Assessing arable plants richness during 3 years in no-till and till

fields

Plan Nacional I+D+i AGL2007-60828

J. Torra1, A. Juárez2, A. Royo-Esnal2, X. Solé-Senan2, J.A. Conesa2 & J. Recasens2

1Fundació Centre UdL-IRTA; 2Dpt. d’Hortofructicultura, Botànica i Jardineria. ETSEA. Universitat de Lleida. Alcalde Rovira Roure 19. 25198, Lleida.

IntroductionWinter cereal fields of the Ebro valley provide habitats that present high biological diversity.

Tetrax tetrax

This diversity has considerably been reduced due to monoculture and different management intensification (manure, chemicals, suppressing field boundaries...).

Coracias garrulus

Among the agri-environmental schemes in the semiarid arable lands in NE Spain, Conservation Agriculture (CA) techniques are included in protected Important Bird Areas (IBA ).

CA techniques provide important benefits in these semiarid areas, such as water preservation, organic matter increase and decrease of erosion.

Biodiversity (including weed diversity) has been reported to gain benefit because of the CA implementation (Murphy et al., 2006; Field et al., 2007; Cantero-Martínez et al., 2007).

Moreover, lack of soil disturbance implies a greater dependence on herbicide application.

But, among the CA techniques, direct drilling (DD) has also been reported as not affecting weed diversity (Légère et al., 2005; Hernández-Plaza et al., 2011), or even having a detrimental effect (Bilalis et al., 2001)

The IBA of Bellmunt-Almenara is a 15 km long by 3 km wide area, 30 km north-east from Lleida (Catalonia).

Management programme by REGSEGA (june 2005-june 2010): evaluation of effects and improvements of an steppe area with application of CA measures (direct drilling -DD-, stubble, straw, cereal varieties, field margins…)

This IBA area presents steppe climate, with high environmental value.

MEDIDAS AGRONOMICAS DE CONSERVACION en Zonas de Especial protección para las aves. (ZEPAs Sierra Bellmunt-Almenara y Llanos de Balaguer) (2005-2010)

Objectives

The main objectives of this study were to:

1. State the relevance of field margins for the preservation of weed flora.

2. Verify the richness of weed flora in DD fields compared to those with conventional management (CM).

3. Clear up if the implementation of DD involves changes on the weed flora.

Material and MethodsThree years, 2007, 2009 and 2010; 28 pairs of DD-CM fields.

Four surveys of 10 x 3 m2 per field, two in the margins and two in the center, separated by 30 m; Presence / Absence (richness).

Herbicides treatments / Season Dose Application time

2006-2007

Glifosate 180 – 230 ? /ha beginning of November 2006

Tralkoxydim+ bromoxynil + ioxynil + mecoprop-p

1.5 l/ha + 1.5 l/ha End February 2007

2008-2009

Glifosate 2 l/ha mid November 2008

Tralkoxydim+ bromoxynil + ioxynil + mecoprop-p

1.5 l/ha + 1.5 l/ha End April 2009

Glifosate 2 l/ha End April 2009

2009-2010

Glifosate 1.5 l/ha Mid November 2009

Tralkoxydim+ bromoxynil + ioxynil + mecoprop-p

1.5 l/ha + 1.25 l/ha

Beginning of April 2010

Iodosulfuron + mesosulfuron 500 gr/ha Beginning of March 2010

Herbicides treatments (active ingredients, dose and application time) in direct drillingfields during three seasons. No data available for conventional tilled fields.

• Multivariate analysis: ordination analysis with a Detrented Correspondence Analysis(DCA).

• Variance partitioning was performed with a CCA for the factors year, management (direct drilling or conventional tillage) and field position (margin or centre)

• The scores from CCA were used to identify the species with the highest relationship to the factors management and field position.

Statistical analysis (for species with more than four presences):

Results

Year DD C

M I M I

2007 5.1 2.5 4.4 2.4

2009 11.8 8.4 8.2 4.7

2010 7.8 2.0 9.3 3.4

Richness (mean number of species per field) for margins in direct drilling (DDM),field centre in direct drilling (DDI), margin of conventional field (CM) andcentre of conventional fields (CI) in 2007, 2009 and 2010.

Results

CSD

• DCA: 9.2 % of the variance explained by the first two axis

ResultsSpecies with the highest fit in the CCA to the factors management (DD: direct drilling,C: conventional tillage) and field position (M: field margin, I: field centre).

CCA explained 21.2% of the variance of DCA: 11.3% year, 4.7% management 4.5% field position

In this three-years study, the factor year has been more decisive than the soil management or field position.

Thus, in the factor year two aspects can be considered key for the weed diversity:

- climatic conditions for each year- herbicide management each year

No clear relation between type of soil management and specific flora.

2007 2009 2010

Arable flora 15 37 26

Rare arable flora 4 17 9

Soil management

Arable flora C > DD DD > C C ≥ DD

Rare arable flora ≈ DD ≈

Presence and abundance of arable species across years and type of soil management. DD: direct drilling; C: conventional tillage.

Linaria micrantha Roemeria hybrida

Fumaria mirabilisConsolida pubescens

Adonis flammea

Conclusions

Data demonstrate the high value of cereal field margins as a refugee of weed flora in Mediterranean semiarid landscapes.

Conservation strategies should focus on field margins, wether they are DD or C fields.

There may not be such high differences on the richness between DD and C fields, as they depend principally on year characteristics (weather and chemical management).

Changes on the weed flora in function of the soil managements have been observed but need further research.

Thank you very much

Assessing arable plants richness during 3 years in no-till and till

fields

Plan Nacional I+D+i AGL2007-60828

J. Torra1, A. Juárez2, A. Royo-Esnal2, X. Solé-Senan2, J.A. Conesa2 & J. Recasens2

1Fundació Centre UdL-IRTA; 2Dpt. d’Hortofructicultura, Botànica i Jardineria. ETSEA. Universitat de Lleida. Alcalde Rovira Roure 19. 25198, Lleida.