IRRIGATION AND DRAINAGE
Irrig. and Drain. 60: 35–41 (2011)
Published online 14 May 2010 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ird.562
YIELD AND WATER USE EFFICIENCY OF CORN PLANTED IN ONE OR TWO ROWS
AND APPLYING FURROW OR DRIP TAPE IRRIGATION SYSTEMS IN GHAZVIN
PROVINCE, IRANy
MOHAMMAD KARIMI* AND AFSHIN GOMROKCHI
Ghazvin Agricultural and Natural Resources Research Centre, Ghazvin, Iran
ABSTRACT
This study investigated water use efficiency and yield in corn (SC 704) irrigated with drip (tape) and furrow irrigation systems in
Ghazvin, Iran, in 2006. Four levels of irrigation including: 80, 100 and 120% of water requirement with drip irrigation (tape)
and 100% water requirement with furrow irrigation as main plots and method of planting (one and two rows), as well as three
levels of crop density including: 75 000, 90 000 and 105 000 (plants ha1) as subplots were considered. The highest average
grain yield was 12.9 t ha1 while the treatment was drip irrigation at level of 120% water requirement in a two-row planting
pattern and crop density equal to 75 000 plants ha1 (I3R2D1 treatment). The highest water use efficiency (WUE) was obtained
in I3R2D1 treatment as 1.96 kg m3, while the lowest was found in drip irrigation at a level of 80% water requirement in a tworow planting pattern and crop density equal to 75 000 plants ha1 (I1R2D1 treatment) as 0.82 kg m3. Variance analysis of the
grain yield data indicated that both planting pattern and interaction of planting pattern and crop density significantly affected the
yields. Generally, the planting of one row resulted in significantly higher grain yields than the other planting pattern. Copyright
# 2010 John Wiley & Sons, Ltd.
key words: drip irrigation; surface irrigation; water use efficiency; corn; planting pattern
Received 24 August 2008; Revised 5 October 2009; Accepted 7 October 2009
RÉSUMÉ
Cette étude s’est penchée sur l’utilisation rationnelle de l’eau et le rendement dans le maı̈s (SC 704) irrigués avec goutte à goutte
(bande magnétique) et des systèmes d’irrigation par rigoles à Ghazvin en Iran en 2006. Quatre niveaux d’irrigation, notamment:
80, 100 et 120% des besoins d’eau avec l’irrigation au goutte à goutte (ruban) et 100% avec un besoin en eau d’irrigation des
parcelles comme sillon principal et la méthode de plantation (une et deux lignes), outre trois niveaux de densité de peuplement,
y compris: 75 000, 90 000 et 105 000 (plantes ha1) en tant que sous-parcelles ont été considérées. Le plus haut rendement en
grain moyen était de 12.9 t ha1 alors que le traitement a été l’irrigation au goutte à goutte au niveau des besoins en eau de 120%
en deux lignes de plantation de modèle et de la densité des cultures égal à 75 000 plants ha1 (traitement I3R2D1). Les plus fortes
efficacité de l’utilisation de l’eau (EUE) a été obtenu dans le traitement I3R2D1 que 1.96 kg m3 alors que le plus faible a été
constaté dans l’irrigation au goutte à goutte au niveau des besoins en eau de 80% en deux lignes de plantation de modèle et de la
densité des cultures égal à 75 000 plantes ha1 (I1R2D1 traitement) 0.82 kg m3. Analyse de la variation des données de
rendement en grain indique que les deux modèles de plantation et de l’interaction de la plantation de modèle et de la densité des
cultures sensiblement affecté les rendements. En règle générale, la plantation d’une rangée a donné des rendements
significativement plus élevés du grain que dans le schéma de plantation autres. Copyright # 2010 John Wiley & Sons, Ltd.
mots clés: irrigation goutte à goutte; irrigation de surface; efficacité de l’utilisation de l’eau; maı̈s; schéma de plantation
INTRODUCTION
* Correspondence to: Mohammad Karimi, Ghazvin Agricultural and
Natural Resources Research Centre, Shahid Beheshti Blv. No. 118, Ghazvin, Iran, P.O. Box. 34185-618. E-mail: [email protected]
y
Rendement de l’eau et l’efficacité d’utilisation de maı̈s planté dans un ou
deux lignes et application de sillon ou systemes d’irrigation goutte de bande
dans Ghazvin Province, Iran.
Copyright # 2010 John Wiley & Sons, Ltd.
The water resources of the world are finite. Efficient use has
economical and environmental benefits for people. Nowadays irrigation is the primary consumer of fresh water on
earth (Shiklomanov, 1998 as cited in Gleick, 2000), but the
36
M. KARIMI AND A. GOMROKCHI
twin drivers of human population and development exert
pressure on our water resource management regimes to be
more productive with less water. To solve totally, or to
reduce, the severity of water scarcity, water management
must improve. Thus, agriculture has the greatest potential for
solving the problem of global water scarcity (Longo and
Spears, 2003). Drip irrigation has been used for agricultural
production for about the past 35 years. Drip irrigation has
advantages over more traditional practices such as surface
and sprinkler irrigation due to reduced labour requirements
and its ability to conform to irregularly shaped fields. It can
also achieve higher efficiencies than sprinkler or surface
irrigation (Camp, 1998). Water is an important factor in
agricultural development. In the sector of agriculture in Iran
more than 90% of extracted water resources are used. Maize
as a strategic plant uses water at 18–20 m3 ha1 (Moayyeri,
2002). A drip irrigation system is one of the methods that in
addition to increase of yield, enables a reduction of water use
and increase of water use efficiency. Today, using of drip
irrigation system is common in row crops. Hamedi et al.
(2005), in a comparison of drip (tape) and surface irrigation
systems in yield of maize with different levels of water
requirement, indicated that drip irrigation increased the
amount of yield to 2015 kg ha1 and water use efficiency by
three times. Kohi et al. (2005) investigated effects of deficit
irrigation use of drip (tape) irrigation on water use efficiency
of maize in planting of one and two rows. Results showed
that maximum water use efficiency related to crop density,
water requirement and planting pattern: 85 000, 125% and
two rows respectively with 1.46 kg m3. Lamm et al. (1995)
studied the water requirement of maize in a field with silt
loam texture under sub-drip irrigation and reported that
water use reduced to 75% but yield of maize remained at a
maximum of 12.5 t ha1.
A study was designed to evaluate the yield response of
trickle-irrigated corn grown on a clay-textured soil under the
arid Southeast Anatolia Project (GAP) area conditions during
the 2000 growing season at Koruklu in Turkey. The effects of
three different irrigation levels (100, 67 and 33% of cumulative
Class-A pan evaporation on a three- and six-day basis), and
two irrigation intervals (three- and six-day) on yield were
investigated. The highest average corn yield (11 920 kg ha1)
was obtained from the full irrigation treatment (100%) with a
six-day interval. Corn grain yields varied from 7940 to
11 330 kg ha1 and 7253 to 11 920 kg/ha1 for three- and sixday irrigation intervals, respectively. Irrigation levels significantly increased yield. Maximum irrigation water use
efficiency (IWUE) and water use efficiency (WUE) were
2.53 and 2.27 kg m3 in the treatment of I-33 with a six-day
interval. Both IWUE and WUE values varied with irrigation
quantity and frequency (Yazar et al., 2002).
Furrow (conventional) and drip-irrigated corn yields (Zea
mays L.) were compared on an old irrigated sierozem deep
Copyright # 2010 John Wiley & Sons, Ltd.
silt loam for two consecutive years in Central Asian
Uzbekistan. Results showed that maize irrigation water use
for furrow irrigation ranged from 547 to 629 mm yr1
compared with 371–428 mm yr1 for drip irrigation.
Irrigation water use efficiency was always superior for drip
irrigation compared with furrow irrigation (Nazirbay et al.,
2005).
Lamm and Trooien (2003) investigated subsurface drip
irrigation (SDI) for corn production (a review of 10 years of
research in Kansas) and concluded that irrigation water use
for corn can be reduced by 35–55% when using SDI
compared with more traditional forms of irrigation in the
region. Irrigation frequency has not been a critical issue
when SDI is used for corn production on the deep silt loam
soils of the region. Payero et al. (2008) evaluated the effect
of irrigation applied with subsurface drip irrigation on field
corn (Zea mays L.) evapotranspiration (ETc), yield, water
use efficiencies (WUE ¼ yield/ETc, and IWUE ¼ yield/
irrigation), and dry matter production in the semi-arid
climate of west central Nebraska in 2005 and 2006. Results
showed that irrigation significantly affected yields, which
increased with irrigation up to a point where irrigation
became excessive. Yields increased linearly with seasonal
ETc and ETc/ETp (ETp ¼ ETc with no water stress). WUE
increased non-linearly with seasonal ETc and with yield.
WUE was more sensitive to irrigation during the drier 2006
season, compared with 2005. In both seasons IWUE
decreased sharply with irrigation. Irrigation significantly
affected dry matter production and partitioning into the
different plant components (grain, cob, and stover).
The large area of the Ghazvin plain is used for growing
corn annually and surface irrigation is utilized in most of it.
Although surface irrigation efficiency is about 30%, a great
amount of water is wasted in this plain. So in order to study
the efficiency of micro-irrigation on function level and some
other corn-growing attributes and also water consumption
efficiency, this research was carried out in the Ghazvin area.
The objective of this study was to evaluate the drip (tape)
irrigation method for corn production practices in Ghazvin
province in Iran. Moreover, water use efficiency and the
yield response of corn to a drip irrigation system in the
region were investigated.
MATERIALS AND METHODS
This study was conducted at the Esmael abad Research
Station of the Agricultural and Natural Resources Research
Centre of Ghazvin Province of Iran during the corngrowing season in 2006. The station is at latitude 368150 N
and longitude 498540 E. Some physical and chemical
properties of the soil of the experimental site are given in
Table I.
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird
37
YIELD AND WATER USE EFFICIENCY OF CORN IN GHAZVIN PROVINCE, IRAN
Table I. Physical and chemical properties of different soil layers of the experimental field
Soil
depth
0–30
30–60
60–90
Particle size
distribution (%)
Texture
class
Sand
Silt
Clay
54
56
44
31
28
34
15
16
22
SL
SL
L
The climate of the research region is cold and semi-dry.
The minimum and maximum temperature of the region is
178C and 368C, respectively. The average annual
precipitation of the area is 330 mm. In order to investigate
water use efficiency and yield of corn in planting of one and
two rows with different crop density in corn (SC 704) in drip
(tape) and furrow irrigation systems, a study was conducted
on randomized complete blocks as a strip split plot design
and three replications. Four levels of irrigation including 80,
100 and 120% of water requirement with drip tape irrigation
(I1, I2 and I3, respectively) and 100% water requirement with
furrow irrigation (I4) as main plots, and method of planting
one and two rows (R1 and R2) with three levels of crop
density including 75 000, 90 000 and 105 000 plants ha1
(D1, D2 and D3, respectively) as subplots were considered.
Therefore, 24 treatments were created. For example, I1R1D1
treatment, namely drip irrigation at level of 80% water
requirement in a one-row planting pattern and crop density
equal to 75 000 plants ha1. The experimental field was
130 50 m and each experimental plot 20 7.5 m (10 rows
with spacing of 0.75 m in any plot). Corn (with a
comparative relative maturity of 130 days) was planted
on June 4th, and matured on October 11th.
Fertilizer applications were based on soil analysis
recommendations. All treatment plots received the same
amount of total fertilizer. The drip irrigation system
consisted of a control unit and distribution lines. The
control unit of the system contained a venturi injector
(50.8 mm), fertilizer tank (90 l), disk filter, control valves
and a water flow meter. Nutrient requirements in the drip
irrigation method were applied by chemical injection using a
venturi injector with irrigation water. Distribution lines
consisted of PE pipe manifolds (supply and discharge) for
each plot. Irrigation laterals of tape pipes with 0.2 mm wall
thickness and 16 mm inside diameter had emitters spaced
0.3 m apart, each delivering 4 l h1 for 1 m of pipe length at a
pressure of 60–70 kPa. The laterals were spaced at 0.75 m
(every other corn row). Irrigation level treatments in drip
irrigation were accomplished after the four-leaf stage of
plants. Water requirement was determined by Class-A
evaporation pan by using crop and pan coefficients and
Copyright # 2010 John Wiley & Sons, Ltd.
PH
7.86
7.93
7.94
EC
(ds m1)
0.87
0.74
0.86
Cations (me l1)
SAR
2.8
2.2
4.9
Naþ
CaþþþMgþþ
5.2
4
6.2
6.5
6.5
3.1
overshadow surface percent (in drip irrigation). The pan was
located near the study site. Crop coefficient (Kp) during
growing period was determinate by FAO method (Figure 1).
The variation of the pan coefficient during different
months of the year (at weather stations in the area) is
presented in Table II.
Percent of overshadow surface was utilized from 4 to 6
leaf stage in crop that is estimated approximately by green
coverage and plant cover situation in field in each irrigation
(Figure 2).
Water requirement was calculated by the following
equation:
ETc ¼ Ep Kp Kc
(1)
where ETc ¼ evapotranspiration of plant or water requirement (mm day1), Ep ¼ Class A evaporation pan (mm
day1), Kp ¼ pan coefficient and Kc ¼ crop coefficient.
In drip irrigation, overshadowed surface (%) was applied
in calculation of the water requirement. Therefore, the water
requirement was modified as
ETC ¼ EP KP KC ð0:1 PC 0:5 Þ
(2)
The irrigation interval in drip and furrow irrigation up to
the 6–8-leaf stage of the crop was 3 and 9 days, respectively.
After this stage, irrigation interval was 4 and 12 days. Depth
and volume of irrigation water were calculated according to
the area of the plot. The amount of water use in a period of
irrigation was measured in drip and furrow irrigation
Figure 1. Variations of Crop coefficient (Kc) in growing season. This figure
is available in colour online at wileyonlinelibrary.com
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird
38
M. KARIMI AND A. GOMROKCHI
Table II. Variations of Kp during different months of the year in weather stations of the research region
Month
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Kp
0.85
0.80
0.75
0.70
0.60
0.55
0.50
0.55
0.60
0.65
0.75
0.80
systems by using a counter and WSC flume, respectively.
Irrigation efficiency (Ea) in drip irrigation was considered
equal to 90%. Furrow irrigation was designed according to
the SCS method. Therefore, the parameters of the family
curve number in the SCS method and the suitable furrow
inflow were determined. In any irrigation, by measuring the
advance time in the length of a furrow (with attention to
depth of irrigation), the cut-off time of irrigation was
determined. The average of irrigation efficiency (Ea) in
furrow irrigation was calculated as 34.7%. After the maturity
of crop, grain yields were determined by hand harvesting the
4 m sections of the two adjacent centre rows in each plot on
10 November in 2006. The harvest area in each plot was 6
m2 (two rows, each 4 m long). Yield and yield components
including 1000-kernel weight, number of kernels per ear,
number of rows per ear and number of kernels per row were
measured. The grain yield per plot was calculated in a ‘‘wetmass basis’’ (standard water content of 14%). Five plants
from each plot were also hand-harvested to determine dry
mass and its partitioning into the different plant components
(grain, Stover, and cob). Plants were cut at ground level and
the ears were separated from the Stover. Grain, Stover and
cob samples were taken, oven-dried at 708C until they
reached a constant mass (7 days), and weighted. Water use
efficiency (WUE, kg m3) and irrigation water use
efficiency (IWUE, kg m3) were calculated as
WUE ¼
Y
ETc
(3)
Y
I
(4)
IWUE ¼
where Y ¼ yield (g m2), ETc ¼ seasonal crop evapotranspiration (mm) and I ¼ seasonal irrigation (mm), which is
I1 ¼
80 ETC
ðdrip irrigation; Ea ¼ 90%Þ
Ea
(5)
I2 ¼
100 ETC
ðdrip irrigation; Ea ¼ 90%Þ
Ea
(6)
I3 ¼
120 ETC
ðdrip irrigation; Ea ¼ 90%Þ
Ea
(7)
I4 ¼
100 ETC
ðdrip irrigation; Ea ¼ 90%Þ
Ea
(8)
The MSTATC program (Michigan State University) was
used to carry out statistical analysis. Treatment means were
compared using Duncan’s multiple range test (Steel and
Torrie, 1980).
RESULTS AND DISCUSSION
Figure 2. Variations of overshadow surface (Pc) in growing season. This
figure is available in colour online at wileyonlinelibrary.com
Water requirement was determined using evaporation pans,
which the pan data was collected daily and manually using
hook gage, by using crop and pan coefficients. Variations of
evaporation of pan (Ep) and evapotranspiration of plant
(ETc) are shown in Figures 3 and 4.
Figure 3. Variations of Class-A evaporation pan in growing season. This figure is available in colour online at wileyonlinelibrary.com
Copyright # 2010 John Wiley & Sons, Ltd.
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird
39
YIELD AND WATER USE EFFICIENCY OF CORN IN GHAZVIN PROVINCE, IRAN
Figure 4. Variations of evapotranspiration of plant in growing season
The seasonal irrigation, seasonal crop evapotranspiration
(mm), dry matter and grain yield, 1000-grain weight, water
use efficiency (WUE) and irrigation water use efficiency
(IWUE) in different treatments are given in Table III.
The highest seasonal irrigation application was observed
in furrow irrigation (I4) as 1886 mm (irrigation efficiency ¼
34.7%), and the lowest was found in the I1 treatment as
582 mm (irrigation efficiency ¼ 90%). Grain yields varied
from 5.4 to 12.9 t ha1 among the treatments: in drip
irrigation at a level of 120% water requirement in the tworow planting pattern and crop density equal to 75 000 plants
ha1 (I3R2D1 treatment) yield was 12.9 t ha1, and the
lowest yield was found in drip irrigation at a level of 80%
water requirement in the two-row planting pattern and crop
density equal to 75 000 plants ha1 (I1R2D1 treatment) as 5.4
t ha1. The highest water use efficiency (WUE) was
obtained in the I3R2D1 treatment (1.96 kg m3), while the
lowest was found in treatment I1R2D1 (0.82 kg m3).
Irrigation water use efficiencies (IWUE) varied from 0.32 to
1.74 kg m3. The highest irrigation water use efficiency was
obtained in drip irrigation at a level of 80% water
requirement in the one-row planting pattern and crop
density equal to 90 000 plants ha1 (I1R1D2 treatment) as
1.74 kg m3. Whereas the lowest was found in furrow
Table III. Calculation of corn grain yield, Irrigation water use efficiency (IWUE) and water use efficiency (WUE)
Treatments
I1R1D1
I1R1D2
I1R1D3
I1R2D1
I1R2D2
I1R2D3
I2R1D1
I2R1D2
I2R1D3
I2R2D1
I2R2D2
I2R2D3
I3R1D1
I3R1D2
I3R1D3
I3R2D1
I3R2D2
I3R2D3
I4R1D1
I4R1D2
I4R1D3
I4R2D1
I4R2D2
I4R2D3
Corn grain
yield (t ha1)
Dry matter
yield (t ha1)
1000- grain
weight (g)
9.8
10.1
8.3
5.4
8.2
7.5
8.8
9.9
8.6
8.1
7.5
11.0
11.3
12.4
10.6
12.9
9.8
11.8
8.8
11.0
10.8
9.1
6.1
10.6
21.5
13.9
17.2
12.2
17.4
13.5
22.8
27.1
14.7
25.0
14.9
21.4
17.4
28.8
23.5
22.4
15.6
28.8
23.8
28.5
25.1
20.7
19.2
34.0
347
325
278
323
284
310
295
331
304
329
322
320
361
347
346
317
306
313
340
331
326
337
294
335
Seasonal
irrigation (mm)
1
1
1
1
1
1
582
582
582
582
582
582
728
728
728
728
728
728
873
873
873
873
873
873
886
886
886
886
886
886
Seasonal crop
evapotranspiration (mm)
WUE
(kg m3)
IWUE
(kg m3)
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
655
1.50
1.54
1.27
0.82
1.24
1.15
1.35
1.51
1.31
1.24
1.15
1.67
1.72
1.89
1.61
1.96
1.49
1.80
1.34
1.68
1.65
1.39
0.92
1.62
1.68
1.74
1.43
0.92
1.40
1.29
1.21
1.36
1.18
1.12
1.03
1.51
1.29
1.42
1.21
1.47
1.12
1.35
0.46
0.58
0.57
0.48
0.32
0.56
Explanations: I1, I2 and I3 indicate drip irrigation levels of 80, 100 and 120% water requirement, respectively. I4: furrow irrigation. R1, R2: planting of one and
two rows and D1, D2 and D3 are crop density of 75 000, 90 000 and 105 000 plants ha1, respectively.
Copyright # 2010 John Wiley & Sons, Ltd.
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird
40
M. KARIMI AND A. GOMROKCHI
Figure 5. Variations of Corn grain yield in different treatments
Figure 6. Variations of irrigation water use efficiency in different treatments
Table IV. Variance analysis of corn grain yield data
Variation source
Degrees of freedom
Mean square
F-value
Probability
2
3
6
1
2
3
6
2
6
2
6
32
71
29.9
34.3
17.6
19.7
1.0
6.0
8.3
2.8
4.7
19.9
4.9
4.1
1.7
1.9
0.260
0.224
19.5
0.048
Replication
I(irrigation method)
Error
R(Planting pattern)
Error
IR
Error
D(crop density)
ID
RD
IRD
Error
Total
0.7
0.7
1.1
4.8
1.2
0.360
0.015
0.335
Significant at 5% level.
Copyright # 2010 John Wiley & Sons, Ltd.
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird
YIELD AND WATER USE EFFICIENCY OF CORN IN GHAZVIN PROVINCE, IRAN
irrigation with the two-row planting pattern and crop density
equal to 90 000 plants ha1 (I4R2D2 treatment) as 0.32 kg
m3. Total dry matter varied from 34.0 to 12.2 t ha1, with
the highest dry matter observed in furrow irrigation with the
two-row planting pattern and crop density equal to 105 000
plants ha1 (I4R2D3 treatment) and the lowest in drip
irrigation at a level of 80% water requirement in the two-row
planting pattern and crop density equal to 75 000 plants ha1
(I1R2D1 treatment). Variations of yield and Irrigation water
use efficiency in the different treatments are shown in
Figures 5 and 6.
The results of simple variance analysis of attributes (Table
IV) showed that the method of planting has a significant
difference on the level of 5 for grain yield, but on the other
measured attributes did not have any significant effect. The
respective effect of planting method and crop density showed
a significant difference on the level of 5% for grain yield,
number of kernels per ear and the 1000-grain weight, whereas
it did not have any significant effect on the other measured
attributes. The respective effects of irrigation method,
planting method and crop density showed a significant
difference on the level of 1% for the attributes of number of
kernels per ear. The planting in one row resulted in
significantly higher grain yields than the other planting
pattern. The R1D2 treatment had higher grain yields than the
other treatments.
CONCLUSIONS
The target of this study was to the evaluate drip (tape)
irrigation method for corn production practices in Ghazvin
province in Iran. In addition, water use efficiency and the
yield response of corn to a drip irrigation system in the
region were investigated.
Results showed that irrigation water use for corn can be
reduced by 60.4% when using drip tape irrigation compared
with furrow irrigation, and the average grain yield can be
increased to 12.9 t ha1 in the region. The highest irrigation
water use efficiencies in drip tape irrigation and furrow
irrigation were obtained as 1.74 and 0.58 kg m3, respectively. Therefore, drip tape irrigation increases irrigation
water use efficiency by three times.
Copyright # 2010 John Wiley & Sons, Ltd.
41
The amount of grain yield in the I1R1D2 treatment (10.1 t
ha1) was more than the mean of yield in the region. On the
other hand, the highest irrigation water use efficiency was
obtained in this treatment (Table II). Therefore, in order to
save water in irrigation and extension of irrigated lands, the
mentioned treatment (I1R1D2) was recommended.
REFERENCES
Camp CR. 1998. Subsurface drip irrigation: a review. Transactions of the
ASAE 41(5): 1353–1367.
Hamedi F, Jafari H, Ghaderi J, Rezaee R, Sayyadian K. 2005. Comparison
of drip and surface irrigation with difference levels of water requirement
on yield of corn. In Proceedings of 9th Soil Science Congress of Iran,
Mashhad, Iran; 120–121.
Kohi N, Azadshahraki F, Ganjeezadeh F, Aghamirzadeh S. 2005. Effects of
irrigation level and plant density on water use efficiency of corn using
surface drip irrigation (tape). In Proceedings of 2nd National Conference
on Watershed and Soil and Water Management, Kerman, Iran; 1819–
1827.
Lamm FR, Manges HL, Stone LR, Khan AH, Rogers DH. 1995. Water
requirement of subsurface drip irrigated corn in Kansas. Transactions of
the ASAE 38(2): 441–448.
Lamm FR, Trooien TP. 2003. Subsurface drip irrigation for corn production:
a review of 10 years of research in Kansas. Irrigation Science 22: 195–
200. DOI: 10.1007/s00271-003-0085-3.
Longo FD, Spears TD. 2003. Water Scarcity and Modern Irrigation,
Valmont Water Management Group, Valmont Industries, Inc.: Valley,
Nebraska, USA.
Moayyeri M. 2002. Investigation of water use efficiency drip and furrow
irrigation systems in the planting of one and two rows of corn. Annual
Research Report. Agricultural Engineering Research Institute, Karaj,
Iran.
Nazirbay I, Evett S, Esanbekov Y, Kamilov B. 2005. Water use of maize for
two irrigation methods and two scheduling methods. In Agronomy
Abstracts, ASA-CSSA-SSSA Annual Meeting, Salt Lake City, Utah.
Payero JO, Tarkalson DD, Irmak S, Davison D, Petersen JL. 2008. Effect of
irrigation amounts applied with subsurface drip irrigation on corn
evapotranspiration, yield, water use efficiency, and dry matter production
in a semiarid climate. Agricultural Water Management in press, corrected
proof, available online 18 April 2008.
Shiklomanov I. 1998. Pictures of the future: a review of global water
resources projections. In The World’s Water 2002–2001, Gleick PH (ed.).
Island Press: Washington, DC; 53.
Steel RGD, Torrie JH. 1980. Principles and Procedures of Statistics, 2nd
edn. McGraw-Hill: New York.
Yazar A, Sezen SM, Gencel B. 2002b. Drip irrigation of corn in the
southeast Anatolia project (GAP) area in Turkey. Irrigation and Drainage
51: 293–300.
Irrig. and Drain. 60: 35–41 (2011)
DOI: 10.1002/ird