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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?

Jennifer Suttles


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 "

Jean Piaget


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.

Philip Charlesworth


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 helps.

Linda Day


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
irrigation.

Tom Spofford


Jennifer said:
>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.

Freddie Lamm


> Freddie:
> 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 Pogue

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
misstatement.

Freddie Lamm


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
38(6):1737-1747.

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.

Terry Howell