TENSIOMETER BASED AUTOMATED IRRIGATION FOR TOMATO UNDER PLASTICULTURE - Management, Performance, and Applications of Micro Irrigation Systems - page 203

Fayette County Station, Lexington, KY [37]). The studies were terminated on 8 and 13
Sept. 2009 and 2010, respectively.
Statistical analyzes were conducted using the GLM, repeated measures, and Fish-
ers least signifi cant difference of SAS statistical software when appropriate (Version
9.1; SAS Institute, Cary, NC).

16.3 RESULTS AND DISCUSSION
The growing season in 2010 was drier and warmer than in 2009. Daily average air
temperatures were 71.3 and 72.6°F in July and Aug. of 2009, respectively; but were
77.5 and 77.4°F in July and Aug. 2010, respectively. Rainfall was greater in 2009
compared to 2010. In 2009 the research site experienced 15.47 inches of rain during
the study, while 10.19 inches were received in 2010. Irrigation events and water use
are summarized in Table 1. In 2010, less water was applied than in 2009, despite being
a hotter and drier growing season. Although it may be expected that greater irrigation
would have been required in 2010, the results are supported by field observations.
High temperatures observed in 2010 were supra optimal for tomato plant growth and
plants were smaller in 2010 than in 2009 [17]. Typically soil moisture sensor-based
irrigation systems will distribute water in a manner that is reflective of canopy and root
growth [22, 42]. Therefore, it is not unexpected that plants with less leaf area would
require less water.

TABLE 1 Mean number of irrigation events, irrigation time per event, and irrigation volume
for the season 'Mountain Fresh' tomato grown under five automated irrigation regimes in 2009
and 2010 in Lexington, KY.

2009 2010

Irrigation
Treatment
on/off

Irriga-
tions

Mean irri-
gation time

Mean ir-
rigation
volume

Irriga-
tions

Mean irri-
gation time

Mean
irrigation
volume

(min/event) (min/event)

kPa z (no.) (gal/acre z, y ) (no.) (gal/acre)

110 144

-30/-10 39 138,996 28 130,637

91 140

-30/-25 59 173,956 22 99,792

221 167

-45/-10 21 150,368 22 119,037

40 146

-45/-40 76 98,496 18 85,147

52 93 156,686 44 84 119,750

-35 or −40 x

z 1 kPa = 1.0 cbar, 1 gal/acre = 9.3540 L·ha -1 .
y Assuming 7200 row feet (2194.6 m) per acre with drip irrigation emitter rate of 0.45 gal/min per 100 ft.
(0.0559 L·min -1 ·m -1 ).
x Single tensiometer treatment set at −35 kPa (-35.0 cbar) in 2009 and −40 kPa (-40.0 cbar) in 2010.

Average water applied ranged from 98,500 to 173,960 gal/acre in 2009 and 85,150