Tips For Scheduling Irrigation During Kansas Drought Conditions

Kansas is prone to periodic droughts and large variations in precipitation. During drought conditions, efficient, well-timed irrigation preserves yield, protects soil and groundwater resources, and reduces pumping costs. This article provides practical, field-ready guidance on scheduling irrigation in Kansas: how to prioritize water, use measurements and weather data, apply drought strategies, and make system adjustments that stretch limited supplies without sacrificing crop or forage value.

Understand the local context: climate, water supply, and soils

Kansas spans climate zones from humid continental in the northeast to semi-arid in the west. The primary water sources for irrigation are the Ogallala (High Plains) Aquifer, surface reservoirs, and smaller local aquifers. Declining water tables in many western Kansas counties and state allocations during severe drought mean scheduling must account for both short-term crop needs and long-term water availability.
Soil texture determines how much plant-available water (PAW) is stored in the root zone. Typical ballpark PAW values:

Sandy soils: 0.5 to 1.0 inches PAW per foot of soil.
Loamy soils: 1.5 to 2.0 inches PAW per foot.
Clay and silty clay loam: 1.2 to 1.8 inches PAW per foot.

These are general estimates; a site-specific soil survey or probe measurements provide the best inputs for scheduling.

Set irrigation priorities and allowable depletion

Drought forces triage. Rank irrigated fields by crop value, growth stage sensitivity, and long-term importance.

High priority: crops in critical growth stages (corn at tassel and pollination, soybeans during flowering and pod set, small grains at heading and grain fill, alfalfa at regrowth).
Medium priority: established forage, non-critical field crops.
Low priority: late-season or low-value crops, newly seeded fields you plan to replace.

Use management allowable depletion (MAD) to decide when to irrigate. MAD is the fraction of PAW a crop can use before irrigation is required. Practical MAD guidelines under drought:

Turf and newly seeded plants: 25% to 35% MAD.
Vegetables and fruit trees: 25% to 40% MAD.
Corn (critical stages): 30% MAD, outside critical stages 40% to 50%.
Soybean: 30% to 50% depending on stage; tightest during pod fill.
Wheat: 30% during heading, 50% early or late.
Alfalfa: 25% to 40% depending on cutting schedule.
Forages/pasture: 40% to 60% if you accept lower quality/yield.

Lower MAD means more frequent irrigation with smaller amounts; higher MAD stretches intervals but increases stress risk.

Use weather and ET-based scheduling

Evapotranspiration (ET) scheduling ties irrigation to actual atmospheric demand. In drought, ETo (reference evapotranspiration) can remain high, so measuring or estimating it is essential.
Steps to use ET scheduling:

Obtain daily ETo from local sources (Kansas Mesonet, nearby weather station, or a reliable regional estimate). If you cannot get station data, use pan evaporation values adjusted to ETo or regional averages.
Select the crop coefficient (Kc) for the crop and growth stage. Examples: early corn Kc 0.3-0.6, mid-season corn Kc 1.05-1.15, full canopy soybean Kc 0.9-1.15.
Compute crop ETc = ETo * Kc (in inches per day).
Determine allowable depletion (MAD * PAW * root depth) to calculate the trigger depletion in inches.
Schedule irrigation to replace that trigger depletion, adjusting for system efficiency.

Example calculation (illustrative):

ETo = 0.30 in/day (hot, dry week).
Crop: mid-season corn, Kc = 1.10, so ETc = 0.33 in/day.
Rooting depth assumed 30 inches, loam soil PAW ~1.8 in/ft -> 1.8 * 2.5 ft = 4.5 in TAW (total available water).
MAD = 0.4 -> allowable depletion = 4.5 * 0.4 = 1.8 in.
If you want to irrigate every 6 days, total ET loss = 0.33 * 6 = 1.98 in; so plan to apply about 2.0 in, factoring application efficiency. If system efficiency is 80%, required application = 2.0 / 0.80 = 2.5 in.

Make these site-specific. Root depths, PAW, Kc, and system efficiency vary.

Measure soil moisture and use sensors

Weather-based scheduling is powerful, but confirm it with soil moisture measurements. Common tools:

Tensiometers: good for wetter ranges; show soil tension directly related to plant uptake.
Capacitance probes/soil moisture sensors: provide volumetric water content and are easy to read remotely.
Watermark sensors/gypsum blocks: affordable, measure soil moisture tension.
Neutron probe or electrical resistance blocks: used on larger operations.

Install sensors at representative depths: for corn monitor at 6, 18, and 30 inches; for soybeans 6 and 24 inches; for turf 4 to 8 inches. Use multiple sensors across fields if soils or irrigation uniformity vary.
Interpretation rules:

When volumetric moisture falls to the MAD-derived trigger, irrigate.
If sensors show inconsistent readings across a field, irrigate smaller zones separately or prioritize lowest-moisture areas.
Calibrate sensors to local soil textures for accuracy.

Adjust irrigation method and timing for efficiency

Kansas irrigation systems include center pivot, wheel line, stationary sprinklers, drip/SDI, and flood/furrow. Under drought, optimize each system.
Center pivot tips:

Use low-pressure nozzles and uniform nozzles matched to speed to reduce misting losses.
Consider LEPA or low-energy application to reduce evaporation and wind drift.
Apply multiple short cycles (cycle and soak) for soils with surface runoff risk or limited infiltration.

Drip and subsurface drip:

Highest application efficiency; prioritize for high-value crops and vegetable production.
Maintain filters and pressure regulators to prevent emitter clogging during low-flow, high-salinity irrigation.

Furrow and flood:

Reduce runoff by scheduling smaller, more frequent applications.
Use surge irrigation where possible to increase infiltration and uniformity.
Shorten furrows or use tailwater recovery.

Timing of day:

Irrigate early morning (before sunrise to a few hours after) to reduce evaporation losses. Avoid late evening unless disease risk is low and air temperatures are cool; night irrigation can increase humidity and disease risk in some crops.

Implement deficit and alternative irrigation strategies

When full water replacement is impossible, consider regulated deficit irrigation (RDI) and partial root-zone drying (PRD) for certain crops.

RDI: intentionally under-irrigate at non-critical stages to conserve water while protecting yield during critical windows. For example, reduce irrigation of corn during vegetative stages and restore full supply at tassel and pollination.
PRD: water one side of the root zone at a time, alternating sides every 7-14 days. This can maintain water use efficiency in some fruit and vine crops but requires careful management and is less common for annual row crops.
Prioritize irrigation to high-value fields and critical growth stages rather than evenly reducing across all fields.

Know the risks: deficit strategies can reduce yield and quality if applied at wrong stages or too severely. Use a conservative MAD and monitor crop response.

Manage root depth and soil health to improve drought resilience

Deeper rooting increases water access. Practices to encourage deeper roots:

Maintain balanced fertility; lack of nitrogen can limit root growth.
Reduce surface compaction with controlled traffic.
Use cover crops in rotation to improve soil structure and organic matter, but be cautious in severe drought years as cover crops may compete for scarce moisture unless terminated early.
Incorporate organic matter and gypsum where appropriate to improve water holding and infiltration.

Mulching and residue management on smaller plots and orchards reduce surface evaporation and moderate soil temperature.

Practical operational checklist for weekly scheduling

Check local ETo and recent rainfall totals every 3 to 7 days.
Read soil moisture sensors at multiple depths and locations.
Compare observed depletion to allowable depletion (MAD).
If depletion exceeds trigger, calculate depth to apply using ETc and interval since last irrigation.
Adjust gross application for system efficiency and expected overlap/uniformity issues.
Run irrigation in early morning and split cycles if infiltration is limited.
Record pump hours, applied depths, well static and pumping water levels to monitor aquifer drawdown.
Inspect and repair leaks, broken nozzles, and poor uniformity zones promptly.

Legal and long-term considerations

Monitor water rights, allotments, and mandatory restrictions from Kansas Department of Agriculture or local water districts. Drought can trigger reduced allocations or curtailments.
Track well drawdown and pumping costs; if water levels are declining rapidly, accelerate conservation measures and consider transition strategies for long-term sustainability.
Evaluate investments: in prolonged droughts, switching to more efficient systems (drip, LEPA pivots, variable rate irrigation) may be economically justified for high-value crops.

Case study example (concise)

A pivoted corn field in western Kansas during a hot, dry two-week period:

Soil: silt loam, estimated PAW 1.8 in/ft, root zone 36 inches -> TAW = 1.8 * 3 = 5.4 in.
ETo: 0.325 in/day, Kc mid-season 1.10 -> ETc = 0.357 in/day.
MAD chosen 40% -> allowable depletion = 5.4 * 0.4 = 2.16 in.
If last irrigation was 7 days ago, ET loss = 0.357 * 7 = 2.50 in > allowable depletion, so irrigate.
System efficiency 85% -> required application = 2.50 / 0.85 = 2.94 in. Because pivot uniformity is strong, schedule a single pass to apply ~3.0 inches, or two passes of 1.5 in if runoff is a concern. Monitor soil moisture post-irrigation and adjust MAD if water supply is constrained.

Final practical takeaways

Use both weather (ETo) and soil moisture data to make informed scheduling decisions; one without the other increases risk.
Prioritize crops and critical stages when water is limited; accept managed deficits on secondary fields.
Choose MAD conservatively when water is scarce and increase frequency with smaller applications rather than full, infrequent irrigations that stress crops.
Improve system efficiency and repair leaks; consider long-term investments in high-efficiency systems for repeated drought years.
Monitor groundwater and legal water allocation changes; adjust operational plans to avoid forced curtailments.
Keep clear records of irrigation events, applied depths, well levels, and yields to refine scheduling over time.

Irrigation during Kansas drought is about balancing immediate crop needs and long-term water stewardship. With disciplined measurement, clear prioritization, and efficient application, you can preserve yield and protect water resources even in tight water years.