Rooting depth for corn
I'm doing a comparative study between furrow and subsurface drip irrigation for field
corn. I'm finding conflicting information on rooting depth. Can anyone offer some sources?
Unless you have previously studied rooting depth under similar conditions you will have
to rely on a wild guess as factors such as variety, time of planting and weather
conditions and especially soil hydraulic conductivity, fertility, compaction,etc-etc are
going to have an influence on the root depth. Consequently you will always find
conflicting " information "
Phene, et al (1991) Effect of high frequency surface and subsurface drip irrigation on
root distribution of sweet corn. <underline>Irrigation Science
12:</underline>135-140, grew sweet corn on Panoche clay loam and found greatest
RLD's in top 60 cms but recorded roots to 1.8 m. In my SDI trial (Griffith, Australia)
growing sweet corn on Hanwood sandy clay loam most root activity was in the top 40 cms but
small RLD's were still recorded at 1m.
Sprinkle and Trickle Irrigation by J. Keller and R.D. Bliesner, 1990 shows the rooting
depth of sweet corn as 0.4 to 0.6 m and grain and silage corn as 0.6 to 1.2 m. Hope this
Unfortunately you are going to receive numerous answers to your question. Rooting
characteristic will vary by application method, management, soil characteristics, crop
varieties, etc. As trickle applies frequent shallow depths of water, the majority of roots
will be found in the upper profile. Surface irrigation generally applies a large volume of
water which the roots will seek deeper in the profile, depending on management. I suggest
that you contact list member Freddie Lamm <Flamm@oznet.ksu.edu>. He likely has or
can lead you to the appropriate individual having comparative information on rooting under
both trickle and surface
>I'm doing a comparative study between furrow and subsurface drip
>irrigation for field corn. I'm finding conflicting information on
>rooting depth. Can anyone offer some sources?
Freddie replied: As many have already said, it is to be expected that you will find
many conflicting answers. Corn can grow on soil profiles as little as 1-2 ft. However, it
can also pull water from as deep as 8 ft or maybe a little deeper. A lot of literature
says 3- 4 ft. But my feelings is that those values are more of a generality for
"typical" irrigation management on soils that have that deep a profile. In many
of my studies, we measure extraction to 8 ft, though not as much from deeper depths and
the amount depends on how dry the irrigation regime is. I have also stated that some of
the old rules of thumb which are approximately 40%, 30%, 20% etc. from successive
depths of 1ft, 2ft, 3ft etc. are just that, RULES OF THUMBS.
They don't always fit real conditions. We can get **relatively** similar amounts of
extraction down through 6 ft on our soil profile and in our climate. No, that does not fit
the textbooks, but it is documented for our soils. I believe I forwarded Jennifer some
papers or bibliographies of some of our work on corn within the last few months.
In reference to rooting depth differences between SDI and surface irrigation????? I
guess I am willing to stake out a position that I am not sure the difference would be very
significant, at least from the background of our soil type and climate. That claim might
start a vigorous discussion, but I guess I'd have to ask why it would be likely that
rooting depth would vary so much. Now, to make my staked position clear, we are now
talking the rooting depth and not the water use from different depths. I saw the posting
from Tom Spofford about differences in irrigation redistribution depths and how that might
encourage deeper uptake under surface irrigation. Corn roots
will not migrate through dry soil to any large extent to find water which sort of follows
Tom's reasoning. However, I believe rootingdepth is more generally governed by the soil
type and particularly the bulk density, nutrient properities, soil water, etc. of the
subsoil than by irrigation system type. I will grant that SDI may encourage more root
growth near the water and nutrient application depth. But if water gets short, and there's
an appropriate moist
subsoil, I bet the corn will go down and get it. Climatic conditions during the vegetative
growth period will also influence root growth.
I have seen corn root growth during the early vegetative period suffer from excessive heat
even though subsoil moisture was good. Some claim excessive irrigation or rainfall during
the vegetative period will not encourage deep corn root growth. I'm not sure I buy into
that idea as much as I used to, though ***excessive*** water is
not really conducive to the other types of corn growth either.
> I always thought this to be 40-30-20-10 from "first quartile, second
> quartile, etc." of the effective root system. Shallow rooted veg crops,
> for example lettuce, would not extract much from the 2-4 foot level.
Am I OK?
Bill and Trickle-L members:
Yes, Bill is right. I was traveling and I did not have a book to look up the old rule of
thumb before I responded. The rule of thumb, 40, 30, 20, 10% extraction should be in
relation to 25, 50, 75 and 100% of root zone. Still as I said in my earlier message, there
are some soils that this works poorly on. Thanks for pointing out my
You might look at Fig. 7 in Howell et al. (1995) for some graphs of soil water content
profiles for corn irrigated by LEPA (I don't think drip, at least alternate row drip, will
be any different) where on our Pullman soil
with near "full" replenishment, corn extracted water to about 1.5 m; to about
1.75 m under moderate deficit, and to over 2.5 m when severely deficiently irrigated. We
have similar data for drip irrigated corn (Howell et al., 1997), but I haven't looked at
the profiles that closely (I don't think they would be different).
Howell, T.A., A. Yazar, A.D. Schneider, D.A. Dusek, and K.S. Copeland.
1995. Yield and water use efficiency of corn in response to LEPA irrigation. Trans. ASAE
Howell, T.A., A.D. Schneider, and S.R. Evett. 1997. Subsurface and
surface microirrigation of corn -- Southern High Plains. Trans. ASAE 40(3):635-641.