Abstract
Major improvements in the productivity of rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) have occurred in South Asia since 1965–1966 when the Green Revolution began. However, after the 1980s, yield stagnated or declined. We analyzed grain yield trends, soil C, N, P, and K status, and P and K balances in a 14‐yr rice–wheat experiment conducted at Punjab, India with 11 treatments comprised of various combinations of inorganic and organic sources of nutrients. Recommended levels of N, P, and K were supplemented with N through farmyard manure (FYM), wheat chopped straw (WCS), or sesbania ( Sesbania cannabina Linn. & Merrill). Soil parameters were analyzed in archived soil samples collected periodically from 1988 to 1999. Rice yield declines ranged from 0.07 to 0.13 Mg ha −1 yr −1 dependent on treatment. Wheat yields declined by 0.04 Mg ha −1 yr −1 with applications of 75 and 100% N‐P‐K fertilizer but were maintained over the 14‐yr period in the other treatments. Total soil N and available P and K declined in all the treatments except with FYM, in which total N was maintained and available P increased. Total soil C was either maintained or increased with time. Nitrogen and K depletion may have collectively contributed to the yield decline. Stable wheat yields may have been because of continuing variety improvement, resulting in higher harvest index (HI). Results show that current fertilizer recommendations are inadequate for maintaining yields. This cropping system may not be sustainable without increased K input to maintain soil K above sufficiency levels.
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Claims 12
Claim · model-written summary
Rice yield declined by 0.07 to 0.13 Mg ha −1 yr −1 depending on treatment.
- Taxon
- Rice
Oryza sativae0 - Outcome
- Rice yielde0
- Direction
- declinese0
- Value
- 0.07 to 0.13 Mg ha −1 yr −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice yield declines ranged from 0.07 to 0.13 Mg ha −1 yr −1 dependent on treatment.”
Claim · model-written summary
Wheat yield declined by 0.04 Mg ha −1 yr −1 with 75 and 100% N-P-K fertilizer.
- Taxon
- Wheat
Triticum aestivume0 - Treatment
- 75 and 100% N‐P‐K fertilizere0
- Outcome
- Wheat yieldse0
- Direction
- declinede0
- Value
- 0.04 Mg ha −1 yr −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat yields declined by 0.04 Mg ha −1 yr −1 with applications of 75 and 100% N‐P‐K fertilizer”
Claim · model-written summary
Wheat yields were maintained over 14 years in other treatments.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- yieldse1
- Direction
- maintainede0
- Qualifier
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were maintained over the 14‐yr period in the other treatments.”
e1“Wheat yields declined”
t0“Wheat”
Claim · model-written summary
Total soil N and available P and K declined in all treatments except FYM.
- Taxon
- riceOryza sativat0
- Outcome
- Total soil N and available P and Ke0
- Direction
- declinede0
- Qualifier
- except with FYMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total soil N and available P and K declined in all the treatments except with FYM”
t0“Rice”
Claim · model-written summary
FYM maintained total soil N.
- Taxon
- riceOryza sativat0
- Treatment
- FYMe0
- Outcome
- total Ne0
- Direction
- maintainede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with FYM, in which total N was maintained and available P increased.”
t0“Rice”
Claim · model-written summary
FYM increased available soil P.
- Taxon
- riceOryza sativat0
- Treatment
- FYMe0
- Outcome
- available Pe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with FYM, in which total N was maintained and available P increased.”
t0“Rice”
Claim · model-written summary
Total soil C was maintained or increased over time.
- Taxon
- riceOryza sativat0
- Outcome
- Total soil Ce0
- Direction
- maintained or increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total soil C was either maintained or increased with time.”
t0“Rice”
Claim · model-written summary
The authors suggest N and K depletion may have contributed to yield decline.
- Taxon
- riceOryza sativat0
- Compound
- Nitrogen and Ke0
- Outcome
- yield declinee0
- Qualifier
- may have collectively contributede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen and K depletion may have collectively contributed to the yield decline.”
t0“Rice”
Claim · model-written summary
The authors suggest continuing variety improvement may explain stable wheat yields.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- Stable wheat yieldse0
- Qualifier
- continuing variety improvemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stable wheat yields may have been because of continuing variety improvement, resulting in higher harvest index (HI).”
t0“Wheat”
Claim · model-written summary
Continuing variety improvement was associated with higher harvest index.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- continuing variety improvemente0
- Outcome
- harvest index (HI)e0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“continuing variety improvement, resulting in higher harvest index (HI).”
t0“Wheat”
Claim · model-written summary
Current fertilizer recommendations were judged inadequate to maintain yields.
- Taxon
- riceOryza sativat0
- Outcome
- fertilizer recommendations are inadequate for maintaining yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“current fertilizer recommendations are inadequate for maintaining yields.”
t0“Rice”
Claim · model-written summary
The authors suggest increased K input may be needed to keep soil K sufficient and sustain the cropping system.
- Taxon
- riceOryza sativat0
- Outcome
- increased K input to maintain soil K above sufficiency levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This cropping system may not be sustainable without increased K input to maintain soil K above sufficiency levels.”
t0“Rice”
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