ontario sugar beet growers - Atrium - University of Guelph

CONCLUSIONS:
The initial intent was to imgate based on a water budget approach applying water when
the soil moisture content reached either the 50% or 65% water holding capacity. The
complication of calculating these two action thresholds was difficult especially under the
rapidly dryng of the gravelly loam soil type and a year when rainfall was limiting. This
approach delayed the application of the first imgations and there after we played catch-up
thereafter separating the three treatments into twice weekly imgations of 7 times vs. a
weekly resulting in 5 imgation intervals vs. no irrigation at all. The trial became
essentially an irrigated vs. a non-imgated trial under severe water stress. In Fig. 20, the
rainfall quantities were considerably less than last year's rainfall at Ridgetown. Last year
even under favourable growing conditions with timely rainfall we demonstrated a yield
increase of 7%. This year under significantly dryer conditions the imgated plots showed
an astonishing 46.2% increase in shelled corn. Not only was corn yields improved the
quality of the corn was also improved. The average number of seed corn kernels per row
was increased on average by 19.3% as well as the number of rows per cob increased by
6.3%. All other growth parameters were significantly increased under both of the
imgation regimes such as a 22.0% increase in the average plant height, a 59.4% increase
in plant vigour, a 14.4% increase in cob length and a 5.6% increase in cob width. The
imgated plots also showed an increase in the number of cobs per plot by 11.2%. The
differences amongst the different seed corn inbreds were also significant. Pride #4,2,3
lNl3 507,508 and Hyland T50-B1 were the tallest seed corn inbreds all of which
developed the highest shelled seed corn yields.
The Capacitance probes, C-Probes, provided a visual ongoing record of the soil moisture
profiles at the 5 soil depths monitored. We report in Figs 12, 13 and 14 only the top three
sensor date as the degree of water penetration was relatively shallow. Most of the water
uptake by the plant was in the top 10cm depth which may be surprising however under
dry soil conditions the root growth was apparently confined to the top 10-30cm or within
the top 1' soil depths. The huge increase in yield and seed quality under these dry
conditions and the corresponding observation of active root growth suggests that using a
C-probe a growth can readily monitor the soil moisture profile and root growth activity
and adjust water accordingly.
The use of a C-probe is a valuable tool to provide the necessary information for growers
to make effective water management decisions to maximize both yield and quality of seed
corn inbred production.