Abstract
Rice–wheat cropping systems managed on 10 million ha in the Indo-Gangetic Plain region (IGPR) of India are the most important production systems for national food security. Recent reports, however, indicate that the system is under production fatigue and the growth rates of rice and wheat have started declining. We, therefore, conducted field experiments at Modipuram, Meerut, India, for 3 consecutive years (1998–99 to 2000–01), to study the conservation of soil organic carbon, improvement in nitrogen use efficiency and increase in system yields through inclusion of a grain legume (pigeon pea) in place of rice. The wheat yields following pigeon pea crops were significantly (P<0.05) greater than those following rice crops during 1999–2000 and 2000–01, but not during 1998–99. The economic optimum doses of fertiliser N for wheat in the pigeon pea–wheat system were smaller (128–133 kg N/ha) than those in the rice–wheat system (139–173 kg N/ha), owing to increased N supply, greater N use efficiencies and a better crop growth environment in the pigeon pea–wheat system. The post-wheat harvest nitrate-N (NO3-N) at 90–105 cm soil depth in plots fertilised with 120 or 180 kg N/ha was greater for the rice–wheat system (6.5–8.1 mg/kg) than for the pigeon pea–wheat system (5.8–6.0 mg/kg), suggesting that inclusion of pigeon pea may help to minimise NO3-N leaching to deeper soil profile layers. In plots of pigeon pea, soil organic carbon at 0–15 cm and 15–30 cm soil depths was increased at the end of the experiment compared with the initial organic carbon content. With continuous rice–wheat cropping, the bulk density of soil increased over the initial bulk density, at different soil profile depths in general, and at 30–45 cm soil depth in particular. Inclusion of pigeon pea in the system maintained soil bulk density at its initial level, and thus eliminated sub-surface soil compaction. Despite these advantages of pigeon pea over rice as a preceding crop to wheat, permanent substitution of rice with pigeon pea in rice–wheat system is unlikely, because rice is a staple foodgrain crop in India. Nonetheless, decline in wheat productivity owing to puddling-induced soil constraints that arise on continuous rice–wheat systems could be minimised by introduction of pigeon pea into the system at longer time intervals.
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Claims 9
Claim · model-written summary
Wheat yields following pigeon pea significantly exceeded yields following rice in 1999–2000 and 2000–01.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- following pigeon pea cropse0
- Outcome
- wheat yieldse0
- Direction
- greatere0
- Qualifier
- during 1999–2000 and 2000–01e0
- Comparator
- following rice cropse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The wheat yields following pigeon pea crops were significantly (P<0.05) greater than those following rice crops during 1999–2000 and 2000–01”
Claim · model-written summary
Wheat yield after pigeon pea did not significantly differ from rice in 1998–99.
- Direction
- note0
Not reportedTaxonTreatmentComparatorOutcome
Verbatim
e0“but not during 1998–99”
Claim · model-written summary
Economic optimum wheat nitrogen dose was lower in the pigeon pea system than the rice system.
- Taxon
- wheatTriticum aestivume0
- Treatment
- pigeon pea–wheat systeme0
- Outcome
- economic optimum doses of fertiliser Ne0
- Direction
- smallere0
- Value
- 128–133 kg N/hae0
- Qualifier
- 139–173 kg N/hae0
- Comparator
- rice–wheat systeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The economic optimum doses of fertiliser N for wheat in the pigeon pea–wheat system were smaller (128–133 kg N/ha) than those in the rice–wheat system (139–173 kg N/ha)”
Claim · model-written summary
Post-harvest soil nitrate at 90–105 cm was greater after rice–wheat than pigeon pea–wheat.
- Treatment
- rice–wheat systeme0
- Outcome
- post-wheat harvest nitrate-N (NO3-N)e0
- Direction
- greatere0
- Value
- 6.5–8.1 mg/kge0
- Qualifier
- 5.8–6.0 mg/kge0
- Comparator
- pigeon pea–wheat systeme0
Not reportedTaxon
Verbatim
e0“post-wheat harvest nitrate-N (NO3-N) at 90–105 cm soil depth in plots fertilised with 120 or 180 kg N/ha was greater for the rice–wheat system (6.5–8.1 mg/kg) than for the pigeon pea–wheat system (5.8–6.0 mg/kg)”
Claim · model-written summary
Soil organic carbon increased at 0–15 cm after pigeon pea cultivation.
- Taxon
- pigeon pea
Cajanus cajane0 - Treatment
- plots of pigeon peae0
- Outcome
- soil organic carbon at 0–15 cme0
- Direction
- increasede0
- Comparator
- initial organic carbon contente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In plots of pigeon pea, soil organic carbon at 0–15 cm and 15–30 cm soil depths was increased at the end of the experiment compared with the initial organic carbon content”
Claim · model-written summary
Soil organic carbon increased at 15–30 cm after pigeon pea cultivation.
- Taxon
- pigeon peaCajanus cajane0
- Treatment
- plots of pigeon peae0
- Outcome
- 15–30 cm soil depthse0
- Direction
- increasede0
- Comparator
- initial organic carbon contente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In plots of pigeon pea, soil organic carbon at 0–15 cm and 15–30 cm soil depths was increased at the end of the experiment compared with the initial organic carbon content”
Claim · model-written summary
Continuous rice–wheat cultivation increased soil bulk density over baseline.
- Taxon
- rice–wheat
Oryza sativaTriticum aestivume0 - Treatment
- continuous rice–wheat croppinge0
- Outcome
- bulk density of soile0
- Direction
- increasede0
- Comparator
- initial bulk densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With continuous rice–wheat cropping, the bulk density of soil increased over the initial bulk density”
Claim · model-written summary
Adding pigeon pea maintained soil bulk density at the initial level.
- Taxon
- pigeon peaCajanus cajane0
- Treatment
- Inclusion of pigeon peae0
- Outcome
- soil bulk densitye0
- Direction
- maintainede0
- Comparator
- initial levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inclusion of pigeon pea in the system maintained soil bulk density at its initial level”
Claim · model-written summary
The authors suggest periodic pigeon pea introduction to reduce wheat productivity decline from continuous rice–wheat cultivation.
- Taxon
- wheatTriticum aestivume0
- Outcome
- introduction of pigeon pea into the system at longer time intervalse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decline in wheat productivity owing to puddling-induced soil constraints that arise on continuous rice–wheat systems could be minimised by introduction of pigeon pea into the system at longer time intervals”
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