Abstract
Rice–wheat cropping system to which graded levels of NPK fertilizers had been applied for 20 years were compared for yield trends, and changes in response function, soil organic‐C and available N, P, K and S status. This study of system in which only chemical fertilizers had been used over a long period enabled long‐term yield declines of rice and wheat at different levels and combinations of NPK fertilizers to be evaluated. The highest rate of yield decline in both rice and wheat was found when 120 kg ha −1 N was applied alone. The lowest rate of decline was observed when all three nutrients (N, P and K) were applied, at 40, 35 and 33 kg ha −1 for N, P and K, respectively, followed by 120, 35 and 33 kg ha −1 (currently recommended levels). The yield response of rice and wheat to N fertilizer declined over the 20 years, with a higher rate of decline in wheat. In contrast, the response to applied P and K increased with time in both crops, with a higher response rate in wheat. With continuous application of N and P fertilizers, there was a marginal change in available N and K in the soil over time, but an approximately 3‐fold increase in available P and an approximately 2‐fold increase in available S were obtained by regular dressing of P fertilizer (SSP: 7 % P, 12 % S) over 20 years. The results revealed that balanced, high doses of NPK fertilizers are required to maintain soil fertility and raise grain yields.
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Claims 8
Claim · model-written summary
Applying N alone at 120 kg ha −1 produced the highest yield decline rate in rice and wheat.
- Taxon
- rice and wheat
Oryza sativa
Triticum aestivume0 - Treatment
- 120 kg ha −1 Ne0
- Outcome
- yield declinee0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest rate of yield decline in both rice and wheat was found when 120 kg ha −1 N was applied alone”
Claim · model-written summary
Applying all three nutrients at 40, 35 and 33 kg ha −1 gave the lowest yield decline rate.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- all three nutrients (N, P and K)e0
- Outcome
- rate of declinee0
- Direction
- loweste0
- Value
- 40, 35 and 33 kg ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lowest rate of decline was observed when all three nutrients (N, P and K) were applied, at 40, 35 and 33 kg ha −1 for N, P and K, respectively”
t0“Rice–Wheat System”
Claim · model-written summary
Yield response to N fertilizer declined over 20 years in both crops, faster in wheat.
- Taxon
- rice and wheatOryza sativaTriticum aestivume0
- Treatment
- N fertilizere0
- Outcome
- yield responsee0
- Direction
- declinede0
- Qualifier
- higher rate of decline in wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The yield response of rice and wheat to N fertilizer declined over the 20 years, with a higher rate of decline in wheat”
Claim · model-written summary
Response to P and K fertilizer increased over time in both crops, more rapidly in wheat.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- applied P and Ke0
- Outcome
- response to applied P and Ke0
- Direction
- increasede0
- Qualifier
- higher response rate in wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the response to applied P and K increased with time in both crops, with a higher response rate in wheat”
t0“Rice–Wheat System”
Claim · model-written summary
Continuous N and P fertilization produced only marginal changes in soil available N and K.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- continuous application of N and P fertilizerse0
- Outcome
- available N and K in the soile0
- Direction
- marginal changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With continuous application of N and P fertilizers, there was a marginal change in available N and K in the soil over time”
t0“Rice–Wheat System”
Claim · model-written summary
Regular P fertilizer dressing increased soil available P about threefold.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- P fertilizere1
- Outcome
- available Pe0
- Direction
- increasee0
- Value
- approximately 3‐folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“approximately 3‐fold increase in available P”
e1“P fertilizer (SSP: 7 % P, 12 % S)”
t0“Rice–Wheat System”
Claim · model-written summary
Regular P fertilizer dressing increased soil available S about twofold.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- P fertilizere1
- Outcome
- available Se0
- Direction
- increasee0
- Value
- approximately 2‐folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“approximately 2‐fold increase in available S”
e1“P fertilizer (SSP: 7 % P, 12 % S)”
t0“Rice–Wheat System”
Claim · model-written summary
Balanced high NPK doses are required to maintain soil fertility and increase grain yields.
- Taxon
- Rice–WheatOryza sativaTriticum aestivumt0
- Treatment
- balanced, high doses of NPK fertilizerse0
- Outcome
- maintain soil fertility and raise grain yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“balanced, high doses of NPK fertilizers are required to maintain soil fertility and raise grain yields”
t0“Rice–Wheat System”
The same questions in other papers
fertilization · soil: chemistry · Triticum aestivum (wheat)Positive and negative results
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- negative
- no effect
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279 papers in the same direction as this paper · 23 in the opposite direction · 2 reporting no difference from an alternative
- no effect
- no effect
- negative
301 papers more in this group
See all 305 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.