Legumes (Fabaceae) play a key role in world agriculture as a dietary protein source, animal fodder and as the main biological pathway connecting the atmosphere with cultivated soils via fixation of nitrogen gas (N2). India accounts for approximately 25% of global pulse production, most under rainfed conditions with low soil fertility (
Directorate of Pulses Development, 2024a;
FAO, 2024). Legumes fix atmospheric N2 and produce plant-available ammonium in the soil, sparing the subsequent crop part of its synthetic nitrogen requirement
(Barbieri et al., 2023; Ghafoor et al., 2024). Their deep, dense root systems mobilise sparingly soluble soil phosphorus, enhance soil aggregation and improve the soil carbon-to-nitrogen ratio, favouring mineralisation upon incorporation
(Ansari et al., 2022; Kaur et al., 2018) and legume-based systems more broadly enhance nutrient cycling and long-term ecosystem sustainability
(Sharma et al., 2025), making legumes essential for intercropping, rotation and green-manuring programmes restoring fertility in intensively cultivated areas such as the rice-wheat systems of the Indo-Gangetic Plains
(Samal et al., 2017; Kumar et al., 2023).
Legume yields in most developing regions remain well below those in developed systems, a gap frequently attributed to nutrient imbalance, poor rhizobial establishment, inadequate phosphorus and micronutrient supply and suboptimal integration of organic and inorganic sources
(Patel et al., 2026; Shukla and Behera, 2021;
Shukla et al., 2021). This review consolidates recent agronomic and soil-fertility literature on legume-based systems, covering: (i) biological nitrogen fixation and its quantification, (ii) cropping-system design, (iii) nutrient and micronutrient management, (iv) biofertilizer and rhizobacterial technologies and (v) organic matter, residue and soil organic carbon dynamics.
Major legume crops of India: distribution and agronomic importance
India is the largest producer, consumer and importer of pulses, accounting for about 28% of world production and 37% of world pulse area (
Directorate of Pulses Development, 2024a, 2024b). Total pulses production reached a record 252.38 lakh tonnes on about 277 lakh ha in 2024-25, up from 242.46 lakh tonnes in 2023-24, with notable gains in moong and tur (
Ministry of Agriculture and Farmers’ Welfare, 2025). Rabi-season pulses contribute more than 60% of national production, with chickpea alone accounting for almost 40% (
Directorate of Pulses Development, 2024b). National productivity remains below the global average of about 910 kg/ha, largely because production occurs predominantly under rainfed, resource-limited conditions (
FAO, 2024;
Kumar et al., 2024; Ministry of Agriculture and Farmers’ Welfare, 2025).
Chickpea (gram), concentrated in Maharashtra, Madhya Pradesh and Rajasthan, is the single most important pulse, valued for its yield stability under residual soil moisture
(Thakur et al., 2024; Kumar et al., 2024). Pigeonpea (tur/arhar), concentrated in Maharashtra, Karnataka and Gujarat, is a long-duration crop contributing substantial biomass and root-zone nitrogen enrichment (
Directorate of Pulses Development, 2024a, 2024b). Mungbean and urdbean are important short-duration options for fitting a legume into intensive rice-wheat and cereal-based rotations, particularly in Rajasthan, Madhya Pradesh, Uttar Pradesh and southern India (
Directorate of Pulses Development, 2024b;
Kaur et al., 2018). Lentil, concentrated in Madhya Pradesh, Uttar Pradesh, West Bengal and Bihar, was one of the few major pulses without a consistent positive production trend over 2010-2020
(Kumar et al., 2024). Among oilseed legumes, soybean production reached a record 152 lakh tonnes, concentrated in Maharashtra, Madhya Pradesh and Rajasthan, while groundnut production reached a record 119 lakh tonnes, up nearly 17% year-on-year, concentrated in Gujarat, Rajasthan, Tamil Nadu and Andhra Pradesh (
Ministry of Agriculture and Farmers’ Welfare, 2025). Groundnut productivity, historically trailing the global average, has converged with recent global benchmarks in several states following expanded irrigation and improved sulphur-zinc nutrition
(Srinivasarao et al., 2008; Yadav et al., 2019).
Table 1 summarises area, production and productivity for the principal legume crops using 2024-25 final crop statistics (
Department of Agriculture and Farmers Welfare, 2026;
Ministry of Agriculture and Farmers’ Welfare, 2025).
Provisional 2025-26 third advance estimates point to further gains, with total pulses area and production placed at about 286 lakh ha and 274 lakh tonnes (
Department of Agriculture and Farmers Welfare, 2026). Chickpea has historically shown the least year-to-year instability among major pulses, whereas mungbean and urdbean are markedly more variable, reflecting sensitivity to moisture stress at flowering and pod-fill; lentil instability has been linked to its frequent cultivation as a secondary or relay crop with lower input priority
(Kumar et al., 2024; Murugananthi et al., 2024). These differences underline why nutrient and cropping-system recommendations for legumes must be calibrated to the specific crop, season and region.
Biological nitrogen fixation and the rhizobium-legume symbiosis
Biological nitrogen fixation is the process by which soil bacteria collectively termed rhizobia infect legume roots, inducing nodule formation within which the enzyme nitrogenase reduces atmospheric N2 to ammonia in exchange for photosynthate from the host plant
(Ghafoor et al., 2024; Peoples et al., 2009; Vance, 2001). Because it depends on an active symbiosis rather than fertiliser inputs, BNF is the most sustainable route of nitrogen entry into agroecosystems and the second-largest natural source of fixed nitrogen after industrial ammonia synthesis
(Barbieri et al., 2023; Herridge et al., 2008).
The proportion of legume nitrogen derived from the atmosphere (Ndfa, estimated via 15N isotope-dilution) varies widely with species, rhizobial strain compatibility, soil nitrate status, moisture and temperature. A global meta-analysis of data from 1980-2018 reported Ndfa ranging from about 5% to 99%, averaging roughly 68%, with fodder legumes generally exceeding grain legumes
(Ghafoor et al., 2024; Herridge et al., 2008). This reflects genuine differences in soil nitrate carry-over, rhizobial population density and moisture availability across trial environments and is the main reason blanket BNF or fertiliser-substitution values cannot be applied uniformly
(Barbieri et al., 2023; Giller, 2001).
Several factors govern BNF efficiency in the field. High residual soil nitrate suppresses nodulation because plants preferentially use the more energetically favourable mineral nitrogen, the physiological basis for restricting fertiliser N to a small starter dose in pulses
(Barbieri et al., 2023; Peoples et al., 2009). Rhizobial strain specificity, host-cultivar compatibility, soil acidity, waterlogging and micronutrient status (particularly molybdenum and cobalt, nitrogenase cofactors) also strongly influence fixation rates
(Peoples et al., 2009; Shukla et al., 2021; Vance, 2001). Legume-grass mixtures have been shown to enhance nodulation and nitrogen transfer to companion grasses through altered root architecture, an effect documented even on the Qinghai-Tibet Plateau
(Luo et al., 2024). Most precise BNF quantification still relies on isotopic or difference methods at experiment-station scale; farmer-field estimates show wider variance, so Table 2 values should be read as central tendencies rather than fixed constants
(Herridge et al., 2008).
Legume-based cropping systems: intercropping and rotation
Integrating legumes into cereal-dominated cropping systems, as intercrops or in rotation, is among the most extensively documented strategies for restoring and sustaining soil fertility. Cereal-legume intercropping enables more complete use of light, water and nutrient resources than sole cropping and consistently reduces soil bulk density, increases cation exchange capacity and organic matter and enhances soil enzymatic activity relative to monocultures, partly by intercepting raindrops before they strike bare soil and limiting erosion
(Singh et al., 2025; Dugassa, 2023).
Because the legume draws less heavily on soil mineral nitrogen than the companion cereal, intercropped systems extract fewer nutrients overall while returning nitrogen-rich residues; on smallholder farms in Eastern and Southern Africa, maize-pigeon pea intercropping has raised maize production by as much as 35% relative to sole maize and cowpea intercropped with millet has raised millet yield by around 30%
(Akchaya et al., 2025; Singh et al., 2025). Reviews synthesising trials across diverse agro-climatic zones report yield gains of 30-35% together with fixed-nitrogen contributions of roughly 125 kg N/ha per season, alongside reduced tillage, lower bulk density, improved infiltration and gains in soil organic carbon and microbial biomass
(Akchaya et al., 2025). The land equivalent ratio (LER), the standard index of intercropping’s resource-use efficiency relative to sole crops, consistently exceeds unity in cereal-legume systems, confirming a genuine productivity advantage, though the magnitude varies with row configuration, sowing density and seasonal rainfall; trials in moisture-limited years or poorly matched row ratios report LER closer to unity
(Akchaya et al., 2025; Dugassa, 2023;
Willey, 1979).
Legume intercrops also promote a more diverse and beneficial rhizosphere bacterial community, including plant growth-promoting rhizobacteria (PGPR) that assist both intercropped species, thought to underlie part of the yield-stability advantage under environmental stress
(Chamkhi et al., 2022). In rotation-based systems, inclusion of a short-duration pulse such as mungbean or urdbean within the rice-wheat sequence of the Indo-Gangetic Plains improves soil water conservation, raises available N, P, K and micronutrient status and improves aggregate stability, bulk density and hydraulic conductivity relative to unbroken rice-wheat rotation
(Samal et al., 2017; Kaur et al., 2018; Kumar et al., 2023). Optimal intercrop configuration depends on relative maturity duration, planting density, row arrangement and local circumstances, so recommendations from one agro-climatic zone do not always transfer directly to another
(Singh et al., 2025; Dugassa, 2023).
Nutrient and micronutrient management in legume production
Legume nutrient requirements differ qualitatively from those of cereals. Because much of nitrogen demand is met through BNF, legumes generally require only a small starter dose (about 15-25 kg N/ha); larger applications tend to depress nodulation and fixation without proportionate yield benefit
(Barbieri et al., 2023; Peoples et al., 1995). Phosphorus and sulphur demand in pulses exceeds that of cereals, being required for root proliferation, nodule formation and protein synthesis, while potassium, often assumed adequate in Indian soils, is in practice deficient to medium in most surveyed districts owing to intensive cropping and inadequate replenishment
(Patel et al., 2026; Pathak et al., 2026).
Micronutrients play a disproportionately important role. Molybdenum is a direct cofactor of nitrogenase and nitrate reductase, so its deficiency directly constrains BNF; zinc, iron and boron support enzymatic and reproductive functions and are widely deficient in intensively cultivated, alkaline or calcareous soils (
Bouis and Saltzman, 2017;
Shukla and Behera, 2021;
Shukla et al., 2021). Because pulses are also a dietary source of these micronutrients, correcting soil deficiency serves both agronomic and biofortification objectives (
Bouis and Saltzman, 2017). These nutrient management options and their major agronomic roles are summarised in Table 3.
Field-scale studies from semi-arid India show how integrated nutrient management (INM), combining inorganic fertiliser, organic manures and microbial inoculants, improves both productivity and residual soil fertility. In a black gram-mustard system, combining fertiliser with organic manures and biofertilisers allowed a 25% reduction in inorganic fertiliser from the second year without loss of productivity
(Pathak et al., 2026). INM significantly improves nodulation, nutrient uptake, productivity and economic returns in soybean
(Biswas et al., 2025) and combining recommended fertiliser doses with farmyard manure more broadly enhances available soil N and P, raises organic carbon and reduces bulk density relative to fertiliser alone, with phosphorus-manure-biofertilizer combinations similarly improving pigeon pea and wheat yield and soil health indicators in rotation studies
(Patel et al., 2026; Kaur et al., 2018).
Sulphur and micronutrient deficiency in indian soils: implications for legumes
A nationwide soil-testing exercise covering more than 2.4 lakh surface soil samples from 615 districts across 28 states has documented widespread and geographically variable deficiencies of sulphur and micronutrients in Indian soils (
Shukla and Behera, 2021;
Shukla et al., 2021). Because sulphur is essential to seed protein synthesis and zinc, boron and molybdenum are implicated in enzymatic, reproductive and nitrogen-fixation processes, these deficiencies translate directly into agronomic and nutritional shortfalls
(Shukla et al., 2021; Singh, 2008). The major micronutrient deficiencies and their agronomic significance for legumes are summarised in Table 4.
Field evidence from groundnut, India’s leading oilseed legume by area and second globally in production, illustrates the practical consequences: trials combining sulphur and zinc fertilisation have shown substantial pod-yield gains over unfertilised controls, along with biofortification of kernel zinc and protein content, addressing agronomic and nutritional goals simultaneously (
Ministry of Agriculture and Farmers’ Welfare, 2025;
Srinivasarao et al., 2008; Yadav et al., 2019). In semi-arid rainfed Rajasthan and elsewhere, sulphur deficiency continues to constrain yield, oil content and grain quality, reinforcing the case for including sulphur and zinc as standard components of legume fertiliser recommendations rather than optional supplements
(Shukla et al., 2021; Srinivasarao et al., 2008). Much of India’s remaining groundnut yield gap is likely addressable through targeted secondary- and micro-nutrient correction rather than new land or germplasm.
Biofertilisers and plant growth-promoting rhizobacteria
Microbial inoculants represent a century-old but continually evolving technology in legume agronomy, dating to the first commercial Rhizobium-based inoculant marketed in the late nineteenth century
(Aloo et al., 2022). Modern formulations extend beyond rhizobial strains to phosphate- and potassium-solubilising bacteria, Azotobacter, Azospirillum and a broad group of PGPR acting through phytohormone synthesis, nutrient solubilisation, siderophore-mediated iron acquisition and induced systemic resistance (
Shakila and Vijaya, 2025;
Wang and Xu, 2026;
Aloo et al., 2022).
Across cropping systems, biofertiliser use has been associated with yield increases of roughly 10-40%, alongside improved grain protein, amino acid and micronutrient content (
Shakila and Vijaya, 2025). In arid-grown chickpea, combined inoculation with nitrogen-fixing, phosphate-solubilising and potassium-solubilising rhizobacteria improved nutrient uptake and yield relative to uninoculated controls
(Nabati et al., 2025). Under drought stress, co-inoculation of Rhizobium leguminosarum with other PGPR strains has improved faba bean performance on poor-fertility, newly reclaimed soils and PGPR strains have also been reported to alleviate heavy-metal stress and improve salinity tolerance in other crops
(Mansour et al., 2021; Wang and Xu, 2026;
Aloo et al., 2022). The observed 10-40% variation in response is largely attributable to differences in indigenous rhizobial abundance, with the greatest responses where native rhizobia are scarce or poorly adapted to the host cultivar
(Mansour et al., 2021; Aloo et al., 2022).
Field-level adoption nonetheless faces practical constraints, including inoculant shelf-life, compatibility with indigenous soil microbiota, sensitivity to pH and temperature and inconsistent commercial quality control
(Aloo et al., 2022). Recommendations continue to stress carrier-based formulation, seed-treatment technique and locally adapted strains over generic inoculants. Rhizosphere engineering-deliberate restructuring of root-zone microbial networks-is positioned as the next stage in biofertiliser development, moving toward designed consortia tailored to specific legume-soil combinations (
Wang and Xu, 2026).
Organic amendments, residue management and soil organic carbon dynamics
Legume residues and green manures contribute organic matter of a comparatively low carbon-to-nitrogen ratio, favouring rapid microbial decomposition and nitrogen mineralisation relative to cereal residues
(Tripolskaja et al., 2023; Bolinder et al., 2020). Long-term studies in the foothills of the Eastern Himalaya show that incorporating legume green manure with residue retention in maize-groundnut systems raises organic carbon stocks, improves soil aggregation and increases microbial biomass carbon over successive seasons
(Ansari et al., 2022). In the Indo-Gangetic Plains, a legume phase such as summer mungbean within conservation-agriculture rice-wheat systems is among the most efficient combinations for simultaneously sustaining yield, soil health and carbon sequestration, in contrast to continuous rice-wheat cultivation, which progressively depletes native reserves
(Samal et al., 2017).
A meta-analysis of 147 peer-reviewed studies across India’s agro-ecological zones found that, among organic amendments, farmyard manure produced the largest gains in soil organic carbon after biochar, followed by green manure and compost, with conservation tillage and residue retention providing moderate but consistent benefits, most pronounced in semi-arid and sub-humid regions over periods exceeding five years
(Patil et al., 2025). A synthesis of twenty independent reviews similarly found the largest response under manure application, followed by residue retention and cover cropping, with nitrogen fertilisation alone producing the smallest carbon benefit
(Bolinder et al., 2020).
At the same time, legume-residue benefits are not unconditional. Rapid mineralisation can increase post-harvest nitrate leaching by roughly 25-33% relative to cereal residues
(Tripolskaja et al., 2023) and in calcareous soils legume green manure has been linked to a greater risk of soil inorganic carbon loss even as organic carbon accumulates
(Xue et al., 2025). These findings highlight the importance of matching residue management to local soil type and cropping calendar rather than a uniform recommendation.
Climate-resilient agronomic practices for legume production
Because most Indian legumes are grown under rainfed conditions, moisture stress at flowering and pod-fill is the single largest source of yield instability, making moisture and canopy-microclimate management inseparable from soil-fertility management
(Boraiah et al., 2023; Tejaswini et al., 2025). In-situ moisture conservation practices such as broad-bed-and-furrow layout, ridge-and-furrow sowing, residue mulching and timely weeding stabilise nodulation and yield under erratic rainfall, since water stress independently suppresses nitrogenase activity even where soil fertility is adequate
(Boraiah et al., 2023; Tejaswini et al., 2025).
Genetic improvement complements these agronomic measures. Breeding programmes have identified drought-adaptive traits -early flowering, a stay-green phenotype, deep and hydraulically efficient rooting and stronger antioxidant defence- as key levers for yield stability
(Rani et al., 2020) and marker-assisted backcrossing has delivered drought-tolerant chickpea lines carrying an introgressed ‘QTL-hotspot’ region
(Asati et al., 2022; Rani et al., 2020). Heat-tolerance screening in lentil and other cool-season legumes has similarly identified genotypes now used as breeding donors
(Sarkar et al., 2025). However, a drought-tolerant genotype on a sulphur- or zinc-deficient, poorly nodulated soil will not express its full potential, underscoring that variety choice and soil-fertility management are complementary strategies
(Nath et al., 2025). The principal agronomic strategies for stabilising legume productivity under climatic stress are summarised in Table 5.
Soil-test-based precision nutrient management: the soil health card experience
India’s Soil Health Card (SHC) scheme, launched nationally in February 2015, illustrates how soil-test-based, site-specific nutrient management can be operationalised for legume and other field crops (
Government of India, Department of Agriculture and Farmers Welfare, 2015). Soil samples are analysed for twelve core parameters- macronutrients (N, P, K), sulphur, micronutrients, organic carbon, electrical conductivity and pH - with each landholding reissued a card every two to three years. Fertiliser dosage recommendations are generated using Soil Test Crop Response (STCR) correlation equations maintained by ICAR and State Agricultural Universities, relating soil-test values to yield response for specific crop-soil combinations rather than a blanket recommendation (
ICAR-Indian Institute of Soil Science, 2011), improving nutrient-use efficiency in grain legumes
(Malathi et al., 2025).
For legume growers, this framework is consequential because sulphur, zinc, boron and molybdenum deficiencies are widespread yet vary by district, so blanket NPK recommendations without micronutrient correction under-serve legume crops (
Shukla and Behera, 2021;
Shukla et al., 2021). Where followed, soil-test-based recommendations reduce over-application of N and P while correcting previously unaddressed zinc and sulphur deficiency (
Directorate of Agriculture, Government of Assam, 2024;
ICAR-Indian Institute of Soil Science, 2011;
Malathi et al., 2025). Implementation challenges persist, including inconsistent sampling protocols, a reissue interval that can lag rapid nutrient depletion in intensive legume-cereal rotations and limited farmer follow-through; STCR equations were also mostly developed for major cereals, so validated equations for minor pulses remain sparse (
Directorate of Agriculture, Government of Assam, 2024). The core parameters of the Soil Health Card and their relevance to legume nutrient management are summarised in Table 6.
Digital agriculture and precision nutrient management in legumes
Alongside soil-test-based and biological approaches, a growing body of work applies remote sensing, UAVs, machine learning and decision-support software to crop nutrient management, increasingly adapted for legume systems. UAV-mounted multispectral, hyperspectral and thermal sensors capture canopy reflectance at sub-metre resolution, from which indices such as NDVI infer canopy nitrogen status, water stress and, indirectly, nodulation vigour, at a resolution ground-based sampling cannot match
(Yang et al., 2025; Xing et al., 2025). UAV-satellite data fusion has been used to build within-field prescription maps directing variable-rate fertiliser or gypsum to zones where sulphur, zinc or nitrogen status is limiting, rather than a single blanket rate
(Chen et al., 2025; Xing et al., 2025).
Machine learning methods, particularly neural networks and random forests, increasingly translate remote-sensing and soil-test data into yield forecasts and nitrogen-status estimates, though accuracy depends heavily on ground-truth data density, a persistent constraint where digitised yield records remain sparse
(Chlingaryan et al., 2018; Liakos et al., 2018). Decision-support systems integrating UAV or satellite-derived canopy status with soil-test databases such as those underpinning the Soil Health Card and STCR programmes could allow dosage recommendations to be updated within a single season rather than every two to three years
(Chen et al., 2025; Government of India, Department of Agriculture and Farmers Welfare, 2015).
For legumes specifically this technology remains at an earlier stage than for cereals, reflecting smaller pulse-holding field size and the more limited canopy signal from short-statured, often heavily branched pulse crops. Canopy-based estimation of nitrogen and water status is nonetheless directly relevant, since both stresses independently suppress nodulation and nitrogenase activity, offering earlier correction than routine field-scout visits allow
(Yang et al., 2025; Xing et al., 2025). Realising this potential will require dedicated calibration datasets linking canopy reflectance to nodulation status and BNF performance, rather than the cereal-derived thresholds applied by default - one of the more immediate research gaps identified here.
Comparative synthesis of nutrient management approaches
The preceding sections describe several distinct routes to correcting nutrient constraints in legume-based systems. Table 7 draws them together for direct comparison, making explicit the trade-offs a practitioner or policy-maker must weigh.
No single approach is sufficient alone: blanket recommendations are simple but nutrient-blind, soil-test-based and biofertilizer approaches add precision but depend on infrastructure or testing frequency inconsistently available at scale and digital tools remain least mature for legumes. The strongest documented outcomes combine at least two rows - for example soil-test-based dosing supplemented with a compatible biofertilizer and residue return - rather than relying on any single instrument.
Constraints and future research priorities
Notwithstanding the well-documented soil-fertility benefits of legumes, several agronomic gaps constrain their fuller exploitation: highly variable BNF and residual-nitrogen quantification across genotype-environment combinations limits fertiliser-recommendation precision for succeeding crops
(Barbieri et al., 2023; Ghafoor et al., 2024); micronutrient management, particularly molybdenum and zinc, remains under-addressed in routine soil-testing frameworks despite its bearing on nodulation efficiency (
Shukla and Behera, 2021;
Shukla et al., 2021); biofertiliser quality control, strain-host compatibility and shelf-life continue to limit consistent field performance
(Aloo et al., 2022); and the interaction between residue management and nitrate leaching or soil inorganic carbon loss requires more region-specific evaluation
(Xue et al., 2025; Tripolskaja et al., 2023).
Future research would benefit from long-term, multi-location trials coupling isotopic BNF quantification with site-specific nutrient recommendations; from breeding efforts targeting rhizobial compatibility and nodulation efficiency under stress; and from integrating precision-agriculture tools across legume-growing agro-ecological zones (
Government of India, Department of Agriculture and Farmers Welfare, 2015;
ICAR-Indian Institute of Soil Science, 2011).
Closing the yield gap in lentil, mungbean, urdbean and groundnut deserves particular attention, since these crops have shown negative or unstable production trends over the past decade despite steady demand growth
(Kumar et al., 2024); continued yield improvement, rather than area expansion, will be necessary for pulse self-sufficiency
(Murugananthi et al., 2024).
