Abstract
The effects of long-term (12 years) continuous cultivation and application of different N-sources (ammonium sulphate, urea and calcium ammonium nitrate) on soil acidity and the growth of three crops were determined. Continuous cultivation, with and without nitrogen fertilizer addition, for twelve years led to a marked reduction in soil pH and an increase in the soil exchange acidity. The exchange acidity in (NH4)2SO4 treated plots were significantly higher than all other treatments. Of the three N-sources used, ammonium sulphate gave the worst effect on the growth of the crops studied. The acid tolerance of the test crops as reflected in the growth parameters measured was in the order: maize > cowpea > tomato. The production of tomato appeared absolutely impossible under an acid soil condition.
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Claims 6
Claim · model-written summary
Continuous cultivation reduced soil pH.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Continuous cultivation, with and without nitrogen fertilizer addition, for twelve years led to a marked reduction in soil pH”
e1“maize > cowpea > tomato”
Claim · model-written summary
Continuous cultivation increased soil exchange acidity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Continuous cultivation, with and without nitrogen fertilizer addition, for twelve years led to a marked reduction in soil pH and an increase in the soil exchange acidity”
e1“maize > cowpea > tomato”
Claim · model-written summary
Ammonium sulphate plots had higher exchange acidity than all other treatments.
- Treatment
- (NH4)2SO4 treated plotse0
- Outcome
- exchange aciditye0
- Direction
- highere0
- Comparator
- all other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The exchange acidity in (NH4)2SO4 treated plots were significantly higher than all other treatments”
e1“maize > cowpea > tomato”
Claim · model-written summary
Ammonium sulphate was the worst nitrogen source for crop growth.
- Treatment
- ammonium sulphatee0
- Outcome
- growth of the crops studiede0
- Direction
- worste0
- Comparator
- three N-sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Of the three N-sources used, ammonium sulphate gave the worst effect on the growth of the crops studied”
e1“maize > cowpea > tomato”
Claim · model-written summary
Acid tolerance ranked maize above cowpea above tomato.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The acid tolerance of the test crops as reflected in the growth parameters measured was in the order: maize > cowpea > tomato”
Claim · model-written summary
Tomato production appeared impossible under acid soil conditions.
- Taxon
- tomato
Solanum lycopersicume0 - Outcome
- production of tomato appeared absolutely impossiblee0
- Qualifier
- under an acid soil conditione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The production of tomato appeared absolutely impossible under an acid soil condition”
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See all 21 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.