下面是俄国不同时期的粮食播种面积表。导致表中所反映现象发生的主要原因是 <table style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; BORDER-COLLAPSE: collapse; BORDER-TOP: medium none; BORDER-RIGHT: medium none; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-alt: solid windowtext .5pt; mso-yfti-tbllook: 480; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext" border="1" cellspacing="0" cellpadding="0" _dj="MsoTableGrid"><tbody><tr style="HEIGHT: 24.5pt; mso-yfti-irow: 0; mso-yfti-firstrow: yes"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 24.5pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-alt: solid windowtext .5pt" width="120">年份</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 24.5pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">1913</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 24.5pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">1920</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 90pt; PADDING-RIGHT: 5.4pt; HEIGHT: 24.5pt; BORDER-TOP: windowtext 1pt solid; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">1921</td></tr><tr style="HEIGHT: 25.3pt; mso-yfti-irow: 1; mso-yfti-lastrow: yes"><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 25.3pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-top-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">播种面积</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 25.3pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-top-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">10 880公顷</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 89.95pt; PADDING-RIGHT: 5.4pt; HEIGHT: 25.3pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-top-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">10 020公顷</td><td style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: medium none; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; WIDTH: 90pt; PADDING-RIGHT: 5.4pt; HEIGHT: 25.3pt; BORDER-TOP: medium none; BORDER-RIGHT: windowtext 1pt solid; PADDING-TOP: 0cm; mso-border-top-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-alt: solid windowtext .5pt" width="120">9 030公顷</td></tr></tbody></table>