The Woburn Organic Manuring Experiment II. Soil Analyses, 1964-72, With Special Reference to Changes in Carbon and Nitrogen

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Mattingly, G. E. G., Chater, M. and Poulton, P. R. 1974. The Woburn

Organic Manuring Experiment II. Soil Analyses, 1964-72, With Special

Reference to Changes in Carbon and Nitrogen. Report - Agricultural

Research Council and Ministry of Agriculture Rothamsted Experimental

Station. 1973 (2), pp. 134-151.

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Rothamsted Experimental

Station Report for 1973 Part

2

Full Table of Content

The Woburn Organic Manuring Experiment II. Soil Analyses,

1964-72, With Special Reference to Changes in Carbon and

Nitrogen

G. E. G. Mattingly, Margaret Chater and P. R. Poulton

The Woburn Organic Manuring Experiment II. Soil Analyses, 1964-72, With Special Reference to Changes in Carbon and Nitrogen , G. E. G. Mattingly, Margaret Chater and P. R. Poulton (1974) Rothamsted Experimental

Station Report For 1973 Part 2, pp 134 - 151 - DOI: https://doi.org/10.23637/ERADOC-1-34636

The

Wobun

Organic

Manuiry

Experimert

II.

Soit Analyses, 7964-7i2,

with

Special

Referene to Chuges

in

Carton

and Nitrogen

G.

E.

G.

MATIINGLY,

MARGARET CIIATER and P.

R.

POULTON

The experiment described in Part

I

(Mattingly, 1974) occupies most of Series B on Stack-yard Field, Woburn, which was cropped

from

193G{0 in a six-course rotation of sugar beet, _{barley, clover, wheat, potatoes, rye (Yates}

&

Patterson, 1958; Rothamsted Experi-mental Station, 1970). Barley was grown over the whole area

in

1961-63 and the land was fallowed

in

1964.

Soil samples (0-23 cm) were taken

from all

plots

at

the start

of

the experinent

in

Aprit

1964, and again

in

autumn, 1968 and 1971 after the winter wheat and winter _rye

crops respectively. Samples were also taken

to

53 cm

in

April

1964 and when the first

phase

of

the experiment was completed after the leys had beea plonghed up. Blocks

I

and

III

were sampled in spring 1972 and Blocks

II

and

IV

in

spring 1973,

This paper describes changes in the composition of the surface soils, and the sub.soils

to 53 cm with spocial rcference to (i) changes in carbon and nitrogen contents, including mineralisable

N

and

(ii)

effects of the different amounts and types of organic matter on the distribution, movement and possible

fxation,

of residues of P,

K

and

Mg

fertilisers.

Mechrnical

ualysis

and epparent decdty of soils

Mechanicrl

analysis.

The soil is a sandy loam (Cottenham Series) derived from Lower Greensand.

The

mean mechanical composition

is

about

801

coarse

and fine

sand

(2000-20 pm),

5.51silt

_QV2

pm)

nd

l0l

clay

(<2

pm). Appendix Table

I

gives the mechanical analysis of soils from all main plots, which are parallel and run from SW to

NE

and slope

in

this direction. The proportions of coarse and fine sand decrease from

over

801on

plots at the SW end of the experiment

to

751

or less at the NE end. The silt and clay contents show minima, 3,2 and 7

.81

resptl

ely, in plot 8 near the junction

of

Blocks

I

and

II

and similar, though larger minimum values, 5.1 and

5.31

and 9.9

and 9.3 % respectively, in plots 24 and 25 at thejunction of Blocks

III

and

ry.

The largest

silt and clay contents

(7-8%

and

l2-l3l)

were

in

plots 3G-32 at the

NE

corner of the experiment. The

initial

C

and

N

contents

of

the soils

follow a

similar pattem

to

the

f

clay, with minima

in

plot 8. The linear regression

%c

:0.32(+

0.058)

₊

0.044(+ 0.005e

f

clay a@ounts

for

66\

of the vaiance in carbon contents in the 32 plots

in

1964.

Applrent

density

of soils.

Crowther (193Q gives

the

weights/acre

for

surface soils (0-9

in.) from

Stackyard as 1370 tons air-dry soi[acre and

l4X

tons air-dry soi|acre

for

sub-surface soils (9-18

in.).

The air-dry soils

now

contala 0,7-1,2%, rnoisture and

these weights, which correspond to apparent densities of

l.5l

and 1.56 g air-dry soit/cms, have been used

by

several other workers

@olton

&

Penny, 1968; Chater

&

Gasser, 1970) and are used

in

this paper

for all

soils other

tlan

those ploughed out

from

leys.

Bulk

densities

of

soils under leys were calculated from

tle

weights

of

soil removed

to

THE YALUE OF

ORGANIC MANURES

AT

WOBURN.

II

mqrsure roots weighs of the leys before ploughing @art

I,

p.

103). The mean apparcnt density was 1.38 g air-dry soifcms, corresponding

to

1300 tons/acre for surface soils.

The following metric equivalents are used

to

calculate gains and losses

of

organic matter (Table 2) and nutrients (Table 4).

Depth of samplilrg

(crD) o-22.9 0-15.2 15.2-22.9 22.9-10.5 ₎

30.5-38.1I

38.1-4s.?

I

4s.1-$.3

₎

All

tr€atm€ots

L

and Ln

except

leys

plots

3.44

3.14

2.29

2.@

I

.15

t .05

1.19

1.19

Soil analyses in 1961

Appendix Table 2 gives mean analyses

of

all

surface soils (G-23 cm) sampled

in

1964,

1968

and

1971.

h

1964, before different organic matter treatments were applied, the soils (averaged over four blocks) contained

little

organic C and values, measured by the Walkley (1947) method, using 1.3

for

the correction factor, were 0-73-{.81%. Nitrogen

contents were O'O824.@l _{% and the} soils contained moderate amounts

of

NaHCOs-soluble P (2,1-30 g.g P/g) but little exchangeable

K

(71-79 pg Klg) or M^g(1220

peMgld.

The variations in C, N and total P contents within blocks are given in Appendix Table

l.

Organic C

ad

N.

The organic C and

N

contents of soils from all sections of Stackyard

Field have diminished steadily since 1876 when the soils were first analysed.

No

carbon

or

nitrogen analyses are available

for

Series B before 1964 but the mean C contents

of

soils from the adjacent Series

A

and C decreased

from

l.5l

to

0.90/" and

from l'32

to

0.701

respectively b€tween 1876

and

1959. The mean annual rate

of

loss

is

about

0'007 _% C, equivalent

to

0.42 tonnes/ha

of

soil organic matter, assuming a conversion factor

of

1,724 g organic matter/g C.

pH

and exchangeable

cations

Unlike

other parts

of

Stackyard, Series

B

was limed regularly between l93G-60. The mean

pH

values ranged only

from

5.7H.m

in

0'0lM

CaClz. The pH, measured

in

water, was related to values in 0.01M CaClz by pH (warcr)

:

0.52(+0.183)

₁

0.96({0.032) pH(CaClz)

Exchongeable

K.

The mean value

in

1964 was 75 pg

K/9,

which is less than Williams

(1973) calculated would be present (108 pg K/g)

in

soils from Stackyard Field when the amounts of

K

removed by crops were balanccd by the amounts applied

in

K

fertilisers. The crops from

tie

six-course rotation (1930-60), which preceded the Wobum Organic Manuring experiment, were not analysed. The evidence here suggests that they removed

more than

the

average amounts

of

K

(52 kg/ha) applied

to

them each year so that

exchangeable

K

values on S€ction B on Stackyard Field were less

in

1964 than

in

1930.

Exchangeable

Mg.

The mean value (15 pg Mg/g) is typical of other Stackyard soils

in

the 1960s (Bolton

&

Penny, 1968; Williams, 1973) and much smaller than

in

the 1930s

(Crowther, 1936). Magnesium deficiency slmptoms and yield responses to Mg fertilisers occur at these soil Mg levels (Bolton

&

Penny, 1968).

ROTHAMSTED

REPORT

FOR

1973,

PART

2

Soluble

P

in

the

mils.

In

coDtrast

to

exchangeable

K

and

Mg

the

soils contained moderate amounts of NaHCOa-soluble P. The mean value (28 pg P/g) exceeds the value

for Stackyard (22 _{pg Pig) quoted by Williams} (1973) and which he caiculated in

tie

same

way as for potassium. The amounts of P added

in

the six-course rotation (16.5 kg p/ha

eash year) were, therefore, more on average than the crops removed.

Water-soluble

B

in tte soils.

The

soils were

not

analysed

for

water-soluble

B

until

symptoms of heart-rot were detected in sugar beet grown

in

I 969 (Ro thamsted Report

_fot

1970,Part

I,

pp. 5G57). The values (0.4-O.6 pg B/g) are ryithin the range where sensitive crops may show visual symptoms of boron deficiency.

Chrnges in soil andyses,

DA-71

Table

I

briefly describes the eight treatments applied to the _{main-plots (Part D and} gives changes in all aaalyses of surface soils (0-23 cm) between 1964-68 and

l9U-71.

ChaaBes

in

soil C and

N

contents are often small and they are difficult to rneasure reliably over short periods. The changes

in

Table

I

were calculated from means

of

16 sub.plots and

Mean value in 1964

TABLE 1

Soil analyses in 1964 and increases between 196448

oul

196,{-71

(All analyses are or airdried soils, 0-23 cm)

o/

pH

Gno.olM

Total Totsl

Orgsnic

CaCl,

Cr

N

P

5.86 0.767 0.085

227

Iocrras6 betc/Eca 1964 ard 1968

ErchadgEable

@tioos

NaHCOs-.----i-soluble

P

K

Ms

28

75

t5

PKMg manuring equivalent

to straw

+

supplementary P

lJys with clover

(Lc)

_-0.67

I-€ys wilh nitrosen

(Ln)

_-O.42

Itat

(Pt) Straw (St)

0.lil8 0.006 3t

7

39

,6

0-094

o.fix

6

ll

6

16

0.266b

0.002 13

15

t8

6

0.044

0.m3 fi

t2

m

9

o-g74

o.o2

m

l2

M

t

-0.06 -0.m3

8

13

l8

7

-0-005

-0.006

7

x3

39

16

0.t53 0.010 25

x

4

D

+0.0t85

+o-ml8 +4.9 +1.6

+3.7

+t.0

-0.57 -0.44

Green matrures

(Gm)

_-0.58

Fertilisers only

(Fs)

_-0.41

PI(Mg manuring equivalcnt

to famyard manurc

Fertilis€rs only

(Fd)

_-0.39

FarmFrd manue

(Dg)

_-0.32

Staadard error of incleas€

Iocrease betw€en 1964 and 1971 PKMg maoudrg equivaleDt to

stBw ₊ supple-seotary P

tays with clover

(Lc)

_-0.01

0.153

0.006

Irys with nitrogeo

(Ln) 0.16 0.107

0-005

Peat

(Pt)

0.03

_O'62y'.b 0'015

Straw

(St)

0.46 0.0&l

0.m4

Greer manures

(Gm)

0.13 0.034

0.m2

Fe.tiliscrs only

(Fs)

0,36 -0.065

0.000

PKMg manuring equivalent

to famyard manu.e

Fertilis.rs only

(Fd)

0.t3

_-0.048

_-o.UN

Fam)rald maoule

(Dg) 0.46 0.304

0.017

t3l

32

3n

84

16

84

16

62

l4

14

16

3t

14

25

t3

21

18

25

t7

414

617

13

36

190

U

30

32

t1t

35

StaDdard €rto. of

increas€

+0.01,18

+0.0029

+6'0 +1.5

+10.8

+2.2

(a) Total C

:

1'30

x

Walkley value; (b) Ircrease id %C

:

1,23

x

Walkley value for pcat only

TIIE

YAIUE

OF ORGAMC

MANURES

AT

WOBURN.

II

the standard errorc tvere derived from analyses of variance of these differences and not from the errors of the separate soil analyses given

in

Appendix Table 2.

Changes in C rtrd N contetrts of

soils.

The carbon contents

ofthe

soils increased

signi-ficantly between 1964-{8

in all

treatments which included organic manures

(p"ut

_@),

straw (SQ _{and farmyard manure (Dg)) green mamres (Gm) or leys}

_with

_clover

_flr)

_or

leys._giyetr _{_'Nitro-Chalk'}

(Ln).

_Carbon contents decreased slightiy

in

soils given only

fertilisers (Fs and

Fd).

Betwem 1968-71 organic

C

further increased wherJfarmyard

manure, _{_peat}

or

straw were applied cumulatively,

but not

where leys were grown. Carbon decreased slightly in soils where only one green manure crop (in l-97t) was _[rown.

The mean loss

ofsoil

carbon from plots given only fertilisers was

-d.OSO 1-O.Ott-t

7

C, corresponding

to

an annual rate of loss of

0.N8\

C. This value is very similar

to

the average loss between 1876

and

1959

from

arable soils

in

experiments

on

other parts

(Series

A

and C) of Stackyard Field.

. The changes

in

I

total C

in

surface soils from all main-plots between 1964_71 were

simila_r.

in

all _{_four blocks, despite the variations}

_in

_{the mechanical composition}

_of

_the soils (Appendix Table

l).

Covariance analyses confirmed

that

the changes

in

carbon contents

_were unrelated

(-0.0033

+

0.00624)

to

%

clay and adjusting the changes

in

lC

to

allow

for

variations

in

clay contents slightly increased the residual varian-ce

of

the mcas.re,ments.

Within

this experiment,

ther;foie,

variations

in

clay contents from 7 .8-13.1 _{% did not} afect _{either the loss or accumulation of soil carbon in seven years.}

Changes in the

N

content of

tie

soils closely followed changes

in

soil carbon 6ut they were more difficult to measure reliably because they were very small; only the increases

oll

plots

gowing

leys or given farmyard manure were significant betwe€n

19ffig.

At

the end

of

l97l

the

N

content of _{soils given farmyard manure or peat had increased by}

TABLE 2

Net gains and losses of carbon, nitroget, o1d otga ic matter, 196+7112

Treatrrcnt

Lcys with clover

I-eys with oi&ogen

Itat

Straw

Grcen manurcs

Fcrtitisers only (Fs)

FertiliseB ody (Fd)

Farmyard maoure

Carbon

Years

rccovercd.

t9a-71

4.8t

BA-72c

5.27

1964-7t r.x

19&-72.

7.15

t 4-7t

21.47

l9&-:

3.23

t9g-71

l.t7

t9a-71 -2.a

1964-71

_-

1.65

1964-1t

10.46 18. t 36.2

Orgadc matter rccovercd. 8.3 9.1 5.8 t2-4 matter addedb 9.2 9.0 8-2 10.5 NitrogEo

rovlned.

l90 455 I@ ,()5 5t5

l&

70 o

-l4o

585 NirogeD add€db I50 160 155 185 535 2X l60d t5m torlnes/ha kp/ha

Oreaaic

,-=ji-=-37.2

4r.8

5.5

43.4

2.O

6.td

3.9

-2.9

(a) _{Calculated from chenses in a ,nd N contenis}

Cfabb 1), usitrg soil weights of 3.14

x

IoE tootrG/ha

for leys atrd 3.,14

x

tos too;es/ha for all other reatinents

"

-(b) For amoults added see Part I, Tabbs _e 3 aDd 6. N values rouoded to oearest 5 kg N/la-(c) R6ults for Blocks II and

w

6ntv-(d) Amoutrts _-of organic matt"' aod lit'ogeo in Italian ryegrass ia 1964 aod 1965 were not measurcd.

(c) Roots and stubblc of barley, wioter wheat, b€ans a;a'rye, ind potat.-.,ia

_{Lie;di i;;'ffi}

plough.d

_h

_{o! arl}

plots

ROTIIAMSTED

REPORT

FOR

1973,

PART

2

0.017

and

0.015

_+0,N29%

respectively.

The

C :

N

ratio

of

all

soils given organic manures, green manures or growing leys increased between 196,1-71 but decreased from 8'9

to

8.1-8.5

on

soils

without

organic manures (Appendix Table

2).

Proportionally

more C than

N

was also lost from land fallowed between arable crops on the adjacent

green manuring site (Series A) betlveen

193ffi6

(Chater

&

Gasser, 1970), and the C :

N

ratio

decreased

from

9.5

to

9'1. The evidence here (Table

l)

suggests

that

the plant

residues (roots and stubble

of

barley, winter wheat and winter _{rye and} potato haulms and sugar beet tops) which were ploughed

in

b€tween 196G71 did not provide enough organic matter to balancc losses.

Table

2

shows net gains and losses

of

C,

N

and organic matter

&lvef-n

1964-7112

in

relation

to

the amounts added

in

organic manures. The amounts

of

soil carbon and nitrogen measured by analysis

in

1971 agree well

with

the amounts present

in

the leys

which were estimated

from the

weights (Part

I,

Table

6) ploug}ed

dowt

in

191112.

Soil analyses made

on two

blocks

(II

and

IV)

in

1972 appeared

to

overestimate the amounts

of

nitrogen (but not carbon) which accumulated under the leys. Much

of

the differencr (220 kg N/ha) between

N

recovered by analysis ('105 kg N/ha) and the 185 kg

N/ha in the tops and roots of the ley given

'Ntro-Chalk'

(Ln) can be explained.

'Nitro-Chalk' ( I 26 kg N/ha) was given on 8 March for the first cut of grass and again on 26 June

for

a second cut, which was not taken because there was

little

rain

in

July-Septcmber.

Much of the fertiliser nitrogen applied appeared to remain in the surface soil (G-23 cm).

It

is more difficult, however, to account for the diference (295 kg N/ha) between the N

in

soils under the clover ley (455 kg N/ha) and the amounts measured

in

the roots of the clover and grass (160 kg N/ha).

In

1972, much mineral N may have accumulated under the clover ley during a long dry summer but was lost when the roots were washed before analysis. These discrepancies, which may also be due to sampling and analltical errors,

emphasise the difficulties of measuring unambiguously the amounts of N that accumulate

in

soil under leys grown for only a few years.

Most ofthe C and N applied in p€at still remained in the soil

in

1971. Very little carbon (about

t37J

but much more nitrogen (zE

l)

remained from six cumulative dressings

of

straw. Some of the N given as 'Nitro-Chalk' was probably immobilised by straw between 1965-71 and retained by the soil as organic N. About 3G{0

f

ofthe

C and

N

remained

in

1971 from the green manures; proportionally more C was recovered

in

1968

(Iable

1)

than

in

1971, because only one crop of red clover

was

grown between 1969-71' About

50%

of

the

C

arLd

371of

the

N

applied as farmyard manure remained

in

the soil

in

197i. Percentage recoveries of C and

N

from peat, straw, green manures and farmyard manure

in

1968 and 1971 are summarised in Table 3.

TABLE 3

Percentdge recoveries of carbon and nilrogm

_from

ctanulative dressings ol peat, strcw @d

farmyard marune atd

from

green rnanures (gtown

in

1965, 1966, 1968, 1971)

Carbon Nitrogen

OrSaoic

manrll6

Pcat

Slras

Gree! maDures

Farmyard manure

after

alter

3

yeals

6 yeals

79

89

l2

11

94

33

50

50

(.)

value ureliablc

after

after

3

years

6 years 97

76

,18

55

43

42

37

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:g

gE

8a

.98 6.n.r\F6N 60 a*s-a- _-- 5E NHq FO i6.l ..r 6 O,

9.8

: c-NO\h-F..r O= -it U

;^a;;;

8 E

H-

_T'I"?TTT

_:'

ohN666 oQ -.166t FF

o..,--._ -

*.E

$5gex=

p5

+nr;--

3e E$

_'83

.

9..

-ee

og

.E B

9E

TE

g:

a{o\h-F6 o= a{o\hFtr- it= !6

;&o;;; BE ;nA;;;

8d9S

'Jd"\JJ

EE

rJJ;JJ

??

.ax

oncro&n

_Fc{..r..r!

F.E

_FF

oncro,ir-

-6 -6

sE

-N6.4{ FF iti

ROTHAMSTED

REPORT

FOR

1973,

PART

2

Changes in orgonic P

co

ents

ofsoils.

Organic

Pin

soils increased significantly between

196,168 where organic or green manures were applied or a clover ley was grown

(fable

l).

Between 1968-71 organic P increased slightly in soils given peat, straw or farmyard manure but much more under the ley given 'Nitro-Chalk'. The plots growing green manures lost organic P between 1968-71 (a result parallel to changes

in

organic C) because only one

green manure crop (red clover) was grown. Organic P contents did not change siCnfficantly between 1964-71

in

plots without organic manures (Fs and Fd) despite net gains of 220

and 550 kg P/ha respectively

from

superphosphate. Other evidence (Oniani, Chater

&

Matringly, 1973) shows that much more superphosphate (up

to

3000 kg P/ha), applied over many years,

did not

alter the organic P contents

of

arable soils

at

Rothamsted. The increases in organic P, as percentages ofthe net gains in P applied during seven yeani,

were 43'%

(l*),

351

_{@n), 33% (Pt),}

N%

(St) and

l9l

_@9.

The increase in organic P

in

soils given peat, which was apparently inert, is surprisingly large and may be mis-leading, because the

igxition

method

of

analysis app€ars

to

overestimate organic P

in

soils containing much carbon (Oniani, Chater

& Mattingly,

1973).

Charges

in pH

and exchargeable

crtiorc.

Some exchangeable

K

and

Mg

(and some

soluble P) moved below the plougtr layer and analyses

of

surface soils (Table

I

and Appendix Table 2) do

not

show the changes

in

the nutrient status of tlle soils between

1964-71 adequately. Most of these changes are discussed in relation

to

soils sampled

to

53 cm

(fable

4 and Figs

l-3).

The mean pH of the soils decreased between 196468 by about 0.5 units. The site was

limed

with

ground limestone (4'8 tonnes/ha)

in

February 1969, before the sugar beet crop, and the pH

in

l97l

was, on average, 0.2 units higher than

in

1964.

Exchangeable

K

in

the

surfac€ soils increased

in all

treatments between 1964-68

(fable

l), tle

increases being more on plots growing leys than on the correspondiDg

plots under arable crops, although balancing

K

dressings were given (Part

I)

to

com-lrnsate for differential renovals. The larger amounts

ofK

given as farmyard manure

or

equivalent fertilisers @d) increased the exchangeable

K

in the surface soils only slightly

more (by _{20-30 i,g} K/g) than the smaller (Fs) dressings. Much

ofthe exra

K

must have leached below 23 cm during this period or been 'fixed'. Exchangeable

K

in

the surface soil increased more between 1968-71 than between 1964-68, partly because more

K

was applied @art

I,

Appendix Table

l).

Changes in exchangeable Mg followed a similar pattem to those

for

exchangeable

K,

more accumulating in surface soils under leys than under arable cropping and more where

farmyard manure

or

equivalent fertilisers were applied.

By

1971 exchangeable

K

and

Mg in

the surface soils ranged

from

14l-267

pg

K/g

and 30-49 pg

Mg/g

(Appendix Table 2). The values

for

Mg are adequate for most crops on this soil _@olton

&

Penny, 1968). Exchangeable

K

in

surface soils, from plots given only the smaller amounts

of

fertiliser, may be insufficient

for

maximum yields

of

some crops (e.9. potatoes, sugar beet)

gown in

the testing phase

of

the experiment

(1972-7,

unless large amounts

of

potassium fertilisers are used.

Figs

I

and

2

show the vertical distribution

of

exchangeable

K

and

Mg

in

tie

soils before the experiment started

in

spring 1964 atrd before potatoes, the

first

test crop, were planted

in

spring 1972 and 1973. Potassium fertiliser (200 kg

I(ha)

was broadcast

in

the

autunl:s

of l97l

and

1972 before ploughing. The distribution

in

the following

springs, shown

in

these Figures, is therefore the result

of

the movement and 'fixation'

of K,

applied between 1964 and

l97ll2,

together

with

the effects

of

ploughing down a large single dressing of potassium fertiliser

in

197213. ^Iable 4 g)ves ttre distribution and

Irrcentage recovery

of

the residues

of

P,

K

and Mg applied as fertilisers, and gained by the soils, between DA-7213.

THE VALUE OF

ORGANIC MANURXS

AT

WOBURN.

II

Betvteen 65-:70% of the total

K

gained by plots given peat, straw, green manures

or

fertilisers only (Fs) was recovered as exchangeable

K

in

the top 53 cm of soil so about 250-300 kg K/ha was lost by 'fixation' or leaching. There are no obvious diflerences

in

the distribution of exchangeable K in the presence and absence of organic matter (Fig.

l).

About

the same proportion

(fi-&%\

of

K

gained

from

farmyard manure,

or

from

300

0

t

t

_[;

LJ

li

lirl

li

Li

oT-,OL

,.L

..1

..1

,.L

o-,OL

.L

€

.,1---l

.! iol

el

E

sol

3

-

of--c

ro

l'-3

zol-*L

I

roL

*L

ol-:o l-I

,ol

,NL

..1

uoL

i\

l\

l\.

i\

i)

1/

_"---'

l,

i./

i\

t\

i

_--'

!/

o

100

200

300 0

100

2oo

300

ExchonEeoblc K (FgK/9

soil)'

Fro.

l.

DirbibutioD of crchaog€ablc K io soils saEpled to 53 cu iD 1954

(a-a-a)

ad

i!

197213

a-a-a).

t4t

26

300

St

ROTHAMSTED

REPORT

FOR

1973,

PART

2

equivalent amounts of fertiliser (Fd), Tas present as exchangeable _{K. About} g00 _kg

_I(ha

were not recovered and the distribution

in

Fig.

I

suggests that some had leached beiow 53 cm.

All

the

K

gained by the all-grass ley

(Lt)

ardTB:z

of that gained by the clover ley

(k)

was recovered as exchangeable

K.

Magnesium gained by plots given peat, stmw, green _{manures or fertilisers (Fs) between}

0

r0 20 30 40 50

0

.t0 20 30 1.0

50

r--'r.-r---.--I.---r---.rr--r---I---]-.----T---l

010

20 30 40 50 0l0

20 30 10

50

Exchongcobl. Mg (FEM9/g soil)

- _-Flc.

2

Distributios of cxchaogeablc Mg in soils

eh

.d to 53 ce

i!

1964

(a-O-a)

aDd itr tyDl3

(a-a-a).

r42

.l-,or

,ol

,L

..f

toL

'f-10r

,o

1--t

_S

rof

!

..1-ol

E

s0L

3 or

bl

.

lo

l-3

,o

l-,l_

I

'or

50L

oT-,"L

,.L

,"L

."1

,OL

tl

)/

i/

i\

j!

it

ll

i

,'!

!./

LI

Ii

,\l

?/

sr

at

'lt

i/

I1

t/

l1

_rl

il

lt

ii

t/

THE VALUE OF ORGAMC

MANURES

AT

WOBURN.

II

1964-72 rema;irred mostly

within

the

top

53 cm

of

soil and its vertical distribution was

independent of the amounts of organic matter which accumulated

in

the soils. IJss

Mg

(73-80 _{%) gained} from farmyard manure, or from equivalent fertilisers (Fd) was recovered

(Iable

4) and slightly more remained

in

the top 30 cm of soils given farmyard manure

than

in

soils given fertilisers.

In

contrast

to

the results

with

soils from the arable crop

o20

405080

0

20 10 60

80

o

'10

20

!eo

ur

_<40

=

E50

o

oO

o

.lo

e

320

30 40

50

'I

,of i \

_lr\

,of i ,/

""1 i

../

-"1

,"1

i!

soL

l,l

f-l- i\

t-i)

l-

.l-/

t{

L.T

I

il

st

t-rr\

t,\

L,i\.

li,/

L'.-/

L !/

LJI

Pt

tI

ti\ ti\

lu/ lr-/

LT

L

T

Lii

Gm

ln

Fs

o20406080o20/o6oao

l,lo HCO! -solu ble P (pSP/g _soil)

F'tc.3. Dirtributiotr

of

0.5M sodium bicarbonaGsoluble

P

itr soils sasplcd to 53 qn itr 1964

(a-a-O)

8od in 1Y1213

(a-a-a).

143

or-I

t0F

li

20

l-

?

tl

so

l-"oL

_{I it}

i/

ro

L

i,i

ROTHAMSTED

REPORT

FOR

1973,

PART

2

sequenc€,

2A-301

more

Mg

was recovered as exchangeable

Mg

under leys

than

was

gained from _{fertilisers applied between l96zt-71 (Table +). This discrepancy could arise} (i)

from

experimental

erors, (ii)

from the release of non-exchangeable _{Mg irom the soil,}

(iii) from underestimating the amounts of Mg removed in cut grasi or (iv) fr-om Mg preseni

in

rain. Bolton and Penny (1968) found

little

non-exchangeible

Mg

was releaied from Woburn soil during exhaustive cropping

with

_ryegrass

in

the glasihouse though

it

is possible, but not proven, that some could be released under

leyigrown

fo,

,"u"i

yeao.

These results can be explained

if

some Mg, and probably

K,

leached from grass

lift

on the plots to dry, after the samples had been cut and removed. They can be more reason-ably explained, however, by the amounts of Mg falling

in

rain. Williams (1973) showed the annual amount of Mg in the rainfall at Woburn between 1960-69 was 2.5 kg Mg/ha.

Between spring 1964 and spring 197213, the soils would, therefo re, gain

n-22.5

kgMilha,

which accounts almost completely for the extra 20-30 kg Mg/ha

in

soils under ieys. The

distribution

of

exchangeable

Mg

in

arable soils (Pt, St, Gm and Fs), shown

in

Fig. 2,

suggests, moreover, that some Mg (approximately 20 kg Mg/ha) has leached below 53 cm.

The amounts and distribution

of

exchangeable

K

and

Mg

in

the soils were slightly

diferent

after leys than after arable cropping, despite the balancing dressings _@art

I)

which ensured

that

the same net amounts

of

K

and

Mg

were applied

to

both

crop

sequences belween 19@-72. Further work is

in

progress on these soils

to

estimate the amounts of

K

and Mg that have been 'fixed'

in

non-exchangeable forms.

Changes

in

0.5114 NaHCOs-sottble

P.

Fig.

3

shows

the

distribution

of

NaHCOs-soluble P

in

soils

in

1964 and

in

1972/3. Superphosphate (100 kg p/ha) was broadcast on the leys _{and rye stubble in} tl.re autumns

of

l97l

and 1972 before ptoughing to provide adequate P for potatoes, ttre fust of the sequenc€ of test crops. Because soil samples were taken in the following spring, much

ofthis

P was found in the lower part (15-29 cm)

of

the plough layer. Very little P appears to have moved below 30 cm in soils where 220 kg

P/ha accumulated betweetr

l9g-71

but

detectable amounts moved below 30

cm

on

plots given farmyard manure

or

equivalent fertilisers

(Fd)

which gained 550

kg

p/ha during the same period. There was no significant diference after seven years between the moyement of P applied as superphosphate or as farmyard manure

(fable

4).

Recent calculations (Holford, Wedderburn

&

Mattingly, 1974) show that surface soils

at Woburn hold about I 14 pg P/g on high-energy surfaces and about 80 pg p/g much less

strongly. The top 30cm of Woburn soil should, tberefore, retain about 520 kg piha before

detectable amounts leach below this depth and the evidence in Table 4 and Fig. 3 supports this prediction.

-

The percentages of total P applied which remained soluble

in

0.5M NaHCO3 ranged

from

2A.4-36.4\ (Iable

4). They were smallest

for

soils under leys (Lc and Ln) and on

plots given straw, and largest (34.0 and,

36.41)

on plots given fertilisers only (Fs)

or

peat (Pt). The smaller recoveries under leys are consistent with the evidence thai 30-40

f

of

tlte

P

applied

to

them accumulated as organic P. The large recovery

of NaHCOi

soluble

P on

plots given peat _{throws further doubt}

_on

_{the apparent accumulation}

_of

organic P in these soils. The proportions of P _{which remained NiHCO3-soluble in plots}

grvcn

only

fertilisers were larger than those measured (abont 251'1

on

Saxmundham soils given much P (250-500

kg

P/ha)

for

three years (Maningly, Johnston

&

Chater

1970), probably because 100 kg P/ha (about one-third of the total applied

to

Fs plots)

was ploughed down only four to five months before sampling. Mineralisable nitrogen in the mils

Surface soil samples, taken

in

autumn 1968 and 1971, were used

in

incubation tests to

THE VALUE OF

ORGANIC MANURES

AT

WOBURN.

tr

incubation

in

1971 but not

in

1968. Soils were incubated for three or eight weeks without

or

with

CaCOs

(0'21),

which brought the soils above

pH

7.

(fhis

amount

of

CaCOs

is approximately equivalent

to

a field dressing of 7 tonnes/ha.) Appendix Table 3 gives

the NOg-N and inorganic

N

contents

ofthe

soils and Table 5 the increases in mineralis-able

N,

calculated as kg N/ha.

TIBLE 5

InoeasesL

in

total soil

N

od

mineralisable-N

_from

residues

of

leys, peat, slraw, gteen ntutures and

_f*myard

mqnure

in

1968 and 1971

Increases (kg N/,ha) ia

Mineralisable N

Unlimed

Mear" as

'/"iacIfar€ in total

soil N

Total

soil ND 3 weeks 8 weeks 3 weeks 8

weeks

MeaD

Tr€atmetrt

Year

Irys ivith

ctover

_{ltrf

Irys with

nitrog.r,

_{i|ri

P€at

_{itri

stras

_{ltri

crEra

ma,uEs

_{itri

Farmyardmaou''

_{i|fl

22 IO

l7

2

t

3l

6

9

l$

36

4

4l

,r8

4l

190 49

,18 X

38

4l

125

I

t7

18

l7

13

l@m33m3421

51523

5I53103t58

t&374452444,4.

70

13

3023n

23

34s t2

22

29

25

2:2

585 37

6t

45

10

53

(a) Relative to plots giveo oDly f€rtilis.Es

(b) _{From Tabl€s I} 8nd 2

(c) Itrc.€ases

lot

rcliabls

Mean increases in mineralisable N (Table 5) were

2l

and 30 kg N/ha on unlimed soils, after three and eight weeks respectively and 26 and 32 kg N/ha on the limed soils. The

averages

of all

four

values, expressed as

a

percentage

of

the

increase

in

total

N

in

soils, ranged from 2

to

33:z$able

5). Nitrogen residues from peat were inert. About

one-third of the residues, accumulated between 1965-71 from straw and green manures, mineralised readily. The absolute amounts of nitrogen that mineralised from residues

of

farmyard manure were 22

kg

N/ha

in

1968 samples and 53 kg

N/ha

in

1971 samples,

about 6 and 9

I

respectively of the total

N

accumulated in the soils. More N mineralised

in

both years after the clover ley than after the ley given

'Nitro-Chalk',

even though much

N

(126 kg N/ha per cut) was given

to

the N-treated ley

in

1970-71

to

avoid the

risk

of

ploughing

in

an N-deficient sward. About twice as much

N

mineralised

in

1971

as

in

1968

from

soils under

the

ley

given

'Nilro-Chalf.

These results indicate the extra amounts of nitrogen which are potentially available in these soils after six to seven

years under regimes which conserve or increase soil organic matter. They also confirm

that

nitrogen added as peat (over 500

kg N/ha) is

largely

inert,

whereas about

l0%

of the residues from farmyard manure (585 kg N/ha) mineralises readily.

Conclosions and summary

l.

This paper describes changes in the C, N and organic P in surface soils (0-23 cm) and

in

NaHCOa-soluble P and exchangeable cations

in

soils, sampled

to

53 cm,

from

an experiment on Stackyard Field, Woburn. The soils were cropped

from

l96Hl,

(a)

with-out

organic manures,

at

two

levels

of

PKMg

manuring, _@)

with

additions

of

peat,

ROTHAMSTED

REPORT

FOR

1973,

PART

2

straw, green manures

or

farmyard manure,

ot

(c) maintained under a grass-+lover ley

(without fertiliser

N)

or a grass ley given 'Nitro-Chalk'.

2.

The amounts

of

organic matter

that

accumulated under the leys ranged

from

8-l0

tonnes/ha and contained 160-180 kg N/ha.

About

9O"/"

of

the organic matter added

as peat, and all the

N,

remained

in

the soil

in

l97l

_; less than

2\

of

the

N

mineralised in incubation tests. About 13 _% of the organic matter added as straw, but nearly one-half

of the

N,

was recovered

in

the soil

in

1971. Between

3H0y.

of

ihe organic matter and

N

from four

green manurc crops remained

in

the soil.

About

30

f

of

the

N

residues

from straw and grcen manures mineralised rapidly on incubation. One-half of the organic matter and over one-third of the

N

from farmyard manure remained

in

the soil

in

1971.

Mineralisable

N

in

soils containing residues

of FYM

more

than

doubled between 1968-71 and exceeded 50 kg N/ha.

3.

Organic

P

accumulated

in

soils under leys and

in

soils given straw

or

FYM.

Its

apparent increase

in

soils given peat, wh.ich was otherwise

inert,

may be an artefact

of the ignition method of analysis. Organic P did not change significantly

in

seven years

in

soils growing green manures or given only fertilisers.

4.

Exchangeable

K

in

surface soils increased

from

75

to

152

pgKlg

on

arable soils and

to

196 g.g K/g under leys on plots which gained 680 kg K/ha, and to 256

p.gKlgon

plots which gained 2000 kg K/ha either from

FYM

or

K

fertiliser given between 1964-71. Only

60-701of

the

K

gained

in

the arable crop sequence vas present as exchangeable

K

(to 53 cm); 250 and 800 kg

I(ha

had been'fixed' or had leached below this depth from

the small and large dressings respectively. More

K (8G.100f ofthe

net gain by the soils) remaitred in the top 53 cm of soils under leys.

5.

Exchangeable

Mg

in

surface soils increased

from

15

to

32 pgMglg

on arable soils

and to 46 pgMglgunder leys on plots which gained 90 kg Mg/ha and

to,l{)-50

peMele

on plots which gained 260 kg Mg/ha either

from

FYM

or from

Mg

fertilisers.

All

Mg

accumulated

from

the smaller dressings

in

the arable crop sequenc€ was recovered as

exchangeable

Mg (to

53 cm).

About

5G-70

kg

Mg/ha from

the larger dressings had leached below 53 cm or was '6xed' by the soil. More Mg (20-30 kg Mg/ha) was present as exchangeable

Mg

under leys, mostly

in

the

top

30 cm

of

soil, than was gained by

manuring. The amounts

of

Mg

added

n

ruia

(20-22

kg

Mg/ha)

betwen

1964-:7213

account

for

the extra Mg

in

soils under leys

ard

show that about 20 kg Mg/ha leached

below 53 cm in arable soils.

6. NaHCOs-soluble P

in

surface soils increased

from

28

to 43

pgPlg

on plots which

gained 220 kg P/ha ard to 65 y.gPlg on plots which gained 550 kg P/ha between 19&-:71.

Little P moved b€low 30 cm when the smaller amount was applied but soil below 30 cm

was slightly enriched with soluble P from the larger dressings.

7.

Organic matter, accumulated in soils between 1965-71 had little effect on the amounts

or vertical distribution of exchangeable

K

or

Mg, or 0.5M NaHCOrsoluble P,

in

soils sampled to a depth of 53 cm. More exchangeable

K

and Mg, and slightly less NaHCOs-soluble

P,

accumulated

in

the

top

30 cm under leys than

in

soils

in

the

arable crop

sequence.

In

the second phase of this experiment (1972-76) the effects

of

different t,?es and amounts of organic matter accumulated

from

1965-71

will,

therefore, be evaluated

on

soils

in

which both the amounts and distribution

of

P,

K

and

Mg

are similar but not identical.

Ac&rowl€dgenents

We

thank R.

W.

M.

Wedderburn and

J.

Bolton

for

helpful comments,

V.

Cosimini, Brenda Messer, R. J. Avery and the late R. A. G. Rawson for some of the chem.ical analyses

and other members of

tle

Chemistry Department for help with soil sampling.

RrFm.ENcEs

BoLroN, J. & PB{NY, A. (1968) Thc effecls of potassium and Eagnesium fertilisers on yield aad com-poeitioo of successive crops of ryegrass, clover, sugar b€et, potatoes. kale aDd barley oD sa[dy soil

it wobun

Jounal of Agticulrural Science, Cambridge 10, 303-311.

Br.Er,$rR. J. M. & JELx${so{ D. S. (1960) Detemination of organic carbon io soils. I. Oxidation

by dichomate of orgadc matter in soil atrd plant malerials. tounal of Soil Science ll,394-4,.2.

Bnnorn, J. M. & KEEN;, D. R.

(l%5)

steam aisdllalion methods for determination of amtnodum,

nitrate and nit

ite.

Aralytica chimica Acla 32,

$5495.

CH^TER. M- & G^ssER- J- K. R (1970) Efects of geeo manuriDs; farmyard matrule, atrd st aw on the or8aDic maner of soil and of g€eo Datruring on available aitogen. Jounul of Soil Sciencc 21,

127-137.

CRowrHE E. M. (1936)

hi

FiIty Years oI FteA Experinentt at ,he Wobum Exryrinerual Statiotr.

Ed, SL E. J. Russell & J. A. Voelcker. Cbap.

)oOI.

The Soils of tbe Wobum Plots. Irndotr: Innclnam cr€en and Co.- DD. 3lt-345.

Gorrnn<fu- E. & Por-hro, A. 6: (1952) A 6odi6ed Eocedure for detemioiog boroo itr plant mat€rial atrd soils usios

l.l'

diaDthrimide, lounal of ,he Scieiae of Food and Agricultuft 3, 622-4z..

HoLFoRD, L C. R.; WEDDERBTTRN, R. W. M- & MATrDtcLy, G.

E

C. (1974) A Langmuir twosurface

equation as a model for phosphate adsorption W soils. lournal of SorT scierce. (In the press.)

M^rrINGLy, G. E G. (1970) Total phosphorus contedts ofsoils by percbloric acid diSestion and sodium

carboDate

fusiorl

lounul of Agricultwal Science, Cambridge 14,79'82.

M^TrDroLy, G- E. G- (1974) The WoburD Orgadc MaDuriog experiment. I. DesiSrL qop yields and outrient balance, 1964-72. Rorhatnsted Expcrinatal Slorion.

Rew

_lot 1973, Pafi 2,98-133.

MaTTDJGL! G. E. G., JoBIsroN, A, E. & C'IrarR, M. (1970) The r€sidual value of faimyard maou€

and superphosphate itr lhe Saxmuldham RotatioD Erperimetrt, 1899-196. Patharnsted Experi'

n@ntal Station. Report for

1

9, Part 2,91-112.

MErsoN, A. J.

(1950

Methods of chemical analysis for soil survey sanples. New Zealord Soil Bueau-Balletin No. 12.

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itr soils by extractiotr with sodiun bicarboDate. United Srates DepartnEnl of Agricubure. Cict l@

No. 939, 19 pp.

ONr Nr, O. G.,

Grrm,

M. & MATTNGLY, G. E. G. (1973) Som€ effects of fertilis€N aod farmyard matrBe o! the orgadc phosphorus in soils. lournal of Soil Science

A,

1-9.

Rqm^usrED E)cERrlcN"rAL STATToN (1970) Delails of the Clasical aad Inng4enn Exper'urEnts up ,o

,tM7.

HarpeEden, 128 pp.

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w:

M. H- & W[u^trs, E. C.

_095,

Ob6ervatiotrs oo the detemiEatiotr of total orgaaic

DhosDhorus io soils. Journol of Soil Sciente 6, 254-267.

Tnisirv.

i.

(1950) The determination of oryaric carbotr itr soils by dichromate mixtures. Tranto.tiont of thc 4th In .narionol Congress of Soil Scieacc, Anstedarn 1, 161 164.

WALKTEY. A. (1947) A critical examiiatioo ofa rapid method for de(eroinisg orgadc carbon iE

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251-26/..

V'lIIllAIrrs, R, J. B. (1973) Chaqges in thc nutrieDt r€serves of lhe Rotharnsted a[d wobum RefereDoe

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THE VALUE OF

ORGANIC MANURES

AT

WOBURN.

II

ROTHAMSTED

REPORT

FOR

1973,

PART

2

APPENDIx

Totat

ni!9gen

_{by,-Kjeldahl digestion using}

_a

_{Cu-Se catalyst,}

_NHs

_in

_{the digests was}

estimated by distillation.

Total carbon was measured on soil ground <0.5 mm by the method described by Walkley (1947);

no

phosphoric acid was added before

titrating

and z-phenylanthranific acid

was used as the indicator.

Surface soils taken

from all

plots

in l97l

were also analysed

by

the Tinsley (1950) method _{described by Bremaer and Jenkinson (1960). The ratio}

_of

_Tinsley

_C/Wilkley

_C ranged

from

l.28-1.35

*

0.026

for all

soils other than those given peat,

for

which -the

ratio was 1.23. The correction factors used were 1.30

for

all treatments exc€pt peat.

Total

P

was estimated, after fusion

with

sodiurr carbonate

(Mattingly,

1970), on the 'Technicon AutoAr:alyzer' using the method described by SaIt

(963).

Orgrrfc

P

was measured

by

an ignition method described

by

Saunders and

Wiliams

(t955). _{Soil (2 e}

_<

60 mesh) was ignited

at

500-550"C

for

2 hours and extracted

with

0.2N HgSOa (100 ml)

for

2 hours at room temperature. Organic P was estimated from

the diflerence between 0.2N HzSOa-soluble P extracted from ignited and air-dry soil.

Sodiom bicerbomtesoluble

P

was measurd,

after

extraction

with

0.5M

NaHCOs

(Ol*a

et a1.,1954), on the 'Technicon AutoAnalyzer' (Salt, 1968).

Water+oluble

bomn

Ten grammes air-dry soil

(<2

mm) were refluxed

with

20

ml

of

boron-free water

for

15 minutes

in

silica flasks. Boron was estimated colorimetrically

with l,l'-dianthrimide

(Gorfinkiel

&

Pollard, 1952).

Exchangeeble

catims

were leached

from

soils

(<2

mm)

with

.lV ammonium acetate

(Metson, 195Q. Aliquots were evaporated

to

dryness, the residue oxidised

with

0.5

ml

conc. HNO3 and dissolved

in

10 ml 0.21{ HCl. Na,

K

and Ca were measured by emission and

Mg

by atomic absorption spoctrophotometry.

MDeralisrbh

nitrogeL

Fifty

grammes soil

(<2 nm),

air-dried and stored

for

18-20 weeks, were incubated

^t

25"C

at

one-half

of

their

water-holding capacity, measured

in

the laboratory. AJter three

or

eight weeks, the soils were extracted

for

i

hours wittr

100 mI jV _{KrSOa, adjusted to}

_pH

_{1. NH4-N and NO3-N were determined in the extracts}

by steam distillation _@rem:rer

&

Keeney, 1965); NO3-N was reduced

witi

Devarda's

alloy (<300 mesh). Phosphate in the extracts did not interfere with

NOrN

estimations.

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