H. F. RHOADES AND LIONEL HARRIS2
Crop rotation experiments were conducted at the Scotts Bluff Experi- ment Station from 1912 to 1949. Scofield and Holden (10)3 and Hastings
(3) reported the results through 1934. T h e results for sugar beets during the entire period are summarized here.
Some of the specific objectives of this paper are: (a) to show the in- fluence of cropping and manurial practices on soil properties and the pro- duction of sugar beets; (b) to show the relationships between soil properties and the sugar percentage of sugar beets; (c) to compare the influence of Table 1.—Some Rotations Including Sugar Beets at the Scotts Bluff Experiment Station.
1912-49.
1 Where rotation numbers are given for both periods, there were only slight changes made in 1942. Where rotation numbers are given for the period 1942-49 only, old rotations were modified appreciably.
2 M = 12 tons manure per acre applied for the crop indicated; N = 250 pounds ammon- ium sulfate or approximately 51 pounds nitrogen ner acre; and P = 125 pounds superphos- phate (45% P2O5) or approximately 56 pounds P2O5 per acre. Manure and commercial fer- tilizer were applied prior to the following crop mentioned. During the period 1942 to 1944, N = 125 pounds ammonium sulfate rather than 250 pounds.
1 Contribution from the Nebraska Agricultural Experiment Station and the Soil and Water Conservation Research Branch, Agricultural Research Service of the U. S. Dept. of Agriculture.
Published with the approval of the Director as Paper No. 645, Journal Series, Nebraska Agri- cultural Experiment Station.
2 Agronomist, Nebraska Agricultural Experiment Station and Western Section of Soil and Water Management, Soil and Water Conservation Research Branch; and Associate Agronomist, Superintendent Scotts Bluff Experiment Station, Nebraska Agricultural Experiment Station and Western Section of Soil and Water Management, Soil and Water Conservation Research Branch, respectively.
3 Numbers in parentheses refer to literature cited.
72 A M E R I C A N SOCIETY OF SUGAR B E E T T E C H N O L O G I S T S
farm manure and commercial fertilizers for the production of sugar beets;
and (d) to discuss the application of the results obtained at the Scotts Bluff Experiment Station to other soils in western Nebraska.
Detailed descriptions of the rotations and cultural practices used at the Scotts Bluff Experiment Station during the period from 1912 to 1941 have been reported (3, 10). Crop sequence and fertilization practices from 1942 to 1949 for the rotations emphasized here are reported in Table 1. Sugar beets were grown in 17 rotations during the period prior to 1942 and in 26 rotations during the period from 1942 to 1949.
Relationships of Cropping and Manurial Practices to Nitrogen, Phosphorus and Potassium Levels in Tripp Soil
Total nitrogen content and nitrification rate of Tripp soil were ma- terially influenced by the cropping and manurial practices followed from 1912 to 1941 (Table 2). Where neither manure was applied nor legume grown (Rotations 20 and 35), the nitrogen content of the soil after 30 years was approximately 36 percent lower than the nitrogen content of the virgin soil. Furthermore, the nitrogen level of the virgin soil was not main- tained even where manure was applied at the rate of 12 tons per acre to one crop in two- and three-year rotations (Rotations 21 and 35B). The nitrogen level was almost maintained at the level of the virgin soil in Rotations 41 and 63 where alfalfa was grown one-half the time, and it was maintained in Rotation 63B where alfalfa was grown one-half the time and manure was applied at the rate of 12 tons per acre to one crop in the six-year rotation. Nitrification rate of the soil was affected more by cropping practice and manure application than was nitrogen percentage of the soil.
Table 2.—Nitrogen, Phosphorus and Potassium Status of Tripp Soil to a Depth of 12 Inches After 30 Years of Cropping and Manurial Practice.1
1 Analyses on samples taken in 1941.
2 Obtained from data reported by Kubota (5).
3 Obtained from data reported by Yien (10).
Total and soluble phosphorus contents were greater in the soil from the manured than from the non-manured rotations, the differences being relatively greater for soluble than for total phosphorus. This effect of
1 Does not include crowns in 1935; includes crowns in 1950.
2 Total removed in tops, crowns, and roots.
3 Data in 1935 obtained by J. C. Russcl, M. D. VVeldon, H. F. Rhoades and Lionel Harris.
Nebraska Agricultural Experiment Station.
4 Yields for 1949 used in calculating total nitrogen and phosphorus used per acre.
Exchangeable potassium was increased materially in T r i p p soil by the application of manure in the non-legume rotations (Table 2) . In contrast, where alfalfa was grown one-half the time there was a reduction in exchange- able potassium. Nevertheless, the levels of exchangeable potassium were well above the amounts needed to supply the crop even where alfalfa was grown.
Nitrogen and phosphorus levels in the soil due to cropping and manure application were also evaluated by determining percentages of nitrogen and phosphorus in various crops at harvest time in 1935 and 1950. Nitro-
PROCEEDINGS—EIGHTH GENERAL MEETING 73 manure application on soil phosphorus levels was obtained even though
the removal of phosphorus by crops was greater in the manured than in the non-manured rotations (Tables 2 and 3) . The relatively greater effect of manure on phosphorus level in the soil from non-legume than in the soil from legume rotations was associated with greater total amounts of manure applied during the 30-year period. Alfalfa in the cropping system increased the use of phosphorus by sugar beets and other crops. No doubt the alfalfa also used considerable phosphorus. Thus the inclusion of alfalfa in the cropping system may be expected to lower the available phosphorus level of the soil compared with cropping systems not including alfalfa or other legumes.
Table 3.—Nitrogen and Phosphorus Contents of Sugar Beets at Harvest Time as Influ- enced by Cropping and Manurial Practices.
7 4 A M E R I C A N SOCIETY O F SUGAR B E E T T E C H N O L O G I S T S
Figure 1. Influence of alfalfa in this cropping system and manure application on the yields of sugar beet roots at the Scotts Bluff Experiment Station for a period of 38 years. Linear regression of yields (Y) and years in rotation (X).
1Represents 78 percent of the green weight of tops as reported by Harris (2).
2 Yield of sugar beet roots and sugar percentage for this period taken from circular nv Nuckolls and Harris (9); yield of edible beet top silage for period 1939-41.
PROCEEDINGS—EIGHTH GENERAL MEETING 75 gen and phosphorus percentages in the tops and roots of sugar beets and
the total amounts of these elements removed per acre in the crops were materially greater for the manured than for the non-manured rotations (Table 3). In general, nitrogen percentages in the tops and roots and the total amounts of nitrogen and phosphorus removed per acre by sugar beets were greater in the legume than in the non-legume rotations. However, phosphorus percentages in the tops and roots of sugar beets from the legume rotations were essentially the same as the percentages of that element in sugar beets from non-manured rotations without a legume.
Yields of Sugar Beet Roots and Edible Beet Top Silage in Relation to Cropping and Manurial Practice
Yields of sugar beet roots and edible beet top silage were much greater in the rotations containing a legume or receiving manure than in the non- legume rotation without manure (Table 4 ) . Nevertheless, the trends in yield of sugar beet roots were generally downward throughout the 38 years of study even in Rotation 63B with alfalfa three out of six years and a 12-ton application of manure for sugar beets (Figure 1). Linear regression lines depict the actual yield trends rather well for Rotations 21, 35B, 41, 63 and 63B. However, the abrupt decline in yields of sugar beets which occurred the first few years after 1912 is not shown accurately by the linear regression lines. It is believed that the decline in yield of sugar beet roots Table 4.—Influence of Cropping and Manurial Practice on Sugar Production and the Yield of Edible Silage by Sugar Beets.
7 6 A M E R I C A N SOCIETY O F SUGAR B E E T T E C H N O L O G I S T S
in the alfalfa r o t a t i o n s is d u e in p a r t to a decline in the available p h o s p h o r u s level in the soil ( T a b l e 2) . Studies n o w u n d e r w a y s h o u l d give m o r e in- formation on t h a t p o i n t . D a t a r e p o r t e d by Schuster a n d H a r r i s (9) suggest the possibility t h a t an increased p r e v a l e n c e of r o o t - k n o t n e m a t o d e could account for a p a r t of the decline in yields of sugar beets.
Sugar Percentage and Sugar Production D u e to Cropping and Manurial Practice
Nuckolls a n d H a r r i s (7) p o i n t e d o u t t h a t the inclusion of m a n u r e in c r o p p i n g systems at the Scotts Bluff E x p e r i m e n t Station decreased sugar percentages of sugar beet roots slightly d u r i n g t h e p e r i o d from 1930 to 1941.
In contrast, t h e r e was a m u c h g r e a t e r r e d u c t i o n in sugar p e r c e n t a g e d u e to the inclusion of alfalfa in the c r o p p i n g systems. S o m e w h a t similar effects of m a n u r e a p p l i c a t i o n a n d alfalfa in t h e r o t a t i o n of sugar p e r c e n t a g e s were o b t a i n e d for the p e r i o d s 1930 to 1941 a n d 1942 to 1949 ( T a b l e 4 ) .
In view of the m a r k e d effects of m a n u r e a p p l i c a t i o n s a n d l e g u m e in the r o t a t i o n on sugar p e r c e n t a g e a n d on n i t r o g e n level of t h e soil, a close r e l a t i o n s h i p b e t w e e n the capacity of the soil to s u p p l y n i t r o g e n a n d t h e sugar p e r c e n t a g e of sugar beets g r o w n on t h e soil is suggested. Such a r e l a t i o n s h i p is further i n d i c a t e d by the negative c o r r e l a t i o n s of p e r c e n t a g e n i t r o g e n a n d nitrification r a t e of t h e soil w i t h sugar p e r c e n t a g e of sugar beets for the r o t a t i o n s at the Scotts Bluff E x p e r i m e n t Station ( T a b l e 5) . In a d d i t i o n , t h e r e was a highly significant correlation of —0.73 b e t w e e n n i t r o - gen a n d sugar percentages of sugar beet roots s a m p l e d in 1935. T h e l a t t e r r e l a t i o n s h i p is in a g r e e m e n t with results o b t a i n e d by H a d d o c k (1) a n d H i l l ( 4 ) .
Table 5.—Correlation of Percentage Nitrogen and Nitrification Rate of Soil with Sugar Percentage of Sugar Beets. Rotation Experiments at the Scotts Bluff Experiment Station.
1 Significant at the 5 percent level.
2 Significant at the 1 percent level.
It is of interest to speculate on t h e resason for t h e relatively small effect of m a n u r e on sugar p e r c e n t a g e of sugar beet roots c o m p a r e d with the effect of legume in t h e r o t a t i o n even t h o u g h b o t h practices influenced the n i t r o g e n level of t h e soil a n d t h e p e r c e n t a g e n i t r o g e n in sugar b e e t
PROCEEDINGS—EIGHTH GENERAL MEETING 77 roots to about the same degree. One suggestion comes from the relatively
high phosphorus levels in the soil and the relatively high phosphorus per- centage in sugar beet roots from the non-legume rotation receiving manure compared with the legume rotations. Possibly the manure supplied suffici- ent phosphorus for sugar beets to reduce the deleterious effect of added nitrogen. This was further suggested by the partial correlation coefficient of 0.45 in 1935 between percentage phosphorus and percentage sugar in sugar beets holding nitrogen percentage constant. Although the partial correlation coefficient of 0.45 was not significant at the 5 percent level (value of 0.47 required for significance) , it seems reasonable to assume that the greater phosphorus supplied by manure might account in part at least for the relatively different effects of manure application and alfalfa in the cropping system on sugar percentage of sugar beets.
Maximum yields of sugar per acre were obtained in the non-legume rotation receiving manure (Table 4) . T h a t was due to a combination of moderate to high yields of roots with relatively high sugar percentages. T h e failure of the legume rotations to produce maximum yields of sugar was definitely associated with the unfavorable effects of legumes on sugar per- centage. Because of this circumstance it should be desirable to grow sugar beets in the rotation as far away from the legume as possible.
Comparison of Manure and Commercial Fertilizer for the Production of Sugar Beets
One of the important differences between the revised rotations and those conducted prior to 1942 was the inclusion of commercial fertilizer in the revised rotations. A combination of nitrogen and phosphorus fer- tilizers was applied in amounts approximately equal to the nitrogen but nearly double the amount of phosphorus supplied by manure in compar- able rotations (Table 1) . There was one important difference; all of the manure used in the rotations was applied for sugar beets, whereas the fer- tilizers were divided among two or more non-legume crops. T h e amount of phosphate applied for sugar beets was constant for all rotations; twice as much nitrogen was applied for sugar beets in the legume as in the non- legume rotations (Table 6) .
There was some advantage of commercial fertilizer compared with manure in terms of root yields and sugar production by sugar beets in the rotations without alfalfa (Table 6) . T h e reverse tended to be true in the alfalfa rotations. Similar sugar percentages and yields of edible beet top silage were obtained from manure and fertilizer applications. It is impos- sible to determine from the results obtained the individual effects of nitro- gen and phosphorus on the production of sugar beets in the different rotations.
Application of Results to Other Soils in Western Nebraska To what extent will the influence of cropping and fertilization prac- tices on soil properties and sugar beet production reported here for T r i p p soil apply to other soils in western Nebraska? It seems likely that the same
7 8 A M E R I C A N SOCIETY O F SUGAR B E E T T E C H N O L O G I S T S
practices w o u l d m a i n t a i n soil n i t r o g e n at a h i g h e r level in the finer-textured Mitchell a n d M i n a t a r e soils t h a n i n t h e T r i p p soil. O n t h e o t h e r h a n d , the n i t r o g e n level w o u l d n o t likely be m a i n t a i n e d as h i g h by the same prac- tices in the sandy Parshall a n d Bayard soils as in T r i p p soil.
T a b l e 6.—Comparison of M a n u r e a n d C o m m e r c i a l Fertilizer for t h e P r o d u c t i o n of Sugar Beets in R o t a t i o n s w i t h a n d w i t h o u t Alfalfa at t h e Scotts Bluff E x p e r i m e n t S t a t i o n . 1945-1949.
N i t r o g e n Fertilization M e a n yields 1945-49, tons p e r acre Sugar
R o t a t i o n c o n t e n t of soil for c o n t e n t , N o . in 1941, % s u g a r beets1 R o o t s Gross Sugar E d i b l e Silage %
R O T A T I O N S W I T H O U T A L F A L F A 21
20C 35B 35C 43B 43C 67B2 67C2
41B 41C 66B 66C 63B 63C
0.079 0.072 0.081 0.072 0.065 0.063 0.088 0.091 0.102 0.090 0.096 0.087 0.094 0.100
M a n u r e N + P M a n u r e N + P
N o L e g u m e 15.3 17.0 16.0 17.0 Field B e a n s Only L e g u m e M a n u r e
N + P M a n u r e 4 / 3 N +
14.6 15.5 15.4 P 17.2
2.69 3.03 2.88 3.04 2.76 2.82 2.60 2.94 R O T A T I O N S W I T H L E G U M E M a n u r e
2 N + P M a n u r e 2 N + P M a n u r e 2 N + P
17.3 17.4 18.3 15.9 17.3 16.3
2.70 2.70 2.78 2.43 2.56 2.43
5.0 5.4 6.6 5.8 4.9 5.5 7.2 7.5 8.8 9.4 9.8 8.6 10.4 9.6
17.6 17.8 18.0 17.9 18.9 18.2 16.9 17.1 15.6 15.5 15.2 15.3 14.8 14.9
1 M = 12 tons m a n u r e p e r acre; N = 250 p o u n d s of a m m o n i u m sulfate or a p p r o x i m a t e l y 5 1 p o u n d s n i t r o g e n p e r acre; a n d P = 125 p o u n d s s u p e r p h o s p h a t e ( 4 5 % P2O5) o r a p p r o x i - mately 56 p o u n d s P2O5 p e r acre.
2 M e a n of two crops of sugar beets p e r r o t a t i o n .
T h e r e is e v i d e n c e of a g r e a t e r n e e d of p h o s p h o r u s by sugar beets g r o w n o n the calcareous M i t c h e l l a n d M i n a t a r e soils t h a n o n t h e non-calcareous T r i p p soil (6, 8) . It seems likely t h a t t h e B a y a r d a n d Parshall soils w o u l d be i n t e r m e d i a t e in p h o s p h o r u s supply. Increases in yields of roots a n d sugar d u e to p h o s p h a t e are m u c h g r e a t e r on the soils of m e d i u m - l o w fertility level t h a n on soils of m e d i u m - h i g h fertility level ( T a b l e 7) . Potassium a p p e a r s to be generally a d e q u a t e for sugar b e e t p r o d u c t i o n on m o s t soils in western N e b r a s k a . Differences in soils s h o u l d be considered w h e n j u d g i n g the a p p l i c a t i o n of t h e results from t h e Scotts Bluff E x p e r i m e n t Station to o t h e r soils in t h e area.
S u m m a r y
C r o p r o t a t i o n e x p e r i m e n t s were c o n d u c t e d a t t h e Scotts Bluff E x p e r i - m e n t Station from 1912 to 1949. T h e results o b t a i n e d w i t h sugar beets d u r i n g t h e e n t i r e p e r i o d were s u m m a r i z e d .
1. T h e r e was a m a r k e d effect of c r o p p i n g practice a n d m a n u r e appli- cation on soil p r o p e r t i e s , on yield of sugar b e e t roots, on sugar p e r c e n t a g e of sugar beets, a n d on yield of e d i b l e silage.
PROCEEDINGS—EIGHTH GENERAL MEETING 79 T a b l e 7.—Response of Sugar Beets to A p p l i c a t i o n of Commercial Fertilizer to T r i p p , Mitchell, and M i n a t a r e Soils in the N o r t h P l a t t e Valley of Nebraska d u r i n g 1947 a n d 1948.1
Soil series
T r i p p Mitchell T r i p p Mitchell T r i p p Mitchell
T r i p p Mitchell M i n a t a r e T r i p p Mitchell M i n a t a r e T r i p p Mitchell M i n a t a r e
N u m b e r of e x p e r i m e n t s
3 3 3 3 3 3
4 5 2 4 5 2 4 5 2
° . „ Increase or decrease d u e commercial
fertilizer N P M E D I U M - H I G H SOIL F E R T I L I T Y LEVEL3
Yield of roots, tons per acre 16.4 0.7 0.0 16.0 0.0 0.7
Sugar c o n t e n t , %
14.0 — 0 . 8 0.2 12.0 — 0 . 6 0.3 Gross yield of sugar, p o u n d s per acre
4,590 — 7 5 65 3,840 — 1 9 0 270 M E D I U M - L O W SOIL F E R T I L I T Y LEVEL4
Yield of roots, tons per acre 9.2 1.2 1.0 8.1 1.0 2.3 8.0 1.2 5.0
Sugar content, %
12.6 —0.1 0.4 12.0 — 0 . 8 0.2 13.2 — 0 . 3 0.0 Gross yield of sugar, p o u n d s per acre
2,320 280 330 1,949 95 590 2,110 265 1,320
N + P
0.5 0.7
—0.9
—0.7
—65
—65
2.0 2.5 5.6
—0.1
—0.6
—0.4 480 470 1,385
to-'
N + P + K
0.8 1.0
—0.7
—0.5
— 1 5 70
2.1 3.2 5.0 0.0
—0.8
—0.4 525 585 1,220 1 E x p e r i m e n t s c o n d u c t e d c o o p e r a t i v e l y w i t h t h e G r e a t W e s t e r n Sugar Co. ( 8 ) . 2 N = 65 p o u n d s n i t r o g e n as a m m o n i u m n i t r a t e ; P = 100 p o u n d s P2O5 as s u p e r p h o s p h a t e ( 4 5 % P2O5) ; a n d K = p o u n d s K2O as p o t a s s i u m c h l o r i d e . Fertilizers w e r e a p p l i e d at t h e side of t h e r o w i m m e d i a t e l y after p l a n t i n g .
3 L e g u m e s i n c l u d e d r e g u l a r l y in t h e c r o p p i n g systems. M a n u r e was a p p l i e d for s u g a r beets a n d h a s been used f r e q u e n t l y .
4 L e g u m e s i n c l u d e d occasionally i n t h e c r o p p i n g systems. L i t t l e m a n u r e used.
2. Sugar percentage of sugar beets was negatively correlated with total nitrogen percentage of the soil, with nitrification rate of the soil, and with nitrogen percentage in the sugar beet roots.
3. There was some advantage of commercial fertilizer compared with manure in terms of root yields and sugar production by sugar beets in rota- tions without alfalfa. T h e reverse tended to be true in alfalfa rotations.
4. Greater yield responses by sugar beets from commercial fertilizers were obtained in western Nebraska on soils of medium-low fertility than on soils of medium-high fertility. The most outstanding response obtained was to phosphorus fertilizer on highly calcareous soils.
Literature Cited
(1) HADDOCK, JAY L.
1953. Sugar beet yield and quality. Utah Agr. Expt. Sta. Bul. 362.
(2) HARRIS, LIONEL.
1948. Studies of beet-top silage production in the irrigated rotation experiments at the Scottsbluff, Nebraska, Field Station, 1942- 1947. Proc. Am. Soc. Sugar Beet Tech. 1-8.
8 0 A M E R I C A N SOCIETY O F SUGAR B E E T T E C H N O L O G I S T S (3) H A S T I N G S , S T E P H E N H .
1936. I r r i g a t e d c r o p r o t a t i o n in western N e b r a s k a , 1912-34. U. S.
D e p t . Agr. T e c h . Bul. 512.
(4) H I L L , K E N N E T H W I L F O R D .
1952. Effect of n i t r o g e n supply on the sucrose p e r c e n t a g e of sugar beets. Proc. Am. Soc. Sugar Beet T e c h . 201-206.
(5) K U B O T A , J O E .
1944. Some chemical p r o p e r t i e s of an i r r i g a t e d c h e s t n u t soil after thirty years of different c r o p p i n g a n d m a n u r i a l practices.
Master's thesis, University of N e b r a s k a . (6) L Y O N S , E. S., R U S S E L , J. C. a n d R H O A D E S , H. F.
1944. C o m m e r c i a l fertilizers for t h e irrigated sections of western N e b r a s k a . N e b r . Agr. E x p . Sta. Bui. 365.
(7) N U C K O L L S , S. B. a n d H A R R I S , L I O N E L .
1948. Effect of c r o p r o t a t i o n a n d m a n u r e on the yield a n d q u a l i t y of sugar beets, U n i t e d States Scotts Bluff (Nebr.) Field Station, 1930-41. U. S. D e p t . Agr. Circ. 779.
(8) R H O A D E S , H . F . a n d J O H N S O N , W E N D E L L .
1949. C o m m e r c i a l fertilizers for sugar beets in N e b r a s k a . N e b r . O u t - state T e s t i n g Circ. 3.
(9) SCHUSTER, M. L. a n d H A R R I S , L I O N E L .
1952. Effects of c r o p r o t a t i o n on t h e incidence of r o o t - k n o t disease of sugar beets in western N e b r a s k a . Proc. Am. Soc. Sugar Beet T e c h . 511-518.
(10) S C O F I E L D , C A R L S. a n d H O L D E N , J A M E S A.
1927. I r r i g a t e d crop r o t a t i o n s in western N e b r a s k a . U. S. D e p t . Agr.
T e c h . Bul. 2.
(11) Y I E N , C H E N H W A .
1949. Influence of m a n a g e m e n t practices on t h e form of p h o s p h o r u s in an irrigated c h e s t n u t soil. Master's thesis, University of N e b r a s k a .