The impact of various organic sources on soil nutrient content and nutrient uptake in green gram (Vigna radiata L. WILCZEK) under organic farming practices

Introduction

The green gram (Vigna radiata), also known as mung bean or golden gram, is a major shortduration pulse crop grown in India. It is a versatile crop cultivated for seeds, green manure and forage. It is an effective green manure when mixed into the soil. Green gram, as a legume crop, has low nitrogen requirements. It uses atmospheric nitrogen by establishing symbiotic nitrogen fixation with nodule bacteria to fulfil almost all its nitrogen needs under typical circumstances (Kannaiyan, 1999) [6] . Green gram is a protein-rich food with a protein content of 25% and a high digestibility (Bandani et al., 2014) [1] . It prevents soil erosion by serving as a cover crop. As a short-duration crop, it is suitable for various intensive crop rotations. In North India, it is grown in both the kharif and summer seasons, while in South India, it is cultivated during the rabi season. The Green Revolution boosted food production but led to permanent soil fertility loss because of the increasing gap between nutrient depletion and availability. Preventing the decrease of soil organic matter is essential to limit the ongoing soil degradation. The application of organic manures to soil is critical for preserving native soil fertility (Zibilske, 1987) [13] . Vermicompost contains nutrients that are easily accessible to plants, such as nitrate, exchangeable phosphorus, potassium, calcium and magnesium. Edwards and Burrows (1988). The substance also includes biologically active compounds like plant growth regulators (Tomatic et al., 1987) [12] . Continuously adding organic materials to the soil over a prolonged period leads to higher levels of organic matter, organic carbon content, crop productivity, soil biological activity and the quality of the produce (Collins et al., 1992) [3] . Panchagavya, Jeevamrut, Beejamrut, Sasyamrut and Vermiwash are fermented liquid organic manures that contain a wide range of macro and micronutrients, vitamins, essential amino acids, various microorganisms and growth-promoting substances. These substances aid in enhancing plant growth, metabolic processes and resilience against pests and diseases.

Materials and Methods

The study took place at Organic Farm, Navsari Agricultural University, Navsari, in the rabi season of 2020-21. The farm where the experiment was conducted, the soil belongs to the Ustochrepts great group and is classified under the Jalalpur series. Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha T10 Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha + EBPS 1% T11

Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha + Cow urine 2% T12

Ghan-jivamrut @500 kg/ha + jivamrut@500l/ha + Vermiwash 1%

Organic nutrient sources like NADEP compost, vermicompost, Ghan-jivamrut and jivamrut were added to the soil during sowing based on the treatments. Provided organic sources (EBPS, Cow urine and Vermiwash) using foliar spray three times at 15, 30 and 45 days after sowing. Seeds were treated with Rhizobium and PSB at a rate of 10 ml per kilogram for all treatments. [5] pH (1:2.5)

7.8 Organic Carbon (%) 0.86 Walkley and Black method (Jackson, 1967) [5] Available Nitrogen(kg/ha) 264.3 Alkaline KMnO4 method (Subbiah and Asija, 1956) [11] Available Phosphorus(kg/ha) 38.9

Olsen's method (Olsen 1954) [8] Available Potassium (kg/ha) 502.0 Flame photometric method (Jackson, 1967) [5] Results and discussion Nutrient content (%) in grain and stover The nutrient content in grain and stover did not vary significantly with different treatments. The nitrogen, phosphorus and potassium content in both the grain and stover of green gram did not show significant differences among the various treatments.

Nutrient Uptake by Grain and Stover Nitrogen uptake

The data in Table 4 indicated that nitrogen uptake was significant across the various treatments. Treatment T6, which consisted of 100% RDN through vermicompost + EBPS 1%, showed significantly higher nitrogen uptake in both grain and stover. However, for grain, it was statistically at par with treatments T2 and T8 and for stover, it was at par with treatments T2, T3, T4, T5 and T8. Lower nitrogen uptake was observed in grain and stover under treatment T9 (Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha), it is at par with treatments T1, T3, T10, T11 and T12 for grain, and at par with treatments T1, T7, T10, T11 and T12 for stover. Treatment T6 showed increased nitrogen uptake possibly due to enhanced nitrogen fixation by bacteria, leading to improved absorption and utilization of plant nutrients, resulting in higher nitrogen and phosphorus content in grain and stover. The results of this study closely aligned with the findings of Davari et al., (2012) [4] and Choudhary et al., (2013) [2] in the green gram crop.

Phosphorus uptake

The data in Table 4 indicated that the uptake of phosphorus was substantial in response to the treatments. In the case of grain, treatment T6 (100% RDN via vermicompost + EBPS 1%) resulted in significantly higher phosphorus uptake, but it was statistically at par with treatments T2, T4 and T8. Treatment T6 showed significantly higher phosphorus uptake compared to other treatments (T2, T3, T4, T5 and T8) but was statistically at par with them. Significantly lower phosphorus absorption by grain was observed in treatment T9 (Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha), which was at par with treatments T1, T3, T10, T11 and T12. Treatment T9 led to a significant decrease in phosphorus uptake compared to treatments T1, T7, T10, T11 and T12. Treatment T6 likely led to increased phosphorus uptake due to the presence of organic nutrient sources with high organic matter content, promoting plant growth and higher phosphorus absorption, resulting in greater grain yield. Seed inoculation with PSB facilitated the release of phosphorus from the soil and prevented the fixation of additional phosphate, resulting in higher phosphorus availability for the plants and increased nutrient content in the plant. The results of this study closely matched the findings of Davari et al., (2012) [4] and Choudhary et al., (2013) [2] in the green gram crop.

Potassium uptake

Table 4 results indicated a significant potassium uptake with the treatments. Treatment T6 (100% RDN through vermicompost + EBPS 1%), showed significantly higher potassium uptake in grains compared to other treatments. However, it was statistically at par with treatment T2. In terms of potassium uptake in stover, treatment T6 also showed significantly higher levels but was statistically at par with treatments T2, T3, T4, T5 and T8. Lower potassium absorption was observed in grain and stover under treatment T9 (Ghan-jivamrut @500 kg/ha + jivamrut @500l/ha), which was at par with treatments T10, T11 and T12 for grain. For stover, it was statistically at par with treatments T1, T7, T10, T11 and T12. Treatment T6 led to increased potassium uptake possibly because of enhanced nitrogen fixation by bacteria, facilitating improved absorption and utilization of plant nutrients, resulting in higher nitrogen and phosphorus content in grain and stover. The results of this study closely aligned with the findings of Davari et al., (2012) [4] and Choudhary et al., (2013) [2] in the green gram crop.

Post-harvest nutrient status of soil

The data from Table 5 indicated that the levels of organic carbon, available nitrogen, available phosphorus, and available potassium in the soil did not show any significant differences among the treatments. Treatment T6 (100% RDN through vermicompost + EBPS 1%), showed the highest levels of organic carbon, available nitrogen, available phosphorus and available potassium in the soil after the harvest.

Conclusion

The study concluded that the highest uptake of nitrogen, phosphorus and potassium, as well as improvement in soil fertility for green gram, can be achieved by applying Treatment T6, which consists of 100% RDN through vermicompost along with Enriched Banana Pseudostem Sap at a 1% concentration sprayed at 15, 30 and 45 days after sowing of green gram crop under organic farming.

Acknowledgement

AcknowledgmentsI am grateful to my institution where this experiment was carried out and always will be grateful to my Major Adviser Dr. P. K. Dubey, who supported and encouraged me during my course of experiment and provided necessary facilities to carry out this experiment.

References

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