Full text of DOI:10.1080/1065657X.2002.10702086

This article was downloaded by: [Temple University Libraries]
On: 23 November 2014, At: 21:06
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Compost Science & Utilization
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/ucsu20
Yield and Quality of Leek in Response
to Compost Applied as a Mulch or
Incorporated Into the Soil
Ulrik Reeha & Marina Bergen Jensena
a Skov & Landskab, Danish Center for Forest, Landscape and
Planning, Hørsholm, Denmark
Published online: 23 Jul 2013.
To cite this article: Ulrik Reeh & Marina Bergen Jensen (2002) Yield and Quality of Leek in Response
to Compost Applied as a Mulch or Incorporated Into the Soil, Compost Science & Utilization, 10:3,
244-248, DOI: 10.1080/1065657X.2002.10702086
To link to this article: http://dx.doi.org/10.1080/1065657X.2002.10702086
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Compost Science & Utilization, (2002), Vol. 10, No. 3, 244-248
Yield and Quality of Leek in Response to
Compost Applied as a Mulch or
Incorporated Into the Soil
Ulrik Reeh and Marina Bergen Jensen
Skov & Landskab, Danish Center for Forest, Landscape and Planning,
Hørsholm, Denmark
Compost is widely used to increase soil fertility, usually practiced by incorporating
the compost into the upper soil layer. This study questions the rationale behind this
practice. Compost was applied as a mulch and compared with compost worked into
the soil in a growth experiment with leek (Allium porrum L. Var. ‘Siegfried Frost’). The
compost used was made of source separated organic waste from either gardens and
parks, or households. Garden-park compost was applied in 2.5 times greater volumes
than household compost to compensate for its lower content of nutrients. The soil was
either sandy loam or clay loam. Each of the eight combinations of variables (applica-
tion method, compost type, and soil type) was repeated three times with 20 leeks in
each replicate. Significantly higher yields were obtained with compost applied as a
mulch. Here, the yield averaged 78 g fresh weight per leek, compared to 59 g per leek
from plots with compost incorporated. Compost mulching also resulted in a signifi-
cantly higher quality leeks, including more first class leeks, longer and thicker shafts,
and a generally better appearance. The advantage of placing the compost on the soil
surface rather than thoroughly mixing it with the soil can be attributed to a higher
availability of plant nutrients. No significant effect of compost type on leek yield was
observed, indicating that the 2.5 times higher volumetric dose of garden-park com-
post provided the same amount of available nutrients as a single dose of household
compost. The soil type did not significantly influence the yields either, which is at-
tributable to both soils being well structured prior to compost amendment.
Introduction
Compost, like other organic soil amendments, is traditionally incorporated and
thoroughly mixed with the soil prior to crop introduction. In the “Nordisk Illustreret
Havebrugsleksikon,” a 1912 encyclopedia and manual for Scandinavian gardeners, in-
corporation of organic amendments is the only method discussed (Helweg 1912). The
encyclopedia made no distinction between the fertilizing value of organic soil amend-
ments and their ability to improve soil structure. Moreover, the potential benefits of
mulching were not considered. In a well-structured soil, mulching with compost may
be more beneficial than incorporating compost. In addition to considerable labor sav-
ings, surface application of compost may result in a higher availability of nutrients, as
described in the discussion of results. It is also well known that compost mulching pro-
tects the soil from compaction during rain and reduces moisture evaporation from the
soil. In addition, mulching with compost can be performed several times with split
doses of compost during the growing season, thus meeting the nutritional needs of the
crop in a more timely manner.
The main objective of the study presented here was to compare the yield and qual-
ity of leeks that were grown either in soil amended with a mulch of compost or in soil
with incorporated compost. The second objective was to compare the effect of two
types of compost; compost derived from organic waste from gardens and parks and
compost made of organic household waste, as well as two types of soil (sandy loam
and clay loam) on yield and quality of leek.
244 Compost Science & Utilization
Summer 2002

Yield and Quality of Leek in Response to Compost Applied
As a Mulch or Incorporated Into the Soil
Materials and Methods
Leek (Allium porrum, L.
TABLE 1.
var. ‘Siegfried Frost’) was se-
lected as the test crop. It has a
long growing season and can
thus utilize nutrients that are
being slowly released, as is
the case for nitrogen release
from compost (Jørgensen
1987). The nutrient demands
of leeks are high, but the plant
is particularly ineffective in
Preparation of growth media
Garden-Park
Compost
Household
Compost
1
Mulch )
5 cm of compost placed
2 cm of compost placed
on top of 38 cm soil
2
2
on top of 35 cm soil
Incorporation 5 cm of compost mixed
with 10 cm of soil and
2 cm of compost mixed
with 8 cm of soil and
2
2
placed on top of 25 cm soil placed on top of 30 cm soil
1
The compost mulch was applied after leek planting to avoid mixing of
2
compost with soil. The soil was either clay loam or sandy loam,
resulting in eight types of growth media.
assimilating N. Båth
&
Rämert (2000) found that
leeks assimilated only 1-2 %
of 465 kg total-N ha that was
TABLE 2.
Physical and chemical properties
of materials used in growth media
-1
applied with compost, which
they attributed to the limited
root system of leeks. Thus, the
species is expected to be sen-
sitive to the changes in N-
availability that may result
from the different treatments.
Leeks were grown in out-
Clay Loam Sandy Loam
Soil texture
Coarse sand
Fine sand
Silt
g pr. 100 g dry soil
(0.2-2.0 mm)
37.1
34.3
13.1
11.4
4.1
58.8
28.4
5.9
(0.02-0.2 mm)
(0.002-0.02 mm)
(< 0.002 mm)
Clay
5.4
Humus
1.5
pH
7.2
6.8
H2O
-1
door drained boxes (depth 0.5
Electric conductivity
10mS cm
1.7
0.4
2
m, area 1.44 m ). There were
Garden-Park Household
3
2
(eight) combinations of
Compost
Compost
treatments: compost applica-
tion method (mulching or in-
corporation), compost type
(garden-park compost or
household compost) and soil
type (sandy loam or clay
loam). The treatments were
randomly distributed over 24
boxes with three replicates of
each treatment combination.
The boxes were filled up to a
depth of 0.4 m with the differ-
ent soil-compost mixtures as
described in Table 1. Physical
and chemical characteristics
of the soils and composts are
shown in Table 2. To compen-
sate for the higher nutrient
content in household com-
post than in garden-park
compost, garden-park com-
post was applied in 2.5 times
Approx. processing age
Dry matter
month
9
6
% of site compost
-3
61
38
Bulk density
Ash
ton m of site compost 0.63
0.43
25
% of dry matter
% of dry matter
82
18
Organic matter
75
pH
8.0
3.8
7.0
19.0
H2O
-1
Electrical conductivity
10mS cm
-1
g kg dry matter
Nitrogen
total
5.7
<0.03
0.89
0.78
1.6
30.0
<0.06
3.7
Nitrogen
water soluble
Phosphorus
total
Phosphorus
citratesoluble
3.1
Potassium
watersoluble
12.2
28.2
Boron
2.9
watersoluble
-1
mg kg dry matter
Cd
Hg
Pb
Ni
0.32
0.11
39
<0.3
<0.06
34
16
8.5
Cr
8.7
120
27
9.5
Zn
Cu
124
61
Compost Science & Utilization
Summer 2002 245

Ulrik Reeh and Marina Bergen Jensen
greater volumes. This resulted in similar application rates of N, P, K and dry matter
(Table 3). The leeks were sown under glass in February, and in May they were trimmed
and transferred to the boxes. Each box contained 20 leeks at a row distance of 20 cm
and a distance in row of 10 cm. The plants were watered and weeded as required for
TABLE 3.
Amounts of N, P, K and dry matter applied with compost
N
P
K
Dry Matter
total
total
water soluble
-1
-1
kg ha
170
ton ha
5 cm garden-park compost
2 cm household compost
1100
980
300
400
192
33
120
TABLE 4.
Results
Compost Mulch
Compost Incorporation
Household
Compost
Garden-Park
Compost
Household
Compost
Garden-Park
Compost
Clay Sandy
Loam Loam
Clay Sandy
Loam Loam avg.
Clay Sandy
Loam Loam
Clay
Loam
Sandy
Loam avg.
8
8
1
Shaft length
(cm)
8.0
8.6
8.4
8.3
6.6
8.4
10.3
8.4
7.1
9.4
8.3
8.0
7.4
8.1
7.7
8.3
7.3
8.0
8.0
8.6
7.7
7.4
7.4
8.0
ns
8.3
2.9
7.9
7
avg.
8.3b,c 7.8a,b
8.6c
8.6c
7.8a,b 7.9a,b
8.1a,b,c
7.6a
2
Shaft diam.
(cm)
3.1
3.1
2.5
2.7
2.9
3.1
3.1
2.9
2.3
2.8
3.3
2.5
3.0
2.3
2.3
2.6
1.9
1.9
2.4
2.3
2.4
2.0
2.4*
2.5
2.3*
19.6*
12.9*
1151*
143**
7
avg.
2.9d
2.9d
2.8c,d 2.9d,e
2.5b,c,d 2.1a
2.4a,b
2.3a,b
3
Total number
17
18
17
20
13
20
20
18
20
18
18
20
18
20
19
20
19
20
20
20
20
18
20
21
18.3
16.4
1433
192
7
avg.
17.3a 17.7a,b
19.3c 18.7a,b,c
19.0b
19.7c
20.0c
19.7c
4
Class 1
17
17
16
17
12
16
15
17
17
16
18
19
11
16
19
14
13
11
9
13
18
11
17
13
7
avg.
16.7c,d 15.0b,c,d
16.3c,d 17.7d,e
15.3b,c,d 12.7a,b
13.3a,b,c 10.3a
5
Fresh weight yield
(g)
1661
1869
1564
1560
884
2046
383
1373
1220
1141
2041
1454
1193
1237
1088
1571
803
786
1183
1091
1131
694
1271
1755
7
avg.
1698d 1497b
992a 1546c,d
1173a,b 1054a
1135a 1240a,b,c
6
Dry matter yield
211
226
180
206e
186
117
234
226
165
174
141
275
171
134
174
130
190
114
77
137
149
140
77
166
225
(g)
7
avg.
179b
188c
196d,e
146a,b,c 127a
142a,b 156ab,c,d
1
2
3
Leek no. 1, 4, 7, 10, 13, 16, and 19 were measured with a slide gauge from above thick basis. Average of measurements.
Leek no. 1, 4, 7, 10, 13, 16, and 19 were measured with a slide gauge right above thick basis. Average of measurements.
4
Total number of leeks in box. Number of leeks in box that passed the EU class 1 criteria for leeks (EU, 1989). This
includes among other things: Good quality although minor superficial defects are accepted as long as these do not lower
the appearance, quality, shelf-life, or sight of the leeks. The leeks shall appear white or greenish-white on at least 1/2 of
5
6
the shaft. Total fresh weight yield per box. Total dry matter yield per box. The leeks were dried at 70°C for 57 hours,
7
and at 106°C for another 46 hours. Average of the three box replicates in each treatment. Numbers followed by same
letter are not significantly different. Cross average of compost application method (12 box replicates). ns: No
8
significant difference. *: The difference is significant at the 95 % level. **: The difference is significant at the 99 % level.
***: The difference is significant at the 99,9 % level.
246 Compost Science & Utilization
Summer 2002

Yield and Quality of Leek in Response to Compost Applied
As a Mulch or Incorporated Into the Soil
commercial production during the growing season. They were harvested in February
of the following year. After washing and removal of roots and other non-usable parts,
the following data were collected: shaft length, shaft diameter, number of leeks, num-
ber of first class leeks, number of non-usable leeks, fresh weight yield, and dry matter
yield. This is described in the footnotes of Table 4.
Data were subjected to statistical analysis of the variance by use of the General Lin-
ear Model in SAS (SAS Institute Inc. 1989).
Results
Compost mulching resulted in higher quality and yield of leeks than incorpora-
tion of compost (Table 4). Average dry matter yields of leek in size of 192 g were ob-
tained from boxes amended with a mulch of compost, as compared to only 143 g in
boxes with compost mixed into the soil. Likewise compost mulching resulted in leeks
with significantly thicker shafts, as well as more first class leeks.
The compost application method was the main explanatory factor in the experi-
ment. Very few significant differences related to compost type and soil type could be
observed.
In July, three months after transplanting, the leeks cropped with a mulch of house-
hold compost on sandy soil showed a poorer establishment compared to other treat-
ments. However, this was a temporary effect that was more than offset by the time of
harvest (Table 4).
Discussion
The results point to mulching as the most favorable way to apply compost, which
is in accordance with the work of others. Agassi et al. (1998) demonstrated an 85% in-
crease in water infiltration rate for mulching compared to 52% for incorporated com-
post and 42% for pure soil. Tripepi et al. (1996) found better growth response for cot-
-1
tonwood (Populus deltoides) with a heavy mulching (90 Mg ha and above) of raw and
composted paper sludge compared to incorporation.
The study’s experimental setup has not provided data that can explain the superi-
ority of mulching with compost compared to compost incorporation in terms of sup-
porting leek growth. The difference is thought to be related to one or more processes that
take place either in the soil, where the soil-embodied compost will be more affected, or
at the soil-air interface, where the compost as a mulch is more exposed. Nutrients de-
rived from soil incorporated compost, for example, are assumed to be more subjected to
immobilization in the soil than compost applied as a mulch, simply due to the difference
in degree of physical contact between soil and compost. Such immobilization of nutri-
ents can be caused by microbial uptake (N and P) or sorption onto soil aggregates (P). It
may also be speculated that infiltrating water more effectively takes up nutrients re-
leased from a compost mulch than from compost mixed with the soil. When compost is
mixed with the soil, part of the compost may end up at locations that are not bypassed
by percolating soil water. In this case, the soil solution that constitutes the mass flow (con-
vection flow) to the roots may be more nutritious in soils with a mulch of compost com-
pared to soils with compost incorporated (Nye and Tinker 1977). This difference is like-
ly to be more extreme the smaller the root system of the crop is. The root system of leek
is shallow and consequently the soil volume from which leek can take up nutrients by
diffusion is limited, making it difficult to compensate for a low mass flow supply of nu-
trients. More experiments are needed to clarify these aspects of how compost works.
Compost Science & Utilization
Summer 2002 247

Ulrik Reeh and Marina Bergen Jensen
The fact that the leeks responded similarly to garden-park compost and household
compost indicates that the experimental application of 2.5 times more garden-park
compost than household compost by volume effectively offset the difference in nutri-
ent content between the compost types.
The lack of effect of soil type on leek yield and quality is attributed to the two soils
being rather alike (Table 2) and well structured prior to compost application. Conse-
quently, the observed results should be transferred to well structured, loamy soils only.
Acknowledgements
The waste and the park administrations in the Danish Municipality of Vejle are
greatly acknowledged for hosting the experiments, for their collaboration and for part-
ly financing the project. The Danish EPA is thanked for the additional financing. The
authors are much obliged to Morten Carlsbæk, Carl Aage Sørensen and Carsten
Damgaard who conducted the planting and observed the plant responses to treatments.
References
Agassi, M., A. Hadas, Y. Benyamini, G.J. Levy, L. Kautsky, L. Avrahamov & H. Zhevelev. 1998.
Mulching effects of composted MSW on water percolation and compost degradation rate.
Compost Sci. Util., 6:34-41.
Båth, B. & B. Rämert. 2000. Organic household wastes as a nitrogen source in leek production.
Acta Agric. Scand., Sect. B, Soil and Plant Sci., 49:201-208.
Helweg, A. 1912. Nordisk Illustreret Havebrugsleksikon. (In Danish). G.E.C. Gads Forlag. Køben-
havn, p 414.
Jørgensen, M.B. 1987. Grønsager på friland. (In Danish). GartnerINFO, pp 199-205.
EU. 1989. Kommissionens forordning (EØF) nr. 1076/89 af 26. april 1989 om fastsættelse af kvalitet-
snormer for porrer og om ændring af forordning (EØF) nr. 1292/81 om fastsættelse af kvalitet-
snormer for porrer, auberginer og courgetter. (In Danish). European Commission, p 4.
Nye, P.H. & P.B. Tinker. 1977. Solute movement in the soil-root system. In: Anderson, D.J. et al.
(eds.). Studies in ecology. Blackwell Scientific Publications, Oxford, pp 80-87.
SAS Institute Inc. 1989. SAS User’s guide: Statistics, 1989 ed. Cary, North Carolina, 946 pp.
Tripepi, R.R., X. Zhang & A.G. Campbell. 1996. Use of raw and composted paper sludge as a soil
additive or mulch for cottonwood plants. Compost Sci. Util., 4(2): 26-36.
248 Compost Science & Utilization
Summer 2002