Water and Nutrient Uptake During the Corn Growing Season
Crop Insights written by Stephen D. Strachan, Ph.D.1 and Mark Jeschke, Ph.D.2
- Soil must provide adequate quantities of 13 of the 16 nutrients essential for high grain yields.
- In addition, soil must release these nutrients quickly enough to meet daily high nutrient demands of the corn plant during the V6 to R1 growth stages.
- The greatest nutrient demand occurs at V6 to R1 when the corn plant is:
- generating new tissue to complete vegetative growth,
- creating the harvestable ear,
- supporting ear growth in preparation for pollination and grain fill, and
- storing additional nutrients in vegetative tissue as a reserve to supply nutrition to the ear during the latter portion of grain fill.
- Rates at which soil-supplied nutrients enter the corn plant depend on nutrient bioavailability in soil, nutritional demand of the corn plant, and the amount of water transpiring through the corn plant.
- Daily extraction of nutrients from soil during R3 to R6 is considerably less than daily nutrient extraction during V6 to R1 due to the sharp decline in new root growth beginning around VT.
- The corn plant compensates for this limited nutrient extraction from soil by transferring nutrients stored in vegetative plant tissue.
Sixteen elements are essential for corn growth (Salisbury and Ross 1978). The soil supplies thirteen. The surrounding atmosphere and soil water supply the remaining three – carbon, hydrogen, and oxygen. Table 1 summarizes the estimated total nutrient content in harvested grain when corn yield is 300 bu/acre. Research at Iowa State University has shown that nutrient concentration in corn grain remains relatively constant across a wide range of yields (Mallarino et al., 2011). One can estimate nutrient removal per acre of soil for a particular grain yield by multiplying the amount of nutrient extracted in lbs/bu (Table 1) by the desired or observed grain yield in bu/acre. Values listed in Table 1 include only nutrient amounts in the grain. During the growing season, the corn plant must extract additional nutrients from soil to supply the vegetative part of the corn plant. Estimated amounts of several nutrients in grain plus stover to support a 300 bu/acre corn yield are shown in Table 2.
Table 1. Nutrient content per bushel of corn grain and total amounts of nutrients removed from the field when grain yield is 300 bushel/acre.
* Heckman et al., 2003
Table 2. Estimated amounts of selected nutrients in corn at maturity to support a 300 bu/acre grain yield.
* Reference: IPNI, 2014
** Reference: IPNI Plant Nutrition Today, Fall 2008, No. 4.
Barber and Olson (1968) published research to illustrate quantities of macronutrients and micronutrients that corn plants remove from soil to support a grain yield of 150 bu/acre (Table 3). Corn hybrids in these studies are from approximately 50 years ago. Although grain yields have improved substantially over the past 50 years, estimated quantities of nitrogen, phosphorus, potassium, magnesium, and sulfur to support grain yields of 300 bu/acre with hybrids from 50 years ago (Table 3) are similar to the amounts of these same nutrients to support corn yields of 300 bu/acre in today’s hybrids (Table 2).
Table 3. Estimated amounts of selected nutrients in corn at maturity to support a 300 bu/acre grain yield for hybrids produced before 1968 based on the 1968 nutrient concentrations for 150 bu/acre corn.
*Data extracted from Barber and Olson (1968).
In addition, the corn plant must extract supplemental nutrients to support root growth. Nutrient contents of roots are not included in this analysis. During the growing season, corn plants must extract approximately 336 lbs of nitrogen, 153 lbs of phosphorus (P2O5), 405 lbs of potassium (K2O), 69 lbs of magnesium, and 45 lbs of sulfur per acre to support a grain yield of 300 bu/acre. In this Crop Insights article, we shall focus on nitrogen, phosphorus, and potassium and explore how nutrient uptake relates to water uptake during the life cycle of the corn plant. As we develop a better understanding of nutrient and water uptake, we may discover one or more potential factors that limit grain yield.
Daily Nutrient Uptake in Corn
Iowa State University (Ritchie et al. 1997) and the University of Illinois (Bender et al. 2013) have published two documents that illustrate daily nutrient uptake of nitrogen, phosphorus, and potassium from the soil as a function of corn growth stage during the growing season. Figure 1 contains estimated averages of nutrient uptake at key corn growth stages based on information presented in these research reports.
Figure 1. Estimated uptake of nitrogen, phosphorus, and potassium from the soil at critical corn growth stages. Estimates from ISU and Univ. of Illinois research.
Information presented in Figure 1 is converted to a pounds/acre/day basis to illustrate quantities of nitrogen, phosphorus, and potassium uptake from the soil estimated to support a corn grain yield of 300 bushels/acre (Figure 2).
Figure 2. Estimated uptake of nitrogen, phosphorus, and potassium from the soil required to support a grain yield of 300 bu/acre at different corn growth stages.
Maximum grain yields require that nutrient supply continuously meets crop demand. From planting to V6, the corn seedling first relies on the nutrient reserve in the seed to initiate seedling growth. As seedling roots become established, the corn plant extracts nutrients from the soil. Nutrient demand from planting to V6 is low because the corn plant is small and crop demand is low.
The physiology of the corn plant changes dramatically and nutrient demand increases substantially during V6 to V12. For many hybrids, initiation of the harvested ear begins at about V6 (Abendroth et al., 2011) (Figure 3).
Figure 3. Dissected corn plant at the V6 growth stage. Three ear shoots are visible at lower nodes. The primary ear shoot has been initiated at this stage but is not visible without magnification. Photo courtesy of Iowa State University.
Daily nutrient supply from V6 to V12 is supporting initial growth and development of the harvested ear. In addition, the plant is increasing greatly in size and stature. Daily nutrient supply is supporting the demand to feed substantial growth in leaf and stalk structures. New leaves subsequently provide photosynthetic factories that supply sugar to the grain. An ample supply of sugar to the grain creates maximum opportunity to convert sugar into harvestable starch.
Physiological processes initiated at V6 to V12 continue from V12 to R1. At about V10 to V12, initial formation of the harvestable ear is complete and the maximum number of ovules that can mature to produce harvestable grain is established (Figure 4). Maximum yield potential in terms of harvestable kernels per plant is established. The majority of daily nutrient supply during V12 to R1 is consumed by the ear; ovules require food, cob growth must increase to provide space for all ovules, and ear development continues to prepare for and support pollination. Nutrients are also consumed to complete the formation of the vegetative portion of the plant. In addition, the corn plant is extracting nutrients from the soil and storing these nutrients in vegetative tissue. Stored nutrients are later released between about R3 to R6 to support the final phases of ear growth and development.
Figure 4. Dissected corn plant at the V12 growth stage. Eight ear shoots are visible at this stage, including the primary ear shoot. Photo courtesy of Iowa State University.
Daily nutrient uptake from the soil slows dramatically between R1 and R2. At this growth phase, nutrients support the growth of fertilized embryos that eventually become harvested kernels of grain. Fertilized embryos consume as many nutrients and as much sugar as they can on a daily basis. If nutrient or sugar supply is limited, embryos toward the base of the ear continue to consume these nutrients while fertilized embryos toward the tip of the ear starve. Fertilized embryos, starting at the tip of the ear and working toward the base of the ear will starve and die if daily nutrient, sugar, and water supplies are insufficient to support growth of the entire ear.
Figure 5. Dissected corn plant at the R1 growth stage and developing ears.
Photos courtesy of Iowa State University.
Daily extraction of nutrients from soil continues during R3 to R6, but is considerably less than daily nutrient extraction during V6 to R1. This seems counter-intuitive because nutrient demand to support kernel growth is very high from R3 to R6. Corn root growth mirrors vegetative corn shoot growth. Corn roots are close to their maximum size at about VT, and new corn root growth slows dramatically (Ordóñez et al., 2018). Young, newly formed corn roots are responsible for the majority of nutrient uptake from soil. Very little new root growth between R3 and R6 causes corn to have a relatively low ability to extract additional nutrients from soil. The corn plant compensates for this limited nutrient extraction from soil by transferring nutrients stored in vegetative plant tissue (the main stalk and older leaf tissues) to the ear. From an agronomic perspective, good early vegetative growth is a critical requirement for high corn yields. Nutrients stored in vegetative tissues are later moved to the ear to feed latter-stage kernel growth. If corn plant growth during vegetative stages is stunted, it is highly likely that late-season growth will also be poor, resulting in lower grain yield.
Daily Water Uptake During the Growing Season
Researchers at Iowa State University published a document showing an average of the daily rate of corn plant transpiration and evapotranspiration for 35 environments (Licht and Archontoulis 2017). This information is summarized in Figure 6. Some of us like to think in terms of gallons of water per acre while others like to think in terms of acre-inches of water. This same information is presented in terms of acre-inch per day in Figure 7. One acre-inch of water is equivalent to 27,154 gallons of water evenly distributed across an acre of soil.
Figure 6. Evapotranspiration of water in gallons/acre to support corn growth in Iowa during different stages of corn growth.
Seasonal evapotranspiration is highly dependent on environmental conditions. For example, the higher temperatures and drier climates of north Texas and Kansas require higher evapotranspiration rates than the generally cooler and more humid climates of Iowa and Minnesota, and sunny windy days require more evapotranspiration than cloudy, calm days. The yellow bars in Figure 6 and Figure 7 illustrate the amount of water that enters and passes through the corn plant. As water moves from soil into corn roots, nutrients dissolved in this water also enter corn roots. Soil water movement into the corn plant influences the daily flux of nutrients from soil into the plant.
Figure 7. Evapotranspiration of water (acre-inch basis) to support corn growth in Iowa during different growth stages.
Daily Nutrient Flux During the Growing Season
Nutrient flux is the amount of nutrient dissolved in a unit of soil water that enters the corn plant every day. Figure 8 shows the daily nutrient flux of nitrogen, phosphorus, and potassium into corn at different growth stages.
Figure 8. Estimated amounts of nutrient flux to support a corn grain yield of 300 bu/acre under environmental conditions based on Iowa weather data.
Nutrient flux is greatest during the vegetative growth phase. This is consistent with the physiology of corn growth. Corn roots must “mine the soil” for nutrients. Roots must penetrate new portions of the soil profile as they grow to extract nutrients. Newly formed roots are most efficient for nutrient uptake. Root growth mirrors shoot growth, so the formation of new roots is most prevalent during vegetative growth. Nutrient influx is particularly high during V6 to V12 when new root growth is most prolific. Nutrient flux during the late vegetative phase is about 10-20 times greater than nutrient flux during ear fill. Figure 9 shows a more detailed look at changes in nutrient flux during grain fill.
Figure 9. Estimated amounts of nutrient flux during ear fill to support a corn grain yield of 300 bu/acre under environmental conditions based on Iowa weather data.
The greater amounts of nutrient flux during R1 to R2 are probably residual effects of new root growth as corn plants switch from very late vegetative stages to very early reproductive growth stages. Between R2 and R6, nutrient flux increases as the corn plant approaches physiological maturity (R6). This increase in nutrient flux from R5 to R6 may be due to the decrease in water uptake during R5 to R6. Nutrient uptake of nitrogen, phosphorus, and potassium between R2 and R6 tends to be linear during this growth interval so total nutrient demand on a daily basis will change little during this growth interval (Figure 1). However, the daily water uptake tends to decrease as the corn plant progresses from R2 to R6 (Figure 7). As the corn plant matures, similar total amounts of nutrients are entering the corn plant daily but less water enters the corn plant daily. During the latter growth stages, water must contain higher concentrations of nutrients (Figure 9).
Based on these observations, the soil must meet two nutritional requirements to support high corn grain yields. First, the soil must provide adequate amounts of all soil-applied nutrients to support grain yield. Years of comparing soil test results with grain yields have established recommended ranges of nutrients in soil to support desired yield levels. A proper soil test program is therefore essential to achieve maximum corn grain yield. Second, the soil must release these nutrients rapidly enough to meet the demand of nutrient flux into the corn plant, especially during the vegetative and very early reproductive growth stages. Nutrients must be bioavailable and readily extractable from soil. For example, Pioneer researchers have shown that multiple applications of lower amounts of nitrogen to corn from before emergence to early brown silk (about R2) improve corn grain yield and increase the efficiency of nitrogen fertilizer better than a single pre-plant broadcast application of a large amount of nitrogen fertilizer (French et al. 2015). In these studies, nitrogen use efficiency increased from 1.3 pounds of N per bushel of corn to 0.8 pound of N per bushel of corn. Perhaps similar results can be obtained with potassium, phosphorus, and other nutrients supplied by the soil. One problem with nutrients other than nitrogen is there currently is no easy and economical method to “spoon-feed” these nutrients through an irrigation system or apply these nutrients as fertilizer in tall, non-irrigated corn.
Soil must feed corn plants daily to provide all of the proper soil-applied nutrients in proper amounts to support high grain yields. For example, the soil must provide approximately 336 pounds of nitrogen, 153 pounds of phosphorus (P2O5), 405 pounds of potassium (K2O), 69 pounds of magnesium, and 45 pounds of sulfur per acre to support a grain yield of 300 bushels per acre. In addition to supplying total amounts of nutrients, the soil must also supply these nutrients rapidly enough on a daily basis to meet the high flux demand during V6 to R1. During this interval, corn roots must extract sufficient nutrients to: (1) complete vegetative growth, (2) support ear growth in preparation for pollination and grain fill, and (3) store additional nutrients in vegetative tissue as a reserve to supply nutrition to the ear during late grain fill. If nutrient demand exceeds nutrient supply, this stress response will probably appear in the ear. Depending on when nutrient supply is limiting, ear response could be a reduction of kernel rows along the ear, tip kernel die-back, and/or reduced individual kernel weight. Whole corn plant response could be vegetative tissues showing nutrient deficiencies, decreased stalk strength, or a higher incidence of stalk diseases. All of these responses reduce potential grain yield. A thorough diagnostic of corn ear and plant responses near harvest provide the basic information to alter appropriate agronomic and production practices to mitigate or eliminate these yield-robbing responses in future production cycles.
- Abendroth, L.J., R.W. Elmore, M.J. Boyer, S.K. Marlay. 2011. Corn growth and development. PMR 1009. Iowa State University Extension.
- Barber, S. A., and R. A. Olson. 1968. Fertilizer use on corn. pp. 163-188. In L. B. Nelson et al. (ed.) Changing patterns in fertilizer use. SSSA. Madison, WI.
- Bender, R. R., J. W. Haegele, M. L. Ruffo, and F. E. Below. 2013. Modern corn hybrids’ nutrient uptake patterns. Better Crops. 97:1, pp 7-10.
- French, R., R. Bowling, A. Abbott, and M. Stewart. 2015. Right fertility components in high-yield corn. The Fluid Journal, Vol. 23 No. 1, Issue 87.
- Heckman, J. R., J. T. Sims, D. B. Beegle, F. J. Coale, S. J. Herbert, T. W. Bruulsema, and W. J. Bamka. 2003. Nutrient removal by corn grain harvest. Agronomy J. 95:587-591.
- IPNI. 2008. Average nutrient removal rates for crops in the Northcentral region. IPNI Plant Nutrition Today. Fall 2008, No. 4.
- IPNI. 2014. IPNI Estimates of Nutrient Uptake and Removal.
- Licht, M. and S. Archontoulis. 2017. Corn water use and evapotranspiration. Integrated Crop Management, June 26, 2017. Iowa State University extension, Ames, Iowa.
- Mallarino, A. P., R. R. Oltmans, J. R. Prater, C. X. Villavicencio, and L. B. Thompson. 2011. Nutrient uptake by corn and soybean, removal, and recycling with crop residue. 2011 Integrated Crop Management Conference – Iowa State University. pp 103-113.
- Ordóñez, R.A., M.J. Castellano, J.L. Hatfield, M.J. Helmers, M.A. Licht, M. Liebman, R. Dietzel, R. Martinez-Feria, J. Iqbal, L.A. Puntel, S.C. Córdova, K. Togliatti, E.E. Wright, S.V. Archontoulis. 2018. Maize and soybean root front velocity and maximum depth in Iowa, USA. Field Crops Research 215:122-131.
- Ritchie, S. W., J. J. Hanway, G. O. Benson. 1997. How a corn plant develops. Special report No. 48. Iowa State University Press. Ames, Iowa.
- Salisbury, F. B., and C. W. Ross. 1978. Plant Physiology 2nd ed. Belmont, California: Wadsworth Publishing Co. pp 79-92.
1Stephen D. Strachan, Ph.D., DuPont Technical Fellow
2Mark Jeschke, Ph.D., Pioneer Agronomy Information Manager