A Grower Survey
1 D . F . COLE AND G . J . SEILER2Received for publication March 22, 1976
S u m m a r y
A survey of c o m m e r c i a l s u g a r beet growers in t h e R e d River Valley of N o r t h D a k o t a a n d Minnesota was c o n d u c t e d t o d e t e r m i n e t h e c h a n g e i n t o n n a g e a n d root quality tht would occur if sugar beets were flailed r a t h e r t h a n t o p p e d conventionally a t harvest. T h e d a t a i n d i c a t e d t h a t the growers removed only 2 0 % of the crown m a t e r i a l by t o p p i n g , which re- d u c e d t o n n a g e b y 5 % .
Removal of all t h e crown m a t e r i a l by h a n d resulted in a 1.2% in- crease in sucrose a n d a 7 . 1 % r e d u c t i o n in n i t r a t e g r a d e . S u g a r beet crown m a t e r i a l a c c o u n t e d for 2 0 . 5 % of t h e t o n n a g e delivered to the factory.
I n t r o d u c t i o n
S u g a r beets a r e n o r m a l l y flailed a n d scalped before harvesting. T h e p u r p o s e of scalping is to remove a p o r t i o n of the crown, which is t h e a r e a above the lowest leaf scar. Crown m a t e r i a l is known to be higher in i m p u r i - ties a n d lower in sucrose relative to the m a i n body of t h e sugar beet root.
M o r e sugar p e r a c r e c a n be recovered from beets which a r e only flailed before harvesting ( 1 , 6 ) .3 T h i s increase c a n c o m e a b o u t for several reasons:
sugar c a n be e x t r a c t e d from the crown m a t e r i a l , respiration losses d u r i n g storage would be r e d u c e d by not c u t t i n g the crown, a n d the a m o u n t of rot would be r e d u c e d by not exposing the most susceptible tissue, the center p o r t i o n of the crown.
If sugar beets were only flailed at harvest, an increase in t o n n a g e a n d a r e d u c t i o n in p e r c e n t sucrose would be e x p e c t e d . However, no d a t a a r e available to indicate the a n t i c i p a t e d c h a n g e in either t o n n a g e or p e r c e n t sugar. A survey at one location in t h e R e d River Valley in t h e 1974-75 p r o - cessing c a m p a i g n i n d i c a t e d t h a t only 6% of the sugar beets were t o p p e d at the lowest leaf scar, 7 1 % were partially t o p p e d , a n d 2 3 % were only flailed (2). T h u s , a considerable a m o u n t of crown tissue is b e i n g processed at t h e present t i m e .
A survey of c o m m e r c i a l s u g a r beet growers was c o n d u c t e d d u r i n g the week of S e p t e m b e r 29 to O c t o b e r 3, 1975, in t h e Red River Valley to deter- m i n e t h e c h a n g e i n t o n n a g e a n d root quality t h a t would occur i f s u g a r beets were only flailed at harvest.
1Cooperative investigation of the Agricultural Research Service, U.S. D e p a r t m e n t of Agriculture, a n d the Agricultural Experiment Station, N o r t h D a k o t a State University, Fargo, ND 58102. Published with the approval of the Director of the N o r t h D a k o t a Agricultural Experiment Station as J o u r n a l P a p e r N o . 7 2 7 .
2Research P l a n t Physiologist a n d Research T e c h n i c i a n , respectively.
3N u m b e r s in parentheses refer to literature cited.
Materials a n d Methods
S u g a r beet samples were o b t a i n e d from r a n d o m l y selected growers in e a c h of the six factory districts in t h e R e d River Valley. F o u r 10-beet sam- ples were harvested from e a c h grower a n d / o r location in a field. In e a c h field, samples were o b t a i n e d from rows adjacent to where the grower h a d t e m p o r a r i l y s t o p p e d scalping. F r o m t h e row which h a d not b e e n flailed or scalped, two 10-beet samples were m a n u a l l y harvested. T h e leaves were removed from b o t h samples at the base of the petiole with a knife. T h e crowns were r e m o v e d from o n e s a m p l e at the lowest leaf scar a n d weighed.
T h e 10 t o p p e d roots a n d the 10 u n t o p p e d roots were t h e n placed into a
" t a r e b a g " for further analysis. T w o 10-beet samples were m a n u a l l y har- vested from the adjacent row w h e r e the grower h a d flailed a n d scalped t h e sugar beets. T h e r e m a i n i n g crown tissue o n o n e s a m p l e was r e m o v e d a n d weighed. Roots of b o t h samples were p l a c e d into t a r e b a g s . L e n g t h of row harvested for e a c h 10-beet s a m p l e was d e t e r m i n e d . Row w i d t h was 22 inches in all fields a n d 68 locations were s a m p l e d . Flailed samples were ob- t a i n e d from an a d d i t i o n a l six fields in t h e East G r a n d Forks, M i n n e s o t a a r e a . Grower-scalped samples were n o t o b t a i n e d on these six fields because t h e factory was n o t receiving beets at the time of t h e survey.
T h e t a r e bags were t r a n s p o r t e d to t h e t a r e l a b o r a t o r y of A m e r i c a n Crystal S u g a r C o m p a n y at East G r a n d Forks, M i n n e s o t a . At the t a r e lab- oratory, the roots were washed, weighed, a n d sawed to o b t a i n p u l p for de- t e r m i n a t i o n o f sucrose, n i t r a t e g r a d e , a n d conductivity g r a d e . P e r c e n t crown tissue was c a l c u l a t e d using t h e weight of the crown m a t e r i a l removed as a p e r c e n t a g e of t h e original root weight.
T w o samples of sugar beet roots were o b t a i n e d from grower trucks at e a c h of six piling stations in t h e valley. Samples o b t a i n e d at Crookston fac- tory, Midway, Hillsboro factory, D r a y t o n factory, a n d H a m i l t o n consisted of 10 roots selected at r a n d o m from a l o a d e d t r u c k . Samples were o b t a i n e d from the M o o r h e a d factory by using t h e s a m p l e b u c k e t on t h e piler to c a t c h two samples p e r truck load. O n e s a m p l e from e a c h l o a d was t o p p e d to t h e lowest leaf scar to d e t e r m i n e the weight of t h e crown m a t e r i a l t h a t was delivered to the factory by t h e grower. Sucrose, n i t r a t e g r a d e , a n d con- ductivity g r a d e were m e a s u r e d o n b o t h samples a t the East G r a n d Forks t a r e l a b o r a t o r y .
Results a n d Discussion
Average l e n g t h of row to harvest 10 s u g a r beets varied from 11.6 to 12.1 ft ( T a b l e 1), indicative of an average p o p u l a t i o n of 19,721 to 20,434 plants p e r a c r e . S u g a r beet roots harvested from t h e grower-scalped row were lower in sucrose t h a n were sugar beets harvested from t h e row with in- tact leaves used to s i m u l a t e flailing. T h e r e d u c e d sucrose levels p r o b a b l y resulted from n o r m a l respiration which is increased by scalping; also t h e leaves h a d b e e n removed from the grower-scalped s u g a r b e e t roots for an u n d e t e r m i n e d time period, thereby e l i m i n a t i n g photosynthesis a n d p r e v e n t i n g further sucrose storage. T h e flailed s u g a r beets were c a p a b l e of
Table 1. Length of row to harvest 10 beets, sucrose, nitrate, conductivity, percent crown, and yield averaged over all growers.
†l) Flailed; 2) flailed, crown removed manually; 3) grower-topped; 4) grower-topped, remaining crown removed manually.
††Mean with standard error of the mean.
photosynthesis a n d storage u p t o harvest. T h e lower sucrose p e r c e n t a g e i n the grower-scalped row m a y have resulted from water u p t a k e by the roots after scalping.
R e m o v a l of t h e e n t i r e crown ( s a m p l e 2, T a b l e 1) resulted in a 1.2%
increase in sucrose, a 7 . 1 % r e d u c t i o n in n i t r a t e g r a d e , a 5% r e d u c t i o n in conductivity g r a d e , a n d a n 1 8 . 6 % r e d u c t i o n i n yield c o m p a r e d t o sugar beet roots with intact crown (sample 1, T a b l e 1). R e m o v a l of the crown m a t e r i a l r e m a i n i n g on s u g a r beet roots after scalping by t h e grower (sam- ple 4, T a b l e 1) resulted in a 1.9% increase in sucrose, a 3 . 4 % r e d u c t i o n in n i t r a t e , a 7 . 3 % r e d u c t i o n in conductivity, a n d a 1 5 . 5 % r e d u c t i o n in yield c o m p a r e d to grower-scalped s u g a r beet roots (sample 3, T a b l e 1).
S u g a r beet crown m a t e r i a l a c c o u n t e d for 1 9 . 4 % of the total yield for the flailed roots a n d 1 5 . 5 % of t h e total yield for the grower-scalped roots ( T a b l e 1). T h i s indicates t h a t a c o n s i d e r a b l e a m o u n t of t h e crown m a t e r i a l is harvested a n d delivered to t h e factory. T h e s e d a t a s u p p o r t those of B u g - bee a n d Cole (2) c o n c e r n i n g t h e p e r c e n t a g e of s u g a r beet roots scalped to the lowest leaf scar.
H o b b i s (5) observed an inverse r e l a t i o n s h i p b e t w e e n sucrose c o n t e n t a n d n i t r a t e g r a d e . Similar d a t a were o b t a i n e d in this survey (Fig. 1).
Flailed a n d grower-scalped s u g a r beet roots e x h i b i t e d similar trends in su- crose r e d u c t i o n with n i t r a t e g r a d e .
Figure 1.—Relationship between percent sucrose and brei nitrate grade in flailed and grower-scalped sugar beet roots. Numbers in parentheses indicate the humber of sam- ples in each mean.
134 JOURNAL OF THE A.S.S.B.T Cole et al. (4) showed t h a t a positive relationship exists between soil n i t r a t e levels a n d p e r c e n t crown tissue. A similar relationship was observed between brei n i t r a t e g r a d e a n d p e r c e n t crown (Fig. 2). T h i s relationship indicates t h a t the a m o u n t of crown m a t e r i a l p r o d u c e d c a n be r e g u l a t e d by nitrogen m a n a g e m e n t . N i t r o g e n m a n a g e m e n t c a n result in an increase in sucrose content a n d a r e d u c t i o n in crown m a t e r i a l .
Figure 2.—Relationship between percent crown and brei nitrate grade in flailed and grower-scalped sugar beet roots. Numbers in parentheses indicate the number of samples in each mean.
Sucrose c o n t e n t showed a decline as p e r c e n t crown m a t e r i a l increased in b o t h flailed a n d grower-scalped sugar beet roots (Fig. 3 a n d 4). A highly significant negative correlation was observed between sucrose c o n t e n t a n d percent crown m a t e r i a l . T h i s relationship c a n be partially e x p l a i n e d by the differential between sucrose level of root vs. crown m a t e r i a l , since the difference becomes larger as n i t r o g e n increases. N i t r o g e n causes a r e d u c - tion in sucrose a n d an increase in the a m o u n t of crown p r o d u c e d .
T h e d a t a r e p o r t e d . above were o b t a i n e d from m a n u a l l y harvested roots where the t a p root a n d lateral roots r e m a i n e d p r i m a r i l y i n t a c t . However, sugar beet roots harvested m e c h a n i c a l l y rarely have lateral roots a n d the m a i n t a p root m a y be b r o k e n or cut by t h e lifter wheels. T h e r e - fore, differences in p e r c e n t a g e s of crown m a t e r i a l would be e x p e c t e d w h e n c o m p a r i n g m a n u a l l y harvested to m e c h a n i c a l l y harvested roots.
Crown m a t e r i a l a c c o u n t e d for 2 0 . 5 % of the t o n n a g e delivered to the piler a n d / o r factory station by t h e growers ( T a b l e 2). R e m o v a l of all t h e r e m a i n i n g crown m a t e r i a l resulted in a 1.2% increase in sucrose, a 5 . 3 %
Figure 3.—Relationship between percent sucrose and percent crown in flailed sugar beet roots.
Figure 4.—Relationship between percent sucrose and percent crown in grower- scalped sugar beet roots.
reduction in nitrate grade, and a 2.2% reduction in conductivity grade (Table 2) averaged over all locations.
Our results indicate that the factories are processing at least 15.5% of
all crown material produced, which accounts for 20.5% of the total ton-
nage processed. Growers remove only 20% of the crown material
produced. Assuming a 13.5 T / A yield, the grower could expect an addi-
tional 0.7 T / A from crown material if he flailed rather than scalped the
beets. This would increase the amount of crown material being processed
136 J O U R N A L O F T H E A . S . S . B . T
T a b l e 2. Sucrose, n i t r a t e , conductivity a n d percent crown of sugar beet roots selected from grower-trucks at selected piles a n d / o r factory locations in the Red River Valley.
†1 = Analysis of sugar beet roots as delivered by grower.
2 = Analysis of sugar beet roots with crown material removed to lowest leaf scar.
by the factory to 2 4 . 6 % of the total t o n n a g e processed. T h e total t o n n a g e processed by the factory from 50,000 acres would be increased from 675,000 to 710,000 tons. T h e a d d i t i o n a l t o n n a g e would increase t h e slicing c a m p a i g n 7 days for a 5,000 ton p e r day factory.
Zielke (6) showed t h a t a ton of crown m a t e r i a l c o n t a i n e d 217 lbs of recoverable sucrose. Akeson, et al. (1) i n d i c a t e d t h a t storage losses would be 10 to 15 p e r c e n t less for flailed sugar beets c o m p a r e d to conventionally t o p p e d sugar beet roots. W i t h an increase in crown m a t e r i a l processed by t h e factory, a r e d u c t i o n in p e r c e n t sucrose extraction would be e x p e c t e d . However, assuming t h e c h a n g e s in yield a n d sucrose levels r e p o r t e d herein, sucrose extraction by the factory would have to d r o p over 3% to offset the gain in a d d i t i o n a l sugar e x t r a c t e d from the crown m a t e r i a l .
Sucrose extraction by the factory drops d u r i n g the latter p a r t of the processing c a m p a i g n d u e to physical d e t e r i o r a t i o n of t h e roots, loss of sugar by respiration, a n d an increase in t h e a m o u n t of rot. Factory ex- traction should not d r o p as rapidly or to the s a m e levels for flailed beets c o m p a r e d to extraction from conventionally t o p p e d roots because respira- tion a n d r o t t i n g d u r i n g storage would be less ( 1 , 3).
Literature Cited
(1) AKESON, W. R., S. D. FOX, and E. L. STOUT. 1974. Effect of topping procedure on beet quality and storage losses. J. Am. Soc. Sugar Beet Technol. 18:125-135.
(2) BUGBEE, W. M. and D. F. COLE. 1976. Sugarbeet storage rot in the Red River Valley, 1974-75. J. Am. Soc. Sugar Beet Technol. 19:19-24.
(3) COLE, D. F. 1975. Effect of cultivar and mechanical damage on respiration and storability of sugarbeet roots. J. Am. Soc. Sugar Beet Technol.
accepted.
(4) COLE, D. F., A. D. HALVORSON, G. P. H A R T M A N . J . D. ETCHEVERS, and J. T.
MORAGHAN. 1976. Effect of nitrogen and phosporus on percentage of crown tissue and quality of sugarbeets. North Dakota Farm Research.
33(5):26-28.
(5) HOBIS, J. K. 1973. Personal communication.
(6) ZlELKE, R. C. 1973. Yield, quality, and sucrose recovery from sugarbeet root and crown. J. Am. Soc. Sugar Beet Technol. 17:332-343.