! therefore research has to be intensified for finding cheap and effective methods of removing heavy metal contamination from solid wastes and liquid water for their safe and efficacious recycling in agriculture.

Integrated plant Nutrient Supply technology for improving the productivity of soybean

Based on four on-farm trials conducted in two villages of Rajgarh and Bhopal districts of Madhya Pradesh, it was found that the integrated use of 50%NPK + 5t FYM/ha + Rhizobium not only increased the soybean seed yield by 11% and 25% over the 100% NPKSZn and Farmers' Practice, respectively but also saved 12 kg N, 30 Kg P 2 O 5 , 15 kg K 2 O' 10 kg S and 2.5 Kg Zn/ha. Rhizobium inoculation with 50% NPK + 5t FYM/ha produced 6% higher yield over 50% NPK + 5t FYM/ha. Irrespective of the INM modules, soybean var JS 9305 produced 5.5% more yield as compared to JS 335.

Productivity of soybean in organic farming

A three years field experiment was conducted during the kharif season (2003-05) to compare the productivity of soybean with organic manures (poultry manure, vermicompost and cattle dung manure @ 1.5, 2.0 t/ha on dry weight basis, respectively) in comparison to recommended doses of chemical fertilizers, in the first year (2003), chemical fertilizer treatment recorded the highest seed yield and application and organic manures resulted in 7.3 to 13.3% reduction in yield. During the second year (2004), in general, the productivity of soybean was lower because of deficient rainfall (737 mm), and occurrence of moisture stress during grain filling stage. However, the productivity of soybean under organic manure application was almost similar to that of chemical fertilizer. During the third year (2005), the productivity of soybean was higher with the organic manure application compared to that under chemical fertilizers. This is especially true with the application of poultry manure, which recorded 17.5% higher yield than the chemical fertilizers.

Also, the soil organic carbon, available NPK and biological activity of soil were improved in organic manure application compared to the chemical fertilizers.

Improved land treatment effect on runoff, soil loss and nitrogen losses

Studies on broad bed and furrow (BBF) and flat-on-grade (FOG) land treatments showed that the runoff was less from BBF than from FOG land treatment. The BBF treatment recorded less ammonical and nitrate nitrogen losses through runoff than FOG. System productivity under BBF was higher than under FOG land treatment.

Soybean nodulation survey in Madhya Pradesh

Soybean nodulation surveys in farmers' fields in the fourth phase in M.P in Bhopal, Sehore, Rajgarh, Ujjain, Dewas, Indore, Dhar, Jhabua, Khargone, Khandwa and Harda districts was completed during Aug-Sept 2005. JS 335 continues to be the most widely cultivated variety; there is high usage of fertilizers, weedicides and pesticides; FYM is applied by most farmers but in moderate amounts (2t/acre) and that too after a gap of 3-4 years. Soybean nodulation is by and large good in black soils and poor in skeletal soils of western Malwa. Complete absence of nodulation was not encountered. Large majority of farmers are using or have used rhizobial cultures as well as phosphate solubilizing bacteria and their perception about its usfulness is very positive. Soybean growth was affected by a prolonged break in the monsoon during August due to water stress and diseases. Farmers' perception of soybean being no more profitable arose mostly because of low input costs which led to high profits in earlier years. However most farmers agreed that soybean is still the best bet and more remunerative and other crops and intercropping with maize fetched higher returns.

Organic and inorganic nutrient sources affect soil biological activity and pomegranate fruit quality

In pomegranate orchard, application of 11 kg vermicompost or 13 kg phosphocompost or 16.6 kg cattle dung manure (CDM) per plant or in combination of 50% CDM 50% recommended dose of fertilizer (RDF) improved the soil biological activity. The highest organic carbon (0.86%) Was recorded in cattle dung manure treatment followed by phosphocompost (0.80%), vermicompost (0.79%) and 50% CDM + 50% RDF (0.78%) treatments, whereas, in absolute control it was the lowest (0.54%). Similarly, soil enzymes such as dehydrogenase, cellulase, acid and alkaline phosphatase activity and microbial biomass C, N and P contents increased significantly in organic treatments followed by integrated nutrient management and inorganic alone and was least in absolute control. The fruit quality parameters viz; total soluble salt %, juice acidity %, Carotenoid and tannin content did not vary significantly due to application of organic, inorganic and organic + inorganic nutrient sources in the first year of the experiment.

Soil and Environmental pollution – An emerging scenario

In modern economies, various types of activity, including agriculture, industry and transportation, produce a large amount of wastes and new type of pollutants. Soil, air and water have traditionally been used as sites for disposal of all these wastes. Sustainability of soil productivity in the present scenario will encounter constraints of degraded resource base, need for higher inputs and energy use which leads to environmental degradation. It is difficult and sometimes misleading to consider soil or land without its environmental context, and concern for the soil and its use is inseparable from the one for ecology as a whole. Concerns for environmental quality in nutrient management context arise mainly from (i) pollution of ground water aquifers (ii) eutrophication of surface water bodies (iii) emission of green house gases and (iv) heavy metal entry into the food chain and consequently affecting human and animal health. In addition, the contaminants deteriorate the quality of produce vis-à-vis its marketability.

With this background, the Division of Environmental soil Science was established in the Institute in 1998. Since then the Division has made humble attempts to generate valuable information on I) Use of distillery effluents in agriculture ii) Effective utilization of sewage water for vegetable/crop production iii) Evaluation of sink capacity of soils for metal pollutants and iv) Some case studies on fluoride contamination of ground water and soil in Mandla district of Madhya Pradesh, etc. some of the findings are high lightened in this issue of newsletter.

Considerable attention has been given to study the extent of soil pollution in urban and peri-urban areas of the country with continuous use of sewage sludge and other city and industrial wastes. In most of the cases, information has been generated on the level of contamination (particularly related to heavy metals) due to use of industrial waste. However, in-depth research efforts are required keeping in view the increased concern for various issues related to soil and environmental pollution.

The future research activities of the programme, ” minimizing Environmental pollution ” includes working on different aspects of (i) Maximum loading limit of particular city and industrial waste for different soil types and climatic conditions keeping in consideration of contamination in food chain as well as in ground water (ii) Devising technologies for utilization of different biodegradable and non-hazardous industrial wastes for crop production, keeping in view effective utilization of plant nutrients which other wise pollute the environment (iii) Soil remediation technologies for cleaning of the soil from the point of view of prevention of food chain contamination (iv) Transport of nutrients and pollutants, leading to loss nutrients under different management practices, so as to attain maximum input use efficiency and reduce pollution (v) Environmental and sustainable aspects of organic farming and its role in improving soil health and quality of crop produce.

Effect of sewage water irrigation on wheat

Application of sewage water (6 irrigations, 5 cm each ) increased the mean plant height by 5%, grain yield by 11.7 q/ha as well as straw yield by 25.9 q/ha of wheat (WH- 147) compared to ground water irrigation. Grain and straw yield of wheat responded significantly to different levels of fertilization in both ground water and sewage water irrigated plots. In ground water irrigated plots, maximum wheat grain and straw yield were obtained with 50% RDF + 10 t FYM/ha which were statistically at par with 50% RDF in sewage water irrigated plots. Further, grain yield obtained (47.4 q/ha) in sewage irrigated control plots (no fertilizer) was almost equivalent to the yield obtained in groundwater irrigated plots receiving 50% RDF, indicating significant nutrient potential of the sewage water for wheat crop.

Distillery effluents on soil fertility and biochemical parameters

There was a significant improvement in fertility of the soil due to spent wash (SW) and post-methanation effluent (PME) application as indicated by organic C, available P, K, S, Zn Cu, Fe and Mn contents of the soil at the end of five cropping cycles. Further, the biochemical properties of the soil viz microbial biomass carbon, respiration and activity of dehydrogenase, alkaline phosphatase and cellulase enzymes were also increased significantly with the effluents.

Sink capacity of soils

Based on the single-surface Langmuir sorption maxima. Sink capacities of seven benchmark soil series viz Linga, kagwad, Sarol, Bajatta, Lohara, Shahzadpur and Guttapalli have been determined from the pure metal solution matrix based on chemical soil test method. In respect of the maximum (S max ) and minimum sink capacity (S min ) values, the soils followed the order:Linga>Kagwad Sarol>Bajatta>Lohara>Shazadpur>Guttapalli.

Phytoremediation of heavy metals with marigold and chrysanthemum

An experiment was conducted to study the effect of different levels of Cd (2.5,5,10,20 and 50 ppm) and Pb (10,20,50,100 and 150 ppm) on some physiological aspects in marigold and chrysanthemum. It was found that Cd and Pb did not show any inhibitory effect on seed germination even at the highest concentration. The study revealed that chrysanthemum was more susceptible than marigold to both Cd and Pb. Between the two elements, Cd was more toxic than Pb.

Effect of contaminated sewage-sludge on soil biological activity and biosorption capacity of isolated fungi

Increased levels of compost prepared from contaminated sewage-sludge decreased the Pb and Cd toxicity in terms of SMBC by about 1.2 to 1.3 fold at 20 Mg ha -1 , and 1.45 to 1.65 fold at 40 Mg ha -1 , respectively. In growth medium, the Cd concentration of 10 mg l -1 showed marked effect on growth of Aspergillus sp-2and Fusarium sp. Whereas Aspergillus sp-1and Alternaria sp. Were affected at 5 mg 1 -1 . In the case of Pb, the growth of Fusarium spand Alternaria sp. Was affected at 50 mg l-1 and the Aspergilus sp. Was affected at 25 mg 1 -1 . The Cd and Pb adsorption equation studies confirmed to the Freundlich isotherm for four fungi and was found that the bio-adsorption of Pb is relatively higher than Cd biosorption.

Mechanical harvest borne wheat residue management options evaluated

The pooled analysis of 5 years data clearly demonstrated that wheat residue incorporation or surface retention resulted in higher yields of soybean-wheat cropping system and led to an improvement in organic carbon and nutrient availability of soil compared to residue burning. Residue incorporation/retention was more effective when N was supplemented through FYM followed by poultry manure. The economic analysis of residue management options also showed that the wheat residue incorporation or surface retention was economically more profitable than residue burning. The value cost ratio (VCR) was 14.7 for residue incorporation and 3.1 for residue retention. The lower VCR for residue retention than for residue incorporation was due to more costs associated (on account of weeding) with residue retention practice.

Efficient utilization of limited available irrigation water in wheat through micro-sprinkler

When irrigation water was available up to maximum tillering stage, application of irrigation (14 cm) through sprinkler in 3 intervals, each at pre sowing (4 cm), crown root initiation (5 cm) and at maximum tillering (5 cm) and at maximum tillering (5 cm) stage registered significantly higher yield and water use efficiency of wheat than the application of same amount of water through flooding in 2 intervals (PS 8 cm + CRI 6 cm). Even for the same frequency of irrigation, application of 14 cm of irrigation through sprinkler or combination of sprinkler and flooding registered higher water use efficiency than irrigation through flooding with same amount of water.

Performance of pigeonpea under organic farming

A two-year field experiment of pigeonpea under organic farming showed that application of cattle dung manure @ 4 t/ha recorded similar crop growth, yield attributes, yield and protein content as that with chemical fertilizers @ 30 Kg N + 26 kg P/ha. Application of vermicompost or phosphocompost @ 3 t/ha resulted in identical crop growth, yield attributes and yield whereas, poultry manure @ 2 t/ha recorded the lowest crop growth and yield. Cattle dung manure recorded higher soil organic carbon, available N and K and increased dehydrogenase and phosphatase activity of soil compared to chemical fertilizers and control. Among the four varieties, ICPL – 87119 recorded higher crop growth and yield compared to Jawahar –4, BDN-2 and Aasha

Effect of organic manures on soil and fruit quality of pomegranate

Different organic sources like phospho-compost and vermicompost applied alone or combination of cattle dung manure + 50% NPK improved the chemical, biochemical and biological properties of soil over control. Similarly, the quality of fruit in terms of total soluble salts, sugar and ascorbic acid content also increased in organic, organic + inorganic and chemical fertilizer over control.

Biofertilizers improve fertiliz quality of fruit in terms of total soluble salts, sugar and ascorbic acid content also increased in organic, organic + inorganic and chemical fertilizer over control.

Biofertilizers improve fertilizer use efficiency

Research leads by the AINP on Biofertilizers-Bhubaneswar center on improving fertilizer use efficiency (FUE), were tested in three farmers fields in Dhenkanal district of Orissa in acidic sandy loams (pH 5.2-5.6). Bioinoculants (Azotobacter + Azospirillum) improved the yield of okra, tomato and brinjal by 13.5-20.0 % over farmer's practice and 8.5-14.3% over recommended dose of fertilizers (RDF). Most significantly the apparent FUE was increased by 6-15% for N, 10-22% for P, 13-28% for K and 2.7-5.0% for S. averaged together they represent an increase in the yield of 16.6 % over farmers' practices and 11.3% over RDF due to the use of bioinoculants. Average increase in FUE due to inoculants was 11.3% in the case of N, 14.2 % in the case of P,20 % in the case of K and 3.6 % in the case of S.

Effect of long-term fertilizer and manure application on P-fractionation in Alfisols of Bangalore

Long-term fertilizer experiment is being continued for the last 14 years with finger millet-maize cropping system in Alfisols at Bangalore. The total P content of soil over the years has increased considerably due to most of the treatments, except 100% N and control, the two treatments devoid of P. Among the various fractions of P, the order of their occurrence is Fe-P>Ca- P> saloid-P. The quantity of saloid-P ranged from 3.82 mg Kg -1 in control to 16.24 mg kg -1 100% NPK+FYM, while that of Al-P varied from78.2 mg kg -1 in control to 163 mg kg -1 in 100% NPK+FYM. The Fe-P content ranged from 145.2 mg kg -1 in control to 200 mg kg -1 in 100% NPK+FYM in the soil. The quantity of Ca-P was relatively higher in plots treated with lime (100% NPK+lime) and Control.

Balanced fertilization for improving the productivity of wheat

Based on the six on – farm trails conducted in farmer's fields in M.P., it was found that the balanced application of N, P,K,S and Zn at recommended rates (120gk N, 60 kg P 2 O 5 , 20 kg K 2 O, 20 kg S and 5 Kg Zn/ha) increased the wheat grain yield by 15-24% as compared to farmers' practice. The results of these trials clearly indicated that higher wheat grain yields could be sustained by encouraging farmers to correct N, P, S and Zn deficiencies by adopting balanced nutrient management practices. Response of wheat to NPKSZn in farmers' field.