BRUCE L. BAIRD, JOSEPH J. BONNEMANN AND ARCH W. RICHARDS2
During the past three years there has been considerable widespread inter- est concerning the possibilities of using chemical additives to improve the physical conditions of soils. The chemicals have the one direct effect of increasing the stability of soil aggregates, which in turn affects pore space, permeability, surface crusting, etc. This report is concerned primarily with the value of a few of the numerous chemical additives for controlling soil crusting arid increasing the emergence of sugar beet seedlings.
There has been a very limited amount of literature in technical pub- lications to date reporting the value of additives for increasing emergence of plant seedlings. In a report summarizing the status of early research work with soil additives Martin (3)3 noted that one-fifth pound of active con- ditioner per hundred square feet prevented serious crusting and greatly facilitated the emergence of bean seedlings and other vegetable crops.
Others have made a similar observation (1) (4) , but usually without re- porting actual experimental results.
A problem of crusting exists, particularly on clay soil. There are ap- proximately 55,000 acres of irrigated land on the Belle Fourche irrigation project in western South Dakota, two-thirds of which is a clay or clay loam soil. Sugar beets are grown commerciallv in the area and in some seasons the poor emergence of sugar beets is attributed to crusting.
The information in this report was obtained from stand counts of sugar beets in five trials conducted in 1952 and 1953. In three of these trials the emergence data were obtained as a part of field experiments designed to study early growth and production as affected by moisture x additive or fertility x additive. The last two trials were conducted to study emergence only. No discussion is made of the value of commercial fertilizer to increase emergence, early growth or production of the sugar beets even though such was a part of the trials conducted. A discussion of the response of sugar beets to fertilization in this area can be found in studies previouslv reported
(2) . (5), (6) .
PROCEEDINGS—EIGHTH GENERAL MEETING 137 Experimental Procedure
T h e following trials were conducted on the Pierre clay at Newell, South Dakota, and on the Orman clay at Arpan, South Dekota:
Trial 1. VAMA was incorporated with Pierre clay soil at the rates and depths indicated in Table 1 in May of 1952. All rates of the additive occurred with and without starter phosphate consisting of 40 pounds of P205 per acre applied as triple superphosphate in bands 4 inches wide and 3 inches deep at the location of the sugar beet row. Application was ac- complished by broadcasting the phosphate a n d / o r VAMA on the soil sur- face and incorporated by the use of a Merry tiller. Each plot was 30 feet long and 4 beet rows wide. T h e treatments were completely randomized in each of the three replications.
Eleven decorticated sugar beet seeds were planted per foot of row by the use of an experimental belt type fertilizer applicator and appropriate furrow openers on May 13. T h e number of seedlings which had emerged were counted on May 21, 24 and 28 for two 100-inch sections of row in each plot.
Composited disturbed soil samples were collected for water stable ag- gregate analysis in July, 1952- These were collected from the unfertilized check plots and from the unfertilized plots treated with .20 percent VAMA to a depth of 6 inches.4
Trial 2. T h e four additive treatments given in Table 1 were placed on plots 70 feet long and 12 beet rows wide on the Orman clay in May, 1952.
T h e four replications of these large plots were subdivided into 6 fertilizer plots each 35 feet long and 4 rows wide. T h e additive and fertilizer were broadcast on the soil surface and incorporated to a depth of 4 inches by the use of a garden size rototiller and a Merry tiller. T h e whole area was then harrowed once to firm the seedbed. Decorticated sugar beet seed was planted at the rate of approximately 6 pounds per acre with a commercial International drill on May 15. T h e number of plants emerged on one 100-inch section of each of the two middle rows of each 4-row plot was counted after emergence was complete.
Trial 3. In the spring of 1952, the Pierre clay on one-half of a series of 18 small plots, 9 x 30 feet, was aggregated with HPAN to a depth of 14 inches. T h e additive was applied by removing the soil with a small crawler- type tractor equipped with a front-mounted blade. As the soil was replaced, a little at a time, the additive was incorporated by the use of a small roto- tiller. Moisture treatments were superimposed and corn produced on the plots in 1952. T h e late fall irrigations and precipitation made the soil moisture content uniformly high for all plots as winter began.
In May of 1953 a seedbed was prepared by rototilling and harrowing.
Decorticated sugar beet seed at the rate of approximately 6 pounds per acre was planted with a commercial type drill on May 5. T h e number of seed- lings emerged was determined by counting six 100-inch sections of row in
4 Aggregate analysis in all trials was determined at the Soil and Water Conservation Re- search Branch Laboratory at Mandan, North Dakota.
138 A M E R I C A N S O C I E T Y O F SUGAR B E E T T E C H N O L O G I S T S
each p l o t o n e a c h o f t h r e e d a t e s . T h e soil t e m p e r a t u r e was d e t e r m i n e d o n various d a t e s by i n s e r t i n g a t h e r m o m e t e r i n t o t h e soil to t h e d e s i r e d d e p t h a n d t a k i n g t h e r e a d i n g after a lapse o f a b o u t o n e m i n u t e . T h r e e such read- ings w e r e m a d e for e a c h p l o t o n e a c h d a t e .
C o m p o s i t e d i s t u r b e d s a m p l e s of soil w e r e collected in J u l y of 1952 for w a t e r stable a g g r e g a t e analysis from t h e t o p six inches of soil on b o t h t h e a d d i t i v e - t r e a t e d a n d u n t r e a t e d p l o t s .
N a t u r a l w e a t h e r c o n d i t i o n s w e r e d e p e n d e d u p o n t o p r o d u c e a crust i n t h e first t h r e e trials a n d a crust was p r o d u c e d artificially in t h e t w o trials w h i c h follow.
T r i a l s 4 a n d 5 . T h e s e t w o trials w e r e c o n d u c t e d o n t h e P i e r r e clay i n the fall of 1953. D e c o r t i c a t e d sugar b e e t seed was p l a n t e d w i t h a h a n d - o p e r a t e d g a r d e n drill on S e p t e m b e r 7 a n d 27 for T r i a l s 4, a n d 5, respectively.
V A M A , I B M A a n d C M C a t 0 t o 6 6 p o u n d s p e r acre, t r e a t e d area, w e r e a p p l i e d as a .3 p e r c e n t w a t e r s o l u t i o n s p r a y e d in a b a n d 4 inches w i d e on t h e soil sur- face a b o v e each p l a n t e d r o w . T h e r a t e s w e r e o b t a i n e d b y m a i n t a i n i n g a c o n s t a n t p r e s s u r e i n t h e p o r t a b l e h a n d s p r a y e r a n d v a r y i n g t h e l e n g t h o f t i m e o f a p p l i c a t i o n . T h e r e w e r e four r e p l i c a t i o n s o f t h e t r e a t m e n t s o n t h e 15-foot single r o w p l o t s .
O n e day or m o r e after t h e a p p l i c a t i o n of t h e a d d i t i v e , w a t e r from a g a r d e n hose was s p r i n k l e d on each r o w to i n s u r e t h e f o r m a t i o n of a crust.
P R O C E E D I N G S — E I G H T H G E N E R A L M E E T I N G 139 T h e e n d o f t h e g a r d e n h o s e was p l a c e d i n a o n e - g a l l o n t a n h a v i n g n a i l
h o l e s p u n c h e d i n t h e b o t t o m a n d h e l d a few i n c h e s a b o v e t h e g r o u n d T h e a m o u n t a p p l i e d t o e a c h p l o t w a s h e l d c o n s t a n t b y m a k i n g t h e l e n g t h o f t i m e o f a p p l i c a t i o n t o e a c h p l o t a b o u t 4 5 s e c o n d s . T h e s u b s o i l was d r y a n d t o f a c i l i t a t e g e r m i n a t i o n i t was necessary t o a p p l y s u p p l e m e n t a l w a t e r b y g e n t l y s p r i n k l i n g w i t h w a t e r . T h i s w a s a p p l i e d a f t e r t h e o t h e r t r e a t - m e n t s a n d w a s g e n t l e e n o u g h t h a t a c r u s t w a s n o t p r o d u c e d o n t h e u n - t r e a t e d soil b e t w e e n t h e r o w s .
T h e n u m b e r o f p l a n t s e m e r g e d p e r 100 i n c h e s o f r o w was d e t e r m i n e d o n t h r e e d a t e s for b o t h T r i a l 4 a n d 5 .
R e s u l t s a n d D i s c u s s i o n
T h e r e s u l t s o f s t a n d c o u n t s a r e g i v e n i n T a b l e 1 . T h e d a t a h a v e b e e n a n a l y z e d s t a t i s t i c a l l y a n d i n n o i n s t a n c e w a s a n i n t e r a c t i o n b e t w e e n d a t e x t r e a t m e n t f o u n d .
T r i a l 1 T h e n u m b e r o f p l a n t s e m e r g e d i n T r i a l 1 was m o r e t h a n 6 0 p e r c e n t of t h e t o t a l n u m b e r of seeds p l a n t e d . S u c h a p r o p o r t i o n is a very g o o d e m e r g e n c e . N e i t h e r t h e a d d i t i v e t r e a t m e n t n o r t h e s t a r t e r p h o s p h a t e h a d a n y effect o n e m e r g e n c e . T h e r e was n o c r u s t i n g p r o b l e m a n d t h e soil m o i s t u r e c o n d i t i o n s w e r e g o o d . T h e r e s u l t s o f t h e l a b o r a t o r y a n a l y s i s g i v e n i n I a b l e 1 , i n d i c a t e t h a t t h e p e r c e n t a g e o f w a t e r - s t a b l e a g g r e g a t e s was i n c r e a s e d b y t r e a t m e n t w i t h a d d i t i v e . T h i s effect was visibly a p p a r e n t i n t h e field.
T r i a l 2 I n t r i a l 2 t h e n u m b e r o f p l a n t s e m e r g e d o n t h e soil t r e a t e d
w i t h 1,320 p o u n d s p e r a c r e o f H P A N w a s 1 0 t o 2 0 p e r c e n t g r e a t e r t h a n t h a t o f t h e o t h e r t r e a t m e n t s . A l t h o u g h n o t s t a t i s t i c a l l y significant, t h e r e w a s a t e n d e n c y f o r t h e e m e r g e n c e o n t h e p l o t s t r e a t e d w i t h 330 p o u n d s p e r
acre of VAMA to be slightly greater then the emergence for either the same rate of HPAN or for the untreated check.
T r i a l 3 . A v e r y d e f i n i t e i n c r e a s e i n t h e e m e r g e n c e o f p l a n t s a n d t h e a g g r e g a t i o n o f t h e soil was a t t r i b u t e d t o t h e t r e a t m e n t w i t h H P A N i n T r i a l 3 . T h e t o t a l n u m b e r o f p l a n t s e m e r g e d p e r 100 i n c h e s o f r o w was
140 A M E R I C A N S O C I E T Y O F SUGAR B E E T T E C H N O L O G I S T S
3 0 o n t h e u n t r e a t e d soil i n c o m p a r i s o n t o 4 6 o n t h e t r e a t e d soil. I n a s m u c h as t h e r e was very l i t t l e c r u s t i n g of t h e soil surface it is likely t h a t o t h e r factors m u s t b e c o n s i d e r e d t o e x p l a i n this large difference. T h e a d d i t i v e - t r e a t e d soil a p p e a r e d t o b e m o r e friable a n d less h a r d t h a n t h e u n t r e a t e d soil. T h e d e g r e e of h a r d n e s s of t h e soil b e l o w t h e surface is no d o u b t j u s t a s i m p o r t a n t a s t h e surface c o n d i t i o n t e r m e d " c r u s t i n g , " e x c e p t t h a t c r u s t i n g is a m o r e e x t r e m e a n d easily o b s e r v e d c o n d i t i o n . It was also o b s e r v e d t h a t d u r i n g t h e p e r i o d o f g e r m i n a t i o n a n d e m e r g e n c e t h e t e m p e r a - t u r e of t h e a d d i t i v e - t r e a t e d soil was h i g h e r t h a n t h a t of t h e n o r m a l soil.
A t t e n t i o n was first focused on t h e difference in soil t e m p e r a t u r e by t h e o b s e r v a n c e of a c h e c k e r b o a r d p a t t e r n p r o d u c e d by t h e l o c a t i o n of t h e m e l t i n g snow on t h e m o r n i n g of A p r i l 8, 1953, as s h o w n in F i g u r e 1. T h e r a t e at w h i c h t h e t h i n layer of s n o w m e l t e d was slower a n d t h e soil t e m p e r - . a t u r e l o w e r o n t h e a d d i t i v e - t r e a t e d p l o t s . I n c o n t r a s t , t h e soil t e m p e r a t u r e d a t a in T a b l e 2 for t h e r e m a i n d e r of t h e s p r i n g season i n d i c a t e s t h a t t h e a d d i t i v e - t r e a t e d soil was " w a r m e d u p " m o r e r e a d i l y b y t h e w a r m s p r i n g air.
T h i s factor m a y h a v e b e e n o f i m p o r t a n c e i n a s m u c h a s t h e h i g h e r t e m p e r a - tures were f a v o r a b l e t o t h e g e r m i n a t i o n a n d g r o w t h o f seedlings.
Figure 2. T y p i c a l appearance of a 4-inch b a n d of soil treated w i t h soil additive ( V A M A at 12 p o u n d s per acre). Left. Contrast w i t h u n t r e a t e d check. R i g h t . N o t e that the string crosses the b a n d a b o u t 3 inches to the left of the division b e t w e e n treated a n d untreated area.
PROCEEDINGS—EIGHTH GENERAL MEETING 141 Trials 4 and 5. There was no difference in the emergence attributed
to additive treatment in Trials 4 or 5. It was possible to see the effect of the additive treatment on a thin layer of soil surface where the spray ap- plications were made (Figure 2) . Nevertheless, the soil just beneath the surface was hard and cracked.
Conclusions
T h e results of these studies indicate that the soil additives will aggre- gate and improve the physical condition of the soil. T h e emergence of sugar beet seedlings was increased, under the conditions of these trials, however, only when the additive was applied at rates of several hundred pounds per acre and incorporated to a depth of four or more inches in the soil. It is possible that emergence would have been increased with the shallower in- corporations of additive, if crusting conditions had prevailed during the time such treatments were being tried.
An increase of emergence was not obtained in the trials where low rate spray applications of dilute solutions of the additive were made. Never- theless there may be some value for such a procedure as in these trials rather a severe "crust" or "caking" was produced. These trials do indicate that wc cannot expect surface applications of soil additives to control thick crusting or caking but they may be of value in controlling a shallow surface crust. T h e economy and ease of applying the additives as a dilute spray suggests that more trials of this type should be conducted under commercial field conditions. Low rates of application per acre can probably be more satisfactorily obtained by reducing the width of the treated area rather than reducing the rate on the area treated.
Summary
T h e value of chemical additives to increase the emergence of sugar beet seedlings was studied in five field plot trials on the clay soils of western South Dakota.
Application was made by broadcasting the additives on the soil sur- face and incorporating them to various depths in three of the trials. Natural weather conditions were depended upon to produce a crust on the soil surface.
Additives were also applied as dilute water solutions, .3 percent, sprayed on the soil surface in two of the trials. A rather severe crust was produced by applying water with a garden hose.
An increase in emergence attributed to the additive treatment was obtained in two of the three trials in which natural weather conditions were depended upon to produce a crust. Although no increase in emergence was obtained by the relatively economical surface spray method of application, this method may be satisfactory with less severe crusting conditions. T h e effect of the additive on the soil was visibly apparent in all of the trials.
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1952. T h e r e s p o n s e o f sugar beets t o fertilizer i n w e s t e r n S o u t h D a k o t a . P r o c . A m e r . Soc. S u g a r B e e t T e c h . , 189-195.
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(4) S H E R W O O D , L. V., a n d E N G I B O U S , J. C.
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(5) TOLMAN, BION
1946. R e s p o n s e t o n i t r o g e n a n d p h o s p h a t e fertilizers i n t h e inter- m o u n t a i n area. P r o c . A m e r . Soc. Sugar Beet T e c h . , 45-53.
(6) T O L M A N , B I O N , J O H N S O N , R O N A L D , a n d B I G L E R , A . J .
1948. Soil fertility studies i n t h e M o u n t a i n States. P r o c A m e r . S o c S u g a r B e e t T e c h . , 397-406.