Effects of fertilizer levels, foliar nutrient sprays and seed treatment with biofertilizers on nutrient uptake, available nutrients and microbial status at harvest of kharif soybean (Glycine max L. Merill).

Introduction

Soybean (Glycine max L.) is known as Chinese pea and Manchurian bean which belongs to the family leguminaceae, subfamily papilionaceae. Soybean is major oilseed crop in world, accounting for nearly 50 per cent of total oilseeds acreage as well as production. It ranks third in vegetable oil economy in India, following groundnut and rapeseed. Soybean has not only gained vital importance in Indian agriculture, but also plays decisive role in oil economy of India. It is one of the most popular pulse and oilseed crop grown in Maharashtra and oftenly called as 'Gold bean' and designated as 'Miracle crop' of 20 th century. Generally, essential plant nutrients are applied as a basal dose during land preparation to attain maximum yield of a crop. Although soil application is the most effective method but under some circumstances foliar fertilization is more effective and economic. Foliar spraying is helpful when crop roots are unable to provide enough nutrients and much more economic since foliar application rate is less compared to soil application. Many researchers reported that supplemental nutrients applied at different reproductive stages of crop through foliar application increases the yield of soybean. Specially, at early flowering or pod initiation stage, soybean requires more nutrients for the development of pod and seed along with optimum soil moisture (Dandge et al., 2018) [5] . Applying of fertilizers as a foliar spray produced effective absorption and usage under rainfed conditions, when the availability of moisture becomes limited. This method is cost-effective compared to other forms of fertilization. The primary problems with soybean are flower senescence and improper pod filling, which can be corrected by foliar application of growth regulators and nutrients (Kumar et al., 2013) [9] . Nutrients contained in compost and biofertilizers can aids in the availability of plant nutrients so that soybean plants show a better number of yield. In addition to this, the microorganisms in biofertilizers also increase the efficiency of nutrient absorption and help to provide nutrients in the soil in the available form to the plants (Garuda

Materials and Methods

The present investigation was conducted at plot no.10 C of B Division; Agronomy Farm, College of Agriculture, Pune, during kharif 2021-22. The experiment was laid out in Randomized Block Design (RBD) with ten treatments and three replications. The gross and net plot size was 4.00 m × 3.60 m and 3.60 m × 2.70 m, respectively. There were ten treatments viz., (T1) 100% GRDF, (T2) 75% GRDF, (T3) 75% GRDF + 2 foliar spray of 2% DAP and seed treatment of Rhizobium, PSB and KSB solid form, (T4) 75% GRDF + PSB and KSB liquid form. The experimental field topography was uniform and levelled. The experimental sites soil was medium black in colour and well drained, with a uniform depth of up to 90 cm. The soil of the experimental field was clay loam in texture with moderately alkaline in reaction (pH 7.73). The soil was low in available nitrogen (168.88 kgha -1 ), medium in available phosphorous (18.22 kgha -1 ) (Olsen and Sommers, 1982) [11] and high in available potassium (260.50 kgha -1 ) (Page et al., 1982) as well as low in organic carbon content (0.35%). Initial population of bacteria (64×10 -7 CFU g -1 soil), fungi (32×10 -3 CFU g -1 soil), actinomycetes (31.33×10 3 CFU g -1 soil) (Cappuccino and Sherman, 1987), Rhizobium (24×10 -7 CFU g -1 soil), PSB (22×10 -7 CFU g -1 soil) and KSB (21.66×10 -7 CFU g -1 soil) (Colwell and Zambruski, 1972). Soybean variety KDS-726 (Phule Sangam) was sown at spacing 45 cm X 5 cm. Before sowing seed treatment with solid and liquid biofertilizers according to the treatments were carried out. Basal dose of chemical fertilizers, FYM and foliar sprays of fertilizers were also applied according to the treatments.

Results and Discussion

Nutrient uptake in seed The data regarding N, P and K uptake by seed and stover of soybean at harvest as a result of different fertilizer levels and foliar nutrient sprays are provided in table 1.The data shows that uptake of N, P, K was significantly varied due to effect of different fertilizer levels and foliar nutrient sprays. The mean uptake of N, P, K by seeds of soybean was 139.05, 14.55 and 27.61 kgha -1 , respectively. Among the different treatments the application of 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB liquid form (T10) noted significantly highest N, P and K uptake in seed (158.94, 17.55 and 33.37 NPK kgha -1 , respectively) as compared to other treatments but it was found at par with (T9) 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB solid form and (T6) 100% GRDF + 2 foliar spray of 2% DAP and seed treatment of Rhizobium, PSB and KSB liquid form. Lowest uptake of N, P and K in seed of soybean nutrients was recorded in (T2) that is 75% GRDF. The maximum uptake of N, P and K in seed in treatment (T10) might be due addition of FYM which improved the soil physical properties. Also single or double seed inoculation with biofertilizers enhances the microbial population and organic acids which resulted quick release of nutrients. Foliar sprays of 19:19:19 possibly resulted in effective absorption of nutrients. Due to this yield contributing characters like number of pods -1 , number of seeds pod -1 , test weight etc. were increased which ultimately increased seed yield. Also the uptake of nutrients depends on yield. Hence as yield increased, uptake also increased. Similar results were noted by Bansode and Math (2018) [1] and Raja and Takankhar (2018) [13] .

Nutrient uptake by stover

The significant variation in N P K uptake of soybean stover was noted due to various fertilizers levels and foliar nutrient sprays. The mean N, P, K uptake in stover was 18.36, 4.922 and 44.77 NPK kgha -1 , respectively. In various treatments (T10) 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB liquid form noted significantly higher uptake of NPK in straw (21.81, 5.83 and 50.86 NPK kgha -1 respectively) but, it was followed by (T9) 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB solid form and (T6) 100% GRDF + 2 foliar spray of 2% DAP and seed treatment of Rhizobium, PSB and KSB liquid form. Lowest uptake of N, P and K in stover of soybean nutrients was recorded in (T2) that is 75% GRDF. The maximum uptake of nutrients in stover in treatment (T10) might be due appropriate basal dose along with FYM which developed soil physical properties and seed treatment with liquid biofertilizer influenced the microbial activities in the rhizosphere. Also foliar application of 19:19:19 stimulated the vegetative growth which ultimately resulted in more stover yield and increased the uptake. Similar results were recorded by Mudalagiriyappa et al. (2016) [10] , Bansode and Math (2018) [1] and Raja and Takankhar (2018) [13] .

Microbial studies Microbial count of Bacteria, fungi and Actinomycetes

The soil microbial count was significantly influenced due to different fertilizer levels and foliar nutrient sprays with inoculation of solid and liquid biofertilizers. The significantly higher count of bacteria, fungi and actinomycetes as (85.50 x 10 -7 CFU, 46.17 x 10 -3 CFU, 42.67 x 10 -3 CFU), respectively were observed with treatment (T10) of 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB liquid form.Whereas, it was at par with (T9) 100% GRDF + 2 foliar spray of 1% 19:19:19 and seed treatment of Rhizobium, PSB and KSB solid form, (T6) 100% GRDF + 2 foliar spray of 2% DAP and seed treatment of Rhizobium, PSB and KSB liquid form and (T5 ) 100% GRDF + 2 foliar spray of 2% DAP and seed treatment of Rhizobium, PSB and KSB solid form, in case of bacteria and also it was found at par with (T9), (T8), (T7), (T6) and (T5) in case of fungi and actinomycetes. Less microbial count was observed in the treatments of uninoculated seed. More microbial count was observed in treatment (T10). It might be due to inoculation of liquid biofertilizer to seed at the time of sowing at proper moisture condition of soil increased the activities and multiplication of beneficial microorganisms.Similar results were also obtained by Bhavya et al. (2020) [2] , Shete et al. (2021) [14] . [2] and Shete et al. (2021) [14] .

Acknowledgement

AcknowledgementI am thankful to Division of Agronomy, College of Agriculture, Pune for timely help and providing me all necessary facilities in conducting research work.

References

1. Bansode C, Math KK. Effect of foliar feeding of 19:19:19 and potassium nitrate water soluble fertilizers on major nutrient status of soybean in a vertisol. Int J Chem Stud. 2018;6(3):2251-2523.
2. Bhavya M, Sridhara CJ, Nandish MS, Mavarkar NS, Suchitha Y, Sumithra BS. Influence of foliar application of water-soluble fertilizers on nodule count and rhizosphere microbial population in green gram (Vigna radiata L.). Int J Curr Microbiol App Sci. 2020;9(2):2383-92.
3. Dandge MS, Ingle YV, Peshattiwar PD, Dikey HH. Effect of foliar nutrition on soybean productivity. Int J Chem Stud. 2018;6(1):1290-1292.
4. Garuda SR, Syaiful SA, Syam'un DE. Growth and production response of soybeans applying compost and biofertilizers. Chem Biomol Eng. 2022;7(3):38-45.
5. Gord NB, Zade SP, Bodke VS, Nakhate PS. Effect of organic farming on enzymatic activity and microbial populations of soybean. The Pharma Innovation J. 2022;11(22):2182-2186.
6. Krishnaprabu S. Liquid microbial consortium: a potential tool for sustainable soil health. J Pharmacogn Phytochem. 2020;9(2):2191-2199.
7. Kumar CV, Vaiyapuri K, Amanullah MM, Gopalaswamy G. Influence of foliar spray of nutrients on yield and economics of soybean (Glycine max L. Merill). J Biol Sci. 2013;13(6):263-265.
8. Mudalagiriyappa, Ali MS, Ramchandrappa BK, Basavaraja PK, Kiran. Effect of foliar application of water soluble fertilizers on nutrient uptake and reproductive efficiency of chickpea (Cicer arietinum L.). The Bioscan. 2016;11(3):1601-1604.
9. Raja D, Takankhar VJ. Response of liquid biofertilizers (Bradyrhizobium and PSB) on nutrient content in soybean. IJCMAS. 2018;7(5):3701-3706.
10. Shete MH, Murumkar DR, Landge KB. Effect of consortium of Rhizobium, PSB and KMB on growth and yield of mungbean (Vigna radiata L.). Int J Curr Microbiol App Sci. 2021;10(01):1697-705.
11. Subbaih BV, Asija GL. A rapid procedure for the estimation of available nitrogen in soils. Curr Sci. 1956;25:259-260.