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Comparative Performance of Three Carrier BasedBlue Green Algal Biofertilizers for Sustainable RiceCultivationDolly Wattal Dhar a , Radha Prasanna b & B. V. Singh ca Centre for Conservation and Utilisation of Blue Green Algae (CCUBGA), Indian AgriculturalResearch Institute (IARI) , New Delhi-110012, India E-mail:b Centre for Conservation and Utilisation of Blue Green Algae (CCUBGA), Indian AgriculturalResearch Institute (IARI) , New Delhi-110012, Indiac Centre for Conservation and Utilisation of Blue Green Algae (CCUBGA), Indian AgriculturalResearch Institute (IARI) , New Delhi-110012, India E-mail:Published online: 21 Sep 2008.

To cite this article: Dolly Wattal Dhar , Radha Prasanna & B. V. Singh (2007) Comparative Performance of Three Carrier BasedBlue Green Algal Biofertilizers for Sustainable Rice Cultivation, Journal of Sustainable Agriculture, 30:2, 41-50, DOI: 10.1300/J064v30n02_06

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Comparative Performanceof Three Carrier Based Blue GreenAlgal Biofertilizers for Sustainable

Rice Cultivation

Dolly Wattal DharRadha Prasanna

B. V. Singh

ABSTRACT. Nitrogen fixing cyanobacteria or blue green algae areecologically significant inputs in rice cultivation in the tropics. Fieldexperiments were conducted to compare the efficiency of two newlydeveloped carrier based blue green algal (BGA) biofertilizers (wheatstraw and multani mitti), with the traditional soil based BGA biofertilizer,on the grain yield of rice for a period of three years. Treatments includedfive levels of nitrogenous fertilizer urea and their interaction with thethree types of BGA biofertilizers, on the grain yield of rice variety ‘PNR381’. Highest grain yields were obtained with the application of multanimitti based biofertilizer along with 90 kg N/ha, although maximum per-cent increase in yield over control (37.97%), when applied along with60 kg N/ha. The straw based and soil based biofertilizer treatmentsshowed highest yields when supplemented with 90 and 120 kg N/ha,

Dolly Wattal Dhar (E-mail: wattaldhar@yahoo.com), Radha Prasanna, and B. V.Singh (E-mail: bvsigh10@yahoo.co.in) are affiliated with Centre for Conservation andUtilisation of Blue Green Algae (CCUBGA), Indian Agricultural Research Institute(IARI), New Delhi-110012, India.

Address correspondence to: Radha Prasanna at the above address (E-mail: radhapr@gmail.com).

The authors are grateful to Director IARI, New Delhi, for the financial help andfacilities provided.

Journal of Sustainable Agriculture, Vol. 30(2) 2007Available online at http://jsa.haworthpress.com

© 2007 by The Haworth Press, Inc. All rights reserved.doi:10.1300/J064v30n02_06 41

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respectively. This investigation clearly emphasizes the need for supple-menting chemical fertilizers with the newly developed BGA biofertilizersin rice cultivation for maximizing crop productivity, reducing inputs ofchemical fertilizers and sustaining soil fertility. doi:10.1300/J064v30n02_06 [Article copies available for a fee from The Haworth DocumentDelivery Service: 1-800-HAWORTH. E-mail address: <docdelivery@haworthpress.com> Website: <http://www.HaworthPress.com> © 2007 by TheHaworth Press, Inc. All rights reserved.]

KEYWORDS. BGA, biofertilizers, carrier, grain yield, multani mitti,straw

INTRODUCTION

With the growing realization that chemical based agriculture is un-sustainable and is slowly leading to ecological imbalance, the latter partof the last century witnessed the emergence of the concept of “organicagriculture” advocating minimum use of chemical fertilizer and in-creasing dependence on biological inputs like compost, farm yardmanure, green manure and biofertilizers. Such inputs are sustainable,effective, cheap, easily manageable, fuel energy independent, ecofriendly,and improve the nutrient status and health of the soil. Amongst the arrayof biofertilizers developed for different crops, cyanobacteria popularlyknown as blue green algae, constitute the most important inputs inrice cultivation. They form an inexpensive farm grown input whichhelps in better crop nutrient management, while working in harmonywith nature. Under the water logged conditions of rice fields, bluegreen algae are potential sources of biologically fixed nitrogen (Rogerand Kulasooriya, 1980). The ecological and agricultural importanceof these organisms depend upon the ability of certain species to carryout both photosynthesis nitrogen fixation and proliferation in diversehabitats.

Field experiments carried out over the last two decades under theAll India Coordinated Research trials, using rural oriented blue green algal(BGA) bioferitlizers developed at Indian Agricultural Research Institute(IARI), New Delhi, have revealed that BGA can provide 25-30 kg N/ha/season (Venkataraman, 1981) and an increase of up to 30% of the paddycrop yield (Venkataraman, 1981; Goyal et al., 1997). Moreover, BGAalso (1) add organic matter, (2) synthesize and liberate amino acids,vitamins and auxins, (3) reduce oxidizable matter content of the soil,

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(4) provide oxygen to the submerged rhizosphere, (5) ameliorate salinityand buffer the pH, (6) solubilize phosphates, and (7) increase the fertilizeruse efficiency of crop plants (Mandal et al., 1999). The water loggedconditions, high humidity, temperature, and shade provided by the paddycrop canopy afford optimal conditions of rapid multiplication for cyano-bacteria (Whitton, 2000).

Based on the natural ecology of these photolithotrophic diazotrophs,a cheap and easily adaptable method for the production of soil basedalgal inoculum, involving very little capital investment was developedfor the benefit of small and marginal farmers (Venkataraman, 1981).This technology was introduced as a package of practices in number ofIndian States. Despite its simplicity, the technology did not becomepopular with the farmers due to the problem of aerial and soil based con-tamination, including insects and predators that ate the desired algae.Also, the fluctuating titre values during its open air production necessi-tated the requirement of a large quantity of biofertilizer per unit area ofcrop (10 kg/ha). In order to reduce the volume of the inoculum per unitarea, besides addressing other problems, efforts were made to developnew and economically feasible protocols for production of qualityinoculum under semi-controlled conditions. The production technologyhas now been substantially improved with the introduction of new andcheap carrier materials such as multani mitti (Fuller’s earth) and wheatstraw that support higher algal load with longer shelf life, thus consider-ably reducing the quantity of inoculum per unit area (Kaushik, 1998;Goyal et al., 1997; Prasanna et al., 1998). Also, production in controlledconditions at polyhouses considerably reduced contamination (Prasannaand Kaushik, 2000).

The present communication was designed to evaluate and comparethe efficiency of newly developed BGA biofertilizers and evolve astrategy of integrated nutrient supply with judicious combination ofchemical fertilizers, biofertilizers and cultivation practices.

MATERIALS AND METHODS

Field Trial Sites and Design

A three year field trial was conducted during kharif season (June-October) at the IARI farm, located at New Delhi, India, with ricecultivar ‘PNR 381.’ The field was initially prepared by discing anduniform puddling–with a bullock drawn wet land puddler–and levelled.

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The treatments comprised five levels of nitrogenous fertilizers in theform of urea (0, 30, 60, 90 and 120 kg N/ha) and their interactions withthree types of carrier based BGA biofertilizers (soil based, multani mittiand straw).

The BGA biofertilizers containing a mixture of heterocystous, nitrogenfixing BGA–Anabaena variabilis, Tolypothrix tenuis, Nostoc muscorum,Aulosira fertilissima and two non-heterocystous forms–Plectonema andLyngbya were used (Venkataraman, 1981). Three types of carrier basedBGA biofertilizers were prepared in the polyhouse using a cheapergrowth medium and mixing with carrier material in optimal ratios, fol-lowing the protocols outlined by Prasanna et al. (1998). In order to min-imize the competition between the different BGA strains and to allowtheir maximal growth, the cultures were grown individually and equalamounts of each culture were mixed with carrier material and sun dried.The BGA biofertilizer produced by this method has been observed tocontain 105-106 propagules gm�1 carrier material, thereby, reducingthe amount of biofertilizer application rate. These were applied oneweek after transplanting by broadcasting over the standing water. Thisimproved product can be stored for 1-2 years without loss in viability(Pabbi et al., 2000). Soil based BGA biofertilizer was applied at the rateof 10 kg/ha while straw based and multani mitti based biofertilizerswere applied at the rate of 2 and 5 kg/ha, respectively. All the plotsreceived a uniform basal dressing of 60 kg/ha P205 as Single SuperPhosphate (16% P2O5) and 40 kg/ha K2O applied as muriate of Potash(60% K2O), respectively.

The experiment was performed in a randomized block design withthree replications and the plot size was 12 sq meters. All the recom-mended cultural practices for raising the rice crop were utilized.

Analyses of Soil Physico-Chemicaland Biological Characteristics

Soil samples were taken at regular intervals to study the algal popula-tions and other physicochemical characteristics. Three sub-samplesof soil were collected from each replicate plot and composite sampleswere made. After removal of visible plant debris, soil was sievedthrough a 2 mm mesh screen. Samples from control plots and inoculatedplots were analysed separately. Field moist samples were used for thedetermination of soil pH using a pH meter (soil:water::1:2). Total organiccarbon was analysed following dichromate oxidation and back titration

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of unused dichromate (Walkley and Black, 1934). Total nitrogen wasestimated by the micro Kjeldahl digestion method (Jackson, 1973).

Soil samples were taken out at regular intervals to identify the BGApopulations, using the keys of Desikachary (1959).

Measurement of Grain Yields

The yield parameters, in terms of grain yields were recorded at thetime of harvest.

Statistical Analysis

The triplicate sets of data for the various parameters evaluated weresubjected to ANOVA (Analysis of Variance) in accordance with theexperimental design (Completely Randomized Design) using MSTAT-Cstatistical package to quantify and evaluate the source of variation, andCD (Critical Differences) values were calculated. The significance ofthe different carrier based BGA biofertilizers and nitrogen levels werecalculated to determine the most optimal combination for highest grainyields.

RESULTS AND DISCUSSION

Rice yields are known to be sustained in certain regions of the world,especially in the tropics, at a moderate level of production of 2 t/ha, evenwhen no fertilizers are used, and this led researchers to speculateregarding the role of nitrogen fixation by BGA in the maintenance ofsoil fertility. De (1939) was among the earliest researchers who recog-nized the potential of these organisms in the maintenance of paddy fieldsoil fertility. In later years, a number of reports on increase in soil fertil-ity due to BGA inoculations were published (Singh 1961; Sankaram,1977; Venkataraman, 1975, 1979, 1992; Roger and Kulasooriya 1980;Yanni, 1992). The present investigation was undertaken to evaluatethe interactive effect of different carrier based BGA biofertilizers anddifferent levels of fertilizer nitrogen on grain yield of rice cultivar‘PNR 381’.

Effect of algalization on grain yield under field conditions has beenreported from China, Egypt, Japan, Philippines, and India (Singh, 1961;Venkataraman, 1975, 1979, 1981). An average relative increase in grainyield over the control was 28% with non-nitrogen fertilizers and 32%

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with nitrogen fertilizers (Relwani and Subrahmanyan, 1963; Sankaramet al., 1966). The beneficial effects of algalization have also been attrib-uted to growth promoting substances produced by BGA or due to tem-porary immobilization of added N, followed by slow release of algaldecomposition, permitting efficient crop N utilization (Venkataramanand Neelakantan, 1967; Misra and Kaushik, 1989). However, theseindividual effects are not separable in most instances (Singh et al., 1988;Roger and Ladha, 1992).

Algalization in the presence of recommended levels of nitrogenousfertilizers resulted in significantly higher yields in comparison to un-inoculated treatments (Table 1). The application of BGA biofertilizersled to a definite increase in grain yield at all levels of fertilizer nitrogen,however, significant differences were not observed. Highest grain yields

46 JOURNAL OF SUSTAINABLE AGRICULTURE

TABLE 1. Influence of nitrogenous fertilizers (@N0–0 kg Nha�1, N30–30 kgNha�1, N60–60 kg Nha�1, N90–90 kg Nha�1, N120–120 kg Nha�1) and differentcarrier based (MMB–Multani mitti or Fuller's earth, STB–Straw, SOB–Soil) BGAbiofertilizers on the average grain yields of rice.

Treatments Grain yield (q/ha) Percent increase over respectivefertilizer level control

N0 31.66 –N0 � MMB 40.86 29.06N0 � STB 30.60 –N0 � SOB 35.36 11.69N30 34.53 –N30 � MMB 43.66 26.44N30 � STB 41.53 20.27N30 � SOB 40.20 16.42N60 38.00 –N60 � MMB 52.43 37.97N60 � STB 49.60 30.53N60 � SOB 45.70 20.26N90 42.00 –N90 � MMB 54.13 28.88N90 � STB 53.06 26.33N90 � SOB 48.80 16.19N120 45.40 –N120 � MMB 53.06 16.87N120 � STB 49.26 8.50N120 � SOB 53.33 17.47CD (P�0.05) (n�3) NS –

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were obtained with 90 kg N/ha for multani mitti based (28.8% over N90control) followed by soil based biofertilizer along with 120 kg N/hashowing 17.47% increase in yield over N12O control (Table 1). The aver-age yield increase was 7.5% over control (uninoculated) treatment, anduse of all the three carrier based fertilizers brought about a 16 to 38%increase over the respective uninoculated controls, when applied alongwith 30 to 90 kg N/ha. These observations prompted us to evaluate theeffect of different levels of fertilizer N and the three carrier based BGAbiofertilizers on grain yields.

Significant differences were observed on studying the independentinfluence of the three carrier based BGA biofertilizers and different lev-els of fertilizer nitrogen on the grain yield of rice (Table 2). A signifi-cant enhancement in grain yield was recorded with the increase in thelevels of fertilizer nitrogen. Comparison of grain yields using differentcarrier based biofertilizers vis-à-vis control revealed that multani mittibased biofertilizer gave the highest yields (48.83 q/ha), while the strawand soil based biofertilizer exhibited yields of 46.01 q/ha and 44.68 q/ha,respectively, although these are not statistically significant.

Since the blue green algae used for inoculation carry out both photo-synthesis and nitrogen fixation; their abundant growth in the soil influ-enced the physical and chemical properties of soil. Continued applicationof chemical fertilizers, over long periods is known to bring about drasticchanges in soil properties. However, integrated application of BGAbiofertilizers and chemical fertilizers helped to maintain the pH and ECof the soils (data not shown). The mean nitrogen content of the soilincreased from 1.6 to 2.9% N (data not shown) as a result of biofertilizerinoculation which is consistent with the earlier reports (Roger and

Research, Reviews, Practices, Policy and Technology 47

TABLE 2. Effect of levels of nitrogenous fertilizers (@ N0–0 kg Nha�1, N30–30 kgNha�1, N60–60 kg Nha�1, N90–90 kg Nha�1, N120–120 kg Nha�1) and differentcarrier based (MMB–Multani mitti or Fuller's earth, STB–Straw, SOB–Soil) BGAbiofertilizers on the grain yields.

N levels Grain yield (q/ha) Carriers Grain yield (q/ha)

N0 36.12 Control 38.32N30 39.98 MMB 48.83N60 46.43 STB 46.01N90 49.50 SOB 44.68N120 50.26 – –CD (P�0.05) 3.74 CD (P�0.05) 3.56

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Ladha, 1992). Algal application resulted in sustenance of total nitrogenlevels beyond tillering stage of the crop. Carbon content increased from12.5 to 28.9%. However, in long term field trials, no appreciableincrease in organic carbon content was observed by Aiyer et al. (1972)which was attributed to rapid loss of organic matter under tropical cli-matic conditions.

Rice field conditions provide an ideal environment for the luxuriantgrowth of algae. Studies on the BGA populations, at different intervalsof crop growth revealed interesting results in control as well as inocu-lated plots. Nostoc punctiforme, a native strain from the soil, continuedto dominate the BGA population throughout the season as comparedwith the BGA population mixture applied as biofertilizer, as in our ear-lier experiments (Nayak et al., 2001). Non-heterocystous forms prolif-erated throughout the crop growth cycle. In the initial crop growthphase, green algae such as Cladophora, Chlorococcum, Oedogoniumdominated the soil population but by post tillering phase, these werereplaced by species of Anabaena, Nostoc, Phormidium, and Oscillatoria.Floristic abundance studies have shown the predominance of NostocAnabaena and Phormidium, irrespective of treatments or stage of growth(Nayak et al., 2001). The significant contribution of BGA to biologi-cally fixed nitrogen (measured as acetylene reducing activity) andphotosynthetic biomass (using chlorophyll accumulation as a growthindex) in soil has been shown in our earlier studies (Nayak et al., 2004).These forms are known to contribute to increased yield of paddy ininoculated fields by their effect on nutrient status and tilth of soil. A sig-nificant feature observed was that within a week after broadcasting ofalgal biofertilizer, mats of BGA were visible in the straw and multanimitti based BGA biofertilizer applied plots, indicative of the presence ofhigh titre of BGA in these biofertilizer preparations. The maximumalgal biomass was produced at the panicle initiation stage followedby late tillering and harvest. The proliferation of BGA during the pani-cle initiation stage is ascribed to the rice canopy as well as physicaland chemical properties of the soil, which perhaps created a favorableenvironment for their luxuriant growth (Roger and Kulasooriya, 1980).In India, Singh (1961) made detailed studies on periodicity of BGAspecies in rice fields of Uttar Pradesh and Bihar and reported abundantgrowth of Aulosira fertilissima, Anabaena ambigua, Anabaena ferti-lissima, and Cylindrospermum. BGA populations are highly suscepti-ble to environmental changes and are subjected to rapid variation bothqualitatively and quantitatively along the paddy cultivation cycle.

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Although algalization can be recommended only as a supplementto nitrogenous fertilizers, this experiment revealed that there was a per-ceptible increase in crop yields at lower levels of chemical fertilizers.Therefore, there is an urgent need to strongly advocate the use ofimproved multani mitti based and straw based BGA biofertilizer, notonly as an economically viable input in integrated nutrient managementbut also as a renewable source of nutrients for sustained soil health andcrop production.

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RECEIVED: 09/27/05REVISED: 02/07/06

ACCEPTED: 03/13/06

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