Abstract
SUMMARY Nitrogen efficiency from Azolla microphylla or Sesbania rostrata green manure, rice straw, and inorganic fertilizer-N was compared in two long-term experiments with irrigated lowland rice ( Oryza sativa L.). Treatments included a control and each nitrogen source alone or in combinations that provided 50% of the total applied nitrogen from an organic and inorganic nitrogen source. All nitrogen sources were applied at equivalent nitrogen rates to 19–22 consecutive rice crops. Residual effects were assessed in two subsequent cropping seasons at one site. Lower grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptake were obtained from green manure and rice straw nitrogen as sole or dual nitrogen sources rather than from a standard split application of prilled urea. Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen, and greater extractable soil nitrogen in the vegetative growth period. After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source. Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than use of green manure because rice straw is often a wasted resource in irrigated rice systems of the humid tropics, the efficiency of rice straw nitrogen in combination with prilled urea is comparable to green manure nitrogen, and the increase in soil nitrogen from rice straw was 50–150% greater than from green manure.
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Claims 8
Claim · model-written summary
Green manure and rice straw nitrogen, alone or in combination with inorganic N, gave lower grain yield, agronomic efficiency and apparent nitrogen uptake than a standard split application of prilled urea.
- Taxon
- Rice
Oryza sativat0 - Treatment
- green manure and rice straw nitrogen as sole or dual nitrogen sourcese0
- Outcome
- grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptakee0
- Direction
- Lowere0
- Comparator
- a standard split application of prilled ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“Lower grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptake were obtained from green manure and rice straw nitrogen as sole or dual nitrogen sources rather than from a standard split application of prilled urea”
Claim · model-written summary
Compared with prilled urea, residual effects of green manure or rice straw included a significant increase in soil organic carbon and total nitrogen.
- Taxon
- RiceOryza sativat0
- Treatment
- green manure or rice strawe0
- Outcome
- soil organic carbon and total nitrogene0
- Direction
- increasee0
- Comparator
- prilled ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen”
Claim · model-written summary
Residual effects of green manure or rice straw, compared with prilled urea, included greater extractable soil nitrogen in the vegetative growth period.
- Taxon
- RiceOryza sativat0
- Treatment
- green manure or rice strawe0
- Outcome
- extractable soil nitrogene0
- Direction
- greatere0
- Qualifier
- in the vegetative growth periode0
- Comparator
- prilled ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen, and greater extractable soil nitrogen in the vegetative growth period”
Claim · model-written summary
After panicle initiation there was no residual effect of previous nitrogen source on the rate of crop nitrogen accumulation.
- Taxon
- RiceOryza sativat0
- Treatment
- previous nitrogen sourcee0
- Outcome
- rate of crop nitrogen accumulatione0
- Direction
- no residual effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source”
Claim · model-written summary
Final grain yields were similar regardless of the previous nitrogen source.
- Taxon
- RiceOryza sativat0
- Treatment
- previous nitrogen sourcee0
- Outcome
- final grain yieldse0
- Direction
- similare0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source”
Claim · model-written summary
Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than green manure.
- Taxon
- RiceOryza sativat0
- Treatment
- Recycling of rice strawe0
- Outcome
- reducing fertilizer-N requirementse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than use of green manure”
Claim · model-written summary
The increase in soil nitrogen from rice straw was 50-150% greater than from green manure.
- Taxon
- RiceOryza sativat0
- Treatment
- rice strawe0
- Outcome
- increase in soil nitrogene0
- Direction
- greatere0
- Value
- 50–150%e0
- Comparator
- green manuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“the increase in soil nitrogen from rice straw was 50–150% greater than from green manure”
Claim · model-written summary
The efficiency of rice straw nitrogen combined with prilled urea is comparable to green manure nitrogen.
- Taxon
- RiceOryza sativat0
- Treatment
- rice straw nitrogen in combination with prilled ureae0
- Outcome
- efficiencye0
- Direction
- comparablee0
- Comparator
- green manure nitrogene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Lowland Rice”
e0“the efficiency of rice straw nitrogen in combination with prilled urea is comparable to green manure nitrogen”
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