Abstract
Yields obtained over a 17-yr period from three grasses, one legume, and three grass–legume mixtures, together with six environmental variables, were subjected to factor analysis. Three of the variables (degree-days, hours of bright sunshine, and solar short-wave energy at the top of the earth’s atmosphere) showed a very close interrelation and were interpreted as measures of environmental energy. Age of crop was classed as a soil fertility factor; the available soil nutrients decreased as the age of the forage stand increased. In the factor patterns developed, differences between crops were small in comparison with the overall similarities. Production from the first harvest of the season was equally dependent on energy, soil moisture, and soil fertility. Regrowth was controlled principally by rainfall during and prior to the regrowth period. The ability of factor analysis to extract relatively simple relations from interrelated variables is clearly demonstrated.
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Claims 6
Claim · model-written summary
Degree-days, sunshine hours and solar energy were closely interrelated.
- Outcome
- very close interrelatione0
Not reportedTaxonSettingDirection
Verbatim
e0“Three of the variables (degree-days, hours of bright sunshine, and solar short-wave energy at the top of the earth’s atmosphere) showed a very close interrelation”
Claim · model-written summary
Available soil nutrients declined as forage stand age increased.
Not reportedTaxon
Verbatim
e0“the available soil nutrients decreased as the age of the forage stand increased”
Claim · model-written summary
Factor patterns were broadly similar across crops.
Not reportedTaxon
Verbatim
e0“In the factor patterns developed, differences between crops were small in comparison with the overall similarities”
Claim · model-written summary
First-harvest production depended equally on energy, soil moisture and soil fertility.
Not reportedTaxonDirection
Verbatim
e0“Production from the first harvest of the season was equally dependent on energy, soil moisture, and soil fertility”
Claim · model-written summary
Regrowth was principally controlled by rainfall during and before regrowth.
Not reportedTaxonDirection
Verbatim
e0“Regrowth was controlled principally by rainfall during and prior to the regrowth period”
Claim · model-written summary
Factor analysis extracted relatively simple relations from interrelated variables.
Not reportedValue
Verbatim
e0“The ability of factor analysis to extract relatively simple relations from interrelated variables is clearly demonstrated”