Response of inorganic and organic fertilizers on yield potential of pigeon pea (Cajanus cajan L.)

Introduction

Pigeon pea (Cajanus cajan L. Huth), a hardy leguminous crop, is distinguished by its deeprooting system and remarkable drought resilience. It constitutes a crucial source of dietary protein across several nations, particularly India. Notable for its nitrogen-fixing ability through symbiosis with rhizobium and its capacity to extract moisture from deeper soil strata, pigeon pea thrives in tropical and subtropical regions worldwide. It is extensively cultivated across South Asia, Southeast Asia, Africa, Latin America, and the Caribbean (Kingwell-Banham and Fuller, 2014) [13] . As a perennial species within the Fabaceae family, it is indigenous to the Eastern Hemisphere (Upadhyaya et al., 2013) [22] . Its exceptional drought tolerance renders it a dietary staple in arid and semi-arid regions (ICRISAT). Pigeon pea seeds serve as an economical and nutrient-rich complement to staple cereals such as maize, wheat, and rice, forming a dietary cornerstone in numerous African, Asian, and South American nations. They provide a balanced composition of proteins, carbohydrates, essential minerals, and B-complex vitamins, making them indispensable in vegetarian diets. When consumed alongside cereals, pigeon pea enhances dietary protein intake, offering a nutritional profile comparable to other high-protein sources like whey and soy (Akporhonor et al., 2006) [2] . Beyond its nutritional significance, pigeon pea exhibits medicinal attributes due to its abundance of polyphenols and flavonoids, compounds known for their therapeutic potential (Singh et al., 2016) [16] . Studies further underscore its role in human health, with evidence linking its consumption to a diminished risk of various chronic ailments (Singh and Basu, 2012) [17] . Pigeon pea, a long-duration pulse crop, thrives predominantly in nutrient-deficient soils under rainfed conditions, exhibiting remarkable adaptability to low-input and challenging agro-ecosystems. It holds immense dietary significance among pulses, serving as a vital protein source. The grain composition of pigeon pea includes 23.3% protein, 3.5% minerals, and 57.6% carbohydrates, delivering an energy value of 335 kcal per 100 grams. While its dry split dhal is a dietary staple, tender green seeds are consumed as vegetables, and its stems and roots serve as a sustainable source of fuelwood. The suboptimal yield of pigeon pea is not solely attributable to its cultivation on sub-marginal lands but is also exacerbated by inadequate crop management and soil moisture deficits during critical phenological stages, such as flowering and pod development, which precipitate substantial reductions in grain yield (Pandey et al., 2015) [14] . Furthermore, the indiscriminate and imbalanced application of fertilizers has led to diminished productivity, soil fertility degradation, and the emergence of multifaceted nutrient deficiencies. Integrating farmyard manure (FYM) with inorganic fertilizers ameliorates soil structure, augments water retention capacity, and enhances overall agroecosystem productivity. The residual effects of organic nutrient amendments in preceding crops confer significant benefits to succeeding crops, thereby ensuring long-term sustainability in agricultural production systems. Empirical studies conducted by Ismail et al. (1994) [11] underscore the profound influence of conservation tillage on improving the physical and chemical properties of soil. Organic inputs, encompassing plant and animal-derived residues, serve as vital nutrient reservoirs that undergo mineralization through microbial decomposition. The tradition of employing organic matter, such as animal, human, and plant waste, to augment crop productivity dates back to the advent of agriculture. Manures, derived from the decomposition of biological residues, encapsulate an array of essential nutrients in complex organic matrices, whereas fertilizers-whether naturally sourced or synthetically manufactured-are explicitly designed to supply crops with readily available nutrients. While fertilizers provide a higher nutrient concentration per unit, manures, despite their relatively lower nutrient content, exert a more profound and enduring impact on soil fertility and crop health by fostering soil microbial diversity and improving soil physicochemical attributes. Vermicomposting, an advanced organic waste management practice involving the cultivation of earthworms for the bioconversion of organic matter, yields Vermicompost, a nutrient-dense organic amendment. This biofertilizer is enriched with essential macronutrients, including nitrogen (2-3%), phosphorus (1.55-2.25%), and potassium (1.85-2.25%), along with a plethora of micronutrients, beneficial soil microbiota, plant growth hormones, and enzymatic compounds. Research by Tiwari and Singh (2021) [19] corroborates that Vermicompost not only enhances plant growth and vigour but also fortifies plants against pest infestations and disease outbreaks. Consequently, it emerges as a crucial component in sustaining soil fertility and bolstering plant development across both agricultural and horticultural landscapes. In recent years, the integration of biostimulats in agronomic practices has gained prominence, particularly within organic farming paradigms, further underscoring their pivotal role in enhancing crop resilience and productivity.

Materials and Methods

This study aimed to explore how varying levels of organic and inorganic fertilizers on growth and yield of pigeonpea variety IPA-203. The research was conducted at the Student Research Farm within the Department of Agronomy at the School of Agriculture Science Technology and Research, Sardar Patel University, Balaghat, Madhya Pradesh, during the Rabi season of 2023, detailing the materials utilized and the methodologies employed throughout the investigation. Balaghat District is situated in the south-eastern region of the Satpura Range and the upper Wainganga River valley, spanning from 21°19' to 22°24' north latitude and 79°31' to 81°30' east longitude.The treatments consisted of T 0 (Control), T 1 (100% RDF [NPK: 30:50:30 kg/ha]), T 2 (100% Farmyard Manure (FYM)), T 3 (100% Vermicompost (VC)), T 4 (100% Poultry Manure (PM)), T 5 (75% VC + 25% FYM), T 6 (75% PM + 25% VC), T 7 (75% PM + 25% FYM), T 8 (50% VC + 50% FYM), T 9 (50% PM + 50% VC), T 10 (50% PM + 50% FYM), and T 11 (33.33% FYM + 33.33% VC + 33.33% PM) each replicated thrice. The height of five randomly selected grafted plants from each plot was measured in centimeters using a meter scale, from the ground level to the tip of the shoot, at 20, 40, and 60 days after sowing (DAS). The average plant height for each replication was recorded and subjected to statistical analysis. Similarly, the total number of trifoliate leaves that emerged in plants was counted at 20, 40, and 60 DAS and documented accordingly. The number of branches per plant was determined by counting branches in randomly selected plants from each plot at 40 and 60 DAS. The average number of branches per plant for each replication was then recorded and analyzed statistically. To assess root nodulation, plants were uprooted at 35 DAS, and the total number of root nodules formed was counted and documented. Additionally, the number of flower pods set per plant was counted and recorded to determine the number of pods per plant for each treatment and replication. The collected data was subjected to statistical analysis. The 1000-seed weight was measured using a physical balance from seeds obtained from five randomly selected plants, and the average weight was recorded and analyzed statistically. The total seed yield/hectare was calculated by unitary method formula given below: Seed yield per hectare = X 10,000 m 2

Harvest index was computed by using following formula as suggested by Singh and Stoskoff (1971) [18] . The harvest index was worked out by using following formula:

The statistical analysis was conducted using Fisher and Yates (1963) [9] .

Results and Discussion

In 2024, India surpassed China to become the world's most populous country, with its population expected to grow from 1.38 billion to nearly 1.5 billion by 2030. This demographic expansion necessitates a rise in food production from 309 million tonnes in 2020-21 to 345 million tonnes by 2030 (Sharma, 2021) [15] . Given that India possesses only 2.4% of the world's land while supporting 18% of the global population, small and marginal farmers play a crucial role in ensuring food security. However, feeding this growing population is challenging due to climate change, water scarcity, and the decreasing availability of arable land. Organic fertilizers present a viable solution for improving environmental sustainability and plant growth. Derived from composted animal manure, human waste, household refuse, municipal and agricultural residues, and plant material, organic fertilizers enhance soil organic matter (SOM), soil structure, and nutrient availability while boosting microbial activity, ultimately increasing crop productivity. Additionally, they improve soil cation exchange capacity (CEC), moisture retention, and modify the characteristics of acidic soils and soil fauna community structure (Zhou et al., 2022) [23] . The application of organic fertilizers also promotes the stability and formation of earthworm populations by providing stable nutrients from manure following aerobic fermentation. In contrast, prolonged use of chemical fertilizers depletes SOM, leading to soil acidification, crust formation, and disruption of microbial communities. The integration of organic fertilizers reduces dependency on synthetic inputs, thereby enhancing soil health, environmental quality, and agricultural productivity (Bertrand et al., 2015) [5] . Organic fertilizers play a vital role in revitalizing soil due to their high SOM and nutrient content. Their application can potentially reduce chemical fertilizer usage by 50%, lowering production costs while improving soil fertility for enhanced crop yields. Rich in both micro and macronutrients, organic fertilizers serve as a crucial nitrogen source for crops. Various studies highlight the positive effects of farmyard manure, slurry, and compost in increasing the yield and quality of crops like tomatoes, maize, and rice. Moreover, organic fertilizers enhance the physicochemical and biological properties of soil, ensuring better nutrient availability and supporting sustainable agro ecosystems. Animal waste remains the largest source of organic manure worldwide, with poultry and pig manure also contributing significantly. The rising demand for milk and beef has led to a 5% increase in cattle production, subsequently increasing the availability of cattle manure, a valuable input for soil fertility and environmental sustainability (Ahmed et al., 2016) [1] . Globally, animal manure contributes between 81.5 to 128. [4] ; and Du et al., 2020 [8] also reported findings that were similar.

Number of branches per plant and number of nodules per plant

Among the treatments ( performed best, as it provided a well-rounded mix of nutrients that enhanced soil health, microbial activity, and nutrient cycling. The organic matter from FYM improves soil structure, facilitating better root expansion, while vermicompost and poultry manure supply essential micronutrients and growthpromoting hormones that foster branching and nodule formation. This organic synergy leads to a more extensive root system capable of supporting more branches and nodules. The treatment with 50% VC + 50% FYM (T 8 ) also showed good results, though the lack of poultry manure may have slightly limited the response compared to T 11 . Nonetheless, these organic inputs still improved root and shoot development, contributing to better branching and nodule formation. Tejasvi and Kumar 2012 [21] ; Dhaliwal et al., 2019 [7] ; and Du et al., 2020 [8] also reported findings that were similar. Potassium contributes to improved photosynthetic efficiency, facilitating better nutrient transport and utilization, which directly results in higher pod production and seed yield. Among the organic treatments, the mixture of 33.33% FYM, 33.33% VC, and 33.33% PM (T 11 ) proved to be the most effective. The organic matter from FYM enhances soil structure and water retention, fostering an environment conducive to root growth and nutrient uptake. Additionally, vermicompost and poultry manure increase nutrient availability, boost microbial activity, and stimulate plant growth hormones, all of which support improved flowering, pod formation, and seed setting, leading to a rise in pod and seed counts per plant. The combination of 50% VC and 50% FYM (T 8 ) also yielded favourable outcomes; however, the lack of poultry manure may have restricted some growth-enhancing factors. Nevertheless, the organic inputs in T 8 still contributed to enhanced overall plant productivity, resulting in a notable increase in pods per plant, seeds per pod, and seed yield compared to other treatments. Similar findings were reported by Tejasvi and Kumar 2012 [21] ; Gadi et al., 2017 [10] ; Bhavya et al., 2018 [6] and Kumar et al., 2021 [12] .

B)

Seed yield; Straw yield; test weight and harvest index

Among the treatments (table 3), T 1 (100% RDF-NPK: 30:50:30 kg/ha) recorded the highest test weight, with 10.47 grams. At par with T 11 (33.33% FYM + 33.33% VC + 33.33% PM), which produced 10.20 grams, followed by T 8 (50% VC + 50% FYM) with 9.74 grams, securing the third position. In contrast, the control treatment (T 0 ) demonstrated the lowest test weight, with only 7.87 grams. Among the treatments, T 1 (100% RDF-NPK: 30:50:30 kg/ha) recorded the highest seed and stover yield, with 21.01 and 51.01 q/ha respectively. At par with T 11 (33.33% FYM + 33.33% VC + 33.33% PM), which produced 20.69 q/ha for seed yield and 49.43 for stover, followed by T 8 (50% VC + 50% FYM) with 19.19 and 48.78 q/ha respectively, securing the third position. In contrast, the control treatment (T 0 ) demonstrated the lowest seed and stover yield, with only 8.04 and 39.82 q/ha respectively. Among the treatments, T 11 (33.33% FYM + 33.33% VC + 33.33% PM) recorded the highest harvest index, with 29.51%. At par with T 1 (100% RDF-NPK: 30:50:30 kg/ha), which produced 29.16%, followed by T 9 (50% PM + 50% FYM) with 29.83%, securing the third position. In contrast, the control treatment (T 0 ) demonstrated the lowest harvest index, with only 16.81%. The enhanced seed yield, straw yield, test weight, and harvest index observed in pigeon pea treated with 100% RDF-NPK (30:50:30 kg/ha) can be linked to the wellbalanced and sufficient provision of vital nutrients. Nitrogen fosters vigorous vegetative growth and optimal pod development, phosphorus supports flowering and seed formation, while potassium plays a crucial role in effective photosynthesis, water management, and nutrient absorption. These elements collectively enhance plant growth, increase seed production, and elevate the harvest index, which represents the ratio of seed yield to total biomass. The balanced nutrient supply from RDF-NPK also facilitates improved seed filling and overall plant health, resulting in greater test weight and seed yield per plant. Among the organic treatments, the blend of 33.33% FYM + 33.33% VC + 33.33% PM (T 11 ) yielded the best results. The organic components in this treatment enhance soil structure, water retention, and nutrient availability through microbial activity and the gradual release of organic matter. The combined nutrient input from FYM, vermicompost, and poultry manure encourages better vegetative growth, an increase in pod numbers, and improved seed setting, leading to higher seed yield and test weight. Furthermore, this combination aids in maintaining soil fertility and enhances microbial activity, which further promotes overall plant health and productivity. The treatment with 50% VC + 50% FYM (T 8 ) also demonstrated positive outcomes, although its slightly lower diversity in organic inputs compared to T 11 may have restricted its full potential regarding yield and harvest index. Nevertheless, it still resulted in significant improvements in seed and straw yield, test weight, and harvest index compared to other organic treatments.

Findings were in accordance with findings of Armin et al., 2016 [3] ; Gadi et al., 2017 [10] ; Bhavya et al., 2018 [6] and Kumar et al., 2021 [12] .

C) Economics parameters

Maximum cost of cultivation(table 4)was recorded in treatment T 1 (100% RDF [NPK: 30:50:30 kg/ha])with (Rs 41,182ha -1 ) followed by T 4 (100% Poultry Manure)having Rs 40,900 ha -1 and the minimum (Rs 37,100ha [6] and Tadewos et al., 2021 [20] .

Conclusion

The findings of this research clearly demonstrate that utilizing a combination of inorganic and organic fertilizers significantly enhances the growth and yield of pigeon pea. Among the various treatments, the 100% RDF-NPK (30:50:30 kg/ha) treatment (T 1 ) consistently showed superior results, producing the tallest plants, the highest number of branches, increased nodule counts, and better seed and stover yields. Specifically, T 1 achieved the highest test weight of 10.47 grams, highlighting its effective nutrient supply that fostered vigorous plant growth and optimal seed production. Organic treatments, especially T 11 (33.33% FYM + 33.33% VC + 33.33% PM), also yielded commendable results, nearly matching the inorganic treatment in growth metrics such as plant height (100.98 cm at 60 DAS), branches per plant (27.56 at 60 DAS), nodules per plant (14.00), test weight (10.20 grams), and a seed yield of 20.69 q/ha. The integrated nutrient supply from farmyard manure (FYM), vermicompost (VC), and poultry manure (PM) in T 11 improved soil fertility, microbial activity, and nutrient availability, resulting in enhanced growth and productivity. Additionally, T 11 achieved the highest harvest index at 29.51%, indicating effective biomass utilization for seed production. From an economic standpoint, both T 1 and T 11 provided the highest net returns and benefit-cost ratios, establishing them as the most financially viable options for pigeon pea cultivation. Therefore, adopting a balanced strategy that includes both inorganic and organic fertilizers can significantly boost productivity and profitability in pigeon pea farming.

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