1966 Soil Plant Nutrient Research Report

compiled by

D.A. RENNIE

Department of Soil Science University of Saskatchewan Saskatoon, Saskatchewan

Printed Sept . , 1967 Saskatchewan Institute

of Pedology Report No . M8

TABLE OF CONTENTS

INTRODUCTION . . .

I. STUBBLE FERTILIZER TESTS

Multi-Treatment Field Tests

School of Agriculture Co-op Tests . Veterans Land Act Co-operative Plots II. NITROGEN PLACEMENT -WHEAT .

I I I .

IV.

PHOSPHORUS PLACEMENT - FLAX

THE PHYSICAL FORM OF UREA PHOSPHATE AND NH 4N0 PHOSPHATE CARRIERS . . . , . . . . 3

V. THEN REQUIREMENTS OF SELECTED WHEAT VARIETIES VI . TRITICALE FERTILIZER EXPERIMENT

.

^'

1

2 2 5 5

7 8

9

16 18 VII. COMPARISON OF NITROGEN SOURCES IN MIXED N-P CARRIERS 19 VIII. PROCAL TEST PLOTS

. .

IX. SOIL TEST IMPROVEMENT INVESTIGATIONS

Sampling Patterns for Representative Soil Samples . . . . Changes in Available Nitrogen Occurring Between October, 1966 and May, 1967

Changes in N and P Fertility Levels During the Crop Year . . . . N and P Fertility Trends for the Period 1965 to 1967

X. MOISTURE INVESTIGATIONS

Water Use and Yield of Wheat Profile Type and Moisture Use

XI. MOISTURE RETENTION OF SELECTED SASKATCHEWAN SOILS Moisture Retention Curves for Soils of

Different Textures . . . . Effect of Clay, Silt and Organic Carbon on Moisture Retention . . . .

Bulk Densities of Soils of Different Texture Acknowledgements

21 22

23 28 28 31 32 32 40 51

52

57 60 60

XII . THE DISPOSITION OF MINERAL NITROGEN DURING CROP GROWTH 74 XIII. ESTIMATES OF YIELD OBTAINED WITH 1- AND 3-SQUARE YARD

SAMPLES 86

APPENDIX A APPENDIX B APPENDIX C

88 92 95

INTRODUCTION

These investigations were supported by research grants from the following sources.

acknowledged.

This financial assistance is gratefully

Cominco, Ltd., Federated Co-Ops, Ltd., Imperial Oil, Ltd., Nat i anal Grain Co. , North-West Line Eleva tors, Sherri tt~Gor don Mines, Northwest Nitro, The Saskatchewan Wheat Pool, Western Co-Operative Fertilizers, and the National Research C~uncil.

The V.L.A. co-operative project provides a coverage of the province which would otherwise be impossible without greatly adding to costs. Grateful acknowledgment and sincere thanks is extended to the V.L.A. supervisors and veteran farmers.

None of these investigations would be possible without the assistance of the many farmers on whose farms the field plots were located.

This report summarizes the field research investigations carried out during the 1966 growing season, together with related laboratory projects. W.A. Rice, Research Assistant, assumed most of the responsibility for the conduct of the investigations. He was assisted by L. Babiuk,

J.

Billett, E. Wawryk, L. Hayes,

E. DeYong, H. Schappert, G. Kowalenko,

J.

Bole, D. Pederson, M. Greenshields and D. Bell.

2,

l, STUBBLE FERTILIZER TESTS

The scope of the 1966 investigations included 49 multi- treatment field-scale test plots; these represent a continua- tion of the soil test calibration tests on stubble land a project ^~hich was initiated in 1965,

for an additional three years.

This program will continue

A total of 12 large field-scale plots, each with 10 sub- plot::: ^:1t selected locations within the field strip area, were

laid out in the Dark Brown, Black and Grey Wooded soil zones.

Fifteen variously treated 8' x i mile strips, seeded with both a discer and drill, were included at each location.

Seamless aluminum tubes were installed at each of the 10 sub-plots; these served as access tubes for the neutron

moist.t.lre meter,. Readings were taken at time of seeding in the spring and at harvest in the fall, Composite soil samples were taken from each sub-plot at 6' intervals to a dep h of 48".

Only 8 of the 12 test locations were harvested. The remainder either were damaged with hail, or severely infested with wild oats ..

The average yields obtained from each test location, o- gether with soil test data, is included in Appendix A,

Response to optimum N and P applications at some of the locations was quite dramatic, ranging as high as 33.7 bushels per acre. The mean response for the various treatments is outlined in Tables l 2 and 3, The individual yield, soil N, soil moisture and precipitation values obtained for the 10 sampling sites at each location has been placed on computer tape for yield-soil test-moisture regression analyses.

While the yield of the discer~check was hig.her than where the drill was used, yield increases due to 11-48-0 or 23-23~0

were greater for the latter seeding unit (Tables 1, 2 and 3).

Reducing the seeding and fertilization (23-23-0) rate by 50% (alternate runs sealed) resulted in a yield decrease, compared to the 'standard', of approximately 3 and 4 bu/acre respectively for the check and fertilized treatment

{Table 3).

Table 1.

Seeding Unit

Discer Drill

Mean Yield of Check and Yield Increases (bu/acre) (A) Wheat on Stubble (8 plots)

Check Yield

25.7 23.5

11-48-0 at 40

7.3 9.5

Yield increase over check 23-23-0

at 87

11-48-0 at 40 plus 33.5-0-0 at

120 180

9.0 15.2

L.S.D. (P

=

^.05)

=

^{2.1 bu/acre}

Discer Drill

10.0 11.7

(B) Barley on Stubble (one plot) 3.4

8.0

4.1

l l . l 12.6 9.7 L.S.D. (P = .05) = 4.3 bu/acre

Dep:th 0- 6 6-12 12-24

(C) Soil Test Values - Wheat (8 plots) N0₃-N,

Avera~e

lL8 10.1 27.3

13.0 6.9 14,0

lb/acre lb P/acre

Ha}l~e (means) Average Range (means)

6.0- 22.8 15.9 8.7-26.0

3.3- 24.8 4.5-104.2

Soil Test Values - Barlev (one plot) 5.8- 28.0

4.2- 12.2 2.1- 25.4

11.3

Table 2

Seeding Unit

Disce Drill

De;eth

o~ 6 6-12 12-24

le 3

Seed it seer i l l

4.

eld sponses ₁ bu acre on a Soil

in N and P

sting

Check eld

12.5 10.9

11~48~0

at 40

7.8

L,S Do (P

=

,05)

=

2,7 bu acre

(B)

11~48~0& plus

33.5~0~0 at

~N lb re _ P l b re

Mean Ran~ Mean

6.2 ^2.1~ 8@0 3.3 ^.7~ ~L 3 4 5 ^Llc~l0©6

Mean Yields (bu/acre)

and Fertilization Rates were eatments with ternative Runs

Rang_e

ere andard Seeding ared to Similar

Sealed (5 plots) Standard

eck eld

Alternative Standard ternati ve Runs Closed

2 ~.L 3 2 L l

32.9 28.5

27.1 L.S.D. (P = .05) - L2

th 0- 6 6-12 12=24

Soil Test Values -N; lb

Mean

re Range 13.8

13.5 38.9

9.2- 22.8 lLl-'24,8 ll,,0-104.2

p lb Mean

re

Ra~~

B. School of ~riculture Co-op Tests

A total of 15 field scale plots were laid down on former School of Agriculture students' farms. Fourteen of these were harvested (see Appendix B for yield data from each test. The soil test data obtained on the samples for many of the sites suggested abnormally high available N and P. This was later traced to contamination by fertilizer materials. All data obtained from the contaminated soil samples has been deleted.

The fertilizer treatments used and the mean yield increases for wheat, barley and Durum seeded on stubble are included in Table 4. Responses to phosphate, in general, are slightly

lower than those given in Table 1, but an almost straight yield increase was recorded as nitrogen rates were increased.

C. Veterans Land Act Co-operative Plots

The V.L.A. supervisors throughout the province again co- operated in a joint stubble fertilizer research project.

Twenty-two of the twenty-four V.L.A. Credit Advisors laid out out one plot each in their respective districts; only 20 plots were harvested. The veteran farmers' equipment was used to seed the field-scale plots. The techniques outlined above for the School of Agriculture plots were followed to obtain an estimate of depth of moisture at time of seeding and to take soil samples for analyses.

The mean yield increases obtained for the respective

treatments are given in Table 5. (See Appendix C for individual plot yield data and soil test values.) These tests, obtained from test sites uniformly distributed throughout the province, clearly demonstrate the strong response to N and P fertiliza- tion on stubble land that occurred under the very favorable growing conditions prevailing during the 1966 growing season.

Table 4

Check

27.0

32.0

17.5

Table 5

Check

6 ⁰

Mean Yield of Check and Yield Increases (bu re) School of Agriculture - Co-operative Tests (A) Wheat on Stubble (9 plots)

11~48-0

at 40

4.0

L.S.D. (P ^::: .05)

<B) Barle;L 7.9

L.S.D •. CP ^::: .05)

:::

on

:::

23-23~,0

at 87

2.2 bu Stubble

8.3 3.1 bu

re (4

re

33.5~0~0 at 120 plus ll-48-0 at

40 13.4

plots)

21 0

(C) Durum on Stubble (1 plot)

14.4

Mean Yield of Check and Yield Increases V.L.A. Co-operative Plots

(A) Wheat on Stubble (14 plots)

11-48-0 23~23-0 33.5-0-0 at 115

~~-~~~~a~t~4~0~~-~~~"""a"'"t~,;;;.8.,;,7~-~~ £1 us 11-,j §..::.,0 at 4 0

27.2 5.8 7.9

L.S.D. ( ::: .05) == 2.1 bu./acre

(B) Barley on Stubble (5 plots)

39.4 12.9 lLO

L,,S .D. (P ^::: ,,, 05) ^::: 3.4 bu re

(C) Oats on Stubble l plot)

82.1 12.1 -4.8 25.0

L.S.D. (P ^::: .05) ^::: 7.4 bu/acre

(D) Soil Test Values

-

^{lb acre*}

Wheat Barle;y

Depth Depth

0-6¹¹ 6-12 ~' 12-24'' 0-6'' 6-12 '' 12-24'' N03-N

Mean 23 20 35 17 9 35

Range 7-65 ^6~53 4-144 10-23 6-14 12-86 p

Mean 31 29

Range ^{14~47 16~51}

*Samples were not taken from the oat test

II. NTTROGEN PT .. Af~F.MENT - WHF.AT

One field-scale experiment was set out in the Nokomis area in which the various fertilizer treatments were applied with the seed, below the seed, and the phosphorus (11-48-0) with the seed and the nitro~en broadcast.

Nl5 tagged 33.5-0-0 was used in a small sub-plot selected on an Eluviated Chernozemic profile within the larger nitrogen placement test. Approximately 2 grams of Nl5 was required to give an Nl5 percentage excess of 1.

The soil sampling pattern together with installation of neutron access tubes was the same as outlined for the multi- treatments field plots described above.

The yield data obtained using a combine (Table 6) suggest that a- yield depressi.on oc'curred eve.n where 20 lb of N was applied to he seed. An application of 40 lb N with tne seed resulted ~n a yield measure of 2 bushels less than the broadcast treatment. In general, similar trends were obtained from the data based on square yard samples.

Broadcasting the nitrogen in mid-June, even with the favorable rainfall that occurred did not result in yield increases comparable to N broadcast at seeding time.

Table 6 Nitrogen Placement Study - Nokomis (one plot)

Treatment Yield of Check, and Increase (bu/acre)

lb/acre Placement taken by

N P205 combine sguare yard

17.6 23.3

5 20 seed 4.4 4.6

5 20 1" below seed 3.2 7.2

20 20 seed 4.8 5.9

20 20 1" below seed 5.2 4.1

15

5 20

broadcast

5.6 3.8

seed

40 20 seed 6.4 6.1

40 20 1" below seed 7.6 7.1

35

5 20

broadcast

8.4 8.8

seed 35

5 20

broadcast

-

^June

seed 6.4

L.S.D. = 2.1

8 .

Table 6A Soil Test Values ~one plot)

Depth N0 3 -N, lb/acre ^p lb/acre

Mean Range Mean Range

0- 6 10.7 5.8-15.4 24.5 7.6-74.2

6-12 7.4 4.8-13.8 12-24 26.0 11.7-73.2

III. PHOSPHORUS PLACEMENT - "FT.AX

Two field-scale plots were laid down on the Regina Heavy Clay soil in the Rosetown area. The various rates of 11-48-0

(Table 7) were applied with the seed, below the seed, and broadcast. In addition, the 10-20-10 liquid fertilizer was applied as a foliage spray four weeks after seeding (the manufacturer's directions were followed).

In geneL.al-, placemen..t. oi t.b.e ll-48-0 with the seed r esulted in higher yield increases than when placed below t h.e s e e d • The b-r o a-d-e as t l - 4 8 -0 p x ^c :v e d.. L'l_e f f e c tj.. v...e • S<rme upward adjustment of yield occurred on those treatments receiving the foliage application 10-20-10. None of the yield increases resulting from the foliage spray treatment were significantly different from the check.

Phosphate fertilizers are not, at the present time, recommended for flax seeded on fallow land. These data

suggest that some consideration should be given to an applica- tion of approximately 35 to 40 lb/acre on the soils in the medium and low phosphorus test range.

Table 7 Yield of Flax (bu/acre) with Varying Fertilizer Placement (mean of two summerfallow tests)

Placement

Treatment With Seed Below Seed Broadcast

11~48-·0 at 20 24.0 23.7

91

"

^{30 25.9 26.7}

"

^{91 40 27.3 24.9}

" "

^{40 23.4}

"

^{I! 60 23.4}

10-20-10 2 gal/acre 10-20-10 4 gal/acre Check yield

24.8 25.9 ::: 23~8

L,S.D. (P = .05) = 2o2 bu/acre

Soil Test Values (two plots) N0 3 -N, lb/acre ^p lb/acre Depth

Mean Range Mean Range

0- 6 37.7 35.7-39.6 18.3 18.0-18.6

6-12 25.2 18.2-32.2

12-24 90.8 45.5

IV. THE PHYSICAL FORM OF UREA PHOSPHATE AND NH4N0 3 PHOSPHATE CARRIERS

Small rod-row experiments were set out on a summerfallow and a stubble Blaine Lake soil. The plots were located

within the same field and approximately 100 yards from each other. The treatments included ammonium dihydrogen phos- phate coated on urea and ammonium nitrate pri1ls, as well as mechanical mixtures and homogenous prills of the phos- phate and respective nitrogen carriers. The various ferti~

lizer materials were prepared in the Sherritt Gordon Experi- mental Fertilizer Laboratories at Fort Saskatchewan.

The treatments were arranged in a lattice design; the fallow test contained 16 treatments replicated five times, the stubble test, 25 treatments with 6 replicates.

10'

Results

The following observations can be drawn from the data printed in Tables 8 t o l l inclusive.

1. The urea phosphates applied at levels of less than 25 lb N per acre performed equally as well as the respective

NH4 N0 3 ~phosphates on both the s tu,b bl e and fall ow plots. At higher rates of application, the yields from the urea phosphate treatments fell much more rapidly than where ammonium nitrate was used as a source of nitrogen.

2. The comparative effects of the physical form of the urea phos- phate carriers varied with the rates of application; the

inferior performance of the homogenous prills was very marked at higher rates of nitrogen application. In general, the mechanical mixture out-performed the urea prills coated with ammonium phosphate.

3. The physical form of the ammonium nitrate-ammonium phosphate carriers did not affect yield to any extent. One exception, however, is evident on the fallow plot where the phosphate- coated ammonium nitrate prills resulted in a 5 bu yield increase over the comparative mechanical mix at the 23 lb N rate of application.

4. The yield data given in Tables 8 and 9 verify the adverse effects of nitrogen application with the seed much above 25 lb N/acre.

5. The ammonium dihydrogen phosphate (fallow site) or the

ammonium dihydrogen phosphate plus ammonium nitrate (stubble site) applied in the p r i l l , liquid or powder form resulted, in general, in similar yield levels.

6~ The very large yield increase due to phosphorus application on the stubble plot site as compared to the fallow suggests that the available phosphorus as measured by the sodium bicar- bonate extractant underestimates the plant available phos- phorus in stubble soils. On the average, the 10 lb P/acre

application resulted in a 6 and 15 bu per acre increase on

the fallow and stubble sites respectively.

7. The addition of urea to ammonium phosphate did not alter the availability of the fertilizer phosphorus. In contrastw the ammonium nitrate significantly increased the plant uptake of fertilizer phosphorus as compared to soil phosphorus, and consequently these latter treatments were characterized by a relatively low

'A'

value (Tables 10 and 11).

8.

'A'

values remained remarkably constant with increasing rates of nitrogen for both nitrogen sources. This suggests that

nitrogen toxicity, due to the close proximity of the fertilizer with the seed and roots, does not specifically damage the

roots in the fertilizer zone, but rather adversely affects the physiology of the plant. If the roots in the fertilizer zone only were damaged,

'A'

values should have risen with increasing rates of N application with the seed.

9. The significant increases in

'A'

values on the stubble plot that occurred with increasing rates of application of ammonium dihydrogen phosphate alone is due to the deficiency of nitrogen that prevailed in the soil.

'A'

values remain constant with increasing P application only where another nutrient is not limiting yield.

10. There is some indication under the moderate soil nitrogen levels characteristic of the stubble plot sites that the ammonium dihydrogen phosphate coated ammonium nitrate may be more effective as a source of phosphorus than mechanical mixtures of the respective N and P sources.

Table 8 Yield of eat (Thatcher) bu ere (16 treatment lattice design with 5 replicates)

Fallow - Rosthern (BCL)

Physical form

( ) +

Mechanical mix¹ coating 2 Homo prill3

(B) +

Mechanical mixl coating2

Pril1ed NH4H 2P04 ^{@ 10 lb} P

=

^51.9

@ 15 lb p

=

^51.6

CHECK YIELD = 45.5

lb/acre N = 60 32 32 p

=

²⁷

L.S.D. (P = ,05) = 1,7 bu re 1N- and _ carriers pri1led; P

Rate of N-P .. 2

47.0

45,2

plication 1b/acre

42.3 40.3

Liquid4 5L4

Powder5 48,4

coated on pri11ed N carrier;

and P carriers powdered, then mixed uniformly before prilling;

and P carriers in the form of a slurry;

and P carriers finely ground.

Table 9 Yield of Wheat (Thatcher) bu/acre (25 treatment lattice design with 6 replicates)

Stubble - Rosthern (BCL)

Rate of Application N·-P, lb/acre

Physical form 23-10 34.5-15 46-10 69-15 CA) CNH2 ) 2CO + _{NH4H 2P04}

Mechanical mixl NH4H 2P04 coating2 Homo prill3

(B) NH4N0 3 + NH4H2P04 Mechanical mi x 1

NH4

H

2 P0 4 coating2 Liquid 4

Powder5

38.4 40.0 40.0

41.5 40.9 38.4 37.6

39.7 37,7 34.4

43.6 4 L l 41.4 40.2

39.6 38.1 30.9

36.7

31.8 32.6 28.5

33.0

CHECK YIELD = 21.3

NH4 H2P04 @ 10 lb P/acre

=

^35.9

@ 15 lb P/acre

=

^41.0

SOIL TEST VALUES, 0-6 6-12

lb/acre 12-24 N03-N 6 7 24

p 21

L.S.D. (P

=

^.05)

=

2.7 bu/acre l N and P carriers prilled;

2NH4 H2 P04 coated on prilled N carrier;

3N and P carriers powdered, then mixed uniformly before prilling;

4N and P carriers in the form of a slurry;

5N and P carriers finely ground.

Table 10 ~A' Values (P lb/acre)

(16 treatment lattice design with 5 replicates) Fallow - Rosthern

(BCL)

Physical form

Mechanical mix1 NH4 H2P04 coating2 Homo prill3

Mechanical mix 1

NH4H₂P04 ^@ 10 lb P/acre

@ 15 lb P/acre

Rate of Application N-P lb/acre

99 93 104

72 76

Prilled 108 115

34.5-15

96 110 105

76 63

Liquid4 Powder5 104 100

L.S.D. (P

=

^.05)

=

15 bu/acre

1 N and P carriers prilled;

2NH4H2 P04 coated on pril1ed N carrier;

3N and P carrier powdered, then mixed uniformly before pri1ling;

4N and P carriers in the form of a slurry;

5N and P carriers finely ground.

Table l l

'A'

Values (P lb/acre)

(25 treatment lattice design with 6 replicates) Stubble - Rosthern CBCL)

Rate of Application N-P lb/acre Physical form

(A) (NH 2 ) 2CO + NH4 H2 P04 Mechanical mix1

NH4H 2P04 coating2 Homo-prill3

Mechanical mix 1 NH4 H2P04 coating2 Liquid4

Powder5

23-10

87 82 78

72 56 79 72

NH4H2P04 ^@ 10 lb P/acre

=

⁸⁹

@ 15 lb P/acre

=

¹²¹

34.5-·15

76 '76 85

67 57 86 64

L.S.D. (P = .05) = 16 bu/acre

1 N and P carriers prilled;

2NH4H2P04 coated on prilled N carrier;

46-10

77 76 71

62

3 N and P carrier powdered, then mixed uniformly before pri1ling;

4 N and P carriers in the form of a slurry;

5N and P carriers finely ground.

82 78 67

62

16,

V. THE N REQUIREMENTS OF SELECTED WHEAT VARIETIES

At two locations a small rod row plot was set out to com~

pare theN requirements of three wheat varieties; Thatcher, and two unnamed varieties ~ F31 and 17-30. Rates of nitrogen ranged from 0-200 lb of N/acre, all applied as a broadcast treatment.

Only one rate of phosphorus, 10 lb P/acre, was used. All varieties responded similarly to the fertilizer treatments (Tables 12 and 13).

The unlicensed high-yielding varieties yielded approximately 10%

more than Thatcher under the conditions in which the tests were conducted. Highly significant upward trends in protein content were recorded for all three wheat varieties as the nitrogen fer- t i l i t y level of the soil was increased.

Nitrogen Treatment N lb/acre

Check 50 100 200

Check 50 100 200

Check 50 100 200

Table 12 Wheat Variety Experiments Rosthern (Stubble) I, Yield of GrainL bu/acre Thatcher

Check 20.6 24.7 34.1 27.8

12.9 15.4 17.5 18.3

27.9 40.0 62.8 53.6

20 lb 29.0 26,0 39.4 4L3

IL

13.1 12.0 18.0 19"0 IIL

40.1 32.9 74.7 82.6

o~ 6

6~12 12~24

Variety and ^p Treatment S-31 p Check 20 lb ^p

22.0 29.0 25 4 35.2 27.5 47.0 36.8 44.2 Protein Content ^~, %

1L6 ll.Z

14.9 15.8 15.9 17.0 16.7 17.6 Yield of N ( g;r ai n onl~) 2

26.9 34.3 39.7 58.5 46,0 84.0 64.7 82.0 Soil Test Values lb/acre

N03~"N p

7 22

8 16

17-20~1

Check 20 lb 22.5 32-4 29.3 39.7 33.1 41.0 37.7 43.0

12.2 12.3 13.8 15.0 15.5 16.2 16.2 17,2 lb/acre

28.9 42.0 42.6 62.7 54.1 60.0 64.3 77.9 p

Nitrogen Treatment N lb/acre

Check 50 100 200

Check 50 100 200

Check 50 100 200

Table 13 Wheat Variety Experiment Nokomis (Stubble) I. Yield of Grain, bu/acre

Variety and P Treatment

Thatcher S-31

Check 20 lb ^p Check 20 lb ^p

19.1 24.4 24.3 25.8

39.8 37.6 38.8 39.7

34.5 35.6 36.7 36.4

33.2 33.8 39.0 42.4

II. Protein Content

-

%

15.1 14.4 14.6 14.0

15.5 16.1 16.1 16.9

17.4 17.2 16.6 16.3

18.2 18.2 17.1 17.3

IlL Yield of Nitrogen (grain on1;y)

30.3 37.1 37.3 38.1

64.9 63.6 65.7 70.5

63.1 64.5 48.2 62.5

63.5 64.6 70.1 77.4

Soil Test Values

-

^1b/acre

N ^p

0- 6 8 29

6-12 8

12-24 6

17-20-l Check 20 lb ^p

19.0 22.0 37.2 39.6 35.5 32.5 37.3 32.5

13.9 14.5 16.6 15.3 16.2 16.6 17.0 17.3

-

N 1b/acre 27.7 33.5 59.7 63.6 60.4 56.7 66.6 59.3

VIo TRITICALE FERTILIZER EXPERIMENT

Two field-scale experiments were set out to investigate the N and P response pattern of triticale. The plot at Nokomis was located on the same field as the nitrogen placement experiment (see Table 6)

At

both locations, Thatcher outyielded the triticale. The triticale at both

locations did not mature in time to escape the fall frost, and the resulting low yields therefore reflect a ¹feed grade' of wheat ^o The relatively high protein content of the triticale seed is in part a reflection of the shrivelled kernel so

All triticale samples contained 'abundant' amounts of Ergot,

VII. COMPARISON OF NITROGEN SOURCES IN MIXED N-P CARRIERS

Comparison of mixed N-P carriers using urea (46-0-0), urea plus ammonium sulfate (34-0-0), and ammonium nitrate (33.5-0-0) as N sources were obtained at a number of test locations in the province. The mean yield data given in Table 14 suggest that, where wheat was used as the test crop, the carriers containing urea or urea plus ammonium sulfate were inferior to the ammonium nitrate-ammonium phos- phate mixture. Barley, on the other hand, responded some- what greater to the urea-phosphates than to the standard 23-23-0. Definite conclusions respecting urea or urea ammonium sulfate materials in mixed N-P carriers cannot be drawn from the data obtained. However, the data suggest that further research must be carried out to answer the

question as to why, at some locations, the different nitrogen sources appear equal, while in others the ammonium nitrate proved considerably superior (see Appendix B).

Table 14 Comparison of Urea and NH4NQ 3 in Mixed Phosphorus - Nitrogen Carriers (Field Scale Tests on Stubble Land) (A) NH4 N0 3 (33.5-0-o) vs <NH4 ) 2 S04 + <NH2) 2CO (34-0-0) Crop Check Yield ll-48-0

@ 40 Wheat

(4 plots) Barley

(3 plots)

Wheat (4 plots) Barley

( l plot)

34.9 3.9

30.1 10.5

Check Yield ll-48-0

@40

23.4 4.3

37.6 o.o

*23-23-0

@ 87

5.6 9.7

*23-23-0

@87 7 . l

4.0

**23-23-0

@ 87

3.1 12.3

**27-27-0

@ 75 3.8 5.1

33.5-0-0 @120 L.S.D.

plus 11-48-0 (P=.05)

@40 10.3 19.1

33.5-0-0 @120 plus 11-48-0

@40 14.2 26.7

2.5 3.6

L.S.D,.

(P=. 05)

3.2 3.1

20,

Table 15 Triticale Fertilizer Plots (2nd crop land)

Fertilizer Treatments

lb/acre

Check

11.,.~48~0 @ 23~23~·0 @

33.5-0-0

11~48~0

40 87

@ 120

@ 40

N0 3 -N 1b/acre Mean

0- 6 9

6~12 6

12-24 34

Check

11-38-·0 ^@ 40 33.5-0-0 ^@ 120

11~48~0 @ 40 33.5-0-·0 ^@ 180 ll-48-0 ^@ 40 Thatcher

-

^Check

N03-N lb/acre Mean

0- 6 14

6-12 5

12-24 12

Yield of Grain Cwt/acre

Yield of N (grain) lb re (A) Weyburn

L.,

Nokomis

'7,00 19.6

7,76 21.9

8.49 25.5

9.34 27.5

Soil Test Values Range

5- 13 3- 8 8-156

P lb/acre Mean

12

(B) Aberdeen

C.,

Saskatoon ( 3 r d crop 1 and )

12.73 30.7

12.25 29,0

12.89 31.8

12.23 36.2

13.37 30.1

Soil Test Values

p lb/acre

Range IVJ,c:an

6- 26 ^o~ 6 17

2- 7 6-12

4~ 42 12-24

% Prot&in

lf3.0 16.1 17.1 16.8

Range

14.6 13.5 14.1 16.9 12.8

Rang~·

11~24

VIII. PROCAL TEST PLOTS

Procal, a product containing primarily calcium sul- fate, with various contaminants, was applied at 300 and 500 lb/acre in field scale tests laid down on two locations on Elstow Clay Loam. Moderate amounts of salinity were present in the soil at both locations. The yield data

given in Table 16 support the conclusion that Procal applied at the rates of application recommended by the distributors is of no value.

Table 16. Procal Test Plots

Check Kobel

ECL (bu/acre, wheat) Goodale

ECL (tons/acre, oat forage)

Rate o£ Application lb/acre

Yield 300 500

22.6 2LO 21.6

0.78 0.63 0.78

2 2 ⁰

IX. SOIL TEST IMPROVEMENT INVESTIGATIONS

On the basis of previous research findings (not too well veri- fied), the instructions for obtaining representative soil samples outlined in soil testing bulletin No. 2 were based on the premise that approximately 10 profile samples taken on the basis of soil variability within any one field would result in samples that approximated the fertility level of the field. The results of

the sampling pattern investigatiorr given in this section verifies that representative soil samples comprised of 10 samples taken on the

basis of soil variability represents closely the fertility level of the field.

Almost without exception, the soil test correlation studies on which the soil testing laboratory's N and P benchmarks were

based included soil samples taken at time of seeding in the spring, In contrast, for obvious reasons, farmers must sample their fields in the fall, An assumption had earlier been made that N levels would very likely change, and approximately 15 lb of N were presumed to be the average amount that should be added to the N level of fall samples. An experiment was set out in which the N, P and K fertility levels of representative samples taken in the fall (October) and at time of seeding in the spring could be compared.

While i t has been reasonably well es~ablished that the nitro- gen contained in the 0-24~' profile is a reasonably good index of available soil nitrogen, an experiment was set out to measure the changes in available nitrogen that occurred at selected depths

to ^{Lf81' .} The results from this study support the need for a 0¹¹ to

24¹ sample, and show fairly clearly, under the growing conditions prevailing during the summer of 1966, that nitrogen contained below the 24n depth probably contributed l i t t l e to crop growth.

Sampling patterns for represent~tive soil samples - J.L. Henry.

The problem of obtaining a representative sample is confounded by the type of landform on which many of the soils have developed.

In areas of level lacustrine soils, the variability in subgroup profile types within one field is at a minimum. However, in

many of the soils developed on glacial t i l l or morainic landforms, the variability in subgroup profile type within one field is quite great and several profile types can occur over relatively short distances. The different profile types have developed because of the sharp topographic differences and the associated micro- climatic differences. These differences result in soil members which have widely different pedogenic properties such as lime con- tent, salt content, and textural change with depth. These indi- vidual members have been studied and placed into quite definite groups by pedologists according to various criteria which can be measured in the laboratory and to some extent estimated in the field.

It therefore appears reasonable that these individual units (i.e. subgroup profiles) should have a more or less definite available nutrient status which is quite characteristic of that individual subgroup profile. If such a relationship does occur, each field may contain a number of different units, each char- acterized by a different nutrient status. Therefore, a number of different possible "answers': for the fertility status of a field could be obtained according to the manner in which the representative samples are collected.

Since about 1958, field irivestigations carried out by the Department of Soil Science have taken into account the type of subgroup profiles occurring both in small plots set down on one member profile and in strip tests.

In the strip tests, profiles have been selected (for both soil and yield samples) such that a profile was continuous across all treatments. In most cases,there were 10 profile sites

within one strip test. In recent years, the profile sites have been selected so that the distributfon coincided with the profile distribution in the plot as a whole. Thus in any one plot, the selection might include 6 Orthic profiles, 2 Gleysolic profiles

and 2 Regosolic or Calcareous profiles. This unequal sampling of the various profiles resulted in something less than the most

a for establishing the productivity, nutrient status, and response pattern for the individual profiles. Some fai:r'ly definite data could be gathered for some individual profiles

which were dominant in a particular landform (usually the Orthics) but comparison with other profiles, which were represented by

too few sampling sites, was difficult.

In view of these difficulties, i t was decided to carry out experimental sampling to:

1) establish a possible sampling paTtern which would elim- inate the need for a large number of sampling sites for each field, and

2) establish the variation in nutrient status within and between subgroup profiles.

METHODS

For the sampling pattern study, two fields were selected on moderately undulating glacial till--one in the Dark Brown soil zone (Weyburn association), and one in the Black soil zone (Oxbow association), A grid was s~aked out, with sites at 55-yard

intervals, On the Oxbow soil, there were 64 individual sampling sites (i,e. 4 rows, 16 per row for a total of 40 acres) and on the Weyburn soil,there were 60 individual sampling sites (i.e, 5 rows, 12 per row for a total of 37.5 acres). Ea.ch of the sites in both plots was sampled individually (0':-6'"), 6"-12':, and l2"-21..J·';) and analyzed individual At each of the sampling sites, a pit was dug and the profile identified according to

the 1963 National Soil Survey Committee report, Additional notes were made at each si~e as to depth of Ah, depth to lime (deter- mined from core if not encountered in pit), slope position, and any other items worthy of note. Sampling was done with a

hydraulically equipped ':punch' truck,

In the profile variation study, one catena at each of the sampling pattern sites was selected for further study. The pro- files on the Oxbow soil were Orthic Regosol (subsequently abbre- viated Rego), Orthic Black (Orthic) and Humic Eluviated Gleysol

(Gley). The profiles on the Weyburn soil were Orthic Regosol

(Rego), Orthic Dark Brown~-midslope (upper Orthic) and Orthic Dark Brown--in a lower slope position (lower Orthic). Samples were taken

( 0¹¹- 6 ' , 6"-12';, 12¹¹-24!1) at 16 foot intervals across the width of the profile and a total of 8 sites were selected for each profile type.

RE. sw:.J,T. S

The results obtained from the sampling pattern work are shown in Table 1. The field average was the average of all the 60 (or 64) sites taken in the field" The site numbers and profile types were then laid out on a grid on paper and from this, 10 sites per field were selected on the basis of profile distribution (i.e.

where 50% of the total number of profiles were Orthics, then 5 of the 10 sites selected were Orthics). These results show clearly that the N and P fertility level of representative samples, com- prised of 10 samples selected on the basis of profile distribution, approximates the N and P fertility level of the field quite closely.

I . Oxbow site

N (lb/acre ^{2 I )} p (lb/acre ^{6 l:)}

Table 1. Sampling Patterns Field

M-€an Range

25 28

6-84 7-96

Aver. of 10 Profiles*

Mean Range

24 22

21-28 14-28 II. Weyburn site

~':

N (lb/acre 2 ' ) p (lb/acre ^{6; )}

34 18

9-96 4-56

33 19

25-44 16-24

Average of 10 profiles selected from the total (60 at Weyburn site, 64 at Oxbow site) on a profile distribution basis. This selection was repeated 6 times.

26.

The results obtained from the profile variation st are summarized in Table 2. The poorly developed Regosolic sails are shown to be more deficient than their counterparts in the lower slope positions. The Gleysolic (or poorly drained) members con- tain abnormally high levels of NaHC0 3 extractable P ^sta~us.

N (lb/acre 21 )

P (lb /acre 51:)

N ( lb /ac:t'e 2') p (lb acre ^{6 1;)}

Table 2. Profile Variation St Oxbow site

Rego

Mean .Range

15 10

8-23 2-17

Weyburn Rego

Mean Range

20 14-28 13 5-21

!vlean

29 30

site Upper lvlean

30 25

Range

18-49 12-48

Orthic Range

17-55 8-43

Gleysol Me;:u1 Range

28 4-8

Lower Mean

49 30

37-55

Or,thic Range

19-79 20-49

Table 3 shows a portion of the indivi l site data for the NaHC0 3 extractable P status at the Oxbow siTe. At most of the site::., the 01.-6¹⁷ depth c.ontained about 10 to 20 lb of extractable P with the amount in the 6¹;-12¹¹ and 12¹¹:-24¹¹f depths being almost non-existent, or at least quite insignificant.

are notable exceptions to this general trend.

'

Hov,rever, there Some sites have from 30 to 100 lb extractable Pin the or~-5¹' depth and a corres-- pondingly large reserve o:f extractable P in both the 6¹⁷-12¹¹ and 12'-24¹ depthso In every case, in the sites where this character-

istic P status was recorded, the profiles were Gleysolic. In

earlier reports, i t has been shown that Gleysols respond to added P as well as the other subgroup profiles in spite of their high NaHC0 3 extractable P values (due to shallow root- ing of cereals grown on these sites), This type of a response pattern indicates that Gleysolic soils should be neglected in establishing a sampling pattern.

Site . No.

on_

_6"

6¹¹-12!1 12¹'-24"

Site No.

on-

6 ^!i 6"-12"

Site No.

6';-12¹¹ 12¹¹-24"

Table 3 . Phosphorus Individual Sites 1

15 0 0

11 7 4 6

21 37 1 2

2 3 4

18 13 14

4 5 2

0 0 0

12 13 14 56 13 70 23 2 74 48 6 108

22 23 24 14 96 12 0 62 2 0 210 24

(lb/acre) ^~ (Oxbow

5 35 12 22

15 29 6 4

25 23 4 0

6 21 2 4

16 8 2 4

26 12 3 2

Soil) 7 32 4 4

17 14 3 2

27 13 0 0

<:~n

8 9 2 4

18 24 9 10

:28

39 53 46

9 7 1 2

19 47 32 24

29 24 2 0

10 68 28 54

20 32 32 54

30 17 3 2

28.

Changes in available nitrogen occurring between October, 1966 and May, 1967.

The data given in Table 1 were obtained from soil samples taken by 21 V.L.A. superviscrs. Fields on which the 1967 test plots were to be laid down were sampled in the fall in 1966 and again at seeding time the following spring . While-variable results were obtained on an ~ndJ.vid.u__al field basis, tlle average 14 lb of N per acr e increase J.n 0 ^1' to 24¹¹ _NO 3 -N sup ports fhe need for an adjustment ~n the soil test benchmarKs based on spr~ng sampling .

There was no signif~cant differe"'f!ce between the O" to 6n

phosphate values-for the fall and spring samp~ing. The relative uniformity of the phosphorus values not only confirms previous data which bas shown litt~~ chan~e in available phosphorus values between fall and spring, but also i llustrates the care taken by the V.L.A. supervi sors in the fall and spring sampling program.

The ammonium a1cetate extractable potassium increased sig- nificantly between fall and spring. The effect or -freezing and thawing on the release of potassium held by vermiculite and illite probably ^{is-respons~b~e} in part.

Changes in N and P fertility levels during the crop year.

The- -practice of basingrritrogen ferti:"J:i ty levels on the

nitrate nitrogen content. of the 0^1: te 24¹¹ pr.of-.ile i.s supported in the data given in Tables 2 and 3. Approximately 100, 90 and 80 pencent of the nitrogen-used by the cro~ at the Goodale, Shields and Wagner sites, respectively, was taken from the 0^1' to 24¹¹

depth. It should be noted, however, that these data were obtained from a check strip located centrally within a field fertility

test trial located on each farm, and that the difference between the spring and fall N levels cannot be presumed to approximate soil nitrogen taken up by the plant. To the amounts listed ^~s N used in Table 3 should be added an unknown amount of nitrogen mineralized during the crop year.

Location 822,..,8...,30,...2

SW28~37.,..23 .. 2 SE24 .. 44~15,..2

SW5-19-14 ... 2

SE33,..J.l.,.5~,3

NE12 ... 24 ... 23~2

SW22 .... 14-3-2 SW4 ... 19...,29~2

N20 .... 25,5..,2 SE6 ... 7 .... 18.-.2 SW19 ... 51..,14,..2 SW6 ... 45~2J..,2 SW33~26,..3.,2

SW20,..10.-18 ... 3 NW11.-19-2-2

NE33,..38,.,25~3

SE32 ... 36,..26 ... 3 SW9,..1±4 ... 17-3 SE9,...35.,13\l".2 SEl0-31-15,4 NE22.,.2Q,.9,..3 Average

N

lb/ac:r-e

~

" " · · · r a ^{i:t ·} roc ^{t: ·\ Y · · ·}

0~6U 6~12~ 12~24~ 0~24~ Or6~

12 9.

5 16 26 9 9 9 7 12 4 4 :.:3 12 24 ::2 3 3 33 2 9 10

9 2 2.

8 26 11 3 14 2 7 1

4

1 3 5.

2 2 2 :1:3 1 9 . 6

16 4 2 6 38 22 4 14

4 26

2 2 2 4 6 2 2 4 22 2 16

37 15 9 30 90 42 16 37 13·

45 7 10 6 19 35 6 7 9 68 5 34 .26.

7 25 8 25 9 10 11 14 18 7 5 15 7 7 25 7 5 7 30 16 16 13·

Sprlng

(May)

6,12\: 12..,24¹¹ 8

8 2 23 11 22 10 16 6 6 4 3 5 4 6 3 3 6 21 5 10 9

20 6 2 40 32 50 14 16 22 38 6 4 8 10 18 4 4 14 28 8 30 18

35 39 12 88 52 82 35 46 46 51 15 22 20 21 49 14 12 27 79 29 56 40

· P lb /acre (0-61:) Fall Spring

28 31 26 18 33 40 12 15 9 36 47 66 20 24 28 14 18 13 18 17 23 26

15 28 50 24 19 43 10 23 12 22

l.J-0

46 21 18 35 24 34 12 12 18 19 25

K lb/acre

(0~6!7)

FalL' Spring 728 880 608 840 368 770 544 680 1268 1190 672 930 512 650 688

344

630 30 0 864 1000 456 340 1024 1300 544 870 688 790 368 700 720 1220 864 1620 3 52 49 0 304 360 1016 1390 672 1020 648 1025 1 Fall sampling taken on a field basis~ spring samples taken from control check strip (field

fertilizer

strip

test),

30.

Table 2. Changes in N and ^p During-the Ct1op Year at Two Locations Wagner, Hague (Oxbow L)l

Nitrate

-

N 1b/acre

Site Spring Fall 0-6¹¹ - ^p lbjacre

No. 0- 24' 0-48'· 0-241. 0-48¹ Spring Fall

1 21 30 7 13 27 21

2 18 31 6 18 11 18

3 31 85 5 37 16 11

4 13 37 6 22 10 11

5 59 70 7 13 108 82

6 11 31 6 24 7 5

7 13 25 5 21 6 11

8 51 108 10 64 9 12

9 14 17 6 10 54 80

10 18 57 6 30 12 17

Av. 25 49 6 25 26 27

Shields, Nokomis (Weyburn L)l

1 33 69 9 43 8 46

2 33 51 14 18 56 62

3 40 86 10 42 8 14

4 38 72 11 39 20 20

5 40 60 12 20 74 48

6 35 51 14 38 10 14

7 56 98 26 76 9 13

8 95 187 35 133 13 12

9 37 55 6 32 28 6

10 24 45 7 23 21 35

Av. 43 77 14 46 25 27

1Yield of wheat (check) a) Wagner

=

^23.2 bu/acre b) Shields

=

^{23. 3 bu/acre}

Table 3. Changes in N0 3-N (1b/acre) With Depth Between Seeding and Harvest

Shields Wagner Goodale

Depth Seeding N use ^d~'t Seeding N ^used~': Seeding N used*

0- 61. 10 5 9 7 14 8

6-12¹ 8 6 5 3 25 22

12-24¹¹ 25 18 11 9 104 36

Sub total 43 29 25 19 143 66

24-36¹¹ 19 3 10 3 73 -15

36-48¹' 15 -1 14 2 60 8

TOTAL 77 31 49 24 286 59

= ^- - -

- -

-

Yield, bu/acre 23.3 23.2 31.1

~t Spcing ^- fall, N03-N

Nand P fertility trends for the period 1965 to 1967,

The V.L.A. Cooperative Stubble Fertilizer Program was started in 1965 and continued in 1966. Soil samples were taken in the fall of 1966 from fields in which the tests would be laid down in the spring of 1967. A few of the veteran farmers have withdrawn from the cooperative program, but a total of 16 farm units have continu- ously cooperated in the project this far. Table 4 lists the avail- able phosphorus and nitrogen in composite samples taken in the spring of 1965, the spring of 1966, and the fall of 1966, respec- tively, (labelled 1967 in Table 4). While these samples were not taken from the same field, they do provide an index of changing

fertility levels. A very rapid decline in nitrogen fertility levels has occurred. It .is interesting to note that a significant drop in available phosphorus has also been recorded. The lower fer- tility level, on the average, of the samples is undoubtedly a reflection of the high yields obtained in 1966.

Table 4. Soil Test Data From the Same Farm (But Different Fields)

for 1965-1966

lb P/acre lb ·NO ;;rrN /acre, (0-24")

Location 1965 1966 1967 1965 1966 1967

Indian Head 19 25 18 51 57 30

Battle ford 16 27 13 68

l8

9

Tisdale 29 29 26 160 31 9

P.A. 26 16 10 210 121 31

Unity 16 29 14 60 35 6

York ton 20 14 20 62 44 6

Strasbourg 87 33 40 76 38 42

Rose town 53 37 17 98 19 5

Kinistino 60 51 66 78 53 10

Outlook 22 14 23 153 31 34

Wadena 10 37 18 106 283 68

Carlyle 23 22 29 186 57 288

Humboldt 24 43 31 134 147 15

Spiritwood 38 29 18 79 139 7

Hearts Hill 33 42 15 53 104 37

Yorkton 33 25 9 63 98 13

Average 32 30 23 102 80:. 38

32.

X. MOISTURE INVESTIGATlONS - E . de Jong

1. Water Use and Yield of Wheat

In this section, the results of two years of fallow tests (1964 and 1965) and three years of stubble tests (1964, 1965 and 1966) are reported. Full details on the exact test locations, soil type, fertilizer response, etc., can be found in the Plant Nutrient Research Reports for these years. The large majority of the soils were either loams or clay loams with some silty loams and clays. Nearly all experiments were conducted in the Dark

Brown and Black soil zones. A detailed l i s t of soil zones and textures is given in Table 1, b4t no breakdown of profile types is provided.

Table 1.

Soil Zone Dark Brown Black

Grey Texture Loam

Clay Loam Silty Clay Clay

Zonal and Textural Distribution of Sites Number

Fallow 1964

21 24

35 10

1965 9 10

10 9

of Sites 1964

20 26

28 18

Stubble 1965

39 30 9

Lf 8 20

10

1966 26 36 18

43 20 10 7

In the analysis, no attempt has been made to separate the data on the basis of soil zone) profile or texture, though such an analysis might provide useful information.

this section is given in Table 2.

A l i s t of the symbols used in

Symbols

S = soil moisture used

=

spring moisture ~ fall moisture, inches R

=

growing season precipitation, inches

W

=

^{S + R}

=

water used by the crop, inches Ych

=

check yield, bu/acre

Yfert

=

yield with fertilizer, 40 lb/acre of 11-48-0 for fallow 80 lb/acre of 23-23-0 for stubble D

=

depth of moist soil at seeding time, inches

There may be some doubt as to the usefulness of separating S and R, since the rain has to be stored in the soil before i t is taken up by the plant. It has been indicated (Anon~ 1954) that both R and S are equally available to the plant under conditions prevailing in Saskatchewan. In the following, separate analyses on S, R and W are nonetheless performed for the sake of complete- ness.

The results of the statistical analysis 1 on the fallow data for 1964 and 1965 are summarized in Table 3. The data clearly show that factors other than water use were limiting yields in 1965, since in comparison with 1964, yields were down and moisture use was up. When all fallow data were treated together, the highest correlation was obtained between check yields and fertilized yields.

The moisture use data were fitted to prediction equations of the form:

y

=

Ao + A1

s

+ A ₂

s

²

y

=

Ao + A1 R + A2R2 y

=

Ao + A1 W + A ₀

w

²

y

=

Ao + A1 R + A2

s

The computer selected the variable, S,

s

2 , R, ... etc., which contributed the most in the first step of the analysis. The remain- ing variable was added in the next step of the multiple linear

reg~ession. If addition of the second variable did not increase r 2 by at least 5%, the second variable was omitted from the equations presented in Table 4. Only equations in which the coefficients were significant at P~0.05 are reported. The equations for Yfert, are calculated using the observed values for S of the adjacent

check; thus, i t was assumed that total water use was not affected l The assistance of Mr. Yanda of the Computer Centre is gratefully

acknowledged.

34.

by fertilization, though fertilization caused an increased yield of about 4 bu/acre (Table 3). This assumption is supported by earlier work (Rennie and Hutcheon, 1963; 1964). The selection of the 40 lb/acre of ll-48-0 treatment for fallow as the fertilized yield was based on the fact that, in the past, this has, in general, proved to be the most economical treatment. The same is true for the 80 lb/acre of 23-23-0 for wheat on stubble.

Table 3. Statistical Analyses of the Fallow Data

Variable

s

R w Yah Yfert

s

R

w

ych

1964~·~ 1965~h': 1964 and

lvleans S.D. Means S.D. !1eans

2.60 L89 5.26 L04 3.39

4.29 0.57 6.04 0,50 4.81

6.89 2.15 11.30 1.16 8.20 22,16 10.09 19.84 4.94 21.47 25.83

Simple Correlation Coefficients

"tltt i:~~

'f'J'II, I> ~'"' of\> ... <!I'\> ~"'

Ych Ych

·o.

830 -0,010 0.522

0.867

45 19 64

sets of data sets of data sets of data

0.863 0.364

ych 0 '52 6 0.213 0.467

The data in Table 4 show some unusual features:

1965thh':

S.D.

2.07 0.97 2.78 8.90 10.48

Yfert 0.599 0.420 0.593 0.898

(1) in many cases, the value for the constant A₀ in the yield equations is not negative as has been generally reported (c£

de Jong and Rennie, 1965);

(2) in 1965, total water use had no significant effect on yield, which is totally unexpected for the Prairie region.

Ca~e

must be used,

howeve~,

in

inte~p~eting

these data, since

the range of yield and moisture use data was limited (cf. fig.

1 and 2).

Table 4. Yield Equations for Fallow

1964

Variables r2

s' s2 Ych = 10.64 + ^{4.44 s}

o.69

R, R2 Ych = 0.60 + ^{1.150 R2 0.28} w, w2 Ych

=

^{7.03 + 0.291 w2 0.76}

s ' R Ych

=

^{-8.44 + 3. 94'S + 4.74 R 0.75}

1965

s ' s2 not significant at P-<::0. 0 5 ....:::::-0 '08 R, R2 ych = -5.85 + ^{0.699 R2 0.75} w, w2 not significant

-c::::::o •

1 7 s' R Ych = -31.42 + 8.48 R 0.75

1964 and 1965

w, w2 y _ch = 9.24 + ^{l . 49 w 0. 22} W, ^w2 ych =-15.95 + ^{8.51 w}

-

^{0.432 w2 0.36}

s , R Ych = 13.83 + ^{2.26 s 0.28} w, w2 Yfert = 7. 51 +. _{2.23 \~} 0,35 W, ^w2 yfert =-14.63 + ^{8.40 w}

-

^{0,380 w2 0.43}

s ' R Yfert

=

^{15.59 + 3.03 s 0 '36}

The statistical data for the stubble plots is summarized in Table 5, while Table 6 shows the yield equations. The same remarks that were made with regard to the fallow data apply:

(1) in the highest correlation is obtained between check yield and fertilized yield;

(2) the correlations between yield and moisture use are, in general, much lower than expected;

(3) the equations do not have the expected negative A₀ value,

Table

5

Statistical Analyses for the Stubble Data

1964~ 1965

1964 1965 1966

&

1966

Variable Nean S.D. Nean So Do Mean S.D. He an SitD¢

s

^{L80 2,00} 3@03 L29 0~75 L48 1.87 L83

R 4.42 0.67 7.68 2.30 10.47 L77 8.01 2.96

\T ' 6.22 1.85 10.71 L97 11.22 L77 9.88 72

y ch 17.40 8.52 18.57 6.12 22.10 8.14 19.70 7.79

y fert 25.32 10.09

Simple Correlation Coefficients

ych ^y ch y

ch y

ch ^y fert

s

0.740 0.083 0.277 0.203 ^0~

R ~0 .. 324 =0@163 0.141 0.162 0.283

It[ 0.684 ~0.136 0.373 0,313 0.375

y ch

o. 715

1964 = 46 sets of data ) 1965 ~ 78 sets of data ) 1966 ⁼ 76 sets of data

)

all years ⁼ 196 sets of data )

These figures donnt add up~ since some data on fertilized yields were missing and fertilized yields were not calcu=

lated for individual years~

w

(j)