1 Introduction

Vegetable production systems are essential to food and nutritional security, but they are also among the most intensively managed agricultural systems, often requiring high rates of fertilization, irrigation, and repeated soil disturbance. This intensity places substantial pressure on soil fertility, especially because many vegetable crops return limited organic residues after harvest, accelerating declines in soil organic matter, nutrient balance, and broader soil health. As vegetable demand continues to rise globally, maintaining productive soils is no longer only a short-term agronomic concern but a central requirement for long-term sustainability in these systems. For this reason, soil fertility management in vegetable production must be approached not simply as nutrient replacement, but as the stewardship of soil chemical, physical, and biological functions that sustain yield, input efficiency, and ecosystem services over time.

Within this context, crop rotation has emerged as one of the foundational strategies for sustainable vegetable production because it addresses soil fertility and crop performance at the system level rather than on a crop-by-crop basis. Rotating crops can improve nutrient cycling, interrupt pest and disease buildup, diversify rooting patterns, and reduce dependence on external inputs when species are selected to complement one another functionally. In vegetable systems especially, where specialization and repeated cropping can intensify degradation, rotation offers a practical framework for integrating residue management, cover crops, green manures, and fertilization practices into a more balanced and self-sustaining production system. Evidence from broader rotation research also shows that diversification can strengthen soil health and long-term productivity, supporting the view that rotation is not an ancillary practice but a core principle of resilient vegetable farming.

Among rotational options, legumes are of particular interest because they contribute to soil fertility through mechanisms that extend beyond simple crop diversification. Their capacity for biological nitrogen fixation can increase soil nitrogen availability and reduce fertilizer requirements for subsequent crops, while their residues, rhizosphere inputs, and rooting characteristics can stimulate microbial activity, improve nutrient cycling, and enhance soil structural properties. Legume rotations are also associated with additional agronomic benefits, including disruption of pest and disease cycles and improved resource-use efficiency in following crops. These legacy effects are especially valuable in intensive systems where fertility depletion and input dependence are recurrent constraints. Thus, the inclusion of legumes in vegetable rotations is increasingly viewed as a biologically grounded strategy for restoring soil function while supporting productive and lower-input cropping systems (Neda, 2021).

Empirical work in cropping systems that include vegetables further supports the relevance of legume rotation for soil fertility improvement, while also showing that outcomes depend on species choice and management context. In semi-arid multiple-cropping systems, cowpea used before broccoli increased soil organic carbon and total nitrogen more effectively than fava bean before melon, indicating that legume effects are not uniform across species or vegetable sequences. Likewise, in cabbage rotations, pea and faba bean as preceding crops increased soil nitrate and total nitrogen, and their integration into rotation schemes was associated with improved soil fertility and higher head yield relative to continuous cabbage cropping. These findings suggest that legume rotation can provide measurable fertility benefits in vegetable production, but that the magnitude of those benefits depends on how legume identity, fertilization strategy, and local production conditions are aligned. This paper therefore examines the effects of legume rotation on soil fertility in vegetable production systems as a promising pathway toward more sustainable and resilient horticultural management (Yfantopoulos et al., 2024).

2 Biological Mechanisms of Legume Rotation Improving Soil Fertility

2.1 Biological nitrogen fixation and nitrogen availability enhancement

Biological nitrogen fixation is the central mechanism by which legume rotation improves soil fertility in vegetable production systems. Legumes form symbioses with rhizobia that convert atmospheric nitrogen into plant-available ammonia, thereby replenishing soil nitrogen pools and reducing dependence on synthetic fertilizers. In agricultural systems, this process commonly contributes substantial nitrogen inputs, with reported fixation ranging from about 20-200 kg N ha^-1 yr^-1 on average and reaching 75-150 kg N ha^-1 yr^-1or even more under favorable conditions (Neda, 2021). These nitrogen additions are important not only for the legume itself, but also for subsequent non-legume crops because biologically fixed nitrogen enters the soil through residues, nodulated roots, and rhizosphere-derived organic inputs that later mineralize.

The enhancement of nitrogen availability after legumes does not depend on a single pathway, but on several complementary processes. Residual mineral nitrogen not taken up by the legume, substitution of legume-derived nitrogen for native soil organic nitrogen, and lower microbial immobilization from low C:N legume residues all increase the nitrogen accessible to following crops, while decomposing shoot and root residues provide an important delayed source of mineralizable nitrogen (Ladha et al., 2022). However, the strength of this benefit depends on legume species and soil conditions. Species differ in fixation efficiency and responsiveness to fertility; for example, some annual legumes maintain higher percentages of nitrogen derived from the atmosphere under low-fertility conditions, whereas others show reduced fixation when soil fertility or manure inputs increase.

2.2 Regulation of soil microbial communities by legume rotation

Legume rotation also improves soil fertility by reshaping the composition, richness, and functional potential of soil microbial communities. Crop diversification changes root exudates, residue quality, and nutrient availability, and these shifts alter the resources available to bacteria, fungi, and other soil biota. Across cropping studies, rotation generally increases microbial biomass carbon and nitrogen as well as bacterial diversity, with stronger effects often observed when legumes are part of the rotation (Liu et al., 2023). This broad pattern is consistent with evidence that crop rotation increases bacterial Shannon diversity and species richness overall, while fungal community composition also shifts in ways linked to soil pH and available nitrogen and phosphorus.

More specific studies show that legume rotations do not merely increase diversity, but reorganize microbial communities toward functions associated with improved soil fertility. Legume-based rotations have been shown to shift rhizosphere microbiome structure and nitrogen-cycling gene profiles, increasing the abundance of several functional genes linked to nitrogen transformation, while environmental variables such as ammonium, phosphorus, and related soil properties help regulate these responses (Enagbonma et al., 2025). Legume rotations can also enrich fungal and protistan richness, increase microbial network complexity, and improve soil multifunctionality, indicating that fertility gains arise partly from more connected and functionally balanced belowground communities rather than from nitrogen inputs alone (Meng et al., 2025).

2.3 Improvement of soil enzyme activities and nutrient cycling processes

A third major mechanism is the stimulation of soil enzyme activities that govern decomposition and nutrient release. Extracellular enzymes are the direct biochemical tools by which soil microorganisms acquire carbon, nitrogen, and phosphorus from organic matter, so changes in enzyme activity provide a mechanistic link between legume rotation and nutrient cycling efficiency. Because legume residues usually have lower C:N ratios and higher nitrogen contents than cereal residues, they stimulate microbial growth and favor greater investment in nitrogen- and phosphorus-acquiring enzymes, accelerating mineralization and sustaining plant-available nutrient supplies for subsequent crops.

Empirical studies support this mechanism across multiple systems. Long-term legume-inclusive rotations increased alkaline phosphatase, arylsulfatase, β-glucosidase, dehydrogenase, and protease activities relative to non-legume rotations, and these enzyme gains tracked increases in soil organic carbon, microbial biomass, and base-crop productivity (Borase et al., 2020). Likewise, leguminous green manure rotations increased extracellular enzyme activities involved in C, N, and P cycling, including average topsoil increases of 20.1% in β-glucosidase and 36.4% in acid phosphatase, while also alleviating microbial nitrogen limitation and intensifying phosphorus cycling constraints as total carbon and nitrogen accumulated.

3 Effects of Legume Rotation on Soil Physical Properties

3.1 Improvement of soil structure and aggregate stability

Legume rotation generally improves soil structure by promoting the formation and persistence of larger, more stable aggregates, although the magnitude of the effect depends on species choice and management context. In a long-term conservation system in the North China Plain, legume-based rotations under no-till significantly increased the proportion of macroaggregates and improved aggregate stability metrics such as mean weight diameter and geometric mean diameter (Liu et al., 2023). A broad meta-analysis similarly found that increasing crop diversity enhanced soil aggregation by 15.9%, and rotations that included grain legumes performed better than cereal-only systems, especially when combined with conservation tillage (Iheshiulo et al., 2023).

Evidence from vegetable and mixed cropping systems suggests that these structural gains are especially relevant where legumes are inserted into intensive rotations with high disturbance or declining soil quality. In semi-arid vegetable-based multiple cropping, cowpea/broccoli sequences increased aggregate stability relative to monoculture, with stronger benefits under organic management. More recent imaging-based work in Vertisols further showed that legume-cover crop rotations increased connected porosity, pore surface area density, and water-air exchange capacity, indicating that improvements in aggregation are accompanied by more functional pore architecture (Ding et al., 2025).

3.2 Enhancement of soil organic matter accumulation

Legume rotation enhances soil organic matter accumulation primarily by increasing biologically active carbon inputs and accelerating their transformation into both particulate and protected organic fractions. A global meta-analysis showed that legume incorporation significantly increased multiple soil organic carbon fractions, including microbial biomass carbon, dissolved organic carbon, particulate organic carbon, light fraction carbon, and recalcitrant carbon pools, with stronger responses under warm, humid, and nutrient-limited conditions. In orchard systems, legume cover crops increased total soil organic carbon by 38%, outperforming non-legume covers, and simultaneously raised mineral-associated and particulate organic carbon, indicating broader improvement in both labile and stabilized carbon pools (Hu et al., 2024).

At the field scale, however, the accumulation of organic matter is not uniform and depends on residue quality, soil mineral protection, and complementary practices. In no-till legume-based rotations, soybean-wheat increased macroaggregate-associated soil organic carbon by 13.6% and improved straw-carbon conversion, showing that legume inputs can strengthen carbon retention within aggregates (Liu et al., 2023). By contrast, in conventionally tilled grain legume rotations, soil organic carbon and soil organic nitrogen declined when legumes were inserted without cover crops, while adding cover crops mitigated these losses, indicating that legumes alone do not guarantee organic matter gains under all management systems.

3.3 Effects on soil water retention and root growth environment

Legume rotation can improve the soil water environment by modifying soil structure, lowering compaction, and increasing the continuity of pores that regulate infiltration and storage. In legume-potato rotation, soil bulk density declined while soil water content and soil organic matter increased, suggesting a direct improvement in the physical rooting environment under vegetable production conditions (Wang et al., 2023). Across southern African conservation agriculture systems, rotations with or without legumes improved water infiltration by 70% to 238% and also increased soil moisture, supporting the view that rotational diversification can enhance hydraulic functioning at farm scale.

The effects on root growth environment appear to arise not only from greater water availability, but also from changes in pore geometry and biologically mediated soil organization. X-ray computed tomography showed that legume-cover crop rotations increased root volume fraction and that fresh particulate organic matter was positively correlated with connected porosity and hydraulic radius, indicating that carbon inputs and pore development reinforce each other in ways favorable for root proliferation (Ding et al., 2025). Still, the water-retention response is not universally consistent: long-term rotation diversification improved drought resistance through higher soil organic matter, yet did not consistently increase measured water retention or infiltration, suggesting that some benefits to root water status may operate through biological or rhizosphere pathways beyond bulk hydraulic change (Renwick et al., 2021).

4 Effects of Legume Rotation on Soil Chemical Fertility

4.1 Changes in soil nitrogen dynamics and nutrient availability

Legume rotation improves soil chemical fertility most directly through its effect on nitrogen cycling and the subsequent availability of plant-accessible nitrogen. The central mechanism is biological nitrogen fixation, which supplies residual nitrogen to following crops and reduces dependence on synthetic fertilizer inputs (Neda, 2021). Across agricultural systems, legumes also tend to raise soil nitrogen availability by accelerating nitrogen cycling and increasing the transfer of nitrogen-rich residues into the soil (Figure 1) (Gou et al., 2023).

Figure 1 Conceptual framework illustrating the mechanisms by which legume rotation enhances soil nitrogen availability through biological nitrogen fixation, residue decomposition, microbial nitrogen cycling, and improved nitrogen uptake by subsequent crops

Field evidence shows that these nitrogen benefits are not only theoretical but agronomically significant. In northern Ethiopia, legume-wheat rotations increased subsequent wheat yield and nitrogen uptake, with available soil nitrogen in legume plots rising by 42-92 kg N/ha compared with continuous wheat. In vegetable-linked rotation systems, legume inclusion has likewise increased soil nitrate and total nitrogen, with pea-cabbage and faba bean-cabbage rotations producing the highest soil NO₃^- and total N values among tested sequences (Yfantopoulos et al., 2024).

4.2 Regulation of soil phosphorus and potassium availability

Legume rotation also regulates soil phosphorus availability through both rhizosphere processes and microbial mediation. Some legumes mobilize less-labile phosphorus through carboxylate and phosphatase exudation, while their root architecture improves access to labile phosphorus pools and can enhance phosphorus uptake in subsequent crops. Rotation studies further show that legume-based systems often improve available phosphorus relative to non-legume sequences, partly because they shift microbial communities and genes involved in phosphorus transformation (Yu et al., 2021).

The effects on phosphorus and potassium, however, depend strongly on rotation design and nutrient management. In long-term systems, greater rotation complexity and the inclusion of legumes or forage phases improved phosphorus and potassium balances, while alfalfa-containing rotations exported large shares of applied P and K and kept annual phosphorus surplus low. A 14-year study similarly found that legume diversification replenished multiple soil potassium pools, with chickpea- and pigeonpea-based systems performing better than simpler cereal rotations in maintaining water-soluble, exchangeable, and non-exchangeable K reserves (Nath et al., 2025).

4.3 Effects on soil pH and nutrient balance

The influence of legume rotation on soil pH is more variable than its effect on nitrogen, because pH responses depend on residue composition, nutrient uptake, and background soil conditions. Recent rotation evidence indicates that phosphorus availability is closely tied to pH regulation, with crop rotation directly affecting phosphorus fractions through pH modulation and related stoichiometric shifts (Yuan et al., 2025). In intensive rotation systems, legume-based treatments can also alter pH alongside broader physicochemical improvements; for example, legume-potato rotation reduced soil pH while increasing total N, total P, and total K content (Wang et al., 2023).

At the same time, legumes can contribute to improved nutrient balance by reducing exchangeable acidity and moderating depletion pathways, especially where chemical fertility has declined under continuous cropping. In South African sugarcane soils, legume cover crops increased soil pH by 6-26% and reduced exchangeable acidity relative to pre-treatment conditions, indicating a capacity to ameliorate acidic conditions in some environments (Zama et al., 2026). More broadly, nutrient balance studies emphasize that the value of legume rotation lies not only in adding nitrogen, but in helping synchronize nutrient inputs, exports, and retention across the whole rotation, thereby supporting longer-term fertility stability rather than short-term input substitution alone.

5 Influence of Legume Rotation on Vegetable Growth and Productivity

5.1 Effects on vegetable yield and biomass production

Legume rotation generally increases subsequent crop productivity, with the strongest gains appearing in low-input systems and in sequences where legumes provide a clear pre-crop effect. A global meta-analysis found that legume pre-crops increased main-crop yield by 20% on average, while a later synthesis reported an average gain of 23%, confirming that the productivity effect is robust across regions and cropping systems (Zhao et al., 2022). These gains are not uniform, however, because rotation outcomes depend on the specific crop sequence, the legume species used, and the baseline fertility of the system.

Evidence from vegetable-related field studies shows that the same pattern extends to intensive horticultural production, where legume inclusion helps counter the productivity losses associated with continuous cropping. In cabbage systems, pea-cabbage and faba bean-cabbage rotations improved head yield relative to continuous cabbage, with the lowest yields occurring where cabbage followed cabbage under organic management (Yfantopoulos et al., 2024). In continuous potato production, pea- and faba bean-based rotations increased tuber yield by 21.19% and 28.38%, respectively, showing that legume breaks can restore biomass production under degraded soil conditions (Wang et al., 2023).

5.2 Improvement of vegetable quality and nutrient use efficiency

Legume rotation improves nutrient use efficiency mainly by strengthening internal nitrogen cycling and reducing the need for external nitrogen inputs. Reviews of vegetable nutrient management show that rotations with complementary rooting patterns and rhizosphere effects improve the nitrogen cycle, increase nutrient and water availability, reduce residual nitrogen losses, and enhance NUE at the whole-farm level. A two-year legume-based field and modeling study in vegetables further showed that nitrogen application could be reduced by 26% and nitrogen leaching by 37% without sacrificing yield, indicating that yield maintenance and fertilizer efficiency can improve simultaneously (Valenzuela, 2024).

The effect on vegetable quality is more context-dependent than the effect on yield, because product nutrient composition responds not only to rotation but also to fertilization regime. In cabbage, head tissue N, P, and K concentrations were determined by the farming system rather than the legume pre-crop itself, with higher tissue nutrient contents under conventional fertilization than under organic management (Yfantopoulos et al., 2024). Still, rotation systems can strengthen the broader nutrition-production relationship: a recent meta-analysis found that crop rotations increased total sequence output of protein, iron, magnesium, and zinc alongside yield, suggesting that legume-based rotations support more nutrient-efficient and nutritionally valuable production systems overall.

5.3 Reduction of soil-borne diseases and pest pressure

Legume rotation can reduce soil-borne disease pressure by disrupting host-pathogen continuity and by reshaping rhizosphere microbial communities toward more suppressive states. Experimental work on root disease suppression showed that monocropping produced microbial assemblies less capable of suppressing root rot than crop rotation, and that the depletion of key rhizosphere taxa under monoculture weakened resistance to pathogen invasion (Zhou et al., 2023). This mechanism is consistent with broader soil health literature showing that rotational crops and other cultural practices directly or indirectly affect soil-borne pathogens and root disease severity in vegetable systems.

The disease-suppression effect also appears in intensive vegetable production through shifts in beneficial and pathogenic taxa rather than through diversity alone. In continuous eggplant systems, diversified rotation reduced fungal pathogens such as Fusarium and increased beneficial taxa including Mortierella and Bacillus, while also improving soil biochemical properties. Long-term microbiome research likewise found that more diverse rotations increased the abundance of disease-suppressive functional groups, indicating that microbial community composition is a key pathway through which rotation lowers pest and disease pressure.

6 Case Study: Long-Term Legume-Vegetable Rotation System for Improving Soil Fertility

6.1 Experimental background and rotation system design

A suitable long-term legume-vegetable rotation case study is best framed as a factorial field experiment that compares diversified legume-inclusive sequences with simpler non-legume systems under contrasting fertility management regimes. One strong model is the nearly 50-year Italian experiment that contrasted continuous cropping, shorter cereal rotation, and a 9-year sequence including three years of alfalfa, while also testing unfertilized, mineral-fertilized, and manure-amended treatments in a replicated design (Figure 2) (Giacometti et al., 2021). A second useful template comes from organic vegetable research, where rotation design integrates legume-derived nitrogen, cover crops, reduced tillage, and plant-based fertilization to compare a more intensified sustainable system against common practice based on manure and simpler seasonal sequencing (Hefner et al., 2022).

Figure 2 Conceptual framework of long-term legume-vegetable rotation experiments integrating cropping sequences and fertility management strategies to evaluate changes in soil fertility and crop productivity

For vegetable production systems, the rotation should include a legume phase selected not only for nitrogen fixation but also for compatibility with local climate, residue quality, and the nutrient demand pattern of the following vegetable crop. Evidence from semi-arid vegetable multiple-cropping systems shows that cowpea before broccoli improved soil carbon, total nitrogen, and subsequent crop performance more effectively than fava bean before melon, indicating that legume species choice materially affects the value of the rotation design. Longer-horizon system experiments also show that rotations with a high share of legumes and vegetables require explicit nutrient-balance planning, especially in stockless or low-external-input systems where phosphorus and potassium deficits can emerge despite good organic matter performance (Möller et al., 2026).

6.2 Changes in soil fertility indicators after legume rotation

After repeated legume inclusion, the clearest soil fertility changes are increases in soil organic carbon, total nitrogen, and biologically active soil fractions. In the long-term Italian trial, the 9-year legume-containing rotation increased soil organic carbon by 24% and total nitrogen by 23%, while also stimulating microbial biomass carbon, microbial biomass nitrogen, and overall microbial activity relative to the simpler rotations (Giacometti et al., 2021). A broader synthesis of rotation effects on soil biology supports this pattern, showing that rotations increase microbial biomass carbon by 13.43% and microbial biomass nitrogen by 15.84%, with stronger effects when legumes are part of the sequence (Liu et al., 2023).

The nutrient response extends beyond carbon and nitrogen, but it is not uniformly positive for all elements, which is why multi-indicator assessment is necessary. In sandy loam rotation trials, legume inclusion raised total nitrogen, available phosphorus, exchangeable potassium, magnesium, and effective cation exchange capacity over monocropping, confirming a broad improvement in chemical fertility status. At the same time, long-term evidence from both legume-inclusive field experiments and stockless organic systems shows that available phosphorus can decline under prolonged legume-based rotation unless balanced by manure, compost, or other external nutrient sources, and potassium deficits can also accumulate where outputs are not replenished (Möller et al., 2026).

6.3 Impacts on vegetable yield and sustainable production benefits

The production effect of legume rotation is usually expressed as higher subsequent crop yield, greater biomass production, and better input efficiency, especially in lower-input systems. Global evidence shows that legume pre-crops increase the yield of following crops by about 20% on average, with the advantage tending to be larger where external nitrogen inputs are low (Zhao et al., 2022). In vegetable-oriented systems, sustainable intensification built around legume cover crops and plant-based fertilization maintained marketable yields across crops such as cabbage, celeriac, leek, lettuce, and onion, while increasing aboveground dry matter and improving nitrogen use efficiency by 8%-16% (Hefner et al., 2022).

The broader sustainability benefit is that legume rotation can raise productivity while improving soil health and reducing reliance on synthetic inputs, although careful nitrogen management is still needed to avoid losses. In diversified long-term rotations, adding legumes increased equivalent yield by up to 38%, raised soil organic carbon stocks by 8%, and improved soil health by 45%, showing that productivity gains can coincide with ecological improvement. Field evidence from intensive subtropical systems likewise shows that legume-integrated rotations can simultaneously improve soil biological health, nutrient availability, and economic return, with one legume-based sequence increasing system productivity by 68.97% over the conventional baseline (Walia et al., 2025).

7 Challenges and Future Perspectives of Legume Rotation Management

7.1 Limitations of current legume rotation practices

Current legume rotation practices improve soil fertility, but their performance remains highly variable across production contexts, which limits straightforward transfer into intensive vegetable systems. Rotational benefits depend on legume species, residue quantity and quality, soil fertility status, and local management, so the same practice can produce markedly different outcomes across farms and seasons (Liu et al., 2023). This variability is especially important in vegetable systems, where short crop cycles, shallow rooting, and high nutrient demand make fertility responses more sensitive to species choice and sequencing than in simpler cereal-based systems. Economic and operational constraints also slow adoption of legume rotation, even where agronomic benefits are clear. Designing rotations that balance soil improvement with profitability is difficult because market demand often favors a narrow set of high-value crops, while diversified rotations require more planning and can reduce short-term returns relative to specialized monocropping (Zou et al., 2024). In addition, management complexity, machinery compatibility, and other socioeconomic barriers continue to limit uptake, particularly where systems are optimized around single-crop production rather than diversified rotation logic (Al-Musawi et al., 2025).

A second limitation is that legume-driven fertility gains do not automatically translate into complete nutrient balance. Long-term evidence shows that legume-inclusive rotations can increase soil organic carbon and total nitrogen while still depleting available phosphorus, indicating that nitrogen benefits may coexist with emerging P constraints if rotations are not paired with complementary nutrient inputs (Giacometti et al., 2021). This matters for vegetable systems because high harvest removal can intensify nutrient imbalance and make legume rotation alone insufficient for sustaining overall chemical fertility. Nutrient management challenges are even clearer in stockless or low-external-input systems, where phosphorus and potassium deficits can accumulate despite good rotational design. Research on stockless organic farming shows that sustainable nutrient management is only possible under specific combinations of rotation and fertilization strategy, and that farm types without livestock often develop P and K deficits unless external organic fertilizers are added (Möller et al., 2026). These findings suggest that legume rotation should be treated as one component of fertility management rather than a stand-alone solution.

7.2 Integration of legume rotation with precision agriculture technologies

A key future direction is to integrate legume rotation with precision agriculture so that species choice, timing, and nutrient management can be adjusted to field-scale variability rather than managed uniformly. Precision agriculture combines geospatial tools, IoT, big-data analysis, and AI to optimize input use and reduce losses, while remote sensing already supports crop monitoring, irrigation scheduling, nutrient management, pest detection, and yield prediction in commercial systems (Sishodia et al., 2020). In legume-based vegetable rotations, these tools could help identify where rotational nitrogen is likely to be sufficient and where supplemental inputs remain necessary. Smart sensor networks strengthen this approach by generating real-time measurements of soil and crop conditions that can inform targeted interventions. Sensors for soil moisture, pH, and plant stress, linked through IoT platforms, enable remote monitoring, AI-assisted analysis, and automated control of irrigation, fertilization, and pest management (Mansoor et al., 2025). For vegetable rotations that include legumes, this creates a practical pathway for synchronizing nutrient release from legume residues with the short and often intensive uptake periods of subsequent vegetable crops.

The challenge is that precision tools are not yet easily deployable in many diversified or small-scale systems. High initial costs, data-management burdens, technical expertise requirements, connectivity problems, and data-security concerns remain important barriers to implementation, especially outside highly capitalized farming environments (Mansoor et al., 2025). These constraints parallel the broader adoption challenges already seen for crop diversification and suggest that technological integration will require economic and institutional support, not just better devices. Future integration therefore depends on making digital systems simpler, more region-specific, and more agronomically connected to rotation design itself. Reviews of remote sensing emphasize the need for reliable but user-friendly workflows for real-time decision support, while rotation research calls for integrating climate, soil, species, and genotype data into models that can better represent system interactions under varying conditions (Sishodia et al., 2020; Akchaya et al., 2025). In practice, this means precision agriculture should evolve from generic monitoring toward rotation-aware decision systems tailored to legume-vegetable sequences.

7.3 Future research directions in sustainable soil fertility management

Future research should prioritize long-term, system-level experiments that capture the full physical, chemical, and biological effects of legume rotation over multiple cycles. Long-term studies are essential because treatment differences in soil fertility and agroecosystem response often strengthen with time, and future work needs to quantify biological nitrogen fixation, greenhouse-gas losses, nitrate leaching, and interacting soil indicators together rather than separately (Möller et al., 2026). This is especially important in vegetable systems, where short-term yield responses can obscure slower changes in soil carbon storage, nutrient balance, and resilience. Research also needs to move beyond generalized claims about “legumes” and resolve how species identity shapes rotational outcomes. Existing evidence shows large differences among legumes in biomass production, nitrogen accumulation, and residual benefits, yet those differences do not always translate into equivalent gains in subsequent crop yield, implying that non-nitrogen effects and recycling efficiency also need closer attention (Raboin et al., 2026). In vegetable production, this points to a need for comparative studies that test which legumes best match particular vegetable crops, climates, and management regimes.

A third priority is to connect soil fertility research with practical farm design, economic feasibility, and participatory validation. Reviews emphasize that current knowledge still lacks enough on-farm testing, and that findings from small plots should be validated through collaboration between researchers and producers to improve real-world relevance and adoption (Akchaya et al., 2025). This is particularly relevant for vegetable farming, where logistical constraints, market timing, and labor demands can determine whether a biologically effective rotation is actually workable. Finally, future work should develop region-specific and climate-resilient legume rotation strategies that integrate ecological, technological, and policy perspectives. Recent syntheses highlight the need for long-term ecological impact quantification, economic and policy modeling, integration of new climate-resilient crop species, and farmer-led innovation, while also stressing that management technologies and efficient ecological cropping systems must be designed for different regional conditions (Al-Musawi et al., 2025). For sustainable soil fertility management in vegetable systems, the most useful next step is therefore not a single universal model, but a set of adaptable legume-rotation frameworks matched to local soils, climates, and production goals.

8 Conclusions

Across the literature, legume rotation consistently improves soil fertility by strengthening nitrogen supply, raising soil organic matter, and enhancing broader soil quality functions that support subsequent crops. In vegetable-linked systems, these benefits include higher soil organic carbon, total nitrogen, available phosphorus, and aggregate stability, although responses vary with legume species and management system. More broadly, legume inclusion supports soil multifunctionality and maintains productive soils by improving nutrient cycling while sustaining soil carbon stocks over time. The fertility effect is not limited to nitrogen alone, because legume-based rotations also influence soil biology, nutrient retention, and disease-suppressive capacity. Long-term and diversified systems show increases in microbial activity, biologically active carbon and nitrogen pools, and soil health indicators that contribute to more stable crop performance and reduced pressure from soil-borne pathogens. At the same time, the literature shows that benefits are context-dependent, with outcomes shaped by residue quality, fertilizer regime, and the particular legume used in the sequence rather than by legume presence alone.

For vegetable production systems, the main implication is that legume rotation offers a practical pathway to sustain yields while reducing dependence on external nitrogen inputs. Evidence from cabbage and potato systems shows that legume pre-crops improve soil nutrient status and increase subsequent vegetable yield relative to continuous cropping, especially where monoculture has already degraded soil conditions. This aligns with broader syntheses showing that legume-based rotations are especially effective in low-input and low-diversity systems, where they can help maintain production with fewer synthetic inputs. The sustainability value of legume rotation extends beyond yield because it can improve nutrient use efficiency, reduce nitrate losses, and support climate-resilient production. Legume-supported systems frequently lower nitrogen fertilizer demand, and in most comparisons they also reduce nitrous oxide emissions and nitrate leaching, which is directly relevant to environmentally sensitive vegetable farming. Rotation diversification also supports longer-term resilience by improving soil health, lowering greenhouse-gas intensity, and increasing the capacity of production systems to balance productivity with environmental performance.

Future agricultural practice should treat legume rotation as a core component of integrated soil fertility management, not as a stand-alone replacement for all external inputs. Rotation design should be tailored to local soils, climate, and vegetable nutrient demand, because optimal sequence length, species choice, and management intensity vary across agroecological settings. In practice, this means selecting legumes with strong residual benefits, synchronizing their nutrient release with vegetable uptake, and combining them with residue management, cover crops, and complementary fertilization where phosphorus or potassium may become limiting. Wider adoption will also require stronger links between research, farm design, and policy support. Evidence from Europe and broader diversification research shows that legume-based systems are more likely to succeed when farmers and advisors are involved in the redesign process and when incentives, extension, and on-farm testing help overcome economic and knowledge barriers. Future practice should therefore emphasize regionally adapted rotations, long-term field validation, and supportive policies that reward soil health, reduced fertilizer dependence, and resilient vegetable production systems.

Acknowledgments

I extend my sincere gratitude to the anonymous reviewers for their valuable and insightful comments, which have greatly strengthened this paper.

Conflict of Interest Disclosure

The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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