The Application of Petiole Analyses to Sugar
PROCEEDINGS—EIGHTH GENERAL MEETING 4 9 tions. T h e nitrogen was supplied as N H4N O3 or as (NH4) 2S04. In addi- tion to the plots receiving only nitrogen fertilizer, four tests included plots treated with phosphorus or both phosphorus and potassium, which were applied with a high rate of nitrogen. The rates applied are given in tables which follow. Both the P2O5 and K2O were applied before planting or at thinning time by sidedressing as treble superphosphate and K2SO4.
Petiole samples wrre collected periodically from each plot throughout the season and analyzed for NO3-N. Certain of the samples were also analyzed for PO4-P and K, but only for selected sampling times. At harvest time the beets were dug and yield and sucrose determinations made.
Results Test 1
T h e harvest data for Trial 1 are given in Table 1 and three of the curves for petiole analyses are shown in Figure 1.
Table 1.—Harvest Results. Trial No. 1, Davis, Yolo County, 1952.
Figure 1.—Effects fertilization on the nitrate-nitrogen con- tent of sugar beet petioles. Trial No. 1, Davis, Yolo County, 1952.
T h e curve indicated by the lower dashed line represents the check plots. In the case of this field the nitrogen level of the plants was below the critical concentration practically all season long when no fertilizer was applied. T h e NO3-N content of the plants which received the 80-pound
1 T h i n n i n g time. Planted September 25.
Figure 2.—Effects of fertilization on N03-N content of sugar beet petioles.
Trial No. 2, Melo- l a n d , I m p e r i a l County, 1952-53.
50 AMERICAN SOCIETY OF SUGAR BEET TECHNOLOGISTS
per acre rate, as can be seen from the solid line curve, increased considerably after the nitrogen application, but declined rapidly as the season progressed and fell below the critical concentration three months prior to harvest. Both of these treatments resulted in lowered yields, which was anticipated from the petiole data. The remaining curve represents the analytical results from beets of the plots to which supplementary 80-pound nitrogen applica- tions were made when petiole analysis showed an impending deficiency.
From the data collected the best time for supplemental nitrogen application could have been predicted but not the amount to apply. At the highest supplemental rate no further significant yield increase was observed, nor was there any yield increase from phosphorus or potassium. The petiole P and K values were well above critical levels and no response was expected.
Test 2
In 1952-53 an experiment was conducted at the Meloland Field Station, Imperial County, California. The treatments, application dates, and yield data are reported in Table 2 and the petiole analysis curves for certain key treatments are found in Figure 2.
Table 2.—Harvest Results. Trial No. 2, Meloland, 1952-53.
PROCEEDINGS—EIGHTH GENERAL MEETING 51 In this test the beets responded to nitrogen rates up to 240 pounds
per acre. There were no significant differences between the single and split applications at corresponding total nitrogen rates. T h e long periods of short nitrogen supply of those plots receiving no nitrogen or 80 pounds per acre at thinning time accounted for the yield reduction. When 80 and 160 pounds of nitrogen were applied as a supplement, the period of suffi- cient supply was extended 2 and 3 months respectively, resulting in yield increases.
Test 3
One of the tests was located on a field of very high nitrogen fertility.
T h e yields of all plots, including check plots, were high and even at har- vest time the NO3-N concentration of the petioles was in excess of the critical level regardless of treatment. Consequently, there were no significant differences in yield due to nitrogen applications. Although petioles of beets which received supplemental nitrogen showed more nitrogen uptake, the difference between such treatments and the check was relatively small at all sampling dates. T h e data for this test are summarized in Table 3.
Table 3.—Harvest Results. Trial No. 3, Santa Barbara County, 1953.
1 Planting time.
2 Calculated using treatment averages for tons beets per acre and percent sugar.
Test 4
Experiment 4 illustrates a case in which no response to added nitrogen was measured, even though such appeared likely. At the time of supple- mental application the concentration of NO3-N in the petioles was ap- proaching the critical concentration. Even though supplemental nitrogen was applied J u n e 5 and the field irrigated June 13 the NO3-N content of the petioles did not increase appreciably. T h e petiole analyses correlated with the yield data, as indicated in Figure 3 and Table 4.
Test 5
In Tests 1, 2, 3, and 4 no response to phosphorus was observed. In Test 5, however, both nitrogen and phosphorus applications stimulated yields. T h e yield data, as reported in Table 5, show that nitrogen alone increased root yields about 7 tons per acre and when combined with adequate phosphorus another 7 ton per acre increase was measured.
52 AMERICAN SOCIETY OF SUGAR BEET TECHNOLOGISTS
T a b l e 5.—Harvest Results. T r i a l N o . 5, T u l a r e County, 1952.
1 Planting time. Fertilizer side-dressed 6 inches S inches from row and about 4 inches deep.
2 This value is low because the yield of one of the plots in this treatment was exception- ally low (11.5 tons/acre).
Figure 4 shows the petiole analyses curves for NO3-N and indicates an interesting effect of phosphorus on nitrate absorption. On May 30 the NO3-N concentration was found to be higher on the plots which received
1 Thinning time.
Table 4.—Harvest Results. Trial No. 4, Santa Barbara County, 1952.
Figure 3.—Effect of fertilization on NO3-N content of sugar beet petioles.
Trial No. 4, Santa B a r b a r a County, 1952.
PROCEEDINGS—EIGHTH GENERAL MEETING 5 3 nitrogen plus phosphorus at planting time than those which received the same amount of nitrogen alone. On July 18 this appeared again in the samples taken soon after the supplementary nitrogen had been added. T h e converse phenomenon had been observed by Lorenz and Johnson (3) in which additions of ammonium sulfate increased the PO4-P content of tomato foliage. In the latter case ammonium sulfate, because of its acid reaction in the soil, made more phosphorus available to the plants. In Trial 5 the greater absorption of nitrate in the presence of phosphorus may be due to faster root development or to increased root activity or to factors not now known.
Figure 4.—Effect of phosphorus fertil- ization of sugar beet petioles. Trial No. 5, Tulare County, 1952.
Figure 5 shows the effect of phosphorus fertilization on the PO4-P con- centration of petioles. Both treatments plotted in this figure received the same amount of nitrogen (240 lbs. N / a c r e ) . T h e phosphate level of the plants which received no fertilizer phosphate ranged from 680 to 440 p.p.m.
PO4-P throughout the season, whereas the phosphate-fertilized plants always had a concentration of 1,600 p.p.m. PO4-P or more. This difference ac- counted for the yield differences measured.
Figure 5.—Effect of phosphorus fertil- ization on the PO4-P concentration of sug- ar b e e t petioles.
Trial No. 5, Tulare County, 1952.
54 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 Diagnosis of Sulfur Deficiency
D u r i n g the s u m m e r of 1953 a field was observed in which t h e r e was a large a r e a of chlorotic sugar beets h a v i n g symptoms i n d i s t i n g u i s h a b l e from those p r o d u c e d by a n i t r o g e n deficiency. Petiole analysis, however, showed that t h e affected beets were h i g h e r in n i t r a t e - n i t r o g e n t h a n the m o r e vigor- ous g r e e n beets. It was d e t e r m i n e d t h a t t h e r e was no a p p r e c i a b l e difference between good a n d p o o r beets i n p o t a s s i u m o r p h o s p h a t e c o n t e n t , b u t t h a t the sulfate c o n t e n t of t h e two v a r i e d widely as r e p o r t e d in T a b l e 6. A l t h o u g h wide differences in t h e c o n c e n t r a t i o n of SO4-S o c c u r r e d in petioles as well as leaf blades, t h e l a t t e r a p p e a r to be b e t t e r for diagnosis of possible sulfur deficiencies.
T a b l e 6.—Sugar Beet Leaf Analyses, B u t t e C o u n t y , J u l y 7, 1953.
After t h e analyses had b e e n m a d e , small strips of soil w i t h t h e deficient beets were t r e a t e d w i t h a m m o n i u m n i t r a t e , gypsum, a n d a m m o n i u m sulfate.
T h e results of s u b s e q u e n t leaf analyses are f o u n d in T a b l e 7.
T a b l e 7.—Sugar Beet Leaf Analyses, B u t t e C o u n t y , August 11, 1953.
1 A p p l i e d to single 4-row strips, J u l y 20, 1953.
T h e r e was a g r e a t i m p r o v e m e n t in the a p p e a r a n c e of sugar beets t r e a t e d w i t h ( N H4) 2S O4. T h e deficiency symptoms d i s a p p e a r e d , t h e leaves t u r n e d d a r k g r e e n , a n d t h e r e was a visible g r o w t h r e s p o n s e . Petioles collected from these p l a n t s i n d i c a t e d t h a t this g r o w t h response was associated w i t h t h e a b s o r p t i o n o f SO4-S. T h e a d d i t i o n o f N H4N O3 d i d n o t correct t h e deficiency symptoms a n d the p l a n t s d i d n o t m a k e the thrifty g r o w t h m a d e b y those receiving ( N H4) 2S O4. W h e n gypsum a l o n e was a d d e d t h e p l a n t s r e a d i l y a b s o r b e d SO4-S b u t m a d e no g r o w t h response; in fact, they m a d e less g r o w t h t h a n p l a n t s receiving N H4N O3.
R e a s o n s for these d i v e r g e n t g r o w t h responses can be seen in t h e d a t a p r e s e n t e d in T a b l e 7. W h e n g y p s u m was a d d e d the sulfur deficiency was readily corrected, b u t almost i m m e d i a t e l y t h e p l a n t s b e c a m e deficient i n n i t r o g e n a n d therefore little o r n o g r o w t h r e s p o n s e w o u l d b e e x p e c t e d . T h e a d d i t i o n o f N H4N O3 k e p t t h e p l a n t s well s u p p l i e d w i t h n i t r a t e s b u t
PROCEEDINGS—EIGHTH GENERAL MEETING 55 they continued to be deficient in sulfur. (NH4) 2SO4 corrected the sulfur
deficiency and also supplied the plants with sufficient nitrogen for good growth.
These observations illustrate that in many instances leaf analysis can be a very effective tool for rapid diagnoses of field problems.
Discussion
These trials have provided case histories showing how leaf analysis might be used to improve practices in sugar beet fertilization. In each instance it was felt that such a technique could have led to better fertiliza- tion and a better understanding of the fertility problems of the fields studied.
Tests 1 and 2 illustrated that petiole analysis can be used to demon- strate impending nitrogen deficiencies and thereby act as a guide to time of application. In Test 2 there was apparently no advantage to applying the fertilizer in two applications rather than one. T h e point is raised, however, that at the beginning of the season there was no satisfactory way to predict with accuracy which of the rates applied would have been best.
In fact, at mid-season petiole analysis could not be used to tell how much nitrogen to apply as indicated by the maximum response to 80 pounds of supplemental nitrogen in Test 1, whereas Test 2 required 160 pounds for best results. For such fields addition of an amount somewhat less than that considered adequate, with supplemental nitrogen applied when indi- cated by the analytical data, would appear most efficient. T h e amount of supplemental fertilizer to be added would depend on the length of growing season remaining and past experience with the field.
Test 3 represented a field in which certainly no supplemental nitrogen was needed or indicated by petiole analvsis. In such fields, i.e., those which may be judged to be high in fertility due to past history or the nature of the soil, it would probably be best to refrain from applying fertilizer until such time as the analyses indicated a need. In the particular field cited any fertilizer expenditure was wasted during that particular crop season.
If petiole analysis had not been used in Trial 4, a false conclusion might have been drawn due to the failure of beets to respond to supple- mental nitrogen applications. T h e conclusion that the beets did not need more nitrogen would have been suggested from the yield data alone. Petiole analysis, however, showed that the plants did not absorb the supplementary nitrogen in amounts sufficient to affect the yields appreciably. Therefore, it may still be possible to obtain yield responses to nitrogen on this field if ways can be found to get supplementary nitrogen into the beets.
Test 5 demonstrated the relationship between both NO2-N and PO4-P concentration in sugar beet petioles and the growth of the plants. Leaf analyses of such a field would indicate the possibility of improving subse- quent crops by phosphate fertilization. In all trials, except Number 5, phosphate and potassium analysis showed no indications of deficient supplies and, since no yield differences arose, the analytical data are not included.
56 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 Summary
T h e use of p e t i o l e analysis as a g u i d e to sugar beet p r o d u c t i o n was s t u d i e d t h r o u g h a series of tests c o n d u c t e d in several California beet-growing districts. Petiole samples were t a k e n periodically from check plots a n d from plots t r e a t e d w i t h p r e d e t e r m i n e d basic fertilizer rates. C e r t a i n of t h e samples were "analyzed for N O3- N , P O4- P , a n d K, a n d curves r e p r e s e n t i n g changes in p l a n t c o n t e n t of the n u t r i e n t s w i t h t i m e were c o n s t r u c t e d . In the case of n i t r o g e n , s u p p l e m e n t a l a p p l i c a t i o n s were m a d e w h e n the curves i n d i c a t e d a n a p p r o a c h i n g deficiency. W h e n e x p e r i m e n t s were c o n d u c t e d on h i g h fertility fields, in which no n e e d of s u p p l e m e n t a l t r e a t m e n t s was i n d i c a t e d , the same t r e a t m e n t s were a p p l i e d at t h e latest practical d a t e .
T h e e x p e r i m e n t s d e m o n s t r a t e d t h a t p e t i o l e analysis can b e a v a l u a b l e aid in sugar b e e t fertilization on fields of h i g h or low fertility. It was possible to p r e d i c t from curves cases in w h i c h n i t r o g e n responses c o u l d or could n o t b e expected, a n d t h e time w h e n s u p p l e m e n t a l a p p l i c a t i o n s s h o u l d be m a d e . It was also possible to use leaf analysis in i m p r o v i n g p h o s p h o r u s fertilization practices, a n d , as was p o i n t e d o u t in a case w h e r e a sulfur de- ficiency was found, to diagnose still o t h e r n u t r i e n t deficiencies.
ACKNOWLEDGMENTS
F a r m Advisers H a r w o o d H a l l , Alan George, and M o r t o n Morse, California Agricultural Extension Service, all r e n d e r e d valuable assistance in c o n d u c t i n g this work. T h e staff of t h e Meloland Field Station, I m p e r i a l County, California, also aided with tests conducted in t h a t area. Sucrose analyses were m a d e by t h e Holly Sugar C o r p o r a t i o n , the U n i o n Sugar C o m p a n y , the Spreckels Sugar C o m p a n y , a n d t h e American Crystal Sugar C o m p a n y .
Literature Cited (1) D U C K W O R T H , W . R., a n d H I L L S , F . J .
1952. Possibilities of i m p r o v e d n i t r o g e n fertilization of sugar beets t h r o u g h t h e use of leaf analysis. Proc. A m e r . Soc. Sugar Beet T e c h . pages 252-254.
(2) H A D D O C K , J. L.
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1953. N i t r o g e n fertilization as r e l a t e d to t h e availability of phos- p h o r u s in certain California soils. Soil Science 75:119-129.
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(5) U L R I C H , A.
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(6) U L R I C H , A.
1946. P l a n t analysis as a g u i d e in the fertilization of sugar beets.
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(7) U L R I C H , A.
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PROCEEDINGS—EIGHTH GENERAL MEETING 57 (8) ULRICH, A.
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Amer. Soc. Sugar Beet Tech. 88-95.
(9) ULRICH, A.
1950. Critical nitrate levels of sugar beets estimated from analysis of petioles and blades with special reference to yield and sucrose concentration. Soil Sci. 69:291-309.
(10) ULRICH, A.
1950. Nitrogen fertilization of sugar beets in the Woodland area of California. II. Effects upon the nitrate-nitrogen of petioles and the relationship to sugar production. Proc. Amer. Soc. Sugar Beet Tech.
(11) WALKER, A. C, H A C , L. R., ULRICH, A., and HILLS, F. J.
1950. Nitrogen fertilization of sugar beets in the Woodland area of California. 1. Effects upon glutamic acid content, sucrose con- centration and yield. Proc. Amer. Soc. Sugar Beet Tech. 362- 371.