Irrigation monitoring for Corn This NebGuide discusses corn irrigation management strategy options and objectives.

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William L. Kranz, irrigation Specialist, Northeast Research and also Extension facility Suat Irmak, agricultural Water administration Specialist, biological Systems engineering Simon J. Van Donk, Water resources Engineer, West central Research and Extension facility C. Dean Yonts, irrigation Engineer, Panhandle Research and Extension facility Derrel L. Martin, Professor, organic Systems Engineering

Soil — plant — Water RelationshipsCorn Water usage CharacteristicsMatching chop Demands through Water ApplicationGrowth StagesIrrigation ManagementSoil TexturesIrrigation SystemsSummaryAcknowledgmentsReferences

over there are an ext than 16 million acre in harvested row chop production in Nebraska. Around 8 million of these acres are irrigated. Corn occupies around 70 percent of the irrigated acreage, or 5.6 million acres. Consequently, improving irrigation management have the right to have far-reaching impact top top the quantity and quality that Nebraska’s most precious resource: water.

Soil — plant — Water Relationships

Understanding the relationships in between plants and also their environment is vital to efficient irrigation management. Plant attributes important to watering management include full seasonal water use, daily crop water use, rate of plant development, and also rooting depth. Necessary soil characteristics include water stop capacity, water entry rate, and also the existence of any type of restrictive soil layers that might inhibit source penetration and/or water movement. Quantity and quality the the accessible water supply likewise must it is in considered. The objective of watering management is to administer supplemental water necessary by the tree while maximizing the worth of water.

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Corn Water use Characteristics

Evapotranspiration (ETc), or chop water use, is the water gotten rid of from the soil by evaporation indigenous the soil surface and also transpiration through the plant. For corn, evaporation have the right to account because that 20 percent to 30 percent of growing season ETc. Transpiration is the last action in a consistent water pathway native the soil, into the plant roots, through the tree stems and also out v leaf surfaces and into the atmosphere. About 70 percent to 80 percent of chop water use results from plant transpiration. The quantity of day-to-day corn water use varies through atmospheric conditions: waiting temperature, humidity, solar radiation and wind speed. High wait temperatures, short humidity, clean skies and high wind speed will result in high and so on demand. High humidity, clear skies and low wind speed will result in lower and so on demand. Atmospheric demand must be changed for the stage of crop development to estimate crop water usage on a day-to-day basis. A high atmospheric need day in early on May will result in little ETc because the corn plant is tiny with a minimal root zone and small leaf area to transpire water. The exact same atmospheric demand day in mid-July will an outcome in near peak chop water use since the corn roots are fully developed and also the plant sheet area is sufficient to transpire water at prices equal to the atmospheric demand. This adjustment is referred to as applying a chop coefficient come the atmospheric demand or potential evapotranspiration.Seasonal water usage is impacted by climatic conditions, loved one maturity range, soil fertility, water accessibility and the interaction of these factors. Back the complete amount that water supplied by corn will differ from season to season and also location to location, the will typically follow the sample dictated through seasonal trends in weather variables and corn development. The smooth curve in Figure 1 (Curve A) illustrates the long-term median water usage pattern for corn. This typical water use pattern shows usual daily and so on levels throughout the farming season based upon the average daily etc over a 10 plus year period. The jagged curve in Figure 1 (Curve B) illustrates the fluctuation feasible in daily and so on values because that an individual year. Thus, irrigation managers must be familiar with the long-term trend but much more importantly be able to determine what the daily and so on was over the last few days. Knowledge of the permanent trend and also actual daily crop water use prices are crucial to determining as soon as to irrigate and also how lot water come apply.
Figure 1.Long-term daily average and individual year corn water usage with select growth stages.
In Nebraska, full corn water use varieties from 28 inches every year in the southwest come 24 inch in the east. Water necessity depends both ~ above the abovementioned atmospheric conditions and corn variety. The loved one maturity range of a specific variety has actually the most influence on seasonal ETc. Because that example, at the exact same location and in the very same year, a corn hybrid with a 113-day maturity will use more water than a 100-day hybrid. Longer-season corn hybrids use more water, yet they additionally have the potential to produce much more grain if the warm units and also water supply are available. If both varieties are able come mature fully, the grain created for each inch of etc is around equal. The difference in seasonal water usage is due to complete days the water use, and also in some cases a distinction in everyday water use. As result of variation in weather problems in a given year and also from year to year, the irreversible average chop water usage per day (Curve A) can vary by to add or inus 0.03 inches per day. Day-to-day variation in ~ a given year (Curve B) deserve to be an ext than 0.20 inches per day. Thus, for reasons defined above, usage of soil water sensors and also accessing daily crop water use estimates based on the weather conditions during the current growing season are very recommended. In addition, the term of each expansion stage might vary by plus or minus 2 days when contrasted to the long-term mean values noted in Table I.
Table I.Average crop water use (ETc) by growth stage for 113-day maturity corn grown in South central Nebraska.