Figures (8)  Tables (6)

    • Figure 1. 

      Opportunities of Conservation Agriculture (CA) in intensive rice-based system.

    • Figure 2. 

      Three interlinked key components of CA.

    • Figure 3. 

      Soybean in zero-till system.

    • Figure 4. 

      Lentil in Conservation Agriculture practices (strip planting system and high residue retention).

    • Figure 5. 

      Lentil sowing using a raised bed planting system.

    • Figure 6. 

      Impact of legumes on soil health. Modified from Gogoi et al.[103].

    • Figure 7. 

      Abiotic and nutrient stress tolerance in plants through endophytic microbes. Adapted from Kirchof et al.[12].

    • Figure 8. 

      Relay sowing lentil into standing monsoonal rice.

    • ConstraintCropping systemCauseConsequenceSolutionReferences
      Stagnation or decline in crop yieldRice-wheatContinuous cereal–cereal rotationsThe decline in soil physical and chemical qualityInclusion of legumes in rice-based system[35]
      Unsustainable production systemRice-wheat; maize-wheatContinuous cereal–cereal rotationsCrop productivity declineInclusion of legumes in rice-based system[23]
      The decline in soil organic carbon, total productivityRice-wheatContinuous cultivation of
      rice-wheat cropping system      		Decline in sustainabilityInclusion of pulses and organic nutrient management practices[19]
      Unsustainable production systemRice-wheatLow yield and farm income; environmental constraints and weather variabilityDeclined crop yield, profitability and resource
      use efficiency, and increased global warming potential      		Adaptation of CA-based systems[13, 36−40]
      Decreasing crop productivityRice-wheat;Cotton-wheatDegradation of soil physical propertiesThe decline in crop productivityApplication of CA-based management system - minimum or no tillage along with crop residue retention[41]
      Soil organic carbon depletionRice-wheatIntensive tillage and removal of crop residueReducesproductivity and causes environmentaldegradationResidue retention and ZT system[42, 43]
      ZT and residue retention[44−46]
      Rice-wheat/lentil-mungbean; rice-mustard-JuteIntensive tillage and removal of crop residueDepletion of SOC and soil N, and causes environmentaldegradationStrip planting system and residue retention[47−50]
      Stagnation of crop yield, greenhouse gas emissionsRice-wheatExcess use of agricultural inputsIncreased the emission of greenhouse gasesChanges transplanted rice to direct-seeded/non-puddled rice, reduce the use of organic sources[51−54]
      Yield reductionRice-wheatHeavy weed infestationDeclined yield as a result of heavy weed infestationIncorporation of legumes in the rotation and cultivation of allelopathic crops[52]
      Input intensive deteriorates soil health and is less profitableRice-maizePuddling in rice and
      complete residue removal      		Negative impact on soil physical status for maizeZTDSR followed by ZTM (zero tillage maize)[55]

      Table 1. 

      Production constraints of conventional rice-based systems in Indo-Gangetic Plains.

    • Cropping pattern Region (land type)
      T. Aman rice – Chickpea – FallowHigh Barind Tract (drought-prone)
      Sesbania (green manure) – Chickpea
      T. Aman rice – Wheat – Mung beanHigh-land (plain)
      Fallow – Legumes – Jute
      T. Aman rice – Maize – Mung beanMedium land (plain)
      T. Aman rice – Mung bean – T. Aus riceSaline and non-saline areas
      T. Aman rice – Soybean – Fallow

      Table 2. 

      Major crop rotations involving legume crops in Bangladesh. Source: Rahman[93].

    • TreatmentsSoil organic C (%)Avail. N (kg/ha)Avail. P2O5 (kg/ha)Avail. K2O (kg/ha)
      Rice-wheat0.35c258.9c18.1c222.9c
      Rice-chickpea0.38b272.5b20.7ab237.9b
      Rice-wheat-rice- chickpea0.37bc266.6b19.2b238.0b
      Rice-wheat-mungbean0.42a286.3a21.1a262.2a
      Adapted from Nadarajan & Kumar[102].

      Table 3. 

      Effect of cropping pattern and nutrient management on soil fertility.

    • Sl No.Legume cropsWater requirement (cm)
      Winter legumes
      1Chickpea12­–21
      2Lentil10–12
      3Field pea12–14
      4Rajmash20–25
      5Lathyrus10–12
      Kharif/summer legumes
      1Black gram (summer)22–30
      2Mungbean (summer)20–35
      3Black gram (Kharif)6–12
      4Mungbean (Kharif)12–15
      5Pigeonpea16–22.5

      Table 4. 

      Water requirement of potential legume crops of the rice-based system in IGP. Adapted from Kumar & Yadav[133].

    • CropN-fixation
      (kg/ha)      		N release into
      the soil (kg/ha)      		References
      Lentil35-10032.8[136]
      Mungbean50–5534.5[136]
      Chickpea26–63–[136]
      Cowpea53–8550.3[136]
      Pigeonpea68–200–[136]
      Field pea4659.4[136]
      Black gram (Urdbean)50–6038.3[136]
      Lathyrus85%–91% Ndfa36–48[137]

      Table 5. 

      Nitrogen fixation and release into the soil of different legume crops.

    • Cropping patternFindingsLocationsReferences
      Legume-based cropping patternsNon-legume-based cropping patterns
      Wheat-mungbean-rice, wheat-blackgram-rice, wheat-sesbania-ricewheat-fallow-riceThe adoption of legumes in the wheat–rice cropping sequence increased the productivity and improved soil SOM, total N, available P and available ZnRajshahi, Bangladesh[138]
      Monsoonal rice-lentil/Lathyrus-rain-fed ricemonsoonal rice-fallow-rain-fed riceThe inclusion of relay-sown legume for fallow in the existing cropping pattern can intensify and diversify the rice-based croppingEIGP and Bangladesh[71]
      Rice-wheat-mung bean, maize-wheat-mung bean, rice-chickpeaRice-wheat, maize-wheatLegume-based rotation increased soil organic carbon and available nitrogen and phosphorus, and system productivity and net returnKanpur, India[23]
      Maize-chickpea, rice-chickpeaMaize-wheat, rice-wheatInclusion of chickpea in the cereal-cereal rotations improved SOC pools over timeKanpur, India[139]
      Rice-chickpea, rice-wheat-mung bean, rice-wheat-rice-chickpeaRice-wheat, maize-wheatInclusion of legume in rice-based rotation improved soil aggregation, carbon concentration in aggregates, and soil carbon poolsKanpur, India[140]
      Rice-wheat-mung bean, rice-wheat-cowpea, rice-maize-mung bean, rice-wheat-mung bean, rice-maize/cowpea, rice-maize/mung bean, rice-lentil-maizeRice-maize-fallow, rice-fallow-maize, rice-wheat-fallowInclusion of legumes in the fallow between two cereal crops could improve soil health and farmers’ incomeNepal[141]
      Rice-wheat-green gram, rice-mustard-green gram, Rice-red gram+turmeric-green gram, maize-wheat-blackgram, maize+blackgram-chickpea-sesbania, blackgram-maize+vegetable pea-sesbaniaRice-wheat, maize-cole crops-sesame,Including legume crops is a viable option for enhancing productivity, profitability and soil health in the rice-based system of EIGP.Bihar, India[142]
      Legume based rotationNon-legume based rotationThe inclusion of legumes enhanced the soil's organic carbon contentGlobal-scale meta-analysis (513 pairwise data from 167 studies)[143]

      Table 6. 

      Success stories of legume inclusion in rice-based cropping system under the CA system.