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Assessment of Nutrient Availability and Microbial Soil Biomass under Different Level of Potassium Humate and Fertility in Mungbean (Vigna radiata)

Yogesh Kumar, Rajhans Verma, Kuldeep Singh, Aakash and Oma Shanker Bhukhar

  • Page No:  174 - 178
  • Published online: 20 Jul 2022
  • DOI: HTTPS://DOI.ORG/10.23910/2/2022.0434a

  • Abstract
  •  kuldeeptamana4@gmail.com

A field trial was conducted to study soil quality parameters influenced by different levels of potassium humate and fertility under mungbean cultivation at SKNAU, Jobner during kharif season of 2019. The experiment was carried out in a factorial randomized block design with three replications and sixteen treatment combinations. Along with nutrients status in the soil after harvest, soil microbial properties were assessed. The response of potassium humate and fertility levels on nutrient content and soil microbial properties were found to be significant. Application of potassium humate @ 4.5 kg ha-1 was recorded maximum OC (%), N, P2O5, K2O (kg ha-1), S, DTPA-Zn and Fe (mg kg-1) (0.23, 158.22, 22.00, 178.00, 9.61, 4.21 and 0.64, respectively) followed by potassium humate @ 3 kg ha-1 over control. Among different fertility levels, 100% RDF recorded a significantly higher value of above available nutrients in soil over control but DTPA-Zn, Fe, S and OC% did not significantly affect by different fertility levels. Application of potassium humate @ 4.5 kg ha-1 and 100% RDF was recorded improved soil microbial biomass viz., microbial biomass C, N, P, dehydrogenase enzyme and alkaline phosphatase activity over control.

Keywords :   Dehydrogenase enzyme, DTPA-Zn, potassium humate, soil microbial biomass and mungbean

  • Introduction

    Pulses are the second most important crop grown in India after cereals. India is leader in pulse production despite it, India has import around 2 million tonne pulse per year (Kumar and Hiramath, 2018). Among pulse, mungbean plays a significant role in the economy as well as health sustainability of Indian people. Mungbean also knows as the golden bean, it is anannual crop thatcomes under fabaceae fabaceaefamily. In India, mungbean mainly cultivated during rainy season (Kumar et al., 2017). It has wider adapatability and grown in different season under varing climate condition in India (Nath et al., 2016). It has ahigh nutritive value containing 24-26% protein in which tryptophan and lysine amino acids are predominant (Kumar et al., 2013). Different types of minerals found in pulses are particularly iron, zinc and magnesium and vitamins like K and E. It is works as dual purpose crop which can be used for seeds as well as for forage (Davies and Stewart, 1987). Mungbean is a leading pulse crop with an area of 3.64 Mha and an annual production of 2.34 MT with the productivity of 8.72 q ha-1 (Anonymous, 2019).

    So many factors affecting the yield and quality of soil, out of that one factor is imbalance nutrient use (Singh et al., 2018). Yield The yield potential of mungbean may be improved by mediating soil fertility and agronomic management practices. Addition The addition of organic substances during crop cultivation enhanced the soil microbial population and diversity (Rani et al., 2017). Humic substances are naturally occurring ligands create in soils predominantly which played life supporting multiple functions in the soil environment (Olaetxea et al., 2018). Potassium humate is the concentrated form of humus having the composition of 50−60% humic and N (3.71%), K (6.25%) and sulphur (0.55%). It enhanced proteins, sugars and fibres content in the plants and directly increasing the yield and quality of crops (Sharma et al., 2018). It also improves the physical properties of soil, i.e. soil aeration, soil structure, water infiltration rate, aggregation, soil tilth and hydraulic conductivity.  Use The use of potassium humate as an modification for improving soil health and soil properties in such Indian soils are are viable option in low organic C soils (Tripura et al., 2017).

    Soil fertility is the ability of soil to provide all essential plant nutrients in the available form in a balanced amount. Optimum nitrogen fertilizer application enhanced the crop yield of mungbean (Mondal et al., 2011). Different growth stages of mungbean responds in adifferent ways with nitrogen application rates. From the young stage to the nodule stage, the requirement of nitrogen in the mungbean is fulfilled by the nitrogen fixation in the mungbean. After the nodule stage accumulated nitrogen content sharply declines to fulfill the nitrogen requirement of a crop may be through the application of chemical N fertilizer. Application of optimum amount of nitrogen resultedin higher dry matter production by increasing in vegetative growth and photosynthetic rate.

    Being a macronutrient potassium has a vital role in protein synthesis, photosynthesis, a resistantresistanceto pests and diseases, activation of a number of enzymes. Stomatal regulation is controlled by potassium through cell expansion and cell growth mechanisms. Potassium humate playes a great role in improving plant nutrient dynamics (Burhan et al., 2018). Potassium humate is an organic fertilizer and ishighly active in the soil system. It is a rich source of phenolic and carboxylic groups which influcence plant growth directly and indirectly by improving soil fertility. It acts as a chelating agent, which binds the metals and micronutrients and prevents to to leaching. Thus, maintain soil fertility levels and it also playing playinga important role in anion uptake kinetics, i.e. nitrate, phosphate etc (Lodi et al., 2013). It reduces the use of chemical fertilizers by improving fertilizers use efficiency. Potassium humate is an organic fertilizer and ishighly active in the soil system (Waqas et al., 2014). It increases the level of available potassium in soil and improves potassium uptake by the plant. It also reduced the losses and fixation of potassium in soil (Kumar et al., 2013).

    Therefore, keeping mentioned facts in view, the present study was undertaken to evaluate the efficacy of potassium humate and RDF on summer mungbean for better soil health and fertility of the soil.

  • Materials and Methods

    This field experiment was conducted at the agronomy farm, S.K.N. College of Agriculture Jobner located at 26°05” North latitude, 75°28 East longitude and altitude of 427 metres above mean sea level during the kharif season of 2019 (3 months). The experiment was carried out in afactorial randomized block design with three replications and 16 treatment combinations. The experiment was comprised of four treatments of potassium humate (control, 1.5 kg ha-1, 3.0 kg ha-1, 4.5 kg ha-1) and four treatments of fertility levels (Control, 50% RDF, 75% RDF and 100% RDF) were applied to the mungbean. The soil of theexperiment field was loamy sand in texture having alkaline ph (8.11), low in organic carbon (0.20%), available nitrogen (127.23 kg ha-1), medium in available phosphorus (18.21 kg ha-1) and potassium (192.15 kg ha-1). Fertilizers were applied as per treatment through diammonium phosphate (DAP) containing 46% P2O5 and 18% N and urea containing 46% N at the time of sowing as per treatment and the entire dose of potassium humate was thoroughly mixed in the soil before sowing of the crop. Potassium humate was applied in the soil as per treatment. The required quantity of seeds (25 kg ha-1) was treated with rhizobium culture and phosphorus solubilising bacterial (PSB) before sowing @ 20 g kg-1  of seed. The seeds were sown in arow drawn 30 cm apart. Plant to plant spacing was maintained at 10cm with 5cm deep of variety RMG- 492. Irrigation wasapplied in thefield only one time at 34 DAS.

    Walkley and Black method,alkaline permanganate method, 0.5 M sodium bicarbonate method, ammonium acetate extraction method and 0.15% CaCl2 method is used for soil organic carbon, available N, P, K and S estimation, respectively. DTPA-CaCl2-TEA method is used for micronutrients estimation. Soil microbial biomass carbon estimate by CHCl3 method (Jenkinson and powlson, 1976), microbial nitrogen and phosphorus by CHCl3 fumigated method (Brookes et al., 1982). Dehydrogenase and alkaline phosphatase activity wereestimated by using themethod given by (Casida et al., 1964 and Tabatabai and Bremner, 1970, respectively). Experimental data were analyzed using analysis of variance (ANOVA) as per Factorial Randomized Block Design (Gomez and Gomez, 1984). Significa the significance of the treatments weretested using theF test with a 5% level of significance (p< 0.05) and the means were compared using the least significant difference (LSD) test at α=0.05.

  • Results and Discussion

    3.1.  Nutrient availability in the soil after harvest

    Potassium humate:Data mentioned in Table 1 indicated that available OC, N, P2O5, K2O, S, DTPA-Zn and Fe were significantly affected due to potassium humate. Application of potassium humate @ 4.5 kg ha-1 was recorded maximum OC (%), N, P2O5, K2O (kg ha-1), S, DTPA-Zn and Fe (mg kg-1) (0.23, 158.22, 22.00, 178.00, 9.61, 4.21 and 0.64, respectively) followed by potassium humate @ 3 kg ha-1 over control. Potassium humate acts as achelating agent which binds the metals and micronutrients to itself and prevents from leaching of essential nutrients. Application of potassium humate significantly increased the mineralization of organic P which increased plant available P in soil. The results were also corroborated with the finding of Hemida (2017).

    Fertility level: DTPA-Zn, Fe, S and OC% were did not significantly affected due to potassium humate. Application of 100% RDF was found maximum maximum N, P2O5 and K2O (kg ha-1) (157.96. 21.91 and 178.64, respectively) followed by 75% RDF over control. Initial application of nitrogen and phosphorus improves root growth and nodulation of mungbean, this leads to more nitrogen fixation and phosphorus availability to the soil. The application of 100 per cent RDF significantly increased the organic carbon, available N, P2O5 and K2O content in thesoil. The results were also in agreement with those of Hemida (2017) (Table 2).

    Nitrogen budgeting:the data pertaining to N budgeting are given in Figure 1. Among potassium humate levels, higher actual gain (35.72 kg ha-1) N over initial soil available nitrogen was recorded in potassium humate @ 4.5 kg ha-1.However, the apparent gain was recorded also higher in potassium humate @ 4.5 kg ha-1 (101.56 kg ha-1). Under different fertility levels, application of 100% RDF was recorded higher actual and apparent gain (30.63 and 96.81 kg ha-1) followed by 75% RDF (21.49 and 85.14 kg ha-1).

    Phosphorus budgeting:the data pertaining to P budgeting are given in Figure 2. Among potassium humate levels, higher actual gain (3.79 kg ha-1) P over initial soil available phosphorus was recorded in potassium humate @ 4.5 kg ha-1 but actual phosphorus loss washigher under control. Minimum apparent loss under control but higher under potassium humate @ 1.5 kg ha-1. Among different fertility levels, higher actual gain under 100% RDF but lowest actual gain under control.

    3.2.  Soil microbial properties

    Potassium humate: The data presented in Table 3 showed that the microbial biomass carbon, nitrogen and phosphorus of the soil at harvest of the crop was increased with increasing level of potassium humate up to 4.5 kg ha-1. Significantly highest microbial biomass carbon, nitrogen and phosphorus content (µg g-1 soil) (230.48, 49.40 and 36.76, respectively) in the soil at harvest of the crop was recorded under potassium humate@4.5 kg ha-1  followed by potassium humate@ 3.0 kg ha-1.

    Fertility level: Significantly highest microbial biomass carbon, nitrogen and phosphorus content (µg g-1 soil) (231.28, 49.75 and 36.89, respectively) in the soil at harvest of the crop was recorded under 100% RDF followed by 75% RDF over control.

    3.3.  Dehydrogenase enzyme and Alkaline phosphatase activity

    Potassium hum ate:  Data presented in Table 4 revealed that the Dehydrogenase enzyme and alkaline phosphatase activity was significantly increased due to the application of increasing levels of potassium humate over control. Application of potassium humate@4.5 kg ha-1  was recorded highest Dehydrogenase enzyme (µg TPF g soil-1 24hr-1) and alkaline phosphatase activity(µg PNP produced g-1 soil hr-1) (139.64 and 11.79) followed by potassium humate @ 3.0 kg ha-1. Application of potassium humate @ 4.5 kg ha-1  enhanced the dehydrogenase enzyme activity by 20.23, 11.75 and 5.02 per cent higher over control, potassium humate @1.5 kg ha-1  and 3.0 kg ha-1, respectively. The increased in microbial biomass C, N, P and enzymatic activities were improved by theapplication of organic matter that applied to soil would serve as a “food” source for microorganisms and organic matter serves as two main functions for microorganisms, providing energy for growth and suppling carbon for the formation of thenew cell. It increased the soil microbial population and diversity in soil which is very help full for nutrient transformation during crop growth. This was confirmed by Vallini et al., 1993 These findings were also  aggremetswith Tripura et al. (2017) and Hemida et al. (2017).

    Fertility levels: Application of 100% RDF was recorded significantly highest Dehydrogenase enzyme (µg TPF g-1  soil 24 hr-1) and alkaline phosphatase activity (µg PNP produced g-1  soil hr-1) (139.77 and 11.83) followed by 75% RDF. 100% RDF registered an increase of 16.78, 9.84 and 4.51 per cent in alkaline phosphatase activity over control, 50% RDF and 75% RDF, respectively.Dehydrogenase activity and alkaline phosphatase activity in the soil after harvest of the crop were significantly increased with the application of SSP+PROM in green gram (Yadav et al., 2013). Application of P upto 40 kg P2O5 ha-1 significantly increases microbial biomass carbon The amount of microbial biomass P and phosphatase activity were found to be the highest under combined application of 100%RDF+FYM and declined with increased rates of fertilizer application (Santhy et al., 2004). Phosphate enzyme activity and community composition of P-solubilizing bacteria was wassignificantly higher in the N treatment than in the control across all soils has hasbeen reported by Widdiy et al. (2019).

  • Conclusion

    Potassium humate enhanced nutrient contents in soil and had positive effects on soil microbial count.  Based on the present finding of the experiment it may be concluded that application of potassium humate @ 4.5 kg ha-1 and 100% RDF may be recommended to improve nutrient availability, soil microbial biomass and soil health.


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Kumar Y, Verma R, Singh K, Aakash , Bhukhar OS. Assessment of Nutrient Availability and Microbial Soil Biomass under Different Level of Potassium Humate and Fertility in Mungbean (Vigna radiata) IJEP [Internet]. 20Jul.2022[cited 8Feb.2022];9(1):174-178. Available from: http://www.pphouse.org/ijep-article-details.php?art=332

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