Abstract
Abstract A two-year field trial was conducted at Al-Marj Research Center, northeast Libya, during the summers of 1996 and 1997 to examine the effect of nitrogen (N) fertilizers on corn (Zea mays L.) growth in a Libyan soil (fine mixed thermic, Typic Haploxerolls) amended with different calcium carbonate (CaCO3) levels. Two N fertilizer sources (urea and diammonium phosphate, or DAP) were used at three application rates (0, 80, and 160 kg N/ha). The CaCO3 treatments were 1%, 6%, and 12% based on the soil weight of a 15 cm furrow slice. A basal phosphorus (P) dose of 46 kg P2O5/ha as triple superphosphate was applied to all experimental plots before planting. The experimental plots were arranged in a randomized split-split plot design with three replications. The parameters measured included corn grain weight, plant dry-matter content, leaf contents of N, P, potassium (K), calcium (Ca), and magnesium (Mg). The plant dry matter and corn-grain yield were significantly decreased by CaCO3, but were significantly increased by N fertilizer rates. Average grain yield dropped from 8 to 3 Mg/ha at 1% and 12% soil CaCO3 content, respectively. Generally, the N source did not have a significant effect on dry matter or on grain yield. The negative effect of CaCO3 on yield was associated with concomitant significant reduction in leaf N, P, K, and Mg contents, and an increase in Ca content. However, the leaf levels of these nutrients were considered sufficient for corn growth. Therefore, the reduction of leaf-N by CaCO3 in fertilized soils might have been the major cause of corn dry-matter and grain-yield reductions. Keywords: calcium carbonatesdiammonium phosphatetriple superphosphate
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Claims 10
Claim · model-written summary
Calcium carbonate significantly decreased corn dry matter.
Not reportedTaxonComparator
Verbatim
e0“The plant dry matter and corn-grain yield were significantly decreased by CaCO3”
Claim · model-written summary
Calcium carbonate significantly decreased corn grain yield.
Not reportedTaxonComparator
Verbatim
e0“The plant dry matter and corn-grain yield were significantly decreased by CaCO3”
Claim · model-written summary
Nitrogen fertilizer rates significantly increased corn dry matter.
Not reportedTaxonComparatorOutcome
Verbatim
e0“but were significantly increased by N fertilizer rates”
Claim · model-written summary
Nitrogen fertilizer rates significantly increased corn grain yield.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- N fertilizer ratese0
- Outcome
- corn-grain yielde0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The plant dry matter and corn-grain yield were significantly decreased by CaCO3, but were significantly increased by N fertilizer rates.”
Claim · model-written summary
Average grain yield declined from 8 to 3 Mg/ha between 1% and 12% soil calcium carbonate.
- Treatment
- 12% soil CaCO3e0
- Outcome
- grain yielde0
- Direction
- droppede0
- Value
- 3 Mg/hae0
- Qualifier
- 8e0
- Comparator
- 1%e0
Not reportedTaxon
Verbatim
e0“Average grain yield dropped from 8 to 3 Mg/ha at 1% and 12% soil CaCO3 content, respectively.”
Claim · model-written summary
Nitrogen source generally did not significantly affect dry matter or grain yield.
- Treatment
- N sourcee0
- Outcome
- dry matter or on grain yielde0
- Direction
- did not have a significant effecte0
Not reportedTaxonComparator
Verbatim
e0“Generally, the N source did not have a significant effect on dry matter or on grain yield.”
Claim · model-written summary
Increasing calcium carbonate reduced leaf N, P, K and Mg contents significantly.
Not reportedTaxon
Verbatim
e0“The negative effect of CaCO3 on yield was associated with concomitant significant reduction in leaf N, P, K, and Mg contents”
Claim · model-written summary
Increasing calcium carbonate increased leaf calcium content.
Not reportedTaxon
Verbatim
e0“and an increase in Ca content”
Claim · model-written summary
Leaf nutrient levels remained sufficient for corn growth.
- Taxon
- cornZea mays subsp. mayse0
- Organ / stage
- leafe0
- Outcome
- levels of these nutrientse0
- Direction
- sufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the leaf levels of these nutrients were considered sufficient for corn growth”
Claim · model-written summary
The authors suggest calcium carbonate related leaf nitrogen reduction may be the major cause of reduced corn dry matter and yield.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- CaCO3e0
- Outcome
- corn dry-matter and grain-yield reductionse0
- Qualifier
- might have beene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the reduction of leaf-N by CaCO3 in fertilized soils might have been the major cause of corn dry-matter and grain-yield reductions”
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