Abstract
The effect of various fertiliser treatments on the yield of maize hybrids was studied on the basis of 26 years of data obtained in a long-term bifactorial split-plot experiment set up in 1967. The seven treatments (NPK ratio 2:1:1) applied were as follows (rates per hectare): 1. Control (no fertiliser), 2. 100 kg NPK, 3. 200 kg NPK, 4. 300 kg NPK, 5. 400 kg NPK, 6. 600 kg NPK, 7. 800 kg NPK. The maize was grown with the conventional cultivation techniques in continuous cropping. The results of analyses carried out with three different methods (analysis of variance, cumulative yield analysis and regression analysis) all indicated that under the given conditions the yield of maize hybrids was highest at an NPK fertiliser rate of 200-400 kg ha -1 . The effect of fertilisation on the maize yield was significant in 21 of the 26 years. Combined analysis of variance for the years showed that the year effect (quantity of rainfall) had the greatest effect on the maize yield, but although the year effect had a fundamental effect on the yield level it did not influence the fertiliser response pattern. The fertiliser responses of the maize hybrids were described by fitting four types of functions (quadratic, square root, inverse exponential, linear-plateau) to the yield data. It was found that when selecting the best function a consideration of the regression deviations (measured yield - calculated yield) was just as important as the coefficient of determination (R 2 ). In 12 of the 26 years the fitting of the quadratic function was not significant and overestimated the fertilisation optimum. The fertiliser response curve generally has a broad maximum which is far better described by the square root function than by the quadratic. If the fertiliser response pattern includes a depressive phase, a square root function should definitely be used in place of the quadratic function. If the maximum of the response surface forms a plateau (as opposed to a maximum point) a linear-plateau function or an inverse exponential function can be recommended. In the present work the linear-plateau function gave the best results.
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Claims 11
Claim · model-written summary
Maize hybrid yield was highest at 200-400 kg ha -1 NPK.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yield of maize hybrids was highest at an NPK fertiliser rate of 200-400 kg ha -1”
Claim · model-written summary
Fertilization significantly affected maize yield in 21 of 26 years.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of fertilisation on the maize yield was significant in 21 of the 26 years”
Claim · model-written summary
Year and rainfall had the greatest effect on maize yield.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the year effect (quantity of rainfall) had the greatest effect on the maize yield”
Claim · model-written summary
Year affected maize yield levels but did not alter the fertilizer response pattern.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the year effect had a fundamental effect on the yield level it did not influence the fertiliser response pattern”
e1“yield of maize hybrids was highest”
Claim · model-written summary
Quadratic fits were not significant in 12 of 26 years.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 12 of the 26 years the fitting of the quadratic function was not significant”
e1“yield of maize hybrids was highest”
Claim · model-written summary
The quadratic function overestimated the fertilizer optimum.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the quadratic function was not significant and overestimated the fertilisation optimum”
e1“yield of maize hybrids was highest”
Claim · model-written summary
The square root function described the broad fertilizer-response maximum better than the quadratic.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“broad maximum which is far better described by the square root function than by the quadratic”
e1“yield of maize hybrids was highest”
Claim · model-written summary
The linear-plateau function gave the best results in this analysis.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the present work the linear-plateau function gave the best results”
e1“yield of maize hybrids was highest”
Claim · model-written summary
The authors recommend using a square root function for responses with a depressive phase.
- Outcome
- a square root function should definitely be used in place of the quadratic functione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“If the fertiliser response pattern includes a depressive phase, a square root function should definitely be used in place of the quadratic function”
e1“yield of maize hybrids was highest”
Claim · model-written summary
The authors recommend linear-plateau or inverse exponential functions for plateau-shaped responses.
- Outcome
- a linear-plateau function or an inverse exponential function can be recommendede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“If the maximum of the response surface forms a plateau (as opposed to a maximum point) a linear-plateau function or an inverse exponential function can be recommended”
e1“yield of maize hybrids was highest”
Claim · model-written summary
Regression deviations were as important as R 2 for selecting the best response function.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when selecting the best function a consideration of the regression deviations (measured yield - calculated yield) was just as important as the coefficient of determination (R 2 )”
e1“yield of maize hybrids was highest”
The same questions in other papers
fertilization · yield · Zea mays (maize)Positive and negative results
3,484 papers in the same direction as this paper · 338 in the opposite direction · 85 reporting no difference from an alternative
- negative
- no effect
- negative
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See all 3,908 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.