temporal changes of soil physical and hydraulic properties in strawberry fields

Temporal changes of soil physical and hydraulic propertiesin strawberry fields

A. L. Bamberg1 , W. M. Cornel is

2 , L. C. T imm3 , D. Gabr iels

2 , E. A. Pauletto1 & L. F. S. P into

1

1Department of Soils, Federal University of Pelotas, Campus Universitario s ⁄ n, Caixa Postal 354, CEP: 96010-900, Pelotas,

Rio Grande do Sul, Brazil, 2Department of Soil Management, Ghent University, Coupure Links, 653 B-9000 Ghent, Belgium, and3Department of Rural Engineering, Federal University of Pelotas, Campus Universitario s ⁄ n, Caixa Postal 354, CEP: 96010-900,

Pelotas, Rio Grande do Sul, Brazil

Abstract

Even over short time intervals, soil properties are subject to variation, especially in managed soils. The

objective of this study was to assess the temporal changes of soil physical and hydraulic properties in

strawberry fields cultivated under surface drip fertigation in Turucu, Brazil. Intact core samples were

collected from the near surface soil layer of seedbeds to determine the total porosity (TP),

macroporosity (MA), matrix porosity, bulk density (BD), available water capacity (AWC), field

capacity, wilting point and Dexter’s S index. Aggregate samples were collected from the arable layer to

determine the aggregate size distribution and aggregate mean weight diameter. All samples were

collected from 15 strawberry fields and at four different times during the 2007–2008 strawberry growing

cycle. Although soil pore-solid relations are expected to adjust soon after seedbed construction, their

variation was only evident after >13 weeks. Even though values of TP and MA decreased with time,

and those of BD increased near the end of the growing cycle, all the soils maintained their capacity

to support root activity as indicated by critical values of Dexter’s index (S > 0.03). The amount

of relatively large aggregates (9.51–2.00 mm) and AWC increased towards the end of the strawberry

cultivation cycle. With changes in soil structure improving soil physical quality, strawberry

development benefitted. We showed that if farmers gradually increase the amount of water through

fertigation to a maximum value occurring at the end of crop cycle instead of applying water at a

constant rate, water and energy use efficiency in agriculture would improve.

Keywords: Tillage, soil physical properties, soil management, fertigation, soil structure, aggregates

Introduction

Temporal changes of soil physical properties have been the

subject of much research to quantify the effects of different

management systems within growing seasons and between

years. With many soil properties being strongly dependent

on the dynamics of soil structure, management systems are

the primary agents for changing soil environmental

conditions (van Es et al., 1999; Alletto & Coquet, 2009).

Properties, such as particle density (PD) and particle size

distribution, usually show a small variation with time

(Cassel, 1983), because they are more dependent on natural

factors, such as soil formation processes and parent

material. In contrast, other variables like soil penetration

resistance (Onofiok, 1988) and macroporosity (MA) show

more variability with time, since they are also dependent on

seasonal climatic conditions, management practices, crop

development and biological activity (Reynolds et al., 2007).

Temporal variability of soil physical properties can be

even greater than spatial variability in agriculturally

managed soils. Studying the relative significance of sources

of spatial and temporal variability at multiple scales on

water infiltrability for agricultural lands, van Es et al. (1999)

concluded that soil management factors are more important

sources of variability than soil type. Soil physical and

hydraulic properties are expected to vary significantly even

in a short time period, such as during a crop cycle,

especially immediately after tillage. Logsdon et al. (1993)

noted that within-season changes in infiltration rates couldCorrespondence: A. L. Bamberg. E-mail: [email protected]

Received August 2010; accepted after revision May 2011

Soil Use and Management, September 2011, 27, 385–394 doi: 10.1111/j.1475-2743.2011.00355.x

ª 2011 The Authors. Journal compilation ª 2011 British Society of Soil Science 385

SoilUseandManagement

be greater than management-induced differences. Mapa

et al. (1986) concluded that soil hydraulic conductivity is

particularly sensitive to temporal changes. Obtaining values

of soil hydraulic conductivity near water-saturation

immediately after ploughing that were about 100 times

larger than those measured several months later, Mapa et al.

(1986) attributed this reduction to soil consolidation

processes.

The technology of strawberry production systems in

irrigated regions has become highly advanced using similar

strategies throughout the world. Farmers cultivate

strawberries in both small (<1 ha) and large (>50 ha) fields

through the formation of seedbeds and black plastic surface

mulching protection. They use surface drip irrigation systems

designed for the application of liquid fertilizers (fertigation)

that incorporate instruments for monitoring soil water

potential, soil water content, soil nutrient status and soil

temperature within the root zone as a function of time and

local weather conditions.

Surface drip fertigation has become an important strategy

because of its considerable improvement in efficient use of

water compared to other irrigation methods. The localized

application of specific chemicals within the root systems

(Souza et al., 2009) leads to a more efficient use of soil, water

and fertilizer resources (Hanson & May, 2004; Selim et al.,

2009). Hence, if the drip fertigation system is correctly

planned and managed, considering soil and climatic

conditions, irrigation water quality and crop productivity

variations along the cycle, the risk of groundwater and soil

pollution can also be reduced (Mubarak et al., 2009b).

However, irrigation can also affect soil structural conditions

(Emdad et al., 2004) as well as expose the irrigated soils

to different water qualities. For example, large salt

concentration in the irrigation water can influence the soil

chemical properties, which can increase soil dispersion and

aggregate breakdown, promoting surface sealing and crusting

(Shainberg & Letey, 1984).

Even with all of the above technology in place and being

further improved using automatic and electronic monitoring

and reaction devices, there has been little concern regarding

the effects of ploughing, surface soil preparation and

subsequent surface drip fertigation modifying soil physical

properties that impinge directly on strawberry production

during each growing season. Mubarak et al. (2009a)

advocated more studies related to temporal changes of soil

properties, especially those that would optimize water

application in drip fertigation systems. The dynamics of

temporal variability in soil physical properties and processes

related to tillage management practices (Ahuja et al., 2006;

Strudley et al., 2008), and during a cropping season under

drip fertigation remain poorly understood (Mubarak et al.,

2009a,b).

The particular management technologies for strawberry

production in Turucu, located in the south of Rio Grande do

Sul State, Brazil, do not differ appreciably from those

presently being used in other major irrigated strawberry

producing regions of the world. The objective of this study is

to assess and interpret the temporal changes of soil physical

and hydraulic properties of strawberry production systems

conducted by 15 farmers under surface drip fertigation and

black plastic mulching in Turucu, Brazil.

Materials and methods

Study area

Fifteen strawberry fields located in Turucu, Rio Grande do

Sul State, Brazil were selected for this study (Figure 1). All

were managed by producers of the Turucu Strawberry

Farmers Association. The region comprises a transition

between the Sul-riograndense Shield and Coastal Plain

geomorphological provinces. Ultisols, Inceptisols and Aqualfs

(Soil Survey Staff, 2006) are the three main soil types found

in this region. Average daily temperature in the region is

17.8 �C and the mean annual rainfall is 1367 mm. Basic soil

physical properties of each field are presented in Table 1. All

fields were of sandy loam texture, except for two – one with

loamy and the other with sandy clay loam texture.

Tillage practices of participating farmers were typical of

those being used in major strawberry producing regions of

the world. After ploughing, a tractor-drawn rotary hoe was

used to construct seedbeds, which were 0.8–1.0 m wide and

0.2 m in height but varying in length. The seedbeds were

constructed in small sections ranging from 0.1 to 0.5 ha in

area. Strawberry seedlings were planted in two or three lines

on the seedbeds, which previously had been covered by black

plastic mulch. Water and nutrients were supplied by a drip

fertigation system located on top of each seedbed. It

consisted of two lines of nozzles separated by 0.3 m.

Additional translucent plastic covering tunnels were installed

during the winter season.

Soil sampling

In the middle part of each field, three intact soil core

samples were collected from the top soil layer at the centre

of the seedbeds using steel cylinders of 3.0 cm height and

4.7 cm in diameter. In as much as the top soil layer was

the most favourable region for strawberry root

development, the largest root density was close to the

surface. Hence, these core samples collected in the 3–6 cm

top soil layer were considered representative of the 0–20 cm

soil layer that was intensively ploughed and tilled before

crop development. Every effort was made to avoid

changing the soil structure inside the cylinders, during

sampling and for transport to the laboratory. Each cylinder

was progressively pressed down into the soil layer until

about 1 cm of soil appeared above the top of the cylinder.

386 A. L. Bamberg et al.

ª 2011 The Authors. Journal compilation ª 2011 British Society of Soil Science, Soil Use and Management, 27, 385–394

At this time, the cylindrical soil sample was separated from

the field soil by slicing the soil about 1 cm below the

cylinder. Each clod containing a cylinder sample inside was

stored and protected in a plastic lined box and laid

horizontally for being transported to the laboratory. The

1 cm of excess soil above and below the cylinder was then

accurately and precisely trimmed so that the intact core

samples could be used for determining the soil total

porosity (TP), soil bulk density (BD), soil water retention

curves and related parameters such as soil MA, soil matrix

porosity (MP), available water capacity (AWC) and

Dexter’s S parameter. Each farmer’s field was divided into

three domains according to the landscape position – upper,

middle and lower elevation. In each of these domains, one

composite sample was taken from five separate locations

randomly selected in the 0–20 cm soil layer to determine

water stable aggregate size distribution and aggregate mean

weight diameter (AMWD).

Table 1 Soil physical properties of 15

strawberry fields in Turucu, BrazilFarmer Clay (g ⁄ kg) Silt (g ⁄ kg) Sand (g ⁄ kg) Textural class

Particle density

(Mg ⁄m3)

1 132.6 223.6 643.8 Sandy loam 2.56

2 126.4 186.9 686.7 Sandy loam 2.57

3 98.9 198.3 702.8 Sandy loam 2.62

4 111.4 188.2 700.4 Sandy loam 2.58

5 138.1 327.5 534.4 Loamy 2.58

6 125.9 181.4 692.7 Sandy loam 2.58

7 149.8 163.1 687.1 Sandy loam 2.54

8 141.0 174.1 684.9 Sandy loam 2.62

9 138.6 194.0 667.4 Sandy loam 2.62

10 126.3 177.8 695.9 Sandy loam 2.61

11 170.4 201.0 628.6 Sandy loam 2.55

12 146.2 184.0 669.8 Sandy loam 2.52

13 248.0 168.0 584.0 Sandy clay loam 2.57

14 144.7 188.8 666.5 Sandy loam 2.54

15 102.5 176.3 721.2 Sandy loam 2.58

Mean 140.1 (±35.1) 195.5 (±39.4) 664.41 (±49.5) 2.58 (±0.03)

URUGUAYARGENTINA

CHILE

BOLIVIA

PARAGUAY

PERUBRAZIL

COLOMBIA

VENEZUELA

FRENCH GUIANAATLANTIC OCEAN

PACIFIC OCEAN

Manaus

Salvador

São PauloRio de Janeiro

Porto Alegre

Brasilia

Belem

–75° –60° –45° –30°

0°

–15°

–30°

0°

–15°

–30°

–75° –60° –45° –30°

0 2 4 8 12 16 km

–31°30’

–31°35’

–31°25’

52°00’W52°05’W52°10’W52°15’W52°20’W

GUYANA

SURINAME

Figure 1 Location of the 15 strawberry production fields in Turucu, Rio Grande do Sul State, Brazil.

Temporal changes of soil properties 387


All the various types of soil samples were collected at four

different times during the strawberry production cycle (1, 13,

27 and 34 weeks after soil preparation). The first samples

were collected just after seedbed construction in the last week

of June 2007, the second took place in the first week of

September 2007 after seedling transplant and before the

productive stage; the third during the main strawberry

harvesting and fertigation season in the second week of

December 2007; and the fourth after harvesting and

fertigation in the last week of January 2008.

Soil physical analysis

Soil water retention data obtained from tension tables (for

potentials of )1, )6 and )10 kPa) and pressure plates (for

pressures of )33, )100 and )1500 kPa) were fitted to van

Genuchten’s equation (van Genuchten, 1980) setting

m = 1 ) 1 ⁄ n. Considering the soil texture class of each field,

initial values of the other van Genuchten parameters (hr, hs,a, and n) were selected as suggested by Carsel & Parrish

(1988). Values of volumetric soil water content at field

capacity (FC) and wilting point (WP) were considered as the

adjusted values of volumetric soil water content in

equilibrium at potentials of )10 and )1500 kPa, respectively.

The AWC was calculated as the volumetric soil water content

stored between FC and WP. Values of the S parameter were

calculated according to Dexter (2004) using gravimetric

rather than volumetric water contents and setting the residual

soil water content (hr) equal to zero. The dry mass of a soil

core was divided by the internal volume of the sampling

cylinder to obtain the BD. With the soil MP calculated as the

volumetric soil water content in equilibrium at a potential of

)6 kPa, the corresponding soil pores had diameters smaller

than 50 lm according to the capillary equation. The TP

was calculated as: TP = (1 ) BD ⁄PD) · 100. Soil MA was

calculated by the difference between TP and MP. Water

stable aggregate size distribution was obtained by the wet

sieving method (Yoder, 1936). Aggregates were classified in

six different size ranges: C1 = 9.51–4.76 mm, C2 = 4.75–

2.00 mm, C3 = 1.99–1.00 mm, C4 = 0.99–0.25 mm, C5 =

0.24–0.105 mm and C6 < 0.104 mm. AMWD was

determined according to Kemper & Rosenau (1986).

Statistical analysis

All data sets were subjected to the Shapiro-Wilk normality

test and box-plot analyses. The 15 fields were considered to

belong to the same population. The proc mixed procedure

was used to verify time effects on soil properties of seedbeds

using a first-order autoregressive equation AR (1) that

characterizes the variance and covariance of variables with

time. LSMEANS procedure and Tukey test (P < 0.05) were

applied for those variables which presented at least two

statistically different mean values.

Results and discussion

Soil physical properties

The relation between solid and pore space was significantly

changed during the 34 weeks following soil preparation

(Figure 2a,b). Between the 1st and 34th week, TP mean

values decreased significantly from 48.0 to 43.3% (Tukey test,

P < 0.05) while BD mean values increased significantly from

1.34 to 1.46 Mg ⁄m3 during the entire strawberry growing

season. MA mean values decreased with time from 25.6 to

14.0% whereas MP increased from 24.1 to 29.3%. Although

mean values of TP, MA and MP did not change significantly

between week 1 and 13, each of them changed significantly

between week 13 and 34.

Interpretation of these results requires knowledge of the

strawberry production procedures conducted throughout the

Weeks after soil preparation0 10 20 30 40

Por

es (

%)

0

10

20

30

40

50

60TP MA MP

a aab b

BAab a

bc

(a)

BB


Bul

k de

nsity

(M

g/m

3 )

0.00.21.1

1.2

1.3

1.4

1.5

1.6

1.7

c cb

a

(b)

Figure 2 Temporal variations of total porosity (TP), macroporosity (MA), matrix porosity (MP) and bulk density (BD) mean values from 15

strawberry cultivation fields of Turucu, Brazil. Vertical bars mean the standard deviation. Different letters represent significant difference

between mean values (Tukey test, P < 0.05).



entire crop cycle. Initially, for seedbed construction, the

ploughing of the soil with a rotary hoe to invert the surface

soil layer caused intensive soil fragmentation and increased

pore space between aggregates. This recently tilled layer

tended to be structurally fragile with smaller BD values and

larger pore space volumes, which reduced the capability of

the surface soil layer to support a load (Leij et al., 2002;

Debiasi et al., 2008). Thereafter consolidation would be

expected (Reichert et al., 2009) and would continue until the

establishment of a new soil structural equilibrium (Leij et al.,

2002). Component soil properties would tend to revert over

time, restoring the soil structure to pre-tillage conditions

(Ahuja et al., 1998; Moret & Arrue, 2007).

Although this sequence of changes in soil pore-solid

relations usually are expected soon after soil preparation

(Cassel, 1983), the major changes that occurred after

>13 weeks following seedbed construction can be attributed

to three effects: (i) consolidation process by compression; (ii)

biophysical root activities; and (iii) soil wetting and drying

cycles. The first refers to a process that describes the increase

in soil mass per unit volume (increase in BD) under an

externally applied load (Horn & Baumgartl, 2002). If the soil

does not receive any significant external pressure, such as

machinery, people and animal traffic or rainfall impact (in

our study soil seedbeds were covered by plastic mulching),

this effect can be considered negligible. The second effect is

related to the soil pore space permeation by root activities

that tend to enmesh and compress groups of soil aggregates

into still larger aggregates (Hillel, 2004). Concomitantly,

water uptake by roots causes differential dehydration,

increasing the BD near the root zone through soil adhesion

(Young, 1998). From the third effect, when the soil is dried

and wetted again, soil particle movement and rearrangement

can occur. As a result, soil structure becomes stronger, the

total soil pore space may be reduced and the soil pore size

distribution also will be modified with time (Semmel et al.,

1990; Leij et al., 2002).

The absence of significant differences in TP, MA, MP and

BD between week 1 and 13 is easily explained by the local

soil moisture condition. In this period, the initial growing

stage of strawberry plants and the seasonal winter condition

of low temperatures favoured small evapotranspiration rates

that sustained uniformly high levels of soil moisture and

avoided the occurrence of wetting and drying cycles. Hence,

only after week 13 did farmers start their fertigation

management. As spring began, crop and fruit development

together with increasing evapotranspiration rates led to

sequential processes of soil wetting and drying cycles. The

effects of drier soil conditions derived from greater

evapotranspiration rates alternating with moist soils resulting

from fertigation events caused significant continuous

modifications to the pore size distribution within the shallow

root zone until the very end of strawberry production.

Although the pore size distribution tends to return to its pre-

tillage conditions, there should be no expectation that soil

physical properties will necessarily remain constant (Carter,

1988; Kladivko, 2001).

Water stable aggregate size distributions measured by the

wet sieving method changed significantly with time

(Figure 3). The larger aggregate sizes, classes C1 and C2,

clearly increased during the first 27 weeks of the growing

season (Figure 3a,b, respectively). On the other hand, C4

decreased significantly after 34 weeks (Figure 3d). Classes C3

and C5 did not change with time (Figure 3c,e). Class C6

decreased after 27 weeks but then increased after 34 weeks

(Figure 3f). Classes C5 and C6 were more or less unaffected,

probably because the stability of these microaggregates is

maintained by inorganic, microbial, fungal and plant debris

serving as strongly effective binding agents (Lal & Shukla,

2004). As illustrated in Figure 4b–d, the increase of C1 + C2

(9.51–2 mm) is inversely related to C4 (0.99–0.25 mm) with

r2 = 0.70*, which has significant at 1% of probability;

inversely related to C5 (0.24–0.105 mm) with r2 = 0.37*; and

inversely related to C6 (0.104–0 mm) with r2 = 0.41*. Even

though there are several mechanisms that can explain the

increase of C1 + C2 with time, it can be concluded that it

was related to the decrease in smaller aggregates, particularly

those in the range of 0.99–0.25 mm diameter. In as much as

the C3 aggregate size class did not show a linear relationship

with C1 + C2 (r2 = 0.08), it did not contribute to the

increasing numbers of larger aggregates (9.51–2 mm) with

time.

The AMWD mean values increased significantly in the

second part of the growing season, from 1.24 mm at week 13

to 1.56 mm at week 27 (Figure 5). These results follow almost

exactly the same aggregation dynamics observed and

presented as a conceptual model by Gale et al. (2000) in a

study where the re-aggregation process of slaked aggregates

from a surface horizon of loess-derived silt loam soil was

evaluated. They concluded that soil aggregate stability values

reached their maximum level at about 180 days after

aggregate slaking.

The most important factors affecting aggregation and

stabilization of soil particles are organic matter and binding

agents produced by microorganisms, root activities, soil

fauna, inorganic binding agents and environmental conditions

(Tisdall & Oades, 1982; Six et al., 2004). Identifying the major

soil aggregating agents and how they act in soils is more

complex since it is difficult to assess the individual effect of

each factor (Six et al., 2004). Because farmers did not apply

organic fertilizers before soil preparation or at any time

during the evaluated strawberry growing period, the impact

of organic agents like organic matter on aggregation

dynamics is of less importance in this study.

Roots enhance soil structure formation and stabilization

through exudation, death and decay, and the turnover of root

hairs, promoting microbial activity and resulting in the

production of humic cements (Hillel, 2004). Strawberry root



activities may be responsible for a small part of the effect on

the increasing of AMWD after week 13, since the strawberry

root system activity is more restricted to the moist soil bulb

generated by drip irrigation nozzles. The soil aggregation

process mediated by inorganic binding agents, such as iron

and aluminium oxides, may have even less influence. The

studied fields are situated in a region with temperate climate,

where 13 of all 15 evaluated fields had the upper soil layer

(0–20 cm) classified as sandy loam texture (Table 1).

Sesquioxides will have more importance in well structured,

clayey and oxide-rich soils, usually found in tropical regions

covered by Oxisols (Neufeldt et al., 1999).

Frequent drying–wetting cycles can induce stabilization of

aggregates formed by addition of material from those

degraded in the wetting process, rather than aggregate

disruption (Denef et al., 2001). The disintegration of an

aggregate caused by a wet event allows soil particles to settle

into more packed configurations, resulting in greater cohesion

upon the next drying event (Kemper & Rosenau, 1984). As a

consequence, the drying–wetting cycles that occurred during

C1 = 9.51 – 4.76 mm

Weeks after soil preparation

Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60

bb ab

a

(a) C2 = 4.75 – 2.00 mm


Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60

bc cab a

(b)

C3 = 1.99 – 1.00 mm


Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60

(c)C4 = 0.99 – 0.25 mm


Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60a a a

b

(d)

C5 = 0.24 – 0.105 mm


Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60

(e) C6 < 0.104 mm


0 10 20 30 40 0 10 20 30 40

0 10 20 30 40 0 10 20 30 40

0 10 20 30 40 0 10 20 30 40Rel

ativ

e w

eigh

t of a

ggre

gate

s (%

)

0

10

20

30

40

50

60

ab ab

a

(f)

Figure 3 Temporal variations of six water stable aggregate size distribution classes obtained by wet sieving from 15 strawberry cultivation fields

of Turucu, Brazil. Vertical bars mean the standard deviation. Different letters represent significant difference between mean values (Tukey test,

P < 0.05).



the cropping season, with the soil being much drier at week

27 and 34 compared to week 1 and 13 (Reisser Junior et al.,

2008), could play an important effect on soil aggregation and

stabilization, thus influencing the water stable aggregate size

distribution.

Soil hydraulic properties

Following the same trend as MP mean values, FC increased

with time, from 0.20 m3 ⁄m3 at week 13 to 0.23 m3 ⁄m3 at

week 34 (Figure 6a). Even though the WP mean value was

not significantly smaller by week 34 compared with weeks 1

and 13, the combination of greater FC and smaller WP

mean values at week 34 resulted in a substantial increase in

AWC – rising from 0.10 to 0.15 m3 ⁄m3 (Figure 6b). The

combined results of a decreasing MA and an increasing MP

indicate that the studied soils changed their structure to a

more packed configuration. Several studies have shown that

moderate soil compaction may benefit crop yield (Alameda

& Villar, 2009) because good root–soil contact can

contribute to water and nutrient uptake (Kooistra et al.,

1992). The substantial increase in AWC towards the end of

the growing season can therefore be related to a moderate

compaction level of the seedbeds that was affected by the

soil water regime and the drip fertigation management.

Thus, this enhancement of AWC may not only benefit

strawberry production, but also allow a reduction in the

frequency of irrigation events. Consequently, the soil

physical conditions become better since not only the amount

of AWC, but also the crop-available water and nutrients are

increased in the rooting zone (Topp et al., 1997; Reynolds

et al., 2007).

Relative weight of aggregates in C3 (%)0 10 20 30 40

Relative weight of aggregates in C6 (%)0 10 20 30 40

Relative weight of aggregates in C5 (%)0 2 4 6 8 10

Relative weight of aggregates in C4 (%)0 10 20 30 40 50 60

in C

1 +

C2

(%)

Rel

ativ

e w

eigh

t of a

ggre

gate

s

0

10

20

30

40

50

in C

1 +

C2

(%)

Rel

ativ

e w

eigh

t of a

ggre

gate

s

0

10

20

30

40

50

in C

1 +

C2

(%)

Rel

ativ

e w

eigh

t of a

ggre

gate

s

0

10

20

30

40

50

in C

1 +

C2

(%)

Rel

ativ

e w

eigh

t of a

ggre

gate

s

0

10

20

30

40

50C1 + C2 = 1.62 + 0.98.C32 = 0.08 r

(a)

C1 + C2 = 67.77 – 1.13.C42 = 0.70* r

(b)

C1 + C2 = 37.37 – 3.73.C52 = 0.37* r

C1 + C2 = 35.97 – 1.12.C62 = 0.41* r

(d)(c)

Figure 4 Linear regression analysis of water stable aggregate size distribution classes obtained by wet sieving from 15 strawberry cultivation

fields of Turucu, Brazil. *Regression is significant at 1% of probability, performed by the t-test with 59 pairs of values for each graph.


Mea

n w

eigh

t dia

met

er (

mm

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

b

b

a

ab

Figure 5 Temporal variations of aggregate mean weight diameter

(AMWD) mean values from 15 strawberry fields of Turucu, Brazil.

Vertical bars mean the standard deviation. Different letters represent

significant difference between mean values (Tukey test, P < 0.05).



Based on those results and considering that tilled soils

tend to return to pre-tillage conditions of structure, a

practical recommendation for farmers can be drawn: the

soil sampling for AWC determinations can be carried out

before soil preparation (pre-tillage) so that farmers know

the AWC of soils before the fertigation events. In addition,

the amount of water applied through the fertigation scheme

can be gradually increased to the maximum required at the

end of the crop cycle since the soil structure of seedbeds

will have returned to its pre-tillage condition. This

approach can be adopted for any field cultivated through

the use of seedbeds plus drip irrigation and would not only

benefit crop development; but it will also help to increase

the water use efficiency in soil seedbeds conducted under

fertigation.

S parameter is often considered as a good and sensible

index of soil physical quality (Beutler et al., 2008; Flores

et al., 2008; Streck et al., 2008). No significant differences (at

P < 0.05) of S mean values were found over the strawberry

growing season (Figure 7). Therefore, no consistent trend of

S with time was identified for the soils in this study. In

evaluating the relation of the S parameter with seven other

established indicators for a range of soil textures from rigid

to moderately expansive soils and artificial porous media,

Reynolds et al. (2009) concluded that S should be used

judiciously and in association with other indicators for

assessing the soil physical quality. However, since Reynolds

et al. (2009) did not investigate the temporal variability of S

parameter, more studies should be carried out to reveal the

performance and temporal variability of this index with other

soil texture classes.

For agricultural purposes, the S parameter has been

considered as an index of the capability of a soil to support

crop production in the sense that adequate root growth

typically requires values of S > 0.030 (Dexter, 2004). This

limiting value was exceeded in all fields studied in this

presentation, except for one soil at week 1 (S = 0.023) and

another soil at week 27 (S = 0.028), indicating that, in

general, no severe restrictions for root activities occurred.

According to Dexter (2004), the S parameter ‘enables

different soils and the effects of different management

treatments and conditions to be compared directly’. Again,

for most soils, large values of the S parameter mean good

and well-defined soil microstructure (Figure 7).

Conclusions

Soil physical and hydraulic properties of the evaluated

strawberry fields showed temporal variation. Although

changes in soil pore-solid relations might be expected to

occur soon after seedbed construction, they only became

measureable >13 weeks after soil preparation. The effects

of drier soil conditions resulting from large rates of

evapotranspiration alternating with high levels of soil water


θ (m

3 /m

3 )

AW

C (

m3 /

m3 )

0.00

0.05

0.10

0.15

0.20

0.25

0.30 FC WP

(a)


0.000.020.040.060.080.100.120.140.160.180.20

b bb

a

(b)

Figure 6 Temporal variations of field capacity (FC), wilting point (WP) and available water capacity (AWC) mean values from 15 strawberry

cultivation fields of Turucu, Brazil. Vertical bars mean the standard deviation. Different letters represent significant difference between mean

values (Tukey test, P < 0.05).


Slo

pe (

S)

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Figure 7 Temporal variations of S parameter mean values from 15

strawberry cultivation fields of Turucu, Brazil. Vertical bars mean

the standard deviation.



following fertigation events caused important pore size

modifications throughout the end of the strawberry

production season.

Although TP and MA values decreased with time and BD

increased considerably towards the end of the production

cycle, the soils generally maintained their capacity to support

root activity. MA varied inversely with MP. The Dexter soil

physical quality index S, however, did not follow any trend

with time. Soil aggregation measured by AMWD improved

considerably with time. The amount of smaller aggregates

decreased during the cropping period, particularly those

between 0.99 and 0.25 mm, while the amount of relatively

large aggregates (9.51–2.00 mm) was consequently increased.

Strawberry development would benefit from increased

AWC values towards the end of the cultivation cycle, being

related to a moderate compaction level of the seedbeds and

affected by the soil water regime and the drip fertigation

management. Considering this pattern, instead of always

applying the same volume of water, farmers can conserve this

resource by gradually increasing the amount applied over the

fertigation schedule and only reach a maximum value at the

end of crop cycle, benefitting crop development and

improving the water and energy use efficiency in agriculture.

Acknowledgements

This work was financially supported by CNPq (National

Council for Scientific and Technological Development) and

CAPES (Foundation for Higher Education and Graduate

Training), Brazil. We are grateful to Prof. Donald R. Nielsen

for editing the initial manuscript of this paper. We also thank

the 15 farmers who accepted to collaborate in this research.

References

Ahuja, L.R., Fiedler, F., Dunn, G.H., Benjamin, J.G. & Garrison,

A. 1998. Changes in soil water retention curves due to tillage and

natural reconsolidation. Soil Science Society of America Journal,

62, 1228–1233.

Ahuja, L.R., Ma, L. & Timlin, D.J. 2006. Trans-disciplinary Soil

Physics research critical to synthesis and modelling of agricultural

systems. Soil Science Society of America Journal, 70, 311–326.

Alameda, D. & Villar, R. 2009. Moderate soil compaction:

implications on growth and architecture in seedlings of 17 woody

plant species. Soil & Tillage Research, 103, 325–331.

Alletto, L. & Coquet, Y. 2009. Temporal and spatial variability of

soil bulk density and near-saturated hydraulic conductivity under

two contrasted tillage management systems. Geoderma, 152, 85–94.

Beutler, A.N., Freddi, O.S., Leone, C.L. & Centurion, J.F. 2008.

Densidade do solo relativa e parametro ‘‘S’’ como indicadores da

qualidade fısica para culturas anuais. Revista de Biologia e

Ciencias da Terra, 8, 27–36.

Carsel, R.F. & Parrish, R.S. 1988. Developing joint probability

distributions of soil water retention characteristics. Water

Resources Research, 24, 755–769.

Carter, M.R. 1988. Temporal variability of soil macroporosity in a

fine sandy loam under mouldboard ploughing and direct drilling.

Soil & Tillage Research, 12, 37–51.

Cassel, D.K. 1983. Spatial and temporal variability of soil physical

properties following tillage of Norfolk loamy sand. Soil Science

Society of America Journal, 47, 196–201.

Debiasi, H., Levien, R., Trein, C.R., Conte, O. & Mazurana, M.

2008. Capacidade de suporte e compressibilidade de um

argissolo, influenciadas pelo trafego e por plantas de

cobertura de inverno. Revista Brasileira de Ciencia do Solo, 32,

2629–2637.

Denef, K., Six, J., Bossuyt, H., Frey, S.D., Elliott, E.T., Merckx, R.

& Paustian, K. 2001. Influence of dry-wet cycles on the

interrelationship between aggregate, particulate organic matter,

and microbial community dynamics. Soil Biology and

Biochemistry, 33, 1599–1611.

Dexter, A.R. 2004. Soil physical quality: Part I. Theory, effects of

soil texture, density, and organic matter, and effects on root

growth. Geoderma, 120, 201–214.

Emdad, M.R., Raine, S.R., Smith, R.J. & Fardad, H. 2004. Effect

of water quality on soil structure and infiltration under furrow

irrigation. Irrigation Science, 23, 55–60.

van Es, H.M., Ogden, C.B., Hill, R.L., Schindelbeck, R.R. &

Tsegaye, T. 1999. Integrated assessment of space, time, and

management-related variability of soil hydraulic properties. Soil

Science Society of America Journal, 63, 1599–1608.

Flores, C.A., Reinert, D.J., Reichert, J.M., Albuquerque, J.A. &

Pauletto, E.A. 2008. Recuperacao da qualidade estrutural, pelo

sistema plantio direto, de um Argissolo Vermelho. Ciencia Rural,

38, 2164–2172.

Gale, W.J., Cambardella, C.A. & Bailey, T.B. 2000. Root-derived

carbon and the formation and stabilization of aggregates. Soil

Science Society of America Journal, 64, 201–207.

van Genuchten, M.T. 1980. A closed-form equation for predicting

the hydraulic conductivity of unsaturated soils. Soil Science

Society of America Journal, 44, 892–897.

Hanson, B. & May, D. 2004. Effect of subsurface drip irrigation on

processing tomato yield, water table depth, soil salinity, and

profitability. Agricultural Water Management, 68, 1–17.

Hillel, D. 2004. Introduction to environmental soil physics. Elsevier

Academic Press, New York.

Horn, R. & Baumgartl, T. 2002. Dynamic properties of soils. In:

Soil physics companion (ed. A.W. Warrick), pp. 17–48. CRC Press,

Boca Raton, FL.

Kemper, W.D. & Rosenau, R.C. 1984. Soil cohesion as affected by

time and water content. Soil Science Society of America Journal,

48, 1001–1006.

Kemper, W.D. & Rosenau, R.C. 1986. Aggregate stability and size

distribution. In: Methods of soil analysis, Part 1. Physical and

mineralogical methods (ed. A. Klute), pp. 425–442. Agronomy

Monograph no. 9. Society of Agronomy ⁄ Soil Science Society of

America, Madison, WI.

Kladivko, E.J. 2001. Tillage systems and soil ecology. Soil & Tillage

Research, 61, 61–76.

Kooistra, M.J., Schoonderbeek, D., Boone, F.R., Veen, B.W. & Van

Noordwijk, M. 1992. Root-soil contact of maize as measured by

thin-section technique. 2. Effects of soil compaction. Plant and

Soil, 139, 119–129.



Lal, R. & Shukla, M.K. 2004. Principles of soil physics. Marcel

Dekker, Inc., New York.

Leij, F.J., Ghezzehei, T.A. & Or, D. 2002. Analytical models for soil

pore-size distribution after tillage. Soil Science Society of America

Journal, 66, 1104–1114.

Logsdon, S.D., Jordahl, J. & Karlen, D.L. 1993. Tillage and crop

effects on ponded and tension infiltration rates. Soil & Tillage

Research, 28, 179–189.

Mapa, R.B., Green, R.E. & Santo, L. 1986. Temporal variability of

soil hydraulic properties with wetting and drying subsequent to

tillage. Soil Science Society of America Journal, 50, 1133–1138.

Moret, D. & Arrue, J.L. 2007. Dynamics of soil hydraulic properties

during fallow as affected by tillage. Soil & Tillage Research, 96,

103–113.

Mubarak, I., Mailhol, J.C., Angulo-Jaramillo, R., Ruelle, P., Boivin,

P. & Khaledian, M. 2009a. Temporal variability in soil hydraulic

properties under drip irrigation. Geoderma, 150, 158–165.

Mubarak, I., Mailhol, J.C., Angulo-Jaramillo, R., Bouarfa, S. &

Ruelle, P. 2009b. Effect of temporal variability in soil hydraulic

properties on simulated water transfer under high-frequency drip

irrigation. Agricultural Water Management, 96, 1547–1559.

Neufeldt, H., Ayarza, M.A., Resck, D.V.S. & Zech, W. 1999.

Distribution of water-stable aggregates and aggregating agents in

Cerrado Oxisols. Geoderma, 93, 85–99.

Onofiok, O.E. 1988. Spatial and temporal variability of some soil

physical properties following tillage of a Nigerian Paleustult. Soil

& Tillage Research, 12, 285–298.

Reichert, J.M., Kaiser, D.R., Reinert, D.J. & Riquelme, U.F.B.

2009. Variacao temporal de propriedades fısicas do solo e

crescimento radicular de feijoeiro em quatro sistemas de manejo.

Pesquisa Agropecuaria Brasileira, 44, 310–319.

Reisser Junior, C., Timm, L.C., Tavares, V.E.Q., Estrela, C.C.,

Aquino, L.S., Furtado, L.G. & Philipsen, L.C. 2008. Manejo da

irrigacao do morangueiro no municıpio de Turucu-RS. In:

Proceedings of the XVIII Brazilian Congress of Irrigation and

Drainage, 27 July – 1 August 2008, (eds H.M. Saturnino, A.A.

Soares & J.G.F. Silva), Sao Mateus, Brazil. ABID 1, pp. 1–6.

Reynolds, W.D., Drury, C.F., Yang, X.M., Fox, C.A., Tan, C.S. &

Zhang, T.Q. 2007. Land management effects on the near-surface

physical quality of a clay loam soil. Soil & Tillage Research, 96,

316–330.

Reynolds, W.D., Drury, C.F., Tan, C.S., Fox, C.A. & Yang, X.M.

2009. Use of indicators and pore volume-function characteristics

to quantify soil physical quality. Geoderma, 152, 252–263.

Selim, E.M., Mosa, A.A. & El-Ghamry, A.M. 2009. Evaluation of

humic substances fertigation through surface and subsurface drip

irrigation systems on potato grown under Egyptian sandy soil

conditions. Agricultural Water Management, 96, 1218–1222.

Semmel, H., Horn, R., Hell, U., Dexter, A.R. & Schulze, E.D. 1990.

The dynamics of soil aggregate formation and the effect on soil

physical properties. Soil Technology, 3, 113–129.

Shainberg, I. & Letey, G.J. 1984. Response of soils to sodic and

saline conditions. Hilgardia, 52, 1–57.

Six, J., Bossuyt, H., Degryze, S. & Denef, K. 2004. A history of

research on the link between (micro) aggregates, soil biota, and

soil organic matter dynamics. Soil & Tillage Research, 79, 7–31.

Soil Survey Staff. 2006. Keys to Soil Taxonomy, 10th ed. USDA-

Natural Resources Conservation Service, Washington, DC.

Souza, C.F., Folegatti, M.V. & Or, D. 2009. Distribution and

storage characterization of soil solution for drip irrigation.

Irrigation Science, 27, 277–288.

Streck, C.A., Reinert, D.J., Reichert, J.M. & Horn, R. 2008. Relacoes

do Parametro S para algumas propriedades fısicas de solos do sul

do Brasil. Revista Brasileira de Ciencia do Solo, 32, 2603–2612.

Strudley, M.W., Green, T.R. & Ascough, J.C. 2008. Tillage effects

on soil hydraulic properties in space and time: state of the science.

Soil & Tillage Research, 99, 4–48.

Tisdall, J.M. & Oades, J.M. 1982. Organic matter and water-stable

aggregates in soils. Soil Science, 62, 141–163.

Topp, G.C., Reynolds, W.D., Cook, F.J., Kirby, J.M. & Carter,

M.R. 1997. Physical attributes of soil quality. In: Soil quality for

crop production and ecosystem health. Developments in Soil Science,

vol. 25 (eds E.G. Gregorich & M.R. Carter), Elsevier, Amsterdam.

Yoder, R.A. 1936. A direct method of aggregate analysis of soil and

a study of the physical nature of erosion losses. Journal of the

American Society of Agronomy, 28, 337–351.

Young, I.M. 1998. Biophysical interactions at the root-soil interface:

a review. Journal of Agricultural Science, 130, 1–7.



temporal changes of soil physical and hydraulic properties in strawberry fields

Documents