|Title||Een statistisch onderzoek naar den invloed van het weer op de opbrengst en het gehalte van suikerbieten in Nederland|
|Source||University. Promotor(en): D. van Gulik. - Groningen : Noordhoff - 173|
|Publication type||Dissertation, internally prepared|
|Keyword(s)||oogsttoename - oogstverliezen - opbrengsten - beta vulgaris - suikerbieten - meteorologische factoren - wind - statistische analyse - statistische gegevens - nederland - yield increases - yield losses - yields - sugarbeet - meteorological factors - statistical analysis - statistical data - netherlands|
|Abstract||Correlation coefficients were calculated to examine the relation over the period 1899-1926 between beet yield and sugar content, and rainfall, sunshine and temperature. For every decade and combinations of two or more decades of the period March-October, the correlation coefficient was calculated. The interrelations between the three elements were also considered. The main purpose was to find critical periods as a basis for forecasting yield.
There were two critical periods for yield. The sowing period (20 April-20 May) had to be dry. The correlation coefficient with the rainfall was -0.66 ± 0. 11. The month of July had to be warm and bright. (Correlation coefficient for temperature + 0.60 ± 0,12 and for hours of sunshine + 0.66 ± 0.11.)
Sugar content was stimulated by a bright dry autumn. Correlation coefficients were for hours of sunshine +0.61±0.12 and for rainfall -0.72 ± 0.09.
The main cropping districts Zeeland and Groningen differed strikingly in the correlation coefficient for temperature in August: for Zeeland (south of the Netherlands) +0.27 ± 0.17 and for Groningen (north of the Netherlands) +0.62 ± 0.12.
The main regression equation for beet yield was X = M + 761x 2 - 75x 3 . M average yield (kg/ha), x 2 = departure from average temperature (°C) during the last 20 days of July and x 3 = departure from average rainfall (mm) during the period 20 April to 20 May.