Effects of Nitrogen and Phosphorus Fertilizer on Yield and Malting Quality of Barley
R. E. ATKINS, GEORGE STANFORD, and LLOYD DUMENIL Iowa State College, Ames, Iowa
Varying rates of nitrogen and phosphorus fertilizer were applied to spring barley plots in northwest Iowa during the 1948 to 1950 seasons. Increases in grain yield through combined nitrogen and phosphorus fertilization were unusually high. The highest yields for the three seasons were 90, 150, and 120% greater than the check or no-treatment plots. Lower rates of application, and nitrogen and phosphorus applied separately, generally gave significant increases, but of lesser magnitude. Malting quality characteristics of the barley produced under conditions of high response to fertilization generally were not significantly altered, but those affected sufficiently to be of practical consequence in the malting and brewing process were improved rather than diminished. Nitrogen fertilizer, applied in excess of that required for maximum yield per acre, resulted in an undesirable increase in protein content and a reduction in malt extract. Phosphorus fertilizer improved malting quality b y increasing weight per 1000 kernels and malt extract, and had no injurious effect on other criteria of malting quality.
I
and upper hlississippi valley areas, barley often follows corn in the rotation. Readily ai-ailable supplies of nitrogen frequently are lo\v with this cropping system and fertilizer must be applied to produce a satisfactory barley crop. On many soils. available phosphorus content also may be low. The grower primarily is interested in increasing the grain yield of the crop through the use of fertilizer and in maintaining standing ability suitable for harvesting. Processors of malting barley, however. are more concerned with effects of the fertilizer upon malting quality of the grain. This paper presents the results of fertilizer experiments with barley conducted in northLvestern Iowa for yield of grain. several criteria of malting quality. and certain interrelationships among quality factors. N THE CORN BELT
Literature Review
The results of numerous fertilizer esperiments with barley have been reviewed by Olson and others (75). Most of the experiments have shown an appreciable yield response from nitrogen and phosphorus fertilizers alone and in combination. The magnitude of response and the significance of variety-fertilizer interactions. however, have varied considerably. Gregory and Croi+ther ( 8 ) . in England, reported no differential response in grain yield for five varieties of barley produced a t eleven different levels of nitrogen, phosphorus, and potassium application. Significant fertilizer-variety interactions for yield were obtained by Frey and others (7) in Michigan experiments n i t h fertilizers varying in nitrogen,
phosphorus. and pctassium content. Pendleton and others (76) in Illinois found significant varietal response to varying combinations of nitrogen, phosphorus, and potassium fertilizer. Nitrogen was observed to be the primary nutrient element limiting grain yields in their experiments, even on highly productive land and in a rotation containing legumes; the response to phosphorus was next in magnitude. The time and rate of application and two sources of nitrogen were varied in studies by Foote and Batchelder (5) in Oregon; all methods gave some yield increase in tWo of the three years tested. Lack of response in the other season was attributed to below average rainfall and very low yield levels. Studies relating fertilizer applications with malting characteristics of the barley generally have shown variable effects on malting quality. In experiments reported by Ahr and Mayr ( 7 ) in Bavaria, calcium and phosphorus applications improved the malting quality of the grain, but nitrogen affected quality adversely. while potassium lowered the protein content of the grain. They noted striking tendencies of climatic and growth conditions to mask varietal differences. Frey and Robertson (6) refer to experiments in Wisconsin which have shown significant effects of fertilizers upon malting quality. The quantity of extract from barley malt was increased from 1 to 2%, protein content and diastatic power were increased with heavy applications of nitrogen fertilizer, and kernel size-i.e., weight per 1000 kernels-was increased lvith the application of fertilizer. Meredith and others (72) in Manitoba,
Canada. found a somewhat greater effect of fertilizer on malting quality with early sown barley than from later plantings. They concluded, however, that the application of fertilizers generally did not affect the malting quality to any great extent. The application of commercial fertilizers of varying composition to five varieties of malting barley by Frey and Robertson (6) in hlichigan resulted in a n average increase of 0.9 and 0.47, in malt extract in nvo different years. Protein content of the barley grain was not appreciably altered by the fertilizer applications in either season, while diastatic activity was decreased by each fertilizer used in one year but not affected in the other. Certain associations among quality measures and of grain yield with quality factors have been reported. Seatby and McCalla ( 7 4 in Alberta, Canada, observed that high yielding barley varieties have a marked tendency to be low in protein content. Correlation coefficients from a number of their experiments were all negative for the comparison of yield and protein content and ranged in magnitude from -0.21 to -0.88. Meredith and Anderson ( 7 7) in Canada obtained a positive intervarietal correlation between 1000-kernel \\.eight and malt extract, but obtained negative correlations for 1000-kernel weight with both nitrogen content and diastatic activity. Nitrogen content also was negatively correlated with malt extract and diastatic activity, although the coefficients were small in magnitude. Correlations among a large number of barley and malt properties have been presented by Anderson and others (2) in
V O L . 3, NO. 7, J U L Y 1 9 5 5
609
activity. Both average kernel iceight and bushel weight were found to be positively associated with malt extract.
Nitrogen was applied a t rates of 20 and 40 pounds per acre as 60 and 120 pounds of ammonium nitrate in 1948 and 1950, and as 100 and 200 pounds of ammonium sulfate in 1949. Phosphorus applications of 40 and 80 pounds per acre, supplied as 200 and 400 pounds of 020-0. Icere made in all three seasons. Fertilizers \cere broadcast and disked in prior to seeding for all experiments. .A11 plots \\-ere seeded a t a rate of 2’:’~ bushels per acre with a small drill and from 52 to 100 square feet of each plot \vas harvested for yield in the different seasons. One-pound grain samples from each of three replicates were submitted each year to the Malting Barley Improvement .%sociation. Milwaukee, \Vis.: for evaluation of malting quality. Quality determinations were made in the laboratories of three members of this association.
Experimental Procedure
ExperimentalResob
The experiments reported herein were conducted in 1948 in O‘Brien County and in 1949 and I 9 5 0 in Lyon County, Iowa. Soil type for the 1948 and 1949 experiments was a Primghar silt loam, while the 1950 experiment was on Galva silt loam. For all three experiments, corn, oats, and corn. respectively, had been grown during the three preceding crop seasons on the experimental area. Soil tests of the experimental areas indicated supplies of available phosphorus to be low. The experimental design used was a 3 X 3 nitrogen-phosphorus (NP) factorial in 1948 and 1949 for the fertilizer treatments, with the barley varieties superimposed as subplots jvithin each treatment. Mars, Moore, Kindred, and Wisconsin 38 varieties were groivn in 1948, and all four varieties \cere used in both the yield and quality analyses. Wisconsin 38 variety was dropped from the field experiments in 1949 and only the Moore variety was analyzed for malting characteristics. In 1950 only the Moore variety was used in both field and quality studies and the factorial arrangement of fertilizer treatments again was used.
The experimental results are presented in three sections: effects of fertilizers on grain yield! effects on malting quality of the grain. and interrelationships among certain of the quality factors. The variance analyses for grain Grain yield given in Table I sholv a highly significant yield response to both nitrogen and phosphorus in all three seasons. Superphosphate applications were particularly effective in increasing yields in the 1948 experiment. greatest response in 1949 was from nitrogen. ivhile a more nearly equal response to the tWo elements was obtained in 1950. The nitrogen-phosphorus interaction was significant only in the 1948 test and then only a t the jL;, level of probability. A significant interaction between varieties and fertilizer treatments was apparent in the 1948 experiment. but all varieties responded in essentially the same manner to the different fertilizer applications in 1949. Yields obtained in 1948 for the four varieties groivn a t varying levels of fertilizer application are given in Table 11. Increases from phosphate application were outstanding: but nitrogen responses
Table I. Analyses of Variance for Grain Yield (In bushels per acre for barley varieties grown on soil receiving different levels of nitrogen and phosphorus fertilizer application, O’Brien and Lyon Counties, Iowa, 1948-50) I948 D.F.
I949
M e a n square
D.F.
Treatments 8 760.9 h2 102.65 P 2 2?97,5a 5-P 4 ?0,9b Error a 16 16.4 Varieties 3 197.4a Var X treat. 24 20.8~ 6 N X var. 44.2a 6 24.6b P X var. 12 NP X var. 7.3 53 Error b 8.2 Exceeds 1 % level of probability. * Exceeds 5% level of probability.
8 2 2 4 16 2 16 4 4 8 36
Source o f Variation
Canada. From intravarietal correlations a close association of protein content, diastatic activity, and malt extract was apparent. 4 positive correlation between diastatic activity and protein was obtained, while both diastatic activity and protein were negatively correlated with extract. Diastatic activity of the malt and of the barley were observed by Meredith and others (73) in Canada to be positively correlated, with a coefficient of 0.902 obtained from 807 samples. A high correlation ( I = 0.824 from 304 samples) between barley extract and malt extract was obtained by Meredith (70). Den Hartog and Lambert ( I ) in Minnesota found the three maltingquality characters-protein, diastatic activity, and extract-to be rather closely interrelated on the basis of both simple and partial correlations. Protein content was positively correlated with diastatic activity and negatively correlated with malt extract. The simple coefficient between diastatic activity and extract was significant, but the partial coefficient, when protein content was held constant, was not. They concluded that the simple correlation between diastatic activity and extract was due to the association of each with protein. Comparisons of agronomic with quality characters showed grain yield to be positively correlated with extract and negatively correlated with both protein and diastatic
Table II.
1950
M e a n square
792 3072 76 9 7 75 4 5
0. 00 8a
6 4 5a 6 9
D.F.
M e a n square
8 2 2 4 16
175.3a 500. 186.6. 6.9 11 6
..
. . . . . . .
.. . .
80 2 2 ’ 1
Yield of Barley Grown on Primghar Silt l o a m Receiving Different levels of Nitrogen and Phosphorus Fertilizer Application (O’Brien County, Iowa, 1948) Fertilizer level“
Variety
h’isconsin 38 Mars Moore Kindred
W
o
29.2 30.6 30.2 33.9
Nopi
NqP?
NiPo
36.1 38.9 38.4 42.5
40.6 45.7 47,9 45.9
27.6 26.4 28.6 33.3
NrPo NiPi Yield, Bushels per acre
30.8 25.7 32.6 35.0
Mean 31 . O 39.0 45.0 29.0 31 . O N I . 20 Ib. Nlacre. N2. 40 Ib. ;\‘/acre. PI. 40 lb. P2/Oj acre. P?. 80 lb. PlOj/acre.
610
AGRICULTURAL AND
FOOD CHEMISTRY
NiPr
NaPi
NrP?
44.3 39.5 46.7 47.4
43 7 42.5 50.7 48.6
40.8 39.6 49.6 41.1
50.5 45.8 58.3 50.8
44.5
46.4
42.8
51.3
Table 111.
by malsters and brelvers. It'hether the malt is to be used by brewers: distillers, or for other purposes affects the evaluation for some criteria. and perferences of individual brewers as to color, taste, and other properties of the bre\v also are reflected in variable emphasis on quality determinations. Ranges of values for the different factors generally considered satisfactory by most commercial maltsters and chemists have been discussed bv Burkhart and Dickson ( 3 ) . Values of 11 to 13% malt protein are cited as sarisfactor). for the production of brei\.er's malts, and 13 to 15.5% protein for distiller's malts. Malt extract values to 7 2 to 7 6 7 , are suggested as satisfactory in most cases, but are somewhat dependent on the variety, season. and location. These two criteria, together with bushel weight and 1000-kernel xveight. are likely to be of particular concern in a study of effects of fertilizer on malting quality. The significant effects and interactions obtained from the analyses of variance for the various quality factors measured in 1948, and 1949, and 1950 are presented in Table IV. The application of nitrogen had a significant effect in increasing barley protein, malt protein. and soluble protein in the wort in the 1948 test. Phosphorus additions to the 1948 experiment resulted in significant increases in bushel weight, 1000-kernel weight, phosphorus content of the grain. soluble protein in the wort, and per cent soluble of total malt protein. The nitrogen-phosphorus interaction was not significant for any of the eleven determinations made on the 1948 samples. Varieties differed significantly in 1948 for all quality criteria, but the interaction of varieties with treatments was not significant for any character measured. Samples for quality analyses in 1948 were submitted from only the NoPo. N ~ P G ,S O P ? , and KzPz treatments. Means for the eleven criteria measured on the four fertilizer treatments are given in Table V. Means of the four varieties tested are shown, as the analvsis
Yield of Moore Barley Grown on Soil Receiving Different levels of Nitrogen and Phosphorus Fertilizer Applications (Lyon County, Iowa, 1949 and 1950) Fertilizer levela
Soil Type
Year
NaPo
NuPi
NoPz
NiPo
NvPo
NiPi
NIP?
NvPi
NvPs
Yield. Bushels Der acre
1949 Primgharsiltloam 1 6 . 6 1 - 8 1 9 . 4 29 4 3 5 . 5 29 9 3 4 . 1 3 8 . 6 4 2 . 7 1950 Galvasiltloam 1 8 5 2 3 2 26.0 2 6 . 6 30.4 3 1 . 8 34.0 4 0 . 3 4 1 . 7 a XI. 20 lb. N/acre. N?.40 lh. S acre. PI. 40 lb. PrO5,'acre. Py. 80 lb. PzOjiacre.
Table IV.
Significant Effects Exerted by Fertilizer Treatments on Malting Quality Criteria in Iowa Tests, 1948, 1949, and 1950 Significant Effecfs and lnteracfions
Qualify Factor
1948
Bushel weiqht Weisht/1000 kernels Phosphorus in grain, % \?ar.". Pa Barley protein Val.. h: S h .NP X Var. Malt extract \'ar,[' Total malt protein \'a?.". x-cj Malt diastase \'ar." a-Amylase \.as." Papain diastase nd Formol N in wort, 70 \'ar,a Soluble protein in wort \'ar.". ?;". P
