Weed infestation during the transition phase from …...weed management Despite conservation agriculture and, overall, the reduction of soil disturbance are considered soil improving

Felice Sartori1, Donato Loddo2, Ilaria Piccoli1, and Antonio Berti1

1) DAFNAE Dept, Padova University, Legnaro (PD), Italy

2) IPSP, CNR, Legnaro (PD), Italy

Corresponding author: [email protected]

EGU2020: Sharing Geoscience Online - SSS8.8 Ecosystem development and critical zone research: Experimental

ecosystem development research and coevolution of soils, landforms and vegetation1

Weed infestation during the transition phase from conventional to

conservation agriculture

© Sartori et al. All rights reserved

mailto:[email protected]


Conservation agriculture and weed management

Despite conservation agriculture and,overall, the reduction of soil disturbanceare considered soil improving croppingsystems, these practices could conflictwith weed control. Indeed, reducedtillage is usually linked to increasedweed species richness and abundanceand, thus, it could increase thedependence on chemical treatments.Weed management is one of thereasons behind the distrust of Europeanfarmers in the conservation agriculture,that is still not widespread, despitesEuropean subsidies. In fact, conservationagriculture is implemented only in the2.8% of European cropland.

Conservation agriculture

Dependence on chemical treatments

So

il im

pro

vin

g

cro

pp

ing

syst

em

Weed

man

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Sustainability

Distrust

EGU2020: Sharing Geoscience Online - SSS8.8 Ecosystem development and critical zone research: Experimental ecosystem development research and coevolution of soils, landforms and vegetation

2

Introduction


Aim of the study

The aim of this study is to evaluate theeffect of different tillage intensities onspring-summer weeds richness andabundance in a maize monoculture,during the transition phase fromconventional to conservation agriculture.

Weed

richness and

abundance

Effect of soil

tillage

Maize

monoculture

Diversity

indices

Conservation

agriculture

transition

phase


3

Introduction


The weed survey was conducted in June2019 on an experiment comparing threelevels of tillage management:conventional agriculture (CT), whichrepresents the most common choice inVeneto region, involving deep ploughingand harrowing in spring; minimumtillage (MT), consisting only in harrowingat 20 cm; and no tillage (NT), namelysod seeding. The experiment started in2018, at Padova University experimentalfarm, in a sub-humid area, with a siltyclay loam soil.

•Conventional

tillage

•Spring

ploughing (30

cm)

•Harrowing

(20 cm)

CT

•Minimum

tillage

•Spring

harrowing (20

cm)

MT

•No tillage

•Conservation

agriculture

NT

Field operations

• 28/03/2019 → Tillage

• 02/04/2019 → Maize seeding

• 03/06/2019 → Weed scouting

Experimental design


4

Treatments (Factors)

Materials and methods


The weed survey

• The frame random throws technique is the same described in Berti et al., 1992 Weed Research (doi.org/10.1111/j.1365-3180.1992.tb01860.x)

The survey was conducted with a set ofrandom throws of a 30×30 cm squareframe in each plot (ca. 3300 m2). Weedplants found within the frame wereclassified and counted. Subsequently,data analysis assessed which botanicalfamilies were promoted by eachtreatment.

Random throws

• 6 random sampling

point per plot

• 3 replications

Weed

observation

• Species

determination

• Count of the

individuals

Statistical

analyses

• Conversion in n° of

individuals per m2

• Indices calculation


5

Materials and methods

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3180.1992.tb01860.x


Weed richness and abundance

The NT resulted the treatment with thehighest weed density (915 plant/m2): 6%higher than MT (823 plant/m2) and four-fold more than CT (209 plant/m2). Thelatter showed to be the treatment withhigher diversity, according to bothShannon and Simpson indices. Thesurvey evidenced higher weed speciesrichness in MT, where both annual andperennial species were identified, whilethe lowest number of species weredetected in NT.


6

2326

15

0

10

20

30

CT MT NT

Species abundance

207

821915

0

500

1000

CT MT NT

Weed richness (plant/m2)

Shannon indexGini-Simpson

indexEvenness

CT 2.64 0.91 0.58

MT 1.22 0.43 0.25

NT 0.67 0.26 0.17

Results


Dominant species

Plantago major and Chenopodiumalbum were the species with the highestdensity in CT (>32 plant/m2) while theyare negligible in NT and MT (7 plant/m2,on average). Digitaria sanguinalis wasinstead the dominant species in MT andNT (>600 plant/m2) while a lowerdensity was observed in CT (11plant/m2). Low levels of Asteraceaeweeds were measured in all treatments.


7

783 59 28 10 540

50

100

150

33 32 26 24

124

0

50

100

150

616 35 34 33 1430

50

100

150

NT

MTCT

Asterceae

n° Species plant/m2

CT 5 22

MT 5 43

NT 3 15

Results


Actual flora differences

These results show that the actual florarapidly changes depending on tillageintensity, with an increase of bothdominance and number of species inMT. Differently, only a limited number ofadapted species germinated in NT,despite higher infestations if comparedwith the other treatments.


8

CT

MT

NT

Average weed density (plant/m2) in each treatment (Digitaria sanguinalis

excluded). The number indicates the average density between

treatments.

Discussion


Main findings

It should be expected that other speciesmore adapted to conservationagriculture (namely Asteraceae), stillmarginally present in the seed bank, willspread in the next years. This stressesthe importance of a continuousmonitoring and effective control ofweeds to avoid uncontrolled evolutionsof the weed flora and increase of seedbank in the transition phase fromconventional to conservation agriculture.


9

No significant increase of Asteraceae was observed after 2 years

Selection of adapted species in NT

Dominance of a D. sanguinalis in reduced tillage systems (MT and NT)

Conclusions



10

Thanks for your attention


Supplementary material – diversity indices


11

Shannon index (H) Gini-Simpson index (ത𝛌) Evenness (J)

𝐻 = −

𝑖=0

𝑆

ln 𝑝𝑖𝑝𝑖 ҧ𝜆 = 1 −

𝑖=0

𝑆

𝑝𝑖2 𝐽 = ൗ𝐻 log2 𝑆

p: proportion of individuals belonging to the ith speciesS: total number of species (richness)

Documents

Weed infestation during the transition phase from …...weed management Despite conservation agriculture and, overall, the reduction of soil disturbance are considered soil improving