High-frequency irrigation for water nutrient management in humid regions
1976
A water-nutrient management method was designed to prevent plant-water and nutrient stresses while maximizing the available soil water storage to accommodate rainfall. This method minimized the need for the soil as a storage reservoir for water and nutrients by frequently irrigating a portion of the root zone with small amounts of water and nutrients. The optimal range of soil matric potential, based on soil oxygen diffusion rate, soil strength, water desorption characteristics, and unsaturated hydraulic conductivity was used to determine high-frequency irrigation criteria for sweet corn (Zea mays L.). Trickle-irrigated plots yielded 12 and 14% more corn than did the furrow- and sprinkler-irrigated plots. When fertilizers were broadcast and banded, soil NO3-N profiles measured near the end of the growing season showed that, compared to furrow and sprinkler irrigation, trickle irrigation reduced NO3-N losses from the root zone. Optimal ear yield was produced with high-frequency trickle irrigation when the soil matric potential at the 15-cm soil depth was controlled at about -0.2 bar and plants were fertilized with 168 kg/ha each of N and K. Ear yield for this treatment was 66% higher than that for nonirrigated corn fertilized at the same rate. Soil NO3-N did not accumulate in the profile with depth and time in plots fertilized at the 168-kg/ha rate, but did accumulate in plots fertilized with 336 kg/ha. Generally, plots trickle-irrigated with fertilizer solution had a higher soil NO3-N content on the row than 50 cm from the row. The results of this research indicate that water use efficiency, N-use efficiency, and N leaching can be controlled in sandy soils when N and K are applied with high-frequency trickle irrigation systems and N and K rates are adjusted to maintain an optimal N-level in corn plants.
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