April 30, 2002

LINCOLN, Neb. — Recent rains brought some relief from dry conditions in parts of Nebraska but drought worries aren't over. Minimizing tillage is one way to conserve precious soil moisture, if dry conditions continue.

No-till and other conservation practices will minimize the risk of soil erosion, conserve soil moisture and keep dust storms at bay this dry spring, said Paul Jasa, an NU Cooperative Extension engineer.

"Every tillage trip across the field depletes about an inch of soil moisture," Jasa said. Most soils hold two inches of available water per foot on average. If a farmer tills six inches deep, about an inch of moisture is lost.

Crops grown without tillage will use topsoil and subsoil moisture more efficiently, Jasa said. Minimizing tillage also increases soil's water-holding capacity, decreases evaporation and reduces soil erosion.

If possible, instead of shredding corn stalks, Jasa suggests leaving them standing.

"Shredded stalks will blow," he said. "If they're standing upright, they will stay anchored to the ground and keep the wind off the soil surface."

If tillage is necessary, farmers should minimize tillage this spring by combining multiple trips into one and setting equipment as shallow as possible to leave more residue, Jasa said.

In tilled fields, planting seeds deeper can help assure they receive moisture. This also would be beneficial for no-tilled crops, he said. Farmers typically worry that lower soil temperatures will inhibit germination if they plant seeds too deeply. With soil temperatures around 60 degrees, there is no need to worry about soil being too cold, Jasa said.

Early weed control also is important.

"If we are in dry conditions, remember weeds use valuable soil moisture and taller weeds will be going into drought stress," Jasa said. "When weeds are under stress, they are harder to kill; however, drought-stressed crops are more vulnerable to injury when spraying post-emergence herbicides."

Some relief might be in store as the long-term forecast for May through July indicates a slightly better chance of seeing above normal precipitation, said Mark Svoboda, climatologist at the National Drought Mitigation Center based at NU. These conditions are more likely in south central and southeastern Nebraska, but the entire state is included in this tendency. Temperatures have equal chances of being above normal, normal or below normal, he said.

Precipitation so far this year is significantly below normal statewide. From Jan. 1 through Monday (April 29), precipitation was 44 percent of normal in the Panhandle, 69 percent of normal in north central Nebraska, 68 percent of normal in northeast Nebraska, 58 percent of normal in central Nebraska, 74 percent of normal in east central Nebraska, 48 percent of normal in southwest Nebraska, 43 percent of normal in south central Nebraska and 72 percent of normal in the southeast portion of the state.

Water shortages could develop for irrigators if dry conditions continue throughout the summer, said Al Dutcher, state climatologist with the NU Institute of Agriculture and Natural Resources.

"Streams should be at their peak now, but we've lost six weeks of runoff from the lack of snow in the Rocky Mountains," Dutcher said.

Snowpack in the Colorado and Wyoming mountains that feeds the Platte watershed was only 80 percent of what it was by the end of March last year. This represents less than 60 percent of the historical average, he said.

Streamflow projections for this summer are for less than 60 percent of normal flow if normal precipitation is received for the period.

The southern Panhandle and southwest Nebraska are areas of major concern for irrigation water supplies, he said. Enders, Harlan, McConaughy, and Swanson reservoirs are all low, he said. Irrigation delivery restrictions are a certainty for Enders and Swanson users, with initial estimates placing deliveries at six inches of water per user for the season.

"There is little if any hope to see those restrictions lifted this year. The drought in the southwest corner of the state is a real nightmare," Dutcher said. "I don't see any serious relief in having those reservoirs come back up in the Republican River system."

No irrigation restrictions are anticipated for Lake McConaughy this year, but a below normal snowpack next winter would likely force authorities to consider the issue next spring, Dutcher said.

04/30/02-SA

Allen Dutcher - Ph.D
School of Natural Resources
State Climatologist
(402) 472-5206

Mark Svoboda
National Drought Mitigation Center
Climatologist
(402) 472-8238

Paul Jasa
Biological Systems Engineering
Extension Engineer
(402) 472-6715

Sandi Alswager Karstens
IANR News and Photography
(402) 472-3030

Department: Biological Systems Engineering|School of Natural Resource Sciences