The Effects of Soil Salinity on Maize

Salinity Causes

• Soil salinity is the measure of water-soluble salts occurring in the soil. Salinization, or an increase in soil salinity, results when evaporating water leaves salt behind to accumulate, which can occur naturally in areas of low annual rainfall or can be caused by improper field management practices, according to the USDA Natural Resources Conservation Service. In arid regions with a high water table, water can leach up through the top layers of soil and evaporate, creating high levels of soil salinity. Soils lacking in organic matter can increase evaporation from underlying water tables while compacted soils can increase surface pooling and evaporation, both of which increase soil salt levels.

Effects on Maize Growth

• Maize, or corn, is one of the most salt-sensitive field crops, showing obvious signs of stress, including wilting even when there is adequate soil moisture, dull leaves, and gray leaf tips, according to the "Maize Doctor" online resource information base of the International Maize and Wheat Improvement Center. Salt in the soil causes more difficulty for corn to absorb water and nutrients through its roots, causing a marked decrease in nitrogen intake, according to a 1996 field study in the "Soil Society of America Journal." Nitrogen is a fundamental component of crop fertilizer and a necessary element for plant growth and photosynthesis.

Effects on Maize Yield

• Soils with high salinity can cause a significant decrease in maize yield, according to a 1996 study by European agricultural researchers published in "Options Mediterraneennes." While maize showed a relatively high tolerance for drought in comparison with sunflowers in that study, soil salinity substantially reduced the grain yield of both crops. Corn yield in the highest salinity category was 25 percent less than corn yield in growing conditions that were not saline. Lower yield is most likely a result of decreased photosynthesis in maize plants grown in saline soils.

Solutions

• Sufficient rainfall or irrigation with clean, non-saline water can alleviate soil salinity by dissolving the soil salts and washing them deeper into the soil, below the root zone of growing crops like maize. Irrigating less frequently but using more water each time can improve soil salinity, according to "Maize Doctor." Maintaining adequate organic matter in the soil also helps reduce salinity by improving drainage and preventing rapid water table evaporation. Managing drainage of irrigation water, rainwater, and snow melt to avoid surface pooling and evaporation reduces salt deposition. Maize's sensitivity to saline means it can be planted in small patches to serve as an indicator crop; soils that are not too saline for corn should be fine for other crop cultivation.