Abstract
Abstract Widespread Mg deficiencies have not been reported in western Nigeria. But with continuous intensive cultivation, heavier fertilization especially with K, and the introduction of high yielding, responsive crop varieties Mg deficiency is likely to become a serious problem in the near future. Knowledge of the critical available Mg levels can be useful in conjunction with routine soil analysis data to monitor the onset of these deficiencies. There is no previously published work on Nigerian soils that estimated the available Mg level below which response to Mg fertilization can be expected. The objective of this investigation therefore was to approximate this critical level under greenhouse conditions. Twenty‐three Nigerian soils collected from various ecological zones and soil types were cropped to maize ( Zea mays L.) in the greenhouse with and without Mg application. The maize tops were cut after 35 days, dried, weighed, milled, and analyzed for Mg. Using the dry matter weights relative yields were worked out for all the soils and the new Cate‐Nelson (6) statistical procedure used to estimate the critical level. This procedure involved a step‐wise splitting of the data into two groups using successive tentative critical levels to determine the level which maximized the overall predictive ability (R 2 ) with the means of the two groups serving as the predictor values. An approximate critical level of 0.28 to 0.35 meq/100 g was obtained by this technique. Tests on individual plot yields showed that 0.28 meg/100 g neutral N NH 4 OAc, extractable Mg was low enough for statistically signficant response to Mg application. All soils (except no. 10) that had less than 5% saturation of CEC responded to Mg application; those with more than 7% Mg saturation did not respond to Mg. Mg deficiency symptoms were associated with soil Mg level of 0.17 meq/100 g or lower prior to planting and with plant Mg content of less than 0.1%. Although the critical level of available Mg approximated in this study (0.28 to 0.35 meq/100 g) is much lower than the average available Mg content (1.2 to 1.5 meq/100 g) of western Nigerian soils. Caution is nonetheless needed in evaluating the findings of the present study as greenhouse results may not necessarily reflect the true situations in the field.
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Claims 7
Claim · model-written summary
The estimated critical soil Mg level was 0.28 to 0.35 meq/100 g.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An approximate critical level of 0.28 to 0.35 meq/100 g was obtained by this technique”
e1“maize ( Zea mays L.)”
Claim · model-written summary
At 0.28 meg/100 g extractable Mg, maize yield responded significantly to Mg application.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“0.28 meg/100 g neutral N NH 4 OAc, extractable Mg was low enough for statistically signficant response to Mg application”
e1“Tests on individual plot yields”
e2“maize ( Zea mays L.)”
Claim · model-written summary
All but soil 10 below 5% CEC Mg saturation responded to Mg.
- Treatment
- Mg applicatione0
- Outcome
- responded to Mg applicatione0
- Value
- less than 5% saturation of CECe0
- Qualifier
- except no. 10e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All soils (except no. 10) that had less than 5% saturation of CEC responded to Mg application”
e1“maize ( Zea mays L.)”
Claim · model-written summary
Soils above 7% Mg saturation did not respond to Mg application.
- Treatment
- Mge0
- Outcome
- did not respond to Mge0
- Direction
- did not responde0
- Value
- more than 7% Mg saturatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“those with more than 7% Mg saturation did not respond to Mg”
e1“maize ( Zea mays L.)”
Claim · model-written summary
Maize Mg deficiency symptoms were associated with initial soil Mg of 0.17 meq/100 g or less.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg deficiency symptoms were associated with soil Mg level of 0.17 meq/100 g or lower prior to planting”
e1“maize ( Zea mays L.)”
Claim · model-written summary
Maize Mg deficiency symptoms were associated with plant Mg content below 0.1%.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg deficiency symptoms were associated with soil Mg level of 0.17 meq/100 g or lower prior to planting and with plant Mg content of less than 0.1%”
e1“maize ( Zea mays L.)”
Claim · model-written summary
The estimated critical Mg level is much lower than average Mg in western Nigerian soils.
- Outcome
- critical level of available Mge0
- Direction
- much lowere0
- Value
- 0.28 to 0.35 meq/100 ge0
- Qualifier
- 1.2 to 1.5 meq/100 ge0
- Comparator
- average available Mg contente0
- Setting
- western Nigerian soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“critical level of available Mg approximated in this study (0.28 to 0.35 meq/100 g) is much lower than the average available Mg content (1.2 to 1.5 meq/100 g) of western Nigerian soils”
e1“maize ( Zea mays L.)”
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