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STILL 3726 No. of Pages 9

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Contents lists available at ScienceDirect

Soil & Tillage Research

journa l homepage: www.elsevier.com/locate/still

Platy structure development under no-tillage in the northern humid

Pampas of and its impact on runoff

a, d c a

María Carolina Sasal *, Hubert Boizard , Adrián E. Andriulo , Marcelo G. Wilson , b

Joël Léonard

a

INTA EEA Paraná, Ruta 11, km 12.5 (3101), Oro Verde, Entre Rios, Argentina

b

INRA, UPR 1158 AgroImpact, site de Laon, F-02000 Barenton-Bugny, France

c

INTA EEA Pergamino, Ruta 32 km 5.5 (2700) , Argentina

d

INRA, UPR 1158 AgroImpact, site d’Estrées-Mons, F-80203 Péronne, France

A R T I C L E I N F O A B S T R A C T

Article history:

Received 28 January 2016 The no-tillage system (NT) is widespread in the silty soils of the Argentine Humid . The aims of

Received in revised form 17 August 2016 this study were i) to characterize the evolution of the structure of the A horizon in the northern Humid

Accepted 19 August 2016

Pampas due to conversion to NT, particularly the presence of platy structure and its development through

Available online xxx

time, by taking advantage of a chronosequence since conversion to NT; and ii) to evaluate how platy

structure extension in the A horizon relates to characteristics of the crop sequences and runoff in a long-

Keywords:

term experiment. Thus, the structure of the A horizon of 25 Argiudolls with different NT history was

Platy structure

analyzed using a visual structure evaluation (VSE) method (“le profil cultural”). Fourteen natural-rainfall

No-tillage

erosion plots with 3.5% slope were used to analyze the relationship between the soil structural state, the

Runoff

crop sequence and runoff. The VSE method allowed us to understand the structure type organization of

silty soils under NT, highlight the regional extent of a platy structure near the soil surface, and study its

evolution and impact on runoff. All the sites analyzed exhibited a horizontal platy structure (2–10 cm

thick), mainly developing on the soil surface or right under the granular structure on the soil surface.

Under the platy structure, a cF structure was observed in all the sites (30–75% of the A horizon). A

relationship was found between the number of consecutive years under NT and the proportion of platy

structure. This evolution may result from the combination of an initial development of the platy structure

and a late development of a cΓ structure from the soil surface. The results obtained during the five-year

period analyzed allowed us to prove that platy structure alters the drainage pattern, restricts water entry

into the soil and favors surface runoff according to its proportion in the profile of A horizon.

ã 2016 Elsevier B.V. All rights reserved.

1. Introduction , where udic water and thermal temperature regimes

prevail. The most representative soil, and by far the most common

Argentina is among the countries with the largest cropped area in the northern Humid Pampas, is the Typic Argiudoll (Hall et al.,

with continuous cropping under no-till systems (NT). Over the last 1992), with high silt content in the A horizon. In this type of soil,

decades, large changes have taken place in crop sequence the absence of tillage can lead to the formation of massive

composition, toward the disappearance of pastures and the rapid structures (Senigagliesi and y Ferrari, 1993). Generally, soybean

expansion of soybean monoculture (Caride et al., 2012; Wingeyer monocultures under NT, which are harvested during the wettest

et al., 2015). Currently, 19 million hectares of soybean are annually period of the year, are sparsely covered by crop residues and have

sown in Argentina, mainly under NT. poor distribution of the root system, long fallow periods and

The most frequent arable soils of the Humid Pampean region non-controlled traffic, all of which contribute to soil compaction

are developed from deep eolian sediments under (Alvarez et al., 2014).

There are specific field observations of a platy soil (P) structure,

with thin and flat fragments oriented parallel to the soil surface,

occurring in the first centimeters of soil in some experiments

* Corresponding author.

E-mail addresses: [email protected], [email protected] (M.C. Sasal). under NT in the Pampas region (Bonel et al., 2005; Sasal et al.,

http://dx.doi.org/10.1016/j.still.2016.08.014

0167-1987/ã 2016 Elsevier B.V. All rights reserved.

Please cite this article in press as: M.C. Sasal, et al., Platy structure development under no-tillage in the northern humid Pampas of Argentina

and its impact on runoff, Soil Tillage Res. (2016), http://dx.doi.org/10.1016/j.still.2016.08.014

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STILL 3726 No. of Pages 9

2 M.C. Sasal et al. / Soil & Tillage Research xxx (2016) xxx–xxx

2006; Alvarez et al., 2009). Some authors have also reported 2. Materials and methods

continuous platy structure in silty soils under NT in other areas

(Pagliai et al., 1983; Shipitalo and Protz, 1987; Ball and Robertson, 2.1. Sampling locations to characterize the soil structure by using a VSE

1994; Boizard et al., 2013). In long-term experiments carried out in and its relation with the cropping system

Pergamino, in the center of the Pampas, this platy structure

restricts the water infiltration rate into the soil profile (Sasal et al., The region of the northern Humid Pampas covers about

2

2006). 165,000 km and is located between 31 and 35 S and 58 and

The negative impact of massive or compacted soil structure on 63 W (Fig. 1). It has an undulating surface with 0.5–3% slopes. The

water movement, crop development and yields has been region has a subhumid and temperate climate with annual rainfall

extensively studied (Lipiec et al., 1991; Oussible et al., 1992; Soane of 1000 mm. Approximately 75% of the precipitations occur in

and van Ouwerkerk, 1995; Arvidsson and Hakansson, 1996). spring and summer. Winter temperatures are rarely below 0 C and

Nevertheless, the evolution of this massive structure and the summers are warm (Hall et al., 1992). Between 50 and 75% of the

description of other types of soil structure under NT are land of the region is used for grain cropping. The main crops in the

considerably less studied. region are soybean Glycine max L.- (S), maize Zea mays L.- (M)

This region has had a trend of increased heavy summer and wheat Triticum aestivum- (W). The latter is always used in

precipitation since the late 1990s (Magrin et al., 2005; Re and double crop with soybean (W/S). The relative homogeneity of the

Barros, 2009). The more frequent occurrence of intense rainfalls, soil and climate conditions, together with the fact that NT has been

the very long slopes (>500 m) despite the relatively low gradient, implemented over different durations, makes this region a very

the silty texture of the A horizon, and the low permeability of the appropriate zone to describe the natural long-term evolution of

B horizon of the Argiudolls (Senigagliesi and y Ferrari, 1993) are the soil structure since the adoption of NT. To describe the soil

important factors contributing to the runoff and erosion structure, we selected twenty-five sites in agricultural farms of the

processes observed in large-scale NT systems. Obtaining data region (Fig. 1), with the following characteristics:

on the evolution of the soil structure associated with changes in

crop management and its potential effect on infiltration and – fine, illitic, thermic Typic Argiudoll soil type (US Soil Taxonomy)

runoff will contribute to develop sustainable management or Luvic Phaeozem soil type (WRB), well drained and without

practices. significant erosion;

By taking advantage of a long chronosequence since the – continuous NT for at least three years, with mechanized seeding,

conversion of field locations to NT, our first objective was to assess harvesting and spraying, and only herbicides for weed control;

the presence of P structure in the A horizon of the northern Humid – availability of detailed information on crop rotation and soil

Pampas, particularly its relation to continuous cropping under NT management.

through a survey. Our second objective was to evaluate how platy

structure extension in the A horizon relates to crop sequences and Data from eight of the selected sites have already been

runoff in a long-term experiment. Our hypotheses were that platy published (De Battista et al., 1997; Gerster and Vidal, 1997;

structure extension increases significantly with time since Ferreras et al., 2000). Data from the other 17 sites were collected

conversion to NT and strongly enhances runoff and erosion risks between 2008 and 2010. The texture of the A horizons (19–22 cm

1

in the northern Humid Pampas. depth) is in all cases of silty loam type, with 200–300 g kg clay

1

(<2 mm) and 600–660 g kg silt (2–50 mm). The argillic horizon

Fig. 1. Location of the study sites in the northern Humid Pampas (Google Earth).

Please cite this article in press as: M.C. Sasal, et al., Platy structure development under no-tillage in the northern humid Pampas of Argentina

and its impact on runoff, Soil Tillage Res. (2016), http://dx.doi.org/10.1016/j.still.2016.08.014