Yield
Among the organic manures, application of P as vermicompost + ghanajeevamrutha based on 100% RDP +
Rhizobium + PSB resulted in higher seed yield (701.33 Kg ha
-1) and recorded higher yield attributing characters
i.e., number of pods per plant (19.33), number of seeds per pod (6.33), haulm yield (2038.7 kg ha
-1) and seed yield compared to other treatments (Table 1).
Nutrient availability
Among the different combination of organic manures, application of vermicompost + ghanajeevamrutha @ 100% RDP +
Rhizobium + PSB has recorded higher SOC (0.70%), available nitrogen (291.39 kg ha
-1), phosphorus (36.30 kg ha
-1) and potassium (580.53 kg ha
-1) as compared to other treatments (Table 2).
Nutrient uptake
Among the different combinations of organic manures, application of P as vermicompost + ghanajeevamrutha @ 100% RDP +
Rhizobium + PSB (T
8) has resulted in higher uptake of nutrients
i.e., nitrogen (52.07 and 75.43 kg ha
-1), phosphorus (10.12 and 16.08 kg ha
-1) and potassium (37.67 and 55.42 kg ha
-1) by the black gram at 45 and 75 DAS respectively (Table 3).
Application of FYM + ghanajeevamrutha @ 100% RDP +
Rhizobium + PSB as well as FYM+ vermicompost @ 100% RDP +
Rhizobium + PSB has resulted in highest nitrogen and phosphorus uptake at both 45 and 75 DAS which was at par with treatment T
8 (Fig 1).
Microbial load
The field experiment was conducted during
Kharif season of 2005 and 2006 at the research farm of SKN College of Agriculture, Jobner, RAU, Bikaner on sandy loam soil.
The higher microbial population in the soil is a positive indicator of soil quality which can be enhanced through the addition of organic matter to the soil. Among the different combination of organic manures, application of FYM + vermicompost @ 100% RDP +
Rhizobium + PSB has resulted in highest bacteria, fungi and actinomycetes population (24.4 *10
6 CFU g
-1, 17.00 *10
4 CFU g
-1, 7.50 *10
3 CFU g
-1, respectively) which was at par with the treatments FYM + ghanajeevamrutha @ 100 % RDP +
Rhizobium + PSB and vermicompost + ghanajeevamrutha @ 100 % RDP +
Rhizobium + PSB were applied (Table 4).
The higher seed yield of black gram might be due to the prolonged and steady availability of major nutrients during the crop growth period with the inclusion of nutrient-rich organics
viz. FYM, vermicompost, Ghanajeevamrutha. The pivotal role of
Rhizobium in fixation of atmospheric nitrogen might have enhanced the supply and translocation of N which influenced the development of photosynthetic organs and inoculation of PSB to solubilize the insoluble P through the production of organic acids and have some augmenting effect on the native
Rhizobium population besides playing a vital role in nodule formation (
Sailaja Kumari and Usha Kumari, 2002,
Kumar et al., 2016 and
Wagadre et al., 2010).
Higher yield attributes due to the application of jeevamrutha might be attributed to the solubilisation of nutrients in soil and absorption of nutrients and moisture
(Sutar et al., 2019). Further, the elements
viz., nitrogen, phosphorus and potassium present in the protoplasm assisted in physiological functions of plants such as chlorophyll and protein synthesis which in turn boosted the plant growth. The results are corroborative with the findings of
Bhatt et al., (2012) and
Jagdeesh et al., (2018).
The maximum availability of nutrients and SOC in the soil might be ascribed to the addition of nutrients into the soil which remained unutilized even after crop harvest and thus improved the soil fertility status and soil physical, chemical and biological properties (
Meena and Ram, 2016). It might also be due to the inclusion of organic sources which promoted the nutrient supplying capacity of the soil and build-up of more and more soil microorganisms and mineralized organic nitrogen resulting in the production of auxins and gibberellins by PSB which might have also helped in increased root growth, N absorption and higher N content in black gram seed. Additionally,
Rhizobium inoculation helped the plant in effective atmospheric N fixation, resulting in higher seed nitrogen content substantially
(Bhalu et al., 1995; Yogananda et al., 2020).
When the organics are applied, nutrients will be released slowly reducing the nutrient losses because of the greater absorption of nutrients as a result of increased cation exchange capacity that is enhanced with organic manure application. Thus, plant nutrients will be available for a long period in sufficient quantity facilitating greater absorption and uptake of nutrients as per the demand. (
Kumawat, 2009;
Tyagi et al., 2018 and
Chaudhary et al., 2018).
The addition of FYM, vermicompost and ghanajeevamrutha to the soil resulted in enhanced microbial activity and release of nitrogenous compounds from organic carbon upon mineralization. Besides, there was an increase in nitrogen-fixing bacteria which might have increased the nitrification process and released more nitrogen into the soil solution. The soil microbes which produce organic acids during their decomposition of organic matter and CO
2 accelerate weathering process and convert unavailable phosphorus and potassium to available form for plants. Therefore, a higher amount of nutrients was left in the soil after maximum uptake by the crop.
ET Similar results were revealed by
Channagouda et al., (2015) Jat et al., (2010).