INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 4, No 1, Copyright by the authors - Licensee IPA- Under Creative Commons license 3.

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1 INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 4, No 1, 2013 Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN Impacts of conventional, sustainable and organic farming system on soil microbial population and soil Department of Ecology and Environmental Sciences, Pondicherry University, Puducherry saintsudha@gmail.com doi: /ijes ABSTRACT This research under field experimental conditions in agro ecosystem investigated the effects of different farm management practices (Conventional, Sustainable and Organic) on soil biochemical and microbial populations including soil physical, chemical and biological factors. Three composite soil samples were collected from each of the 10 farms from the fall of January 2012 to May Composite samples were done by sampling approximately 15kg of soil from each of the three farming systems (Conventional, Sustainable and Organic) using augur at 0-15cm cm depth. Soils from organic farms had improved soil chemical parameters (total elements and plant available nutrients) and higher level of total N, total P, total K, total Ca, total Mg,total Fe, total Cu, organic C, NH 4 -N, NO 3 -N, extractable P, SO 4 -S and soluble Na. In addition, β- glucosidase activities, soil respiration and microbial population (bacteria, fungi, actinimycetes, beijerinckia, azotobacter, rhizobium, bacillus and phosphobacteria) were higher in soils from organic farming than sustainable and conventional farms. This study shows organic farming was improving the soil health and plant available nutrients without any inorganic external inputs. Key words: Conventional, Sustainable and Organic farming, soil properties, β- glucosidase activities and soil microbial population. 1. Introduction Physical, chemical, biological and biochemical properties are involved in soil functioning, biological and biochemical properties tend to react quickly to changes in the external environment, and are therefore generally used in assessing soil quality (Nannipieri et al., 1990; Vanhala and Ahtiainen, 1994). The biogeochemical process through which microbial conversion of complex organic compounds into simple inorganic compounds & their constituent elements is known as mineralization. Soil microbes play vital role in the biochemical cycling of elements in the biosphere where the essential elements (C, P, S, N & Iron etc.) undergo chemical transformations. Through the process of mineralization organic carbon, nitrogen, phosphorus, Sulphur, Iron etc. are made available for reuse by plants. Soil microorganisms, such as bacteria and fungi, control the functioning of ecosystem through decomposition and nutrient cycling which in turn may serve as indicators of land-use change and ecosystem health (Doran and Zeiss 2000; Waldrop et al., 2000; Yao et al., 2000). The general biochemical parameters most commonly used to estimate the changes in soil quality include carbon associated with microbial biomass, dehydrogenase activity and N mineralization capacity, while the most commonly used specific parameters include ß- glucosidase and urease activities (Gil-Sotres et al., 2005). Received on July 2013 Published on July

2 Agriculture intensification and anthropogenic activities affect the soil quality at all levels, including the structure and function of soil microbial communities. Farming management systems alter the soil microbial community structure through changes in carbon availability, ph (Cookson et al., 2007), nutrient availability or other chemical parameters. During past few years, conventionally managed agricultural system has used synthetic fertilizer and pesticides to improve crop productivity. This intensive use of agrochemicals will definitely reduce the biodiversity, increase irreversible erosion of soil and reduce soil organic matter (Dick, 1992: Schiavon et al., 1995).Organic Farming System does not use synthetic chemical amendments and may be more sustainable in the long-term than conventional farming systems (CFS). Organic farming has improved food quality and safety, because the nutrient supply and pest control methods are largely depend on biological processes in organic systems (Gewin, 2004). Carine Floch et al., (2009) also reported that the soil enzyme activities and microbial population are higher in organically managed farming when compared to the conventional and integrated managed farming.the objective of the present study is to evaluate the impacts of different farming systems (organic, sustainable and conventional) on soil microbial population and soil biochemical properties. 2. Study area Pondicherry is located along the Coramandel coast of peninsular India with the geographical coordinates N, E and N and E covering an area of 480 km. The mean annual rainfall of the study area is about mm.The mean number of annual rainy days is 55; the mean monthly temperature ranges between 21 0 C and 30 0 C in the study area. This region gets more rainfall during north east monsoon. Humidity is also high as the area is nearer to the coastal region. The study site, Sorriyankuppam is located 25 km away from the town which is nearer to Cuddalore district and the other site is Kalapet, located very near to Pondicherry University. In these two study sites the texture of soils is sandy loam. Rice, Groundnut and Sugarcane are most predominant crops. During the study period groundnut is the most predominant crop in the study fields. Soils from 10 farms in organic, sustainable and conventional farming were sampled from January 2012 to April Three farms were certified organic farming and any synthetic fertilizer, pesticides and herbicides were not used. They are located in Sorriyankuppam (organic-1, organic-2) and in Nallavadu (organic -3). The other three farms are classified as sustainable, which means that synthetic fertilizers were used but synthetic pesticides were not used. These farms were located in Sorriyankuppam (sustainable-1, 2 &3). Remaining three conventional farms were sampled. In these farms monoculture, synthetic fertilizer and pesticides were used. These farms are located in Kalapet (conventional 1 and 3) and Sorriyankuppam (conventional 2) remaining is barren land (non cropping land) to be treated as control (Bo liu et al., 2007). Three composite soil samples were collected from each of the 10 farms from the fall of January 2012 to May2012. Composite samples were done by sampling approximately 15kg of soil from each of the three farming system using augur at 0-15cm depth. Bulked samples were kept separately according to the location within each field for replication maintenance. Composite soil samples were stored in deep freezer to control microbial and enzyme activities for soil dilution, plating and biological analysis. The soils were transferred to storage room and were stored at 4 0 c until the time of analysis. Microbial and enzyme analysis were done within 48 to 72 hrs. 29

3 3. Data analysis All the experimental data were analyzed using SPSS 16. The variations among farming management, soil biological and microbial population were analyzed by one way ANOVA test. Figure 1: study area (source: travelinfo.com) 3. Methodology 3.1 Physical properties Soil moisture content was determined by gravimetric method (Hesse 1971). Soil Particle density and volume of soil particle were determined by volumetric flask method (Bashour and sayegh 2007). Soil texture was determined by feel method (Thien 1979). 3.2 Chemical properties Organic carbon was determined by Chromic acid wet digestion (Walkley and Black 1934). Total nitrogen (N) was determined by Macro-Kjeldahl digestion (Piper 1966). Ammonium nitrogen (NH N) was determined by Nitroprusside catalyst method (Bashour and Sayegh 2007). Nitrate nitrogen (NO 3 - N) was determined by Chromotrophic acid spectrophotometric method (Sims and Jakson 1971). Extractable phosphorus was determined by modified Olsen method (Olsen and Sommers 1982). Available potassium (K + ), soluble calcium (Ca) and soluble sodium (Na) were determined by Flame photometry (Stanford and English 1949). Sulphate (SO 4 ) amount was determined by Turbidimetric method (Tandon 1991). Total phosphorus, total potassium, elements such as Silicon (Si), Sulphur(S), Calcium (Ca), Magnesium(Mg), Sodium(Na), Iron(Ir), Manganese (Mn) and Copper (Cu) were analyzed by WD XRF (Becckhoff et al., 2006). 3.3 Soil biological properties 30

4 Soil respiration was determined by CO 2 during the incubation of soil in closed system, CO 2 is trapped in NaOH (0.05 M) solution, then the trapped solution was titrated with HCl solution (0.05 M)which was expressed as CO 2 (mg).100 g of soil -1 day -1 (Isermeyer 1952). β glucosidase activity was determined by para nitrophenol release after the incubation of soil with para nitrophenyl glucoside solution for 1 hr. at 37 0 C (Tabatabai 1982; Eivazi and Tabatabai 1988). The enzyme activity was expressed as p-nitrophenol µg g -1 dwt h Soil microbes The numbers of bacteria, fungi and actinomycetes were determined by serial dilution plate count method (Germida 1993). In brief, soil dilution (10-1 ) prepared by 10 g of soil sample was transferred into 100 ml sterile water and mixing the solution for few seconds. Then 1 ml of dilution was transferred into 9 ml of sterile water test tube (10-2 ) and subsequent soil serial dilution were prepared up to Spread 0.2 ml of diluted soil suspension from each serial dilution (10-6 for Bacteria, 10-4 for fungi, 10-5 for actinomyces) on different selective media (Nutrient agar medium for bacteria, Beijierinckia medium for Beijerinckia spp., Azotobacter agar medium for Azotobacter spp., Pikovskaya s agar medium for Phosphate solubilizing soil microbes, Bacillus medium for Bacillus spp, Rhizobium medium for Rhizobium spp, Rosebengal agar medium for fungi and Ken kinght s medium for actinomyces) and the incubated plates were incubated at temperatures between 25 o C and 30 o C at the duration of 5-7 days for fungi, 1-2 days for bacteria, days for acinomycetes respectively. The colony forming units are expressed as CFU 10 n g of soil on a moisture basis. 4. Results Table 1: Soil physical properties in different farming systems Soil physical properties Conventional Sustainable Organic Control Moisture content (%) Bulk density (g/cm 3 ) Volume of the soil particle (cm 3 ) Particle density (g/cm 3 ) Soil physical properties Based on the experiment, the highest moisture content was recorded as11.4% in control. Then the organic farming system contains 8% and the sustainable farming contains 4.2% but the conventional farming is approximately equal to the sustainable farming system. The bulk density of the soil recorded was 1.5 g/cm 3 in control and the organic farming system was 1.4 g/cm 3. Then the sustainable farming system contains 1.4 g/cm 3 and the conventional farming system possess 1.3 g/cm 3. Therefore, the conventional system has the lowest bulk density. Volume of the soil particle has the highest value in control level and the organic and sustainable farming systems are almost equal. But the lowest volume of the soil particle was recorded in conventional farming. Control has the highest particle density, lowest value was recorded in sustainable and organic farming systems 2.7% (Table 1). 4.2 Soil physiochemical properties 31

5 Based on the soil analysis the highest ph value in sustainable farming was 7.4. Then the organic farming was The lowest ph value was 6 in control. From the experiment, the electrical conductivity in control was 0.4(mS. cm -1 ). Organic farming system was 0.3(mS. cm -1 ), then the sustainable farming system was 0.2(mS. cm -1 ) and the EC for the conventional farming system was 0.15(mS. cm -1 ). (Table2). Table 2: Soil physio-chemical properties in different farming systems Soil physio-chemical properties Conventional Sustainable Organic Control ph EC (ms. Cm -1 ) Table 3: Primary and secondary Macronutrients levels in different farming systems. Primary Macronutrients(g/kg) Conventional Sustainable Organic Control P-value Total nitrogen 2.2 ± ± ± ± * Total phosphorous 1.2 ± ± ± ± Total potassium 22.1 ± ± ± ± * Secondary Macronutrient (g/kg) Total sulphur(s) 6.1 ± ± ± ± Total calcium(ca) 13.6 ± ± ±1.42 Total sodium(na) 4.7 ± ± ±0.65 Total silicon(si) 84.2 ± ± ± ± ± ± * * Total magnesium(mg) 20.7 ± ± ± Primary macronutrients 47.1 ± *significantly different at p=0.05, **significantly different at p=0.01 From the experiment, the amount of total nitrogen was higher in organic farming and the control level is 2.4(g/kg). Sustainable farming had 1.8(g/kg), conventional farming had 2.2(g/kg). The total amount of phosphorus was higher in organic farming compared to the other farming systems. Similarly the amount of potassium level was higher in organic farm but the control had 34.4(g/kg) sustainable farming had 36(g/kg) and conventional farming had 22.1(g/kg) (Table 3). 32

6 4.4 Secondary macronutrients The total amount of Sulphur was higher in sustainable farm than the other farming. Based on the experiment, the amount of total calcium was higher in organic system. Compared to the other systems, conventional had lower value. Sustainable farm had 28.2(g/kg) and the control level 33.4(g/kg). From the experiment, highest amount of total sodium was recorded in organic farm. Conventional farm had lower value and the sustainable farm had 10.6(g/kg), the control had 13.7(g/kg). Total amount of silicon was higher in conventional farm and organic farming system had the lowest value. Sustainable farm contained 78.9(g/kg) and the control had 78(g/kg). From the experiment it was concluded that the total magnesium was higher in organic farm system. Sustainable farm had 36.1(g/kg) and the lowest value was found in conventional farming (Table3). 4.5 Micronutrients Based on the experiment, the highest amount of iron (Fe) was found in organic farming and the lowest was found in conventional farming system. Control had 33.4(g/kg) and the sustainable farm had 36.2(g/kg). From the analysis, control had the highest manganese value and the lowest value was in conventional farm. Organic farm contained 1.2(g/kg) and the sustainable farm had 1.1(g/kg), Copper was found higher in organic farming (14 mg/kg) and the lowest value had occurred in conventional (9.3 mg/kg), control had 12(mg/kg), sustainable had 10.7(mg/kg). Conventional had the highest Zinc value (39.3 mg/kg), lowest value was found in sustainable (33.7 mg/kg). Organic had 34.7(mg/kg) and control had 36(mg/kg) of zinc value. The organic had the highest Molybdenum value and control had the lowest value, conventional and sustainable had 1.3(mg/kg). Cobalt was found higher in organic 7.3(mg/kg), the lowest in control (4 mg/kg), sustainable had 6.3(mg/kg) and conventional had 4.7(mg/kg).Vanadium was higher in organic (49.3 g/kg) and lower in sustainable (34.7 mg/kg), conventional had 37(mg/kg), control has 36(mg/kg) (Table 4). 4.6 Available nutrients Based on the analysis Organic carbon was higher in organic farm 8.63(g/kg) and lowest was occurred in conventional (6.40 g/kg), sustainable had 7.15(g/kg), and control had 8.40(g/kg). Ammonia nitrogen was higher in organic farm (0.86 g/kg), and lesser in control (0.65 g/kg), conventional had 0.79(g/kg), sustainable had 0.65(g/kg). Nitrate- nitrogen was higher in organic (2.26 g/kg), lower in sustainable had 0.93(g/kg), control had 1.0(g/kg) and conventional had 1.17(g/kg). Extractable phosphorus was higher in organic (0.61g/kg) and lower was occurred in control (0.27 g/kg). Sustainable had 0.39(g/kg) and conventional had 0.28(g/kg). Available potassium was higher in control and conventional had 0.27(g/kg), lowest was occurred in organic 0.25(g/kg), sustainable had 0.26(g/kg). Available sulphate was high in organic 0.91(g/kg), low in conventional 0.54(g/kg), sustainable had 0.63(g/kg) and control had 0.66(g/kg). Soluble calcium highly occurred in sustainable 12.68(mg/kg), lowest value in conventional (9.02 mg/kg), organic had 12.01(mg/kg) and control had 10.40(mg/kg). Soluble sodium was high in organic 0.57(g/kg), low in control 0.51(g/kg), conventional had 0.53(g/kg) and sustainable had 0.51(g/kg) (Table 5) Micronutrients Table 4: Micronutrients levels in different farming systems Conventional Sustainable Organic Control P-value Iron(Fe) (g/kg) 29.6 ± ± 56.8 ±

7 ±1.04 Manganese(Mn) (g/kg) 0.6 ± ± ± ± * Copper(Cu) (mg/kg) 9.3 ± ± ± ± Zinc(Zn) (mg/kg) 39.3 ± ± ± ± Molybdenum(Mo) (mg/kg) 1.3 ± ± ± ± Cobalt(Co) (mg/kg) 4.7 ± ± ± ± Vanadium(V) ± ± ±4.9 (mg/kg) ± *significantly different at p=0.05, **significantly different at p=0.01 Table 5: Available nutrients in different farming systems Available nutrients Conventional Sustainable Organic Control P-value Organic carbon (g/kg) 6.40 ± ± ± ± * NH4+-N (g/kg) 0.79 ± ± ± ± NO3 -N (g/kg) 1.17 ± ± ± ± ** Extractable Phosphorus (g/kg) Available Potassium (g/kg) 0.28 ± ± ± ± * 0.27 ± ± ± ± SO 4 S (g/kg) 0.54 ± ± ± ± * soluble Calcium(mg/Kg) 9.02 ± ± ± ± soluble Sodium (g/kg) 0.53 ± ± ± ± *significantly different at p=0.05, **significantly different at p= Soil biological parameters Based on the experiment organic system consists of higher β-glucosidase activity and the control had 37.2 (mg p-np g -1 soil h -1 ) and conventional farming system had 34.1(mg p- Nitrophenol g -1 soil h -1 ) and the lowest β-glucosidase value had appeared in sustainable farming system (Figure 2a). Figure 2: Effects of different farming systems on β- glucocidase activities and soil respiration. Error bars represent the standard error of mean. ( a ) symbol indicates significantly different at p=0.05 ( b ) symbol indicates significantly different at p=

8 From the experiment the soil respiration was higher in organic farming system and sustainable farm had 3.7(CO2 (mg).100g of soil -1 day -1 ) and conventional farm had 3.5 (CO2 (mg).100g of soil -1 day -1 ), the lowest value of soil respiration was identified in control (Figure.ure.2b). Figure 3: Effects of different farming system on soil bacterial, fungi and actinomycetes population. Error bars represent the standard error of mean. ( a ) symbol indicates significantly different at p=0.05 ( b ) symbol indicates significantly different at p= Microbial analysis The experiment on soil microbial analysis had shown that the bacterial population was higher in the organic farming and the sustainable contained 24.3(CFU g ) and the control had 23(CFU g ) but the lowest bacterial population was recorded in conventional farm system (Figure.ure 3a). Microbial analysis of fungal population was recorded higher in organic farming and sustainable farm had 29.7(CFU g ), control had 24(CFU g ) but the lowest fungal population had occurred in conventional farm (Figure.ure 3b). Microbial analysis of actinomycetes was higher in organic farming system compared with other framing system. Sustainable had 24 (CFU g ) and the conventional farm has 26.3(CFU g ). The lowest actinomycetes population had occurred in control (2 CFU g ) (Figure.ure 3c). From the experiment it was concluded that the population of Beijerinckia was higher in organic farm and the control had 1(CFU g ). Conventional and sustainable farming had equal amount of Beijerinckia population (Figure.ure 4a). Based on the microbial analysis the azotobacter population was higher in organic farm and the lower population in control. The sustainable farm had 24.7 (CFU g ) and conventional had 26.3(CFU g ) (Figure.ure 4b). Rhizobium population was higher in organic farm and 35

9 the lowest one occurred in sustainable farm. The control system had 15(CFU g ) and the conventional farm had 13.3(CFU g ) (Figure.ure 4c). Based on the microbial analysis bacillus population 9.7 (CFU g ) had occurred in organic farms, Conventional farm had 5 (CFU g ). Bacillus population in sustainable was 4.7(CFU g ). The lowest value of bacillus population had occurred in control (Figure.ure 4d). This microbial analysis shows that the organic farm had higher phosphobacteria population. The conventional farm had 4.7(CFU g ) and the sustainable had 4(CFU g ). The lowest population of phosphobacteria had occurred in control (Figure.ure4e). Figure 4: Effects of different farming system on soil Beijerinckia, Azotobacter, Rhizobium, Bacillus and Phosphobacteria populations. Error bars represent the standard error of mean. ( a ) symbol indicates significantly different at p=0.05 ( b ) symbol indicates significantly different at p=

10 4.9 Discussion Based on the study, organic farms had improved soil chemical factors compared to conventional and sustainable farming system (Drinkwater et al., 1995: Reganold et al., 2001). The levels of total N, total P, total K, total Calcium, total Si and total Mg were higher in organic farming and show significant variations. Other conventional and sustainable farming systems were less in the above mentioned soil chemical factors. These findings agree with several research studies (Bo Liu et al., 2007, Bending et al., 2000, Kennedy and smith 1995). We found that soil ph was significantly different in organic farming, sustainable farming, conventional farming and control. The ph value was higher in sustainable rather than organic farming, conventional farming and control. However other studies had shown that ph was not significantly different between organic carbon and conventional farm management (Clark et al., 1998). The most plant available soil nutrients were showed significant variation in our study. Organic carbon, nitrate nitrogen, extractable P, extractable Na and sulphate S were higher in organic farming compared to sustainable and conventional farming. These findings agree with Hopkins DW and Gregorich EG (2005) studies. NH 3 -N and soluble Ca showed no variation in these three farming systems. β-glucosidase activity was significantly higher in organic farming than the conventional and sustainable farming. This enzyme has been detected in micro-organisms, animals and plants. But the presence of this enzyme in Toluene treated soil indicates that it could be free extra cellular enzyme which is observed on the surface of the soil clay particles (Hayano & Katami, 1977). These findings also agreed with some other research findings (Acosta Martinez & Tabatabi, 2000; Madejon et al., 2001). These enzyme properties can be used as a good biochemical indicator for measuring ecological changes resulting from soil acidification. Soil respiration was significantly higher in organic farming compared to the other two farms. This indicates a higher soil microbial activity due to the addition of liable organic matter to the soil (SafFigure.na, P.G et al., 1989; Ademir S. F et al., 2009) because of the stimulation of heterotrophic micro-organisms. Other comparisons of the conventional and organic farming systems have also reported an increase in the soil microbial respiration under organic management (Glovwer, J.D. et al. 2000; Hel Weg.A, 1988). Additional higher soil respiration was found in the organic farming system which show higher microbial activities in the soil. Soil microbial population shows significant variation at P<0.05 interval. Similarly Actinomycedes is significant at P<0.001 interval. Organic farming shows higher bacterial, fungul, actinomycetes, Beijerinckia, Azotobacter, rhizobium, bacillus and phosphobacteria population compared to sustainable and conventional farming systems. The application of animal manures and compost increase the activity and diversity of the microbial community (Bolton et al., 1985; Hassink 1995). Such enhancement to the soil microbial community might have benefits for plant productivity through increased nutrient cycling rate (Gajda et al., 2000). 5. Conclusion From the above study it is concluded that the different farming practices have a great impact on soil biochemical properties and microbial populations. The study indicates that plant available nutrients are higher in soil from organic farming systems compared to conventional 37

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