European Geosciences Union-General Assembly 2013
Impact of climate change on water balance components in Mediterranean rainfed olive orchards under tillage or cover crop soil management Rodríguez-Carretero,
Institute for Sustainable Agriculture
1
1 M.T. ,
Lorite,
The complexity of water balance in a system that incorporates bare soil (by tillage or herbicide) and partial ground cover (by the olive trees) indicates the need of model analysis to fully characterize this system for different soil, climate, orchard configuration and soil management (Abazi et al., 2013). Even in recent years these systems become more complex with the use of a cover crop in part of the bare area to protect the soil against water erosion (Gómez 2009). This communication presents a preliminary study of different kind of olive orchards in Andalusia under future climate change scenarios.
Materials and Methods A water balance for olive orchards, WABOL ( Water Balance in Olive, Abazi et al. 2013) was used in this study. This model allows simulation the water balance in the soil under different types of soil, management strategies and climatic conditions.
The study was focused on four areas representative of olive cultivation in Andalusia : Archidona, Baena, Córdoba and Mancha Real, considering different climatic and soil conditions and orchard characteristics. These characteristics are depicted in Table 1. Simulations considered the two most common soil management: bare soil using tillage, and cover crop grown in winter and mowed in early spring, April 1st, as Gómez (2009) recommended to prevent competition for soil water with the tree. Slope (%)
24
Soil depth (m) 1.2
21
1.2
12
100
25
5.5
1.40
3
1.4
11
138
29
5
1.44
4
1.2
12
100
18
4.5
1.48
14
Tree density Olive ground Canopy Diameter Leaf Area (tree ha-1) cover (%) (m) Density (m2 m-3 ) 69 13 5 1.44
Table 1: Summary of the properties of the orchards simulated.
Average Runoff (mm)
Past M1 Tillage
Past M2 Cover Crop
Future M1 Tillage
Future M2 Cover Crop
120
102.3 100
80.1
Past M1 Tillage
Past M2 Cover Crop
Future M1 Tillage
Future M2 Cover Crop
140
80
59.8
56.0
60
37.1 25.5
28.2
24.6
31.4
58.0
60 19.7
16.5
20
98.9 84.9
78.1
80
40.1
112.6
97.2
100
53.4
46.7 40
119.3
120
65.4
64.7
93.3
86.0 74.0
66.4 51.0
66.1 48.8
48.7 36.8
40 20 0
0
ARCHIDONA Average Soil Evaporation (mm) 300 279.3
BAENA Past M1 Tillage
CÓRDOBA Past M2 Cover Crop
Future M1 Tillage
Future M2 Cover Crop
310.5
250.8 233.0 201.2
200
280.5
277
264.4
250
MANCHA REAL
231.4 218.8 189.9
242.7 228.1
ARCHIDONA Average Percolation 120 (mm) 107.7
252.8 225.6
199.0
100
Past M1 Tillage
BAENA Past M2 Cover Crop
CÓRDOBA Future M1 Tillage
MANCHA REAL Future M2 Cover Crop
98.6
80 69.2 60.3
150
60
56.6 48.5
44.7 36.6
40
50
20
0
Taking into account the four climate change models previously analyzed and contrasted, a reduction around 21% in rainfall and increases around 13% in ETo and around 3.5ºC in average temperature are foreseen as the Table 2 shows.
Average Olive Transpiration 200 (mm) 180
160
32.5 25.8 21.1 15.2
33.1 23.5
20.0
14.6
0 ARCHIDONA
BAENA
CÓRDOBA
MANCHA REAL
ARCHIDONA
BAENA
CÓRDOBA
MANCHA REAL
Table 2: Variations in average rainfall, ETo and temperatures. In brackets, coefficient of variation (0-1).
Figure 3: Summary of the water balance component predictions. Predictions indicate that the decrease in rainfall combined with the increase in ETo will result in decreases in runoff (around 10% for all management and locations considered), as well as in olive transpiration (around 15%) and percolation (around 25%), with a huge variability among stations (Fig. 3). They suggest that the use of a well implanted cover crop instead of tillage management, produces a strong reduction of runoff (around 55% comparing both managements in the same period, past and future) and contributes to increase olive transpiration (around 30% comparing both managements in the same period, past and future). The difference in these variations is similar for the four climate change models considered.
Figure 2 depicts the average annual values of rainfall, ETo and temperature referred to the control and future periods for the four study areas using a specific climate scenario developed by the Centre for Climate Prediction and Research (Hc HadCM3Q0). It can be appreciated a general trend based on a reduction of rainfall, and increases of ETo and temperature.
In addition to soil conservation benefits, transition from a tilled into a cover crop soil management might mitigate the decrease in olive transpiration under expected climate scenarios. This is dependent on the assumptions assumed in this study, good implantation and management of the cover to enhance infiltration and also killing in early spring. Research to properly established a cover crop is required since it remains challenging in some conditions.
.
Rainfall (%)
ETo (%)
Tmax (°C)
Tmin (°C)
Tmed (°C)
ARCHIDONA
22.08 (-0.17)
14.45(0.30)
5.3 (0.38)
2.3 (0.11)
3.9 (0.23)
BAENA
21.75 (-0.20)
10.77(0.18)
3.7 (0.20)
2.1 (0.04)
3.3 (0.17)
CÓRDOBA
20.98 (-0.23)
9.87(0.20)
3.6 (0.20)
2.4 (0.09)
3.3 (0.18)
MANCHA REAL
21.97 (0.14)
15.2(0.35)
5.4( 0.40)
2.1 (0.20)
3.9 (0.24)
21.695
12.5725
4.5
2.225
3.6
Rainfall Future (mm)
Eto Past (mm)
Eto Future (mm)
1478.8
(mm)
Average Rainfall (mm), Eto (mm) and Temperature (°C)
Figure 1: View of olive orchards with cover crop and tillage soil management.
clay loam Baena clay loam Cordoba clay loam Mancha Real clay
Gómez,
Results
Rainfall Past (mm)
Archidona
Dosio,
4 J.A.
100
AVERAGE VALUES
Stone (%)
Ruiz-Ramos,
3 A. ,
To determine the impact of climate change on water balance components, two climate periods were considered for comparison. One as control period (from 1971 to 2001) and another as future period (from 2068 to 2098). Climate data corresponding to control and future periods were provided by different climate scenarios developed by different European research groups (C4l HadCMQ16, CNRM ARPEGE, ETHZ and Hc HadCM3Q0). Reference evapotranspiration (ETo) values were calculated using Hargreaves equation (Allen et al. 1990). By means of these climate models were possible to determinate the uncertainty of the results obtained.
Olive orchards in Southern Spain constitute one of the main socioeconomic system of its Mediterranean agriculture. Despite recent advances in deficit irrigation in this crop, still more than 1 Mha of olive trees are rainfed. This suggests that this system has a high sensitivity to changes in temperature and precipitation, and then the interest in performing an preliminary analysis about the impact of climate change predictions on olive orchards in Andalusia.
Text. Class
2 M. ,
IFAPA-Centro Alameda del Obispo, Natural Resources Department, Córdoba, Spain 2 3 4 Instituto de Agricultura Sostenible (IAS-CSIC), Cordoba, Spain
[email protected]
Introduction
Area
1 I.J. ,
1350.2
1400
Tmed Past (mm)
Tmed Future (mm)
1573.4
1422.3
1444.6
(°C) 25
1326.1 1249.8
21.6
1183.0 1200
20
19.3 18.4
18.5
18.3 1000
16.2 14.71
14.7
15
800 603.5 600 476.3
408.2
10
527.5
506.3
487.5
435.9
409.5
400 5 200
0
0
ARCHIDONA
BAENA
CÓRDOBA
MANCHA REAL
Figure 2: Average annual values or rainfall, ETo and temperature These results indicate that expected climate will be more adverse for rainfed olive orchards in Southern Spain since rainfall will be reduced while the water demand of the atmosphere, ETo, will increases significantly. However, understanding the interactions for the different components of the water balance further analyses are required. Figure 3 summarizes the results of the water balance simulations carried out to study the expected evolution of the water balance components under different climate scenarios for rainfed olive orchards in Southern Spain under different soil managements, tillage and cover crop.
Conclusions Climate scenarios suggests as probable an average decrease of 21% in rainfall and increase of 13% in ETo for the period 2068-2098 in olive growing locations in Southern Spain. Model analysis suggests that a properly managed cover crop (in terms of implantation and killing dates) can be improve water balance and olive transpiration under current and future scenarios, and then provide an strategy to mitigate the expected decrease in olive transpiration under future climate scenarios. References U. Abazi, I.J. Lorite, B. Cárceles, A. Martínez Raya, V.H. Durán, J.R. Francia, J.A. Gómez 2013. WABOL: A conceptual water balance model for analyzing rainfall water use in olive orchards under different soil and cover crop management strategies. Computers and Electronics in Agriculture 91: 35 – 48. Gómez, J.A., 2009. Ed. Sostenibilidad de la producción de olivar en Andalucía. Consejería de Agricultura y Pesca. Junta de Andalucía. Sevilla. Allen et al., 1990. Software Reference Evapotranspiration Calculator. Acknowledgments To projects P08-AGR-03643 and P10EXC10-0036/AGR6126 (Andalusian Government), AGL2009-12936-C03-01 (Spanish Ministry of Science and Innovation), and FEDER funds (Spanish Ministry for Agriculture, Food and the Environment) for its support ..
