Long-Term Study Suggests Management Adaptations for Weather Extremes

Long-Term Study Suggests Management Adaptations for Weather Extremes

From droughts to flooding, extreme hydrological phenomena are the costliest hazards in rainfed agriculture in Nebraska and around the world. Precipitation trends in the coming decades are expected to become more variable as the climate changes, making these rainfed production systems potentially more vulnerable to large hydrological fluctuations.

A recent article published in the Soil and Tillage Research Journal explores how a long-term tillage study in northeast Nebraska can offer insights on how to successfully adapt to future climate changes by adjusting specific management practices. The article, What do meteorological indices tell us about a long-term tillage study?, is by Ankit Shekhar of the Indian Institute of Technology Kharagpur and Charles Shapiro, emeritus, University of Nebraska-Lincoln professor and soil scientist. The article looks at water and climate conditions and crop responses to various management changes.

The researchers used two meteorological drought indices, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), to determine if either helps differentiate the tillage, nitrogen, and rotation treatments across the indices’ ranges and in making management decisions. 

Among the findings are:

  • A corn-soybean rotation under normal and wet conditions increased corn yields 28% and 17% compared to a corn-corn sequence; however, under extreme and prolonged drought conditions (more than a year) corn yield was 17% greater in continuous corn compared to a corn-soybean rotation.
  • If future seasonal climatic conditions are wetter, nitrogen rates may need to be increased.
  • Under dry conditions for both a corn-corn and corn-soybean rotation, no-till had 10% and 24% greater yield than disk and plowing, respectively. However, under wet conditions, corn yield under disk or plow was 3% greater than under no-till.

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Study Details

Site: Haskell Agricultural Laboratory, northeast Nebraska

Period: 1986-2016

Soils: A mixture of Coleridge silty clay loam, Baltic silty clay, and Maskell loam.

Moisture: Long-term average (1973–2016) yearly rainfall and seasonal evapotranspiration (ET) was 27.64 ± 7.28 inches (standard deviation) and 34.69 ± 4.12 inches, respectively. 

Tillage: Split-split plot with four replications; blocks were tillage, no-till, spring-fall plow, and disk.

Fertilizer: Five nitrogen rates were broadcast preplant as ammonium nitrate (34-0-0) in the corn sub-subplots at a rate of 0, 40, 80, 120 and 160 kg hectare (1 kg/hectare = 0.892 lb/ac).