How Does Flooding Affect Corn Yield?
June 21, 2001 8(14):96-97
Joe Lauer, Corn Agronomist
Recent rains have caused periods of flooding in many cornfields. Growers are asking
questions about corn growth and development and any yield effects that might occur
from short periods of flooding.
The extent to which flooding injures corn is determined by several factors including:
timing of flooding (plant stage of development when flooding occurs), frequency
and duration of flooding, and air-soil temperatures during flooding.
Flooding restricts root growth in the upper 18 inches of soil, but root elongation
continues in deeper horizons. Almost immediately leaf elongation ceases and N, P
and K concentration in the leaves decrease, whereas in roots N, P and K concentrations
increase (Ashraf and Rehman, 1999). Measurable short term reductions for root and
leaf growth rates begin immediately within 1-12 h, but tend to recover quickly within
2-3 d (Wenkert et al., 1981).
Prior to V6 (6 visible leaf collars) the growing point is near or below the soil
surface. The oxygen supply in the soil is depleted after about 48 hours in a flooded
soil (Purvis and Williamson, 1972; Fausey and McDonald, 1985). Without oxygen, the
plant cannot perform critical life sustaining functions; e.g. nutrient and water
uptake is impaired, root growth is inhibited, etc. If temperatures are warm during
flooding (greater than 77 degrees F) plants may not survive 24-hours. Cooler temperatures
If flooding in corn is less than 48 hours, crop injury should be limited. To confirm
plant survival, check the color of the growing point. It should be white to cream
colored, while a darkening and/or softening usually precedes plant death. Also look
for new leaf growth 3 to 5 days after water drains from the field. Once the growing
point is above the water level, the chances of survival improve greatly.
Even if flooding doesn't kill plants outright, it may have a long-term negative
impact on crop performance. Excess moisture during the early vegetative stages retards
root development (Wenkert et al., 1981). As a result, plants may be subject to greater
injury during a dry summer because root systems are not sufficiently developed to
access available subsoil water. Flooding can also result in losses of nitrogen through
denitrification and leaching.
Flooding causes greater crop yield losses when it occurs early in the season (Meyer
et al., 1987; Kanwar et al., 1988; Mukhtar et al., 1990; Lizaso and Ritchie, 1997).
When six-inch corn was flooded for 24, 48 and 72 h corn yields were reduced 18,
22, and 32% at a low N fertilizer level. At a high N level, these reductions ranged
from 19 to 14 % one year and <5% in another year (Ritter and Beer, 1969). When
corn at a height of 30 inches was flooded for 24 and 96 h, yields were reduced 14
to 30%. With a high level of N in the soil, very little yield reduction occurred
even with 96 h of flooding. When flooded near silking, no reduction in yield occurred
at a high N level, but yield reductions up to 16% occurred with 96 h of flooding
at the low level of N.
Disease problems that may become greater risks due to flooding and cool temperatures
are corn smut and crazy top. There is limited hybrid resistance to these diseases
and predicting damage is difficult until later in the growing season.
Ashraf, M. and H. Rehman. 1999. Mineral nutrient status of corn in relation to nitrate
and long-term waterlogging. Journal of Plant Nutrition 22:1253-1268.
Fausey, N. R. and M. B. McDonald. 1985. Emergence of inbred and hybrid corn following
flooding. Agronomy Journal 77:51-56.
Kanwar, R. S., J. L. Baker, and S. Mukhtar. 1988. Excessive soil water effects at
various stages of development on the growth and yield of corn. Transactions of the
American Society of Agricultural Engineers 31:133-141.
Lizaso, J. I. and J. T. Ritchie. 1997. Maize shoot and root response to root zone
saturation during vegetative growth. Agronomy Journal 89:125-134.
Meyer, W. S., H. D. Barrs, A. R. Mosier, and N. L. Schaefer. 1987. Response of maize
to three short-term periods of waterlogging at high and low nitrogen levels on undisturbed
and repacked soil. Irrigation Science 8:257-272.
Mukhtar, S., J. L. Baker, and R. S. Kanwar. 1990. Corn growth as affected by excess
soil water. Transactions of the American Society of Agricultural Engineers 33:437-442.
Purvis, A. C. and R. E. Williamson. 1972. Effects of flooding and gaseous composition
of the root environment on growth of corn. Agronomy Journal 64:674-678.
Ritter, W. F. and C. E. Beer. 1969. Yield reduction by controlled flooding of corn.
Transactions of the American Society of Agricultural Engineers 12:46-50.
Wenkert, W., N. R. Fausey, and H. D. Watters. 1981. Flooding responses in Zea mays
L. Plant Soil 62:351-366.