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ASSESSMENT OF MICROIRRIGATION SYSTEMS POTENTIAL OF THE
KIWIFRUIT ORCHARD USING MIRRIG DSS
Pedras, C.M.G. 1, 2, Lança, R.1, Martins, F.1,3, Fernandez, H.1,3, Valín, M.I. 2,4
1 UALG, University of Algarve, Faro, Portugal cpedras@ualg.pt
2 LEAF Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Lisbon, Portugal
3 CIEO - Research Centre for Spatial and Organizational Dynamics, Faro, Portugal
4 ESA, Polytechnic School of Viana do Castelo, 4990-706 Refoios do Lima, Portugal,
ABSTRACT
Nowadays, the kiwifruit (Actinidia deliciosa A. Chev) extends over a wide area in north
of Portugal. Microirrigation systems are the method used to irrigate these orchards. The
irrigation systems allow to deliver water and nutrients in precise amounts and controlled
frequencies directly to the plants root zone. The present paper describes the main features
of a decision support system (DSS) MIRRIG applied to a kiwifruits orchard that allows
enhancing the existing irrigation systems and the design of new microirrigation systems
.The study was conducted in an orchard in the district of Braga (41o 31’ N, 8o 27´ W,
Portugal) in 2011. The plot was irrigated daily between June until October through a drip
irrigation system. The results include performance analysis and the simulation of
alternative improvements of the systems operating in the kiwifruit orchard. Results from
field evaluations were used for direct advice to farmer.
KEYWORDS: Decision Support Systems, Kiwifruit, Microirrigation systems, MIRRIG,
Performance indicators
1. NTRODUCTION
The country that produces the most quantity kiwifruit (Actinidia deliciosa) in the world is
its origin country – China, about 1,76 million tonnes, (Zdinjak, 2016). Nevertheless, there
is an increase of production in other countries. In Portugal the production has been growing:
in 2013 and 2015 was about 21,30 and 28,33 thousand tonnes, respectively (Pelicano,
2017). The north of Portugal is the region that presents the highest kiwifruit production and
the highest orchard area. In this region, in 2015, were harvested about 23,20 thousand tonnes
of kiwifruit on 1721 ha, of which 15 thousand tonnes were exported (Pelicano, 2017). Drip
irrigation is the most commonly used system to irrigate the kiwifruit orchard. These systems
allow to deliver water and nutrients in precise amounts and controlled frequencies directly
to the plant root zone. To achieve high performance, will be necessary to minimize the
effects of both water deficits and over watering. Under application of water slows growth;
over application will waste water, energy, and money and often encourage water-related
diseases. Improvement of irrigation water management is an important measure to save
water, increase water distribution uniformity and water use efficiency.
The decision support systems (DSS) MIRRIG supports the design decisions and helps to
explore the results of field evaluation of microirrigation systems under operation. This DSS
has already been used successfully to design and evaluate irrigation systems for different
crops and landscapes (Pedras et al., 2009; Darouich et al., 2014).
The study was conducted in a commercial orchard in the district of Braga (41o 31’ N, 8o 27´
W, Portugal) in 2011. The plot was irrigated daily between June and October through a drip
irrigation system. The results include performance analysis and the simulation of alternative
improvements of the systems operating in the kiwifruit orchard. Results from field
evaluations were used for direct advice to the farmer.
2. MATERIAL AND METHODS
The MIRRIG decision support system (DSS) has the purpose of supporting farmers to adapt
and implement improved microirrigation systems solutions, thus gaining more benefits
from the irrigation technology (Pedras and Pereira, 2009). MIRRIG includes the following
components: (1) a database on emitters, pipes, crop, soil and systems, which design or
evaluate the irrigation system, (2) a design module that simulates the functioning of the
system under consideration and computes the relevant performance indicators, and (3) an
evaluation module that supports the analysis of data collected during field evaluations. The
model is available freeware. Performance indicators determined by MIRRIG in the design
and in the irrigation systems are showed in Table 1.
The evaluation of operating irrigation systems aims the understanding of the system's
adequacy and the determination of the necessary procedures for improving the system's
performance. The in-field irrigation evaluation was performed according to Merriam and
Keller (1978) and ASAE-EP458 (2004) methodology.
Table 1- Performance indicators for design and microirrigation systems under operation.
Performance indicators of microirrigation systems (Pedras and Pereira, 2009; Pereira, 1999)
Design
Irrigation systems under operation
Annual fixed cost, AFC (€ year-1)
Average emitter discharge, qa (L h-1)
Operation and maintenance cost, OMC (€ year-1)
Uniformity Coefficient, UC (%)
Percentage of deficit relative to the required application depth, PD (%)
Distribution uniformity, DU (%)
Volume of water percolated out of the root zone indicating the potential
contamination with nitrates and agricultural chemicals, Vp (mm year-1)
Emitter discharge coefficient of variation, Vqs (%)
Uniformity coefficient, UC (%)
Volume per day per plant, D (L/plt/day)
3. CASE STUDY
The case study was performed in a commercial kiwifruit orchard in 2011, from June until
October, in a plot with 2 ha located at S. Salvador de Briteiros, Guimarães, Portugal
(41o39’49’’ N, 8o19’12’’ W; elevation 150 m).
The climate is Mediterranean with Atlantic influence. The warm temperate climate with dry
and warm summers is classified as a Csb by the Köppen–Geiger (Kottek et al., 2006). The
climate data were obtained from the Merelim meteorological station (Fig. 1).
Figure 1 - Total mensal precipitation (P) and, minimum and maximum temperature (T) from
1958 until 1988, at the Braga/Merelim meteorological station (41º34’N; 08º27’W, and
altitude : 60 m).
-5,0
0,0
5,0
10,0
15,0
20,0
25,0
30,0
35,0
40,0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
Jan Fev Mar Apr May Jun Jul Aug Sep Out Nov Dez
Temperature (oC)
Precipitation (mm)
Precipitation (mm) Minimum Temperature (oC) Maximum Temperature (oC)
Kiwifruit orchard require a temperature climate of mild winters and a long, warm growing
season of 225 to 240 frost-free days (Hasey, 1994). During the dormant season (November to
February), they require 600 to 850 chilling hours at or below 7.2 oC to bloom and set reliably
(Hasey, 1994). The growing season begins in March when the vines leaf come out; bloom
occurs in May, and fruit is harvested in November reliably. To archive top production, kiwifruit
require deep, well-drained soils (Hasey, 1994). The kiwifruit orchard needs approximately 1433
mm yr-1 of water without water stress.
The irrigation events occurs from June until September. The peak water use by the kiwi
orchard, during summer when temperatures is higher, is about 13.2 mm/day in a 45 min of
irrigation time. Soils are silt loam with an average of 66 % sand, 8 % silt and 26 % clay; the
bulk density is 1.45. The total available soil water (TAW) down to 1 m depth is 139 mm.
The kiwi orchard was planted in 1989 with orientation NE-SE (Fig. 2). The plants spacing and
the plants rows spacing are about 5 m X 5 m for the females and 5 m X 20 m for males plants.
In 2004, the trellis system was changed from T-bar to pergola and a new vine was added
between two plants in each row (Fig.3). Hayward is the female cultivar; Matua and Tomuri are
the males cultivars (male pollinisers) used in the orchard.
Figure 2 - The location of discharge sample sites in the sector of kiwifruit orchard. Image
adapted from Goggle Earth, 12/05/2013.
4. RESULTS AND DISCUSSION
A microirrigation system is installed in the kiwifruit orchard with self-compensating
drippers: NAAN PC, discharge rate, q= 2.2 L h-1; pressure-regulating range: 0.5 – 3.5 bar;
16 mm external pipe diameter and 13.9 mm internal pipe diameter. Two pairs of laterals are
installed in both sites of each plant row. The emitters spacing is about 0.5 m. However,
considering that the ramps are misaligned, there are emitters every 0.25 m (Fig.3), so there
are twenty emitters per plant. The length of the laterals evaluated has 165 m. All sectors are
similar with an area of about 1.76 ha.
Figure 3 - Schematic location of the vines, the laterals and the wet area in the kiwifruit
orchard.
Table 2 shows the volumes collected in each emitter, in the evaluated sector, during one minute.
The minimum emitter discharge obtained is about 2.3 L h-1 and the average discharge is 2.4 L
h-1, which represents about 0.5% of the emitter discharge coefficient of variation. The high
value for the distribution uniformity (97.5%) for the drip irrigation revealed the good
performance of the system. The volume per day per plant is 36.05 L/plt/day, when the
application time is of 0.7h.
Table2- The volumes collected in the evaluated sector during one minute, in ml.
Outlet location
on the lateral
Lateral location in the manifold
At beginning
At 1/3 of the length
At 2/3 of the length
At the end
At beginning
40.25
40.25
40.50
40.25
At 1/3 of the length
39.75
38.75
40.25
40.25
At 2/3 of the length
40.00
40.50
40.00
40.25
At the end
39.25
39.25
38.25
40.25
To improve the performance of a system under operation, it is required the comparison with
alternative improvements, they can have new emitters and pipes available on the market,
and a new layout of sectors being designed.
The simulation of design alternatives was performed using data created during design and
data collected from the evaluation of the field system (Table 3). The maximum velocity
limit did not allow to simulate an alternative (two laterals per plant row with 0.25 m of
emitter spacing) with the same characteristics of the microirrigation evaluated system.
Table 3 – Data characterizing the design alternatives.
Alternative
A
B
C
Type
Online Dripper
Micro-sprinkler
Dripper Discharge equation (q, L/h) (H; m)
q = 1.92259 H0.056
q = 11.6 H0.4132
Discharge rate (q, L/h)
2.2
40.0
Emitter pressure head, H (m)
5.0-35.0
20.0
Length of the laterals (m)
165
2 X 82.5
Emitter spacing (m)
0.5
0.25
2.5
Number the laterals per plant row
4
2
1
Lateral diameter (mm): low density polyethylene
16
25
Manifold diameter (mm): high density polyethylene
NP4/50
The best uniformity coefficient (UC) values in Table 4 correspond to pressure-compensating
dripper: alternative B. This alternative also show the best values for the Annual fixed cost
(AFC) and the Operation and maintenance cost (OMC). The alternatives A and C present higher
emitter flow variation (Vq) but lower than 10%.
Alternative with microsprinkler have higher AFC due to the high cost of the emitters; however,
the total costs are compensated because they use a single lateral per crop row while two laterals
per crop row are required for drippers. The results that include performance analysis and the
simulation of alternative improvements of the systems operating in the kiwifruit orchard help
the farmer to make better decision according to the alternatives characteristics in favour of one
or another criteria.
Table 4 – Main characteristics of the pipe systems for the considered alternatives.
Alternative
A
B
C
Sector discharge rate (m3/h)
22.9
22.9
20.9
Pressure head at sector entrance (m)
24
16
24
Uniformity coefficient, UC (%)
98.0
98.9
98.1
Average emitters flow rate (q, L/h)
2.2
2.2
40
Emitter flow variation, Vq (%)
8.8
5.3
9.2
Pressure head variation, VH (%)
80.7
62.3
20.9
Annual fixed cost, AFC (€ year-1)
226.4
145.1
238.6
Operation and maintenance cost, OMC (€ year-1)
500.0
224.1
250.0
5. CONCLUSION
A microirrigation system has a potential to be a very efficient way to irrigate crops.
However, to be efficiently applied, the irrigation water must be uniformly applied, i.e.,
approximately the water must evenly applied to the area occupied by the plants. The
accurate analysis of the operation of microirrigation systems is required to determine the
need to enhance water efficiency, gaining an economic advantage while reducing
environmental impacts from the irrigation. MIRRIG DSS was developed to help
stakeholders to improve the performance of microirrigation systems that are already under
operation and/or implementing optimal design solutions of these systems.
6. BIBIOGRAFY
Darouich, H. M., Pedras, C. M., Gonçalves, J. M., Pereira, L. S. (2014). Drip vs. surface
irrigation: A comparison focussing on water saving and economic returns using multicriteria
analysis applied to cotton. Biosystems Engineering, 122, 74-90.
Hasey, J. K. (1994). Kiwifruit growing and handling (Vol. 3344). UCANR Publications.
Pelicano, S. (2017). Kiwi Português deve projetar a sua qualidade. Frutas, legumes e flores.
(171) 18-19 .
Zdinjak, N. (2016). Eight Countries that Produce the Most Kiwi Fruit in the World.
http://www.insidermonkey.com/blog/8-countries-that-produce-the-most-kiwi-fruit-in-the-
world-439753/?singlepage=1
Merriam J.L., Keller J. (1978). Farm irrigation evaluation: A guide for management,
Department of Agricultural and Irrigation Engineering, Utah State University: Logan, Utah.
Plastro (2017). http://www.plastro.co.jp/data/BuleBookProductData.pdf
Pedras, C. M. G., Farrajota, M. P., Valín, M. I., and Pereira, L. S. (2010). A rega nos espaços
verdes públicos. Caso de estudo: Campus Gambelas da Universidade do Algarve. In 10. º
Congresso da Água (Março, 2010, Alvor, Portugal).
Naandanjain(2017). http://www.naandanjain.com/uploads/catalogerfiles/Drip%20Irrigation%20Booklet/NDJ_Drip_cat_eng.pdf
