EFFECT OF HUMIC ACID ON SOIL MICRONUTRIENTS UNDER DIFFERENT WET AND DRY CYCLES USING TWO SOIL SERIES

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1 Life Sci. Int. J., Vol: 9, (Issue, 1, 2, 3, & 4) Jan., April, July & Oct Page: EFFECT OF HUMIC ACID ON SOIL MICRONUTRIENTS UNDER DIFFERENT WET AND DRY CYCLES USING TWO SOIL SERIES Muhammad Iqbal Jakhro 1, Gul Mohammad Panezai 2, Sajida Parveen 2, Mohammad Hashim Tareen 2, Mohammad Saleem 2 and Sanaullah 2 1 Sindh Agriculture University Tandojam, Sindh, Pakistan 2 Agriculture Research Institute Quetta, Balochistan, Pakistan of Corresponding Author: iqbal.jakhro@gmail.com ABSTRACT The unavailability of micronutrients in calcareous soil is one of the major causes of low crop production. Humic acid extracted from low grade coal have exhibited potential for enhancing the availability of soil micronutrients. For this purpose a pot experiment was conducted at the department of Soil Science Sindh Agriculture University Tandojam during 2013 to study the effect of different levels of coal derived humic acid on soil micronutrients. The experiment was laid out in randomized complete design (factorial) with treatments of three factors (A, B and C) which were replicated thrice. Factor A was four humic acid levels (0, 5, 10 and 15 mg kg -1 ), factor B was two wet and dry cycles (first cycle-3 months and second cycle-6 months) and factor C was two soil series (Guliana and Missa). The results revealed that humic acids levels, wetting and drying cycles, soil type and their interaction were statistically highly significant. Amon the micronutrients, the greater Cu and Zn concentration (0.63 an 0.60 mg kg -1 ) were recorded at medium HA (10 mg kg -1 ) while, maximum Fe and Mn concentration (4.10 and 6.19 mg kg -1 ) were observed at HA (15 mg kg -1 ). While, Guliana soil series exhibited combatively higher concentration of micronutrients except Fe which was greater in Missa soil series. The first wetting and drying cycle showed higher concentration of micronutrients except Cu which was maximum at second wetting and drying cycles. So, it is suggested that coal derived humic acid can be used as potential source of soil amendment for enhancing soil fertility and productivity. KEYWORDS: humic acid, low grade coal, soil type, wetting and drying cycles, micronutrients INTRODUCTION One of the important components of high quality soil is organic matter which directly affects soil physical, chemical and biological properties and its presence in sufficient quantity is indispensible for sustainable crop production and friendly environment (Bloem et al., 2005). In tropical and sub-tropical areas of the world where high temperature results in high decomposition rate of soil organic matter affecting soil fertility and productivity with low crop growth and yield (Giardina et al., 2000; Steiner et al.,2007). In developing countries like Pakistan where inputs are in short supply and removal of crop residues for fuel and feed purpose further enhance the loss of organic matter in soil resulting in low yield. However, the enriched deposits of low rank coal containing humic acid are found in large quantities in Pakistan which can be used as a source of organic matter by extracting its humic acid contents (Hai and Mir, 1998) because it contain phenolic, acidic, amino and quinione groups which helps in the availability of nutrients in calcareous alkaline soil poor in organic matter. This has aromatic structure and is soluble in alkali because it is surrogated by carboxyl, phenolic, hydroxyl, and alkyl groups which are connected together through either linkage (Gaines et al., 1983). The application of coal-derived sodium humate under calcareous soil increased growth, yield and nutrient uptake of various crops (Van de Venter et al., 1991; Sharif et al., 2002 a,b; Sarir and Durrani, 2006; El-Nemr, 2012 and Daur and Bakhashwain, 2013). MATERIALS AND METHODS A pot experiment was conducted at the department of Soil Science Sindh Agriculture University Tandojam during 2013 to study the effect of different levels of coal derived humic acid on soil micronutrients. The study was aimed to evaluate the role of humic acid in releasing plant nutrient. The experiment was based on randomized complete design (factorial) with treatments of three factors (A, B and C) which were replicated thrice. The detail of the treatments is as under: 3264

2 Treatments = three factors (A, B and C) Factor (A)-humic acid levels = 04 H0 = 0.0 mg kg -1 humic acid (control) H1= 5.0 mg kg -1 humic acid H2 = 10.0 mg kg -1 humic acid H3 = 15.0 mg kg -1 humic acid Factor (B)-cycles = 02 C1 = First cycle (after three months) C1 = Second cycle (after six months) Factor (C)-Soil series = 02 S1 = Guliana S2 = Missa The humic acid levels 0,5,10 and 15 mg kg-1 of soil from two soil series Guliana and Missa were used for the study. The soils were subjected to welting and drying cycles. And this was the 8 th cycle of the wetting and drying process. Extraction of humic and fulvic acid from lignitic coal Water soluble constituents of organic matter are called fulvic acids. They have lower molecular weight as compared to humic acids. Humic acid is water insoluble and extracted with alkalis, sodium hydroxide (NaOH). Humic acid was extracted from the lignitic coal by the standard procedure. Coal was grinded and passed through 2.0 mm sieve. Samples were treated (oxidation) with concentrated HNO3 and water solution (HNO3 1:10) with coal sample. The sample to solution ratio was 1:4 and it was kept for 1 hour. Residues were separated using filter paper (watman 42) by suction pump. Supernatant was dried for Fulvic acid determination. At 65 0 C Residues were treated with 0.5 M NaOH (1:10) for a minimum of 4 hour or 2 hour. Supernatant was collected by means of centrifugation and dried for humic acid. (Reagent blank was determined with the samples). Extraction method A 500 ml of distilled water taken in 2 liter volumetric flack, add 80 grams NaOH, 8 ml of 0.1N DTPA (Dissolve grams DTPA in 100 ml Distilled Water) and 40 ml ethonole and volume was made up to the mark. One gram of dried sample was put in to 100 ml volumetric flask, it was dissolved in extraction solution and volume was made up to the mark with extraction solution and were filtered the sample or the filter and measure 1 ml (if sample is liquid) in 100 ml volumetric flask and dissolve it in extraction solution and make volume up to the mark with extraction solution. All the samples were centrifuge at 4000 rpm for five minutes before taking reading on spectrometer. Standard working solution Dry humic acid standard for four hours at 105 o C and weight of gram of humic acid and dilute to 100 ml with extraction solution and make volume up to the mark with extraction solution it will be 1000 ppm or 0.1 % solution and prepared 0.1 %, 1.5 %, 2.5%, and extraction solution as Blank. Humic acid extraction from lignitic coal Coal was grinded and passed through 2.0 mm sieve. Samples were treated (oxidation) with concentrated HNO3: water (1:10) with coal sample: solution 1:4 for 1 hour. Residues were separated using filter paper (Whatman-42) by suction pump. Supernatant was dried for Fulvic acid determination at 65 0 C. Residues were treated with 0.5 M NaOH (1:10) for a minimum of 4 hour or 2 hour. Supernatant was collected by means of centrifugation and dried for humic acid. (Reagent blank was determined with the samples). Soil analysis Soil used in pot experiment was taken from Guliana and Missa soil series and were analyzed for soil texture, organic matter contents (%), EC (ds m -1 ), ph and micro nutrients (Cu, Fe, Mn and Zn). Soil texture was determined by Bouyoucos hydrometer method (Bouyoucos 1962), organic matter content by oxidation method (Walkley and Black method, 1934). Soil ph and EC were determined using digital meters following the method described by McKeague, (1978) and McLean, (1982). AB-DTPA soil extraction method was used for the determination of soil micronutrients (Soltanpour and Schwab, 1977). 3265

3 Statistical analysis The data were computed through factorial analysis of variance (ANOVA) up to 3-way to found the significant levels among the factors (Gomez and Gomez, 1984), while LSD test (P 0.05) was performed for mean comparison among the treatments using computer software Statistix 8.1. RESULTS AND DISCUSSION The soil used in pot experiment was brought from Guliana and Missa soil series. The pre-soil analysis indicated that soil of both series (Guliana and Missa) was clay loam in texture, alkaline ph (7.4 and 7.5), non-saline (ECE 0.87 and 1.20 dsm -1 ) with low organic matter contents (0.42 and 0.60%). The effect of coal derived humic on soil micronutrients under the influence of wetting and drying cycles and soil types is given in Table 1 and 2. The statistical analysis showed that humic acid levels, soil type, wetting and drying cycles and their interaction (humic acid x cycle, humic acid x soil series, cycles x soil series and humic acid x cycle x soil series) were highly significant for the studies micronutrients. The LSD test (p 0.05) for comparison of mean as given in Table 1 revealed that humic acid treatments (0, 5, 10 and 15 mg kg -1 ) affected micronutrients status significantly. Amon them, the greater Cu and Zn concentration (0.63 an 0.60 mg kg -1 ) were recorded at medium level of humic acid i.e. 10 mg kg -1 while, maximum Fe and Mn concentration (4.10 and 6.19 mg kg -1 ) were observed at higher humic acid level i.e. 15 mg kg -1. However, minimum concentration of Cu, Fe, Mn and Zn were noted in control pot where no humic acid was applied. It means that among the humic acid levels, 10 and 15 mg kg -1 increased micronutrients availability as compared to 5 and 0 mg kg -1 humic acid levels because it has high affinity for chelating the metals and protect them from adsorption on soil matrix of calcareous nature. The other reason is that the humic acid application improve the overall soil physical, chemical and biological properties and ultimately increase the availability of micronutrients. These findings are in line with those reported by Boyle et al. (1989) and Schnitzer (1992) that the effect of organic matter on the soil properties such as physical, chemical, and biological ones has been well known for a long time. Humic acid affect physical and chemical properties of soils. In case of two soil series, Guliana soil series exhibited combatively higher concentration of micronutrients except Fe which was greater in Missa soil series (Table 1). The comparison of two cycles such as first wetting and drying cycle of 3 months and the second wetting and drying cycle of 6 months indicated significant differences in the availability of soil micronutrients. The first wetting and drying cycle showed higher concentration of micronutrients except Cu which was maximum at second wetting and drying cycles. This improvement in the availability of micronutrients particularly Fe, Mn and Zn might be due to higher chelating efficiency of humic acid which become fade away with the passage of time and also because of higher buffering capacity of soil. Similar results were observed by Falah and Parkinson (2007) who investigated the effect of a commercial humic substance (HS) on the micronutrients availability of: Fe, Mn, Zn & Cu in two composite surface soil samples. Their result showed a significant increase in the concentration of the available micronutrients due to chelation. While, Sharif (2002) conducted pot experiment using two soil types i.e. silty clay loam, tarnab soil and one hydroponic type to study the effect of different humic acid (0, 50, 100, 150, 200, 250 and 300 mg/kg soil) on maize growth nutrient availability and found that the increasing the levels of HA above 50 and 100mg kg -1 soil produced no significant effect on maize yield and nutrients. The interactive effect of humic x cycle, humic acid x soil series, cycle x soil series and humic acid x cycle x soil series on the availability of soil micronutrients were highly significant (Table 2). The interaction of humic acid x cycle showed that maximum Cu (0.66 mg kg -1 ) and Zn (0.66 mg kg -1 ) were noted at 10 mg kg -1 humic with second wetting and drying cycle, while the interaction of 10 and 15 mg kg -1 humic acid x first cycle revealed higher Fe (4.31 mg kg -1 ) and Mn (7.95 mg kg -1 ) concentration which were statistically at par from each other. While minimum micronutrients concentration was observed at 0 mg kg -1 humic acid x second wetting and drying cycle. In case of humic acid x soil series, the humic acid of 10 mg kg -1 with Guliana soil series indicated maximum Cu (0.82 mg kg -1 ) and Zn concentration (0.71 mg kg -1 ). Whereas, the interactive effect of second wetting and drying cycle x Guliana soil series showed higher Cu and Zn concentration (0.76 and 0.60 mg kg -1 ) but maximum Fe and Mn concentration of 4.47 and 8.54 mg kg -1 was manifested by the interaction of first cycle with Missa and Guliana soil series respectively. Similarly, the interactive effect of humic acid x cycle x soil series showed that maximum Cu and Zn concentration of 0.89 and 0.87 mg kg -1 was recorded at 10 mg kg -1 humic acid in second cycle with Guliana soil series while higher Fe and Mn concentration of were exhibited at the interaction of 10 mg kg -1 humic acid in first cycle with Missa and Guliana soil series. However, minimum micronutrients concentration was found at the interaction of 0 mg kg -1 humic acid x second cycle x Guliana soil series. The scientist like Piccolo et al. (1997) studied the effect of coal derive humic substance on soil aggregation and reported that low rates of humic substance (equivalent to kg/ha) not only improved aggregate stability significantly (P 0.05) on all the three soils but also reduced substantially the disaggregating effects of wetting and drying cycles. This work indicates that exogenous humic substances have a potential as soil conditioners. Similar effect 3266

4 of humic acid on soil micronutrients and soil properties was determined by Kutuk et al. (2002) in an incubation study where seven rates of humic acid (0, 100, 250, 500, 1000, 2000 and 4000 ppm) were added to the soil at three incubation periods (30,60,90 days). Humic acid addition decreased ph values at the fist incubation period. EC values were increased depending on humic acid rates at the all incubation periods. It was seen that the effect of HA on available Fe, Mn, Zn contents of the soil were more clear above 500 ppm rates of HA. They found higher available concentration of Fe, Mn and Zn contents soil at first incubation period than in other periods which coincide with this study where available micronutrients concentration was observed in first wetting and drying cycle of 3 months and further increase in wetting and drying cycles resulted in low micronutrient concentration. CONCLUSTION The use of coal derived humic acid exhibited big potential for enhancing the availability of soil micronutrients and behaved differently in various soil types. From this study, it was noticed that the application rate of 10.0 and 15.0 mg kg -1 humic acid increased Cu, Fe, Mn and Zn concentration in first wetting and drying cycle using soil of Guliana soil series which is evident from the interaction of humic acid (10 or 15 mg kg -1 ) x Guliana soil series and first wetting drying cycle x Guliana soil series. So, it is suggested that coal derived humic acid can be used as potential source of soil amendment for enhancing soil fertility and productivity. Table 1: Effect of coal derived humic acid on the status of soil micronutrients under the influence of wetting and drying cycles using two soil series Studied factors Micronutrients (ppm) Cu Fe Mn Zn Humic acid treatments 0.0 mg kg d 3.31 d 5.10 d 0.44 d 5.0 mg kg c 3.71 c 5.58 c 0.49 c 10.0 mg kg a 3.89 b 5.78 b 0.60 a 15.0 mg kg b 4.10 a 6.19 a 0.51 b S.E.± LSD at P Wetting and drying cycles First cycle (3 months) 0.57 b 4.11 a 7.53 a 0.52 a Second cycle (6 months) 0.60 a 3.38 b 3.78 b 0.51 b S.E.± LSD at P Soil series Guliana 0.72 a 3.51 b 6.25 a 0.57 a Missa 0.44 b 3.97 a 5.07 b 0.45 b S.E.± LSD at P Type Mean square values Humic acid ** ** ** ** Cycle ** ** ** ** Soil series ** ** ** ** Humic acid x cycle ** ** ** ** Humic acid x soil series ** ** ** ** Cycle x soil series ** ** ** ** Humic acid x cycle x soil ** ** ** ** series Error Mean bearing the same letters are statistically alike ** Highly significant 3267

5 Table 2: The Interactive effect of humic acid x cycles, humic acid x soil series, cycle x soil series and humic acid x cycle x soil series on the status of soil micronutrients Interactions Micronutrients (mg kg -1 ) Cu Fe Mn Zn Humic acid x cycles 0.0 mg kg -1 First cycle 0.52 f 3.71 e 6.70 c 0.48 f Second cycle 0.52 f 2.92 h 3.50 f 0.39 g 5.0 mg kg -1 First cycle 0.56 e 4.17 c 7.64 b 0.51 d Second cycle 0.58 d 3.24 g 3.51 f 0.47f 10.0 mg kg -1 First cycle 0.60 c 4.26 b 7.85 a 0.55 b Second cycle 0.66 a 3.51 f 3.71 e 0.66 a 15.0 mg kg -1 First cycle 0.59 d 4.31 a 7.95 a 0.53 c Second cycle 0.62 b 3.85 d 4.44 d 0.49 e S.E.± LSD at P Humic acid x soil series 0.0 mg kg -1 Guliana 0.61 d 3.25 h 5.85 d 0.50 c Missa 0.42 g 3.37 g 4.34 g 0.38 f 5.0 mg kg -1 Guliana 0.71 c 3.48 f 6.15c 0.53 b Missa 0.43 g 3.93 c 4.99 f 0.45 e 10.0 mg kg -1 Guliana 0.82 a 3.63 e 6.34 b 0.71 a Missa 0.45 f 4.14 b 5.21 e 0.49 c 15.0 mg kg -1 Guliana 0.75 b 3.69 d 6.65 a 0.54 b Missa 0.46 e 4.46 a 5.74 d 0.48 d S.E.± LSD at P Cycle x soil series First cycle Guliana 0.68 b 3.76 b 8.54 a 0.54 b Missa 0.45 c 4.47 a 6.52 b 0.49 c Second cycle Guliana 0.76 a 3.27 d 3.95 c 0.60 a Missa 0.43 d 3.48 c 3.62 d 0.41 d S.E.± LSD at P Humic acid x cycles x soil series 0.0 mg kg -1 First cycle Guliana 0.60 g 3.63 e 8.01 b 0.52 d Missa 0.43 ij 3.78 d 5.39 e 0.44 g Second cycle Guliana 0.63 f 2.86 k 3.69 h 0.48 e Missa 0.41 j 2.97 j 3.29 j 0.31 i 5.0 mg kg -1 First cycle Guliana 0.67 e 3.78 d 8.65 a 0.53 c Missa 0.45 hi 4.56 b 6.63 d 0.49 e Second cycle Guliana 0.75 c 3.19 i 3.65 hi 0.53 c Missa 0.41 j 3.29 h 3.36 j 0.41 h 10.0 mg kg -1 First cycle Guliana 0.74 c 3.78 d 8.71 a 0.56 b Missa 0.46 h 4.73 a 6.98 c 0.53 c Second cycle Guliana 0.89 a 3.47 g 3.96 g 0.87 a Missa 0.43 ij 3.55 f 3.45 ij 0.46 f 15.0 mg kg -1 First cycle Guliana 0.71 d 3.83 d 8.79 a 0.54 c Missa 0.46 h 4.79 a 7.10 c 0.52 d Second cycle Guliana 0.79 b 3.55 f 4.50 f 0.54 c Missa 0.46 h 4.14 c 4.38 f 0.44 g S.E.± LSD at P Mean bearing the same letters are statistically alike 3268

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