Assessing the Effects of Yeast Vinasse with Conventional Manures on Soybean Performance and Soil Properties

Soybean [Glycine max (L.) Merrill] is an energy rich legume requiring higher amounts of nutrients (Sikka et al., 2018), but the imbalanced application of inorganic fertilizers over a long period causes micronutrient deficiencies and deteriorates the productivity and profitability of soybean day by day (Arbad et al., 2014). To combat such challenges, the strategy for integrated nutrient management (INM) using conventional organic manures like FYM/vermicompost draws huge attention across the world (Bandyopadhyay et al., 2010). Yeast vinasse is an organic waste from sugarcane processing industry, having low pH, high volatile solids, organic and inorganic nutrients, mainly potassium (Pinto et al., 2022). Its use improves the availability of nitrogen, potassium and organic matter in soil (Moran-Salazar et al., 2016), calcium, sulphur and micronutrients to crops (Vadivel et al., 2014) and enhances crop yields. However, the information on efficacy of yeast vinasse as organic source of plant nutrients is meagre in India. Again, Zn deficiency in 48% of Indian soils affects the growth and productivity of legumes including soybean (Shukla et al., 2018) due to inhibiting protein synthesis, chlorophyll formation, enzyme activation and stimulation of growth hormones (Singh et al., 2018). Hence, Zn fertilization becomes an integral part of nutrient management to enhance yield and quality of soybean (Yadav et al., 2022).
       
Keeping in view, an attempt was made to assess the effects of yeast vinasse compared to vermicompost and FYM on soybean productivity and soil properties in INM under Zn deficient alluvial zone of West Bengal.

Field experiment was carried out in kharif seasons (June-October) of 2020 and 2021 at the instructional farm of BCKV, West Bengal under sub-tropical and sub-humid climate of eastern India. The experimental soil was sandy loam in texture (Entisol) with 53.91% sand, 21.83% silt and 15.90% clay; and initial soil fertility in 0-30 cm depth is presented in Table 3. Soybean was grown as rainfed crop and the rainfall received in crop period was 1052 mm (67 rainy days) in 2020 and 1186.9 mm (60 rainy days) in 2021. Monthly average maximum and minimum temperatures were recorded in June and October in both the years and the values were 33.5°C (2020) and 33.7°C (2021); 20.8°C (2020) and 21°C (2021) respectively. The experiment was laid out in randomized block design with three replications and eight treatments such as T₁-100% RDF (Control), T₂-75% RDF+1.5 t ha^-1 vermicompost, T₃-75% RDF+3 t ha^-1 farmyard manure (FYM), T₄-75% RDF+2 t ha^-1 yeast vinasse, T₅-100% RDF+ZnSO₄ @ 0.5% foliar spray, T₆-75% RDF+1.5 t ha^-1 vermicompost+ ZnSO₄ @ 0.5% foliar spray, T₇-75% RDF+3 t ha^-1 FYM +  ZnSO₄ @ 0.5% foliar spray and T₈-75% RDF+2 t ha^-1 yeast vinasse+ ZnSO₄ @ 0.5% foliar spray. N, P₂O₅ and K₂O were applied @ 20, 60 and 40 kg ha^-1, respectively in 100% RDF through of urea (46% N), SSP (16% P₂O₅) and MOP (60% K₂O), respectively. The nutrient composition of different organic sources is presented in below:

 

       
As per the treatments, the organic manures were applied ten days before sowing and NPK fertilizers were applied at sowing and mixed thoroughly with the soil.Seeds of soybean variety ‘PS24’ having duration of 110-115 days and semi-determinate type was sown on 28^th June in 2020 and 25^th June in 2021 with 45cm x 10cm spacing. Foliar spray of heptahydrate ZnSO₄  (containing 31% Zn) was done @ 0.5% at 30 and 60 days after sowing (DAS) as per treatment. The crop was harvested at 22^nd and 20^th October in 2020 and 2021, respectively. All growth and yield parameters were recorded at harvest; however, number and dry weight of nodules was recorded at 60 DAS.
       
Collected soil samples at initial and harvest were processed and standard methods were followed for analysis of pH (Jackson, 1973), organic carbon (Walkley and Black wet digestion method; Jackson, 1973), available N (Subbiah and Asajia, 1956), available P₂O₅ (Olsen et al., 1954), available K₂O (flame photometric method; Jackson, 1973) and Zn content (DTPA extraction followed by atomic absorption spectrophotometry method). Total bacteria (Thronton agar medium), fungi (Martin’s Rose Bengal medium) and actinomycetes population (actinomycetes isolation agar medium), dehydrogenase activity (Casida et al., 1964) and microbial biomass carbon (MBC) (Vance et al., 1987) of different treatments were analysed at harvest. Plant samples (both seed and stover) at harvest were subjected towet digestion to estimate N (Micro Kjeldahl method; Piper, 1966), P (Vanado Molybdate Phosphoric yellow colour method; Jackson, 1973), K (Flame Photometer method; Jackson, 1973) and Zn (DTPA extraction followed by atomic absorption spectrophotometry method) content (%) and multiplied with biomass to work out nutrient uptake. The nitrogen content of seed samples was also multiplied with a factor of 6.25 to get crude protein (Gupta et al., 1972). Soxhlet apparatus method (Ajaye et al., 2004) was followed to determine oil content of seeds. The data collected from field and laboratory were analysed through analysis of variance and the comparison among the treatment means wasdone using critical difference (CD) at 5% level of significance (Gomez and Gomez, 1984).

Growth attributes, nodule number and dry weight, yield attributes and yields
 
It was observed in both years that integrated application of organic manures and NPK and Zn fertilizers significantly improved the growth attributes, nodulation and yields of soybean over NPK fertilization alone (control-T₁). Plant height and dry matter accumulation was recorded highest in T₆ (65.57 and 69.73 cm and 481.55 and 516.62 g m^-2 in 2020 and 2021, respectively), which was statistically at par with T₂, T₇ and T₈ in 2020 and with T₈ in 2021 for plant height and with T₂ and T₈ in 2020 and with T₈ in 2021 for dry matter accumulation (Table 1). Though, significantly the highest number of nodules plant^-1 was noted in T₂ (35.09) in 2020, which was at par with T₄, T₆ and T₇; and T₆ (41.79) in 2021, which was at par with T₂, T₄ and T₇  (Fig 1). However, the dry weight of nodules plant^-1 was maximum in T₆ (127.73 mg) in 2020, which was at par with T₂, T₄ and T₇ and in T₂ (139.63 mg) in 2021, which was at par with T₄, T₆, T₇ and T₈ (Fig1). T₆ treatment showed the highest number of pods plant^-1 (24.17 and 26.41), which was at par with T₂, T₇ and T₈; and also 100-seed weight (14.81 g and 14.94 g) which was at par with T₇ and T₈ in 2020 and 2021, respectively (Fig 2). The number of seeds pod^-1 did not vary significantly among the treatments. The greater production of photosynthates enhanced the yield attributes, resulting in the highest seed and stover yields recorded in T₆ (1810 and 1906 kg ha^-1 and 3820 and 4000 kg ha^-1 in 1^st and 2^nd year, respectively), which was on a par with T₂ and T₈ in 2020 and T₇ and T₈ in 2021 in case of seed yield and with T₂ and T₈ for stover yield in both years (Table 1). The lowest values of growth attributes, nodulation, yield components and yields were registered with sole application of 100% RDF. The enhanced results in INM over NPK fertilization alone might be due to the greater and prolong availability of essential nutrients throughout the growth period by the combined sources of nutrients. Moreover, among the organic manures, the more impacts of vermicompost on growth, yield attributes and yields might be attributed to the abundance of readily accessible plant nutrients, growth-promoting substances and a variety of beneficial microorganisms present within it (Rehman et al., 2023), however, the effects of vermicompost were also comparable and at par with yeast vinasse and in most of observations, yeast vinasse showed better than FYM.  Besides organic manuring and NPK fertilization, the additional effects by foliar feeding of Zn on growth and yield parameters might be the cause of accelerated cell metabolism and hormonal activities (Aytac, 2007). Our results were similar to Verma et al., (2017) and Mahato et al., (2020).






 
Nutrient uptake and quality
 
Higher biomass production in T₆ encouraged uptake of N (186.22 and 206.45 kg ha^-1), P₂O₅ (22.12 and 26.56 kg ha^-1), K₂O (93.21 and 102.39 kg ha^-1) and Zn (182 and 228.85 g ha^-1), which was at par with T₈  and with T₇ and T₈ for N uptake in 2020 and 2021, respectively (Table 1). This treatment was also on a par with T₇  and T₈ for P₂O₅  and K₂O uptake; and with T₈ for Zn uptake in both the years. The higher growth and proliferation of roots, better physical condition of the soil and greater availability of nutrients in INM might hasten the uptake of nutrients (Paramesh et al., 2023). The oil content of seeds remained non-significant among the treatments in 2020 (Table 2), but varied significantly in 2021 with maximum oil content in T₅ (20.47 and 20.04%, respectively). Protein content of seeds was highest in T₈ (38.19 and 40.38%, respectively), which was at par with T₆ (Table 2). The results exhibited the favourable effects of yeast vinasse on N uptake and protein content of seeds. The lower values of qualities were recorded in control. Similar findings were reported by Verma et al., (2017).


 
Microbial population, microbial biomass carbon (MBC) and dehydrogenase activity
 
Application of organics with fertilizers significantly affected the biological properties of the soil (Table 2). T₇ recorded the maximum bacterial population in 2020 (14.19 CFU x 106) whereas, T₆ during 2021 (15.19 CFU x 106). T8 showed the maximum population of fungi (9.88 and 11.31 CFU×104) and actinomycetes (6.28 and 8.09 CFU x 105) for both the years. The highest microbial biomass carbon was obtained in T_7­ (171.82 and 188.88 µg C g^-1 soil in 2020 and 2021, respectively), which was at par with T₃, T₄, T₆ and T₈ in 2020 and T₂, T₃ and T₆ in 2021. T₇ also showed the highest dehydrogenase activity in 2020 (55.66 µg TPF g^-1 of soil 24 hr^-1), at par with T₂, T₄, T₆ and T₈. But in 2021, it was highest under T₃ (66.35µg TPF g^-1 of soil 24 hr^-1), at par with T₂, T₄ and T₇. Integration of nutrient sources, where organics served as feeding materials for the microorganisms, resulted to greater counts of microbes and higher microbial biomass carbon and more activities of dehydrogenase due to higher activity of microorganisms. Similar finding was reported by Paramesh et al., (2023).
 
Residual fertility
 
Organic carbon of the soil was increased at harvest from initial level in the plots where organic manures were added to the soil and it was maximumin T₇ (0.59 and 0.63% in 2020 and 2021, respectively), followed by T₆ and T₈ (Table 3). Similarly, the residual soil N improved from initial status in all treatments in two years might be the contribution of biological nitrogen fixation by legumes. It was maximum under T₇ (218.95 kg ha^-1 and 235.43 kg ha^-1, respectively), at par with T₃, T₆ and T₈ during both the years. T₃ recorded the maximum soil available P₂O₅ (33.67 and 30.71 kg ha^-1 in 2020 and 2021, respectively), at par with T₂, T₄, T₆, T₇  and T₈ in both years (Table 3). Residual soil K₂O was highest under T₄ (240.74 and 260.48 kg ha^-1 in 2020 and 2021, respectively), at par with T₈. However, Zn content of soil at harvest was non-significant among the treatments. Integrated application of nutrients kept higher levels of residual NPK than sole inorganic fertilizers even after meeting the nutrient demand for the exhaustive legume soyabean and it was attributed to the slow nutrient release property of organic manures. The greater carbon sequestration of organic manures might improve organic carbon of the soil. More residual nutrients after harvest in second year than first year might be the cumulative effects of organic manures added in two years. Higher residual organic carbon, N and P₂O₅ in FYM treated plots followed by vermicompost and yeast vinasse treatments indicated the potentiality of yeast vinasse in enhancing soil fertility. Moreover, the significant enrichment of soil K₂O by yeast vinasse might be the addition of substantial amount K₂O through it. However, the non-significant effects of treatments on soil residual zinc might be due to foliar application of Zn fertilizer.This result was in congruities with the findings of Vyas and Kushwah (2015).

The two years study exhibited that though the integrated application of vermicompost along with 75% RDF and 0.5% ZnSO₄ as foliar spray (T₆) was found superior over other treatments but it was statistically comparable with the application of yeast vinasse along with 75% RDF and foliar spray of 0.5% ZnSO4 (T₈) in terms of growth attributes, yield and yield attributes as well as uptake of nutrients. Therefore, T₈ can be a viable option for soybean cultivation in per-humid region of West Bengal under alluvial soil. It also saved 25 % of inorganic fertilizer (NPK). Besides, yeast vinasse application also increased seed protein %, residual fertility and fungi and actinomycetes population and K₂O in soil. Therefore, this comparative study revealed the potentiality of yeast vinasseas organic source of nutrients in soybean crop like other conventional manures and hence, it is necessary to explore this organic waste as an alternative source of nutrients in other crops.

The authors declare that they have no conflict of interest.