Basal crop coefficients for early-season peach trees

Agricultural Water Management 121 (2013) 158–163

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Basal crop coefficients for early-season peach trees I. Abrisqueta a , J.M. Abrisqueta a,b , L.M. Tapia c , J.P. Munguía d , W. Conejero a , J. Vera a,b , M.C. Ruiz-Sánchez a,b,∗ a

Dpto. Riego, Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), P.O. Box 164, 30100 Murcia, Spain Unidad Asociada al CSIC de Horticultura Sostenible en Zonas Áridas (UPCT-CEBAS), Paseo Alfonso XIII 48, 30203 Cartagena, Murcia, Spain Instituto Nacional de Investigaciones Forestales y Agropecuarias (INIFAP), Uruapan, Mexico d Centro de Investigación en Química Aplicada (CIQA-CONACYT) Saltillo, Coahuila, Mexico b c

a r t i c l e

i n f o

Article history: Received 7 September 2012 Accepted 2 February 2013 Keywords: Basal crop coefficient Drainage lysimeter Neutron probe Peach tree Soil evaporation coefficient Water use Water balance

a b s t r a c t A 4-year long experiment was conducted using drainage lysimeters to determine the basal crop coefficients of an early season drip irrigated peach tree cultivar growing in a clay loam textured soil in southern Spain. The lysimeters were equipped with irrigation and drainage water meters and access tubes for monitoring the soil water content by neutron probe. Crop evapotranspiration (ETc ) was obtained from the water balance equation. Following the dual crop coefficient approach, Kc was split into the basal crop coefficient (Kcb ) and the soil evaporation coefficient (Ke ). The effect of tree size on Kcb was determined for two canopy covers. The Kcb for full yield peach trees changed during the growing season gradually increasing from 0.15 at the beginning of the year (January) to a maximum of 1.0 during July, followed by a rapid fall to 0.15 at the end of year. The proposed curvilinear Kcb pattern fitted well with the phenological stages and their water use, and could serve for irrigation scheduling for early maturing peach trees growing in Mediterranean semi-arid climatic conditions. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Peach tree (Prunus persica (L.) Batsch) is the second most important fruit tree worldwide and the first stone fruit crop in Spain, with a cultivated area of 82,700 ha in 2010. The area dedicated to peach tree varieties with low cold requirements have increased in recent years, especially in southern regions. The Region of Murcia is one of the foremost growing regions in Europe, with a cultivated area of 13,800 ha, mostly under drip irrigation, representing 18% of the total Spanish production (www.magrama.gob.es). As the water supply becomes scarce and energy costs for irrigation increases in semi-arid Mediterranean areas, where agriculture accounts for the greatest part of water demand, it become increasingly necessary to precisely determine crop water use. There has been considerable research into the amount of water used by trees. Most of the water taken from the soil by plants is destined for evapotranspiration (ET), so that the measurement of actual crop evapotranspiration (ETc ) for the whole vegetative cycle corresponds to the crop water needs. Calculating reference crop evapotranspiration (ET0 ) and then adjusting by means of specific crop coefficients (Kc ) has been widely adopted for irrigation

∗ Corresponding author at: Dpto. Riego, CEBAS-CSIC, P.O. Box 164, 30100 Espinardo, Murcia, Spain. Tel.: +34 968 396320; fax: +34 968 396213. E-mail address: [email protected] (M.C. Ruiz-Sánchez). 0378-3774/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.agwat.2013.02.001

scheduling (Doorenbos and Pruitt, 1977; Wright, 1982; Allen et al., 1998, 2005; Allen and Pereira, 2009). The crop coefficient can be expressed as Kc = ETc /ET0 , and the main factors affecting this relation are (i) crop height and architecture, both of which influence the aerodynamic resistance and turbulent vapour transfer from the crop into the atmosphere, (ii) canopy resistance, which determines the transfer of vapour through the stomata, thus depending on leaf number, age, position and stomatal control, (iii) albedo, which determines the net radiation of the surface, and (iv) soil surface evaporation (Allen et al., 1998). In the dual crop coefficient approach (Wright, 1982; Allen et al., 1998), Kc can be splitting into two separate coefficients: the basal crop coefficient (Kcb ) which represents the transpiration of the crop, and the soil water evaporation coefficient (Ke ). The single coefficient Kc is replaced by Kcb + Ke . The basal crop coefficient, Kcb , is defined as the ratio between ETc and ET0 when soil water evaporation is zero and soil water availability remains non-limiting for plant transpiration and it is often assumed to include diffusion through a dry soil surface. As Kc includes the effects of evaporation from the soil surface after irrigation or rainfall, Kcb is less than or equal to Kc . Deciduous tree orchards with no cover crop do not begin to transpire until leaf out. Kcb increases rapidly during the rapid leaf development period until the mid season and is related to foliage development. Before leaf growth and after senescence, Kc is equal to bare soil evaporation and soil diffusion produced by

I. Abrisqueta et al. / Agricultural Water Management 121 (2013) 158–163 Table 1 Physical properties of the soil in the lysimeters. 0.205 ± 0.013 kg kg−1 0.502 ± 0.015 kg kg−1 0.293 ± 0.006 kg kg−1 Clay-loam 1560 kg m−3 0.31 m3 m−3 0.15 m3 m−3 0.36 m3 m−3

Sand Silt Clay Texture Bulk density Field capacity Wilting point Saturation

rainfall/irrigation events. As the canopy develops along the season Kcb increases while Ke decreases. Direct soil evaporation measurements have principally focused on the use of microlysimeters in bare soil or the soil beneath canopies (Ritchie and Johnson, 1990; Pac¸o et al., 2006, 2011; Sun et al., 2012). Alternative methods for the direct measurement of losses in soil water content through evaporation include capacitance or time domain reflectometry probes, which present the advantage of permitting continuous recording. Several studies using the water balance method with weighing and drainage lysimeters have produced widely varying crop coefficients for fruit trees (Miyamoto, 1983; Chalmers et al., 1992; Abrisqueta et al., 2001; Girona et al., 2011), including peach trees (Worthington et al., 1984; Mitchell et al., 1991; Johnson et al., 2000; Ayars et al., 2003). Several years are needed to collect sufficient data for good estimates (Castel et al., 1987; Allen et al., 2011). Furthermore, Kc should account for specific orchard conditions such as cultivar, orchard orientation, plant spacing, training system and soil management, among other factors. Poor water management due to low irrigation efficiency or inadequate irrigation scheduling can lead to the loss of water, resulting in higher costs and negative environmental impacts. In order to avoid the under- or overestimation of crop water consumption, knowledge of the exact water loss through evapotranspiration is necessary for sustainable development and environmentally sound water management, especially in areas like the Mediterranean region. For the present study drainage lysimeters were used to quantify the ETc for a drip irrigated early-season peach variety, and to develop basal crop coefficients to describe crop water use throughout the year. 2. Materials and methods 2.1. Site description and experimental design The work was conducted in 2007, 2008, 2009 and 2010 in a mature peach tree (P. persica (L.) Batsch, cv. Flordastar, on GF677 rootstock) orchard, located in the CEBAS-CSIC experimental station, in Santomera, Murcia, Spain (38◦ 06 31.2 N; 1◦ 02 13.7 W, 110 m altitude). The soil is highly calcareous, rocky and shallow with a clay-loam texture (Table 1) and classified as Lithic xeric haploxeroll (Soil Survey Staff, 2006). The soil has low organic

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matter content, cationic exchange capacity, and available potassium and phosphorus concentrations. The average soil bulk density was 1560 kg m−3 . The experimental plot occupied 0.8 ha and the tree spacing followed a 5 m × 5 m square pattern. The trees were planted in February 2002, and trained to an open vase system. The trees were commercially harvested beginning in 2004 and reached full yields in 2006. The effective fraction of soil surface shaded by the tree canopy (fc eff ) increased from 0.44 in 2007 to 0.79 in 2008/09/10 (Table 2). Average fruit yield during the experimental period was 45 kg tree−1 . Crop management (including pest control) was that commonly used in commercial orchards. The soil was kept free of weeds and was not tilled, and the peach trees were pruned annually during the dormancy period, hand-thinned in March, and harvested in the first week of May. Seasonal fertilizer applications were 180, 110, and 195 kg ha−1 of N, P2 O5 , and K2 O, respectively, applied through the drip irrigation water. The drip irrigation system consisted of a single lateral line per tree row, located close to the tree trunk, with 8 pressure compensating on-line drip emitters with 2 L h−1 discharge rates, spaced 0.5, 1.0, 1.5, and 2.0 m from each tree trunk. The irrigation water quality did not represent a risk to the soil structure stability or pose infiltration problems. The trees were irrigated in excess of the estimated crop evapotranspiration (120–140% of the ETc ) to ensure non-limiting soil water availability, as determined by daily reference crop evapotranspiration (ET0 ), calculated with the Penman–Monteith equation and a crop coefficient based on the time of year (Allen et al., 1998). Data for ET0 were obtained from a weather station located 70 m from the orchard over a grass reference surface. Irrigation was scheduled on a weekly basis according to the ET0 data for the previous week and evenly applied each night. Irrigation was controlled by a head unit controller operating an electro-hydraulic valve. The irrigation water volume applied was measured with a pulse volumetric water meter. The experimental plot had two drainage lysimeters (5 m × 5 m × 1.5 m deep) (Fig. 1), built in 2001, each containing one tree, which were planted in February 2002. The underground lysimeters were constructed of cement blocks covered with a thick metalized-plastic film. Plastic tubes were inserted at the bottom of each lysimeter to carry the drainage water, which discharged into an automatic tipping bucket gauge, connected to a telemetry system. Rainfall was also recorded in real-time using a rain gauge sited 2 m above the ground and connected to the automatic meteorological station. Prior to planting, the lysimeters were repacked with soil to obtain bulk densities similar to that of the surrounding field, for which reason the soil profile can be considered homogeneous. This lysimeter in question, according to Allen et al. (2011), is classified as a non-weighing, percolation-type lysimeter. In 2006, five neutron probe access tubes were installed in each lysimeter in a line perpendicular to the drip tubing 0, 0.5, 1, 1.5 and 2 m away from the second emitter from the tree trunk (positions 1, 2, 3, 4, and 5, respectively) (Fig. 1).

Table 2 Vegetative growth and phenological stages for Flordastar peach trees during the experimental period. Year

2007 2008 2009 2010 a

Vegetative growth

Phenological stages

Trunk diameter (m)

Canopy covera

Full bloom

Fruit Thinning

Harvest

0.12 0.14 0.16 0.18

0.44 0.78 0.80 0.79

February 12 January 30 January, 29 February 15

March 4–11 March 14–19 March 20–24 March 21–28

May 7 April 30 May 6–11 May 13–21

Effective fraction of soil surface shaded by the tree canopy (fc eff ).

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Fig. 1. Layout of lysimeters and neutron probe access tubes (䊉) in relation to tree trunk (

2.2. Soil water content measurements The soil water content was measured every 4–10 days in the morning with a neutron probe (TROXLER® , mod. 4300; Troxler Electronic Laboratories Inc., Research Triangle Park, NC, USA) from 0.2 to 1.2 m depth in 0.1 m increments. Because the neutron probe produces errors in the soil surface layer, two stainless steel rods were installed near each access tube to measure the volumetric soil water content in the surface 0.15 m of the soil by time domain reflectometry (TDR) (TEKTRONIX® , mod. 1502B; Tektronix Inc., Beaverton, OR, USA). The neutron probe readings were calibrated for the experimental soil in situ with undisturbed soil samples, which produced the following equation:  = 0.76

R − 0.09, SC

r = 0.91∗∗∗

(1)

where R is the neutron probe count reading,  is the volumetric soil water content (m3 m−3 ), and SC is the standard count reading. 2.3. Soil water balance The soil water balance was used as an indirect method for determining crop water use (ETc ), where ETc is a residual term in the mass conservation water balance equation. A simplified form of the water balance equation is: ETc = P + I − S − D − R

(2)

S =

(3)



(i − i−1 ) Z

where P is the precipitation (all P was considered effective), I is the irrigation, S is the change in soil water storage in the lysimeter between two consecutive dates, Z is the thickness of each horizon, D is the drainage, and R is the runoff (R was assumed 0 since the high edges of the lysimeter prevented runoff). All the terms are expressed in millimeters. Within the lysimeters, three different soil volumes were identified with significantly different soil water contents due to the line-source nature of the drip irrigation system. The different volumes assigned to the neutron probe access tubes were determined by analysis of variance considering the cumulative soil water content data down to 1.2 m depth. The volume not influenced by irrigation was represented by tubes in positions 4 and 5 farthest from the drip emitters. The volume influenced by irrigation was represented by tubes in positions 1, 2 and 3, but analysis of variance showed that soil moisture in the tubes in positions 2 and 3 were significantly different from the values recorded for the tube

) and drippers (). Letters indicate the different soil wetted zones.

in position 1. Accordingly, the zones considered were: A: strongly influenced (tube 1), B: lightly influenced (tubes 2 and 3), and C: not influenced by irrigation (tubes 4 and 5) (Fig. 1). As a result, for the weighted soil water content variation (S*) values, an area of 2.5 m2 was assigned to tube 1 (S1 ), 10 m2 to tubes 2 (S2 ) and 3 (S3 ), and 12.5 m2 to tubes 4 (S4 ) and 5 (S5 ) (Fig. 1). The mathematical expression used to calculate the changes in the weighted soil water content was: S∗ = 0.10S1 + 0.20 (S2 + S3 ) + 0.25 (S4 + S5 )

(4)

After calculating crop evapotranspiration (ETc ), the crop coefficients (Kc ) were estimated as the ratio between ETc and ET0 . Then, following the dual method (Allen et al., 1998, 2005, 2007), Kc was divided into a basal crop coefficient (Kcb ) and a soil evaporation coefficient (Ke ). In this experiment, the Ke coefficient was estimated using the continuous data of soil water content (SWC) from two multi-sensor capacitance probes installed in the dry area (half way between the tree rows) and ET0 . Each probe had a sensor located at 0.05 m depth, exploring from 0 to 0.1 m depth, and connected to a telemetry system, which recorded data every 15 min. Those sensors were previously calibrated as described in Abrisqueta et al. (2012). Soil surface evaporation (E) was calculated according to the following procedure after a rainfall event: If SWC > soil field capacity (FC), infiltration was allowed to proceed until FC was reached, and, from then on, E was computed as the decrease of SWC, using the same time span of the neutron probe measurements. 3. Results and discussion Daily crop reference evapotranspiration (ET0 ) data were calculated using the Penman–Monteith equation and are plotted for the four years of the experiment in Fig. 2. ET0 for the experimental period averaged 1340 mm, with only minor year-to-year deviations from this value, although variations tended to increase as the length of the period considered decreased, as can be deduced from the data dispersion in Fig. 2. The data show the typical bell shape for ET0 for this latitude and the year to year consistency. It should be noted that from June to September, there was no significant amount of rainfall or cloud cover at the experimental station at Santomera, Murcia, Spain, which reduces variability on ET0 data. The crop evapotranspiration (ETc ) data, as calculated by the water balance method in the lysimeters, are shown in Fig. 3. The plotted data, which are average daily values for the corresponding 4–10 day period between soil water content measurements, follow

9

1,2

10

8

Kc and Kcb

-1

Kc

1,0

7

ET0 (mm d )

161

6 5 4

Kcb

20

0,8 30 0,6

3

0,4

2

0,2

40

2007

50

Rainfall and irrigation (mm)

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1 122

152

182

213

243

274

304

334

DOY Feb Mar

Apr

May

Jun

Jul

Aug Sep Oct

Nov Dec

Month Fig. 2. Reference crop evapotranspiration (ET0 , mm d−1 ) for 2007 (䊉), 2008 (), 2009 () and 2010 () in CEBAS-CSIC Experimental Station, in Santomera, Murcia, Spain. DOY: day of the year.

10

1,0

Kc and Kcb

Jan

1,2

20

0,8 30 0,6 40

0,4

50

2008

0,2

1,2

10

Kc and Kcb

1,0

20

0,8 30 0,6 40

0,4 0,2

50

2009

1,2

10

1,0

Kc and Kcb

a similar pattern to that shown in Fig. 2 for the ET0 . ETc increased to reach a peak in July (DOY 182–213), and then showed a certain asymmetry by falling at a faster rate during leaf senescence (Fig. 3). Both, ET0 and ETc showed considerable noise due to several factors: the biological system (peach tree), the environmental conditions and the inaccuracy of the soil water balance terms (Eq. (2)). The annual figures of the water balance components were: rainfall between 327 (2008) and 429 (2009) mm, with annual average of 388 mm for the experimental period; drainage between 64 (2010) and 192 (2007), and ETc between 712.6 and 996.2 mm, for 2007 and 2010, respectively, with an average of 877 mm. The soil evaporation component was mainly caused of intense rainfall events, which accounted for 19–35% of the annual rainfall. Fig. 4 shows the crop coefficient (Kc ) values, as calculated from ETc /ET0 ; the basal crop coefficient (Kcb ) values, as calculated from Kc − Ke , for 4–10 day periods in the experimental period (2007–2010), together with the rainfall and irrigation events. For each year, a five-segment linear regression was drawn for Kcb data, according to the phenological stages reported in Table 2. Kc reached maximum values of 0.8 in 2007 and 1.2 in 2009 (Fig. 4). The annual patterns point to an asymmetry, similar to

20

0,8 30 0,6 40

0,4 9

0,2 30

-1

ETc (mm d )

7

50

2010

8 61

91

122

152

182

213

243

274

304

Rainfall and irrigation (mm)

91

Rainfall and irrigation (mm)

61

Rainfall and irrigation (mm)

30

334

DOY

6 5

Jan

Feb Mar

Apr

May

Jun

Jul

Aug Sep Oct

Nov Dec

4

Month 3 2 1 30

61

91

122

152

182

213

243

274

304

334

Fig. 4. Crop coefficient (Kc ) (), basal crop coefficient (Kcb ) (), for Flordastar peach trees, rainfall (thick vertical bars) and irrigation (thin vertical bars) during the experimental period: 2007 (a), 2008 (b), 2009 (c) and 2010 (d). X indicates harvest period. DOY: day of the year. Five-segment linear regressions of Kcb ( ) are included for each year.

DOY Jan

Feb Mar

Apr

May

Jun

Jul

Aug Sep Oct

Nov Dec

Month Fig. 3. Crop evapotranspiration (ETc , mm d−1 ) for Flordastar peach trees calculated in the drainage lysimeters for 2007 (䊉), 2008 (), 2009 () and 2010 ().DOY: day of the year.

that observed for ETc (Fig. 3), and also a turning point in Kc , which occurred right after harvest. Several hypotheses in the literature seek to explain the dip in Kc after harvest: (i) light interception decreases due to the lower cover fraction, although Ayars et al. (2003) found no changes in peach tree light interception, and (ii) physiological adjustments related to hormonal signals.

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4. Conclusions 2007 2008 2009 2010 FAO 56

1,2

K cb

1,0

Fc eff = 0.8

0,8 0,6 0,4

Fc eff = 0.4

0,2 Harvest

30

61

91

122 152 182 213 243 274 304 334

DOY Jan

Feb Mar

Apr

May

Jun

Jul

Aug Sep Oct

Nov Dec

Month Fig. 5. Basal crop coefficient (Kcb ) for Flordastar peach trees for 2007 (䊉), 2008 (), 2009 () and 2010 (), Kcb fitted line for fc eff = 0.4 (thin line) and fc eff = 0.8 (thick line), and Kcb from FAO-56 (Allen et al., 1998) (dashed line). DOY: day of the year.

Nonetheless, in this experiment due to the high vigor of the combination ‘GFF-677 rootstock x Flordastar’ used, a number of water sprouts were observed in the field that could explain the dramatic increase in both Kcb and Kc values right after harvest (Fig. 4). It is important to note that a similar variability in Kc values was observed in other experiments, e.g. apple (Girona et al., 2011) and peach (Ayars et al., 2003) trees, indicating that other factors involved in the process are not considered in the model. In Fig. 5, the Kcb values for each year were plotted along with, for comparative purposes, those of FAO-56 (Allen et al., 1998) cultivated in similar conditions: no ground cover, no frosts. The results suggest that Kcb did not fit well with the simplified FAO linear model but rather a curvilinear model, as proposed by Wright (1982). Two smoothed curves were fitted for effective canopy covers of 0.4 and 0.8. They showed a typical asymmetric bell shape, as indicated for ETc , where the Kcb mid FAO value remained between the two mentioned curves. The increase in Kcb can be attributed to both the seasonal increase in canopy development, from leaf out to full cover, and the increase in effective canopy cover, fc eff = 0.44 (in 2007) and 0.79 (in 2008/09/10) (Table 2). When comparing experimental Kcb data (Fig. 5) with those modeled by Allen and Pereira (2009), several remarks may be made: the phenological stages, which are assumed to be the same as those of Doorenbos and Pruitt (1977), do not fit well early season cultivars, and, in this study, would lead to an overestimation in the period from Kcb ini to Kcb mid . For the effective canopy cover fc eff = 0.8, the extrapolated Kcb ini and Kcb mid values (Allen and Pereira, 2009) were 100 and 12% higher than the experimental values, respectively; and for fc eff = 0.4, the extrapolated Kcb ini also overestimated experimental Kcb , whereas Kcb mid showed a similar value of 0.76. Finally, the Kcb end only provided data for the first part of the leaf senescence period. However, for perennial crops, as demonstrated in the experiment, Kcb might include values for the whole year. As a result, for mature, full yield peach trees, the behavior of Kcb reflects the following phenological stages: bloom and leaf-fruitshoot development, with values of Kcb increasing from 0.15 to 0.45 (from DOY 30 to 120), harvest (from DOY 120 to 140), when the Kcb experienced a turning point, and then the appearance and growth of water sprouts, which caused a dramatic increase in Kcb , reaching a peak value of 1.0 at DOY 220 (by mid-July). After that, leaf drop started, causing a continuous decrease in Kcb , reaching 0.15 by the end of the year (Fig. 5).

The soil water balance technique carried out in percolationtype lysimeters proved to be sound in spite of the scatter in Kcb data, which is due to the meteorological conditions, the physiological mechanisms involved and the inaccuracy of the water balance terms. According to the four year experimental results, it can be concluded that the basal crop coefficients obtained for early season peach trees under Mediterranean climatic conditions follow a bell shape pattern linked to the phenological stages of the crop and the canopy size, with an asymmetric fall during the senescence period. These results contrast with the four-segment linear pattern commonly found in the literature for Kcb and Kc . For practical purposes Kcb would start the year with a value of 0.15, which would remain constant up to the bloom, and then increase to 1.00 in the peak season, decreasing afterwards to 0.15 by the end of the year, and thus could be adopted for irrigation scheduling in drip irrigated peach trees. As a result, annual water use of peach trees in this experiment was 712 to 996 mm, leading to an irrigation volume of about 4120–5960 m3 ha−1 , which is usually lower than that used in commercial practice. Acknowledgements The authors are grateful to Dr. J. Ayars, from USDA-ARS Fresno, USA and Dr. L.S. Pereira, from the Technical University of Lisbon, Portugal, for their critical revision of an earlier version of this manuscript. Thanks also go to the reviewers of this paper. This study was supported by Spanish Ministry of Science and Innovation (AGL2006-12914-C02-01; AGL2009-06981; AGL2010-14861), Consolider-Ingenio 2010 (CSD2006-0067), and Fundación Séneca, Murcia (08847/PI/08) grants to the authors. I. Abrisqueta received a research fellowship from CSIC-I3P Spain. References Abrisqueta, J.M., Ruiz, A., Franco, J.A., 2001. Water balance of apricot trees (Prunus armeniaca L. cv. Búlida) under drip irrigation. Agric. Water Manage. 50, 211–227. Abrisqueta, I., Vera, J., Tapia, L.M., Abrisqueta, J.M., Ruiz-Sánchez, M.C., 2012. Soil water content criteria for peach trees water stress detection during the postharvest period. Agric. Water Manage. 104, 62–67. Allen, R.G., Pereira, L.S., 2009. Estimating crop coefficients form fraction of ground cover and height. Irrig. Sci. 28, 17–34. Allen, R.G., Pereira, L.S., Howell, T.A., Jensen, M.E., 2011. Evapotranspiration information reporting. I. Factors governing measurement accuracy. Agric. Water Manage. 98, 899–920. Allen, R.G., Pereira, L.S., Smith, M., Raes, D., Wright, J.L., 2005. FAO-56 dual crop coefficient method for estimating evaporation from soil and application extensions. J. Irrig Drain Eng. – ASCE 131, 2–13. Allen, R.G., Wright, J.L., Pruitt, W.O., Pereira, L.S., Jensen, M.E., 2007. Water requirements. In: Hoffman, G.J., Evans, R.G., Jensen, M.E., Martin, D.L., Elliot, R.L. (Eds.), Design and Operation of Farm Irrigation Systems. , 2nd ed. ASABE, St., Joseph, MI, USA, pp. 208–288. Allen, R.G., Pereira, L.S., Raes, D., Smith, M., 1998. Crop evapotranspiration-guidelines for computing crop water requirements. Irrigation and Drainage, 56. FAO, Roma. Ayars, J.E., Johnson, R.S., Phene, C.J., Trout, T.J., Clark, D.A., Mead, R.M., 2003. Water use by drip-irrigated late-season peaches. Irrig. Sci. 22, 187–194. Castel, J.R., Bautista, I., Ramos, C., Cruz, G., 1987. Evapotranspiration and irrigation efficiency of mature orange orchard in Valencia (Spain). Irrig. Drain. Syst. 3, 205–217. Chalmers, D.J., Andrews, P.K., Harris, K.M., Cameron, E.A., 1992. Performance of drainage lysimeters for evaluation of water use by Asian pears. HortScience 27, 263–265. Doorenbos, J., Pruitt, W.O., 1977. Crop water requirements. Irrigation and Drainage Paper No. 24 (rev.). FAO, Rome, 144 pp. Girona, J., del Campo, J., Mata, M., López, G., Marsal, J., 2011. A comparative study of apple and pear tree water consumption measured with two weighing lysimeters. Irrig. Sci. 29, 55–63. Johnson, R.S., Ayars, J., Trout, T., Mead, R., Phene, C., 2000. Crop coefficients for mature peach trees are well correlated with midday canopy light interception. Acta Hortic. 537, 455–459. Mitchell, P.D., Boland, A.M., Irvine, J.L., Jerie, P.H., 1991. Growth and water use of young, closely planted peach trees. Sci. Hortic. 47, 283–293.

I. Abrisqueta et al. / Agricultural Water Management 121 (2013) 158–163 Miyamoto, S., 1983. Consumptive water use of irrigated pecans. J. Am. Soc. Hortic. Sci. 108, 676–681. Pac¸o, T.A., Ferreira, M.I., Conceic¸ao, N., 2006. Peach orchard evapotranspiration in a sandy soil: comparison between eddy covariance measurements and estimates by the FAO 56 approach. Agric. Water Manage. 85, 305–313. Pac¸o, T.A., Ferreira, M.I., Rosa, R.D., Paredes, P., Rodrigues, G.C., Conceic¸ão, N., Pacheco, C.A., Pereira, L.S., 2011. The dual crop coefficient approach using a density factor to simulate the evapotranspiration of a peach orchard: SIMDualKc model versus eddy covariance measurements. Irrig. Sci. 30, 115–126. Ritchie, J.T., Johnson, S.S., 1990. Soil and plant factors affecting evaporation. In: Steward, B.A., Nielsen, D.R. (Eds.), Irrigation of Agricultural Crops. Agronomy Monograph No. 30. ASA, CSSA and SSSA, Madison, WI, USA, pp. 363–390.

163

Soil Survey Staff, 2006. Keys to soil taxonomy, 10th ed. United States Department of Agriculture, Natural Resources Conservation Service, Washington, DC, USA, 341 pp. Sun, H., Shao, L., Liu, X., Miao, W., Chen, S., Zhang, X., 2012. Determination of water consumption and the water-saving potential or three mulching methods in a jujube orchard. Eur. J. Agron. 43, 87–95. Worthington, J.W., McFarland, M.J., Rodriguez, P., 1984. Water requirement of peach as recorded by weighing lysimeters. HortScience 19, 90–91. Wright, J.L., 1982. New evapotranspiration crop coefficients. J. Irrig. Drain. Div. ASCE 108, 57–74.