Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 1997
Publication Date: N/A
Interpretive Summary: Some fine-textured soils in the Southern Great Plains infiltrate irrigation water rather slowly. With the furrow irrigation method, water is applied through sloping furrows (small ditches) between crop rows. Tractor wheel traffic also passes through these furrows during cultural operations, such as planting and cultivating, which packs the soil and further reduces water rinfiltration. Irrigation water infiltration tests were made after both on and two passes through furrows with light (9,000 lb) and heavy (18,000 lb) tractors. One pass with the heavy tractor reduced furrow infiltration by 38% compared to 23% with the light tractor. Two passes reduced infiltration 43% with the heavy tractor compared to 33% with the light tractor. Normal tillage to about 6 inches deep after crop harvest eliminated most of the soil compaction problem. This information helps furrow irrigators in planning operations to improve irrigation water use efficiency, thereby reducing the amount of water used to supplement rainfall for dependable crop production.
Technical Abstract: Pullman clay loam and related soils in the Southern High Plains are slowly to moderately permeable, and furrow wheel traffic reduces irrigation intake. Traffic effects were evaluated with treatments of one (1) and two (2) furrow passes with light (L) and heavy (H) tractors of 4.1 and 8.2 Mg mass. Treatments are designated L**1, L**2, H**1, and H**2. Both heavier tractors and repeated traffic increased compaction, reducing irrigation intake rates and total intake. Soil strength was greatest at the 100 to 150-mm depth for all compaction treatments. For the first 8-h infiltration test after tillage, the L**1, L**2, H**1, and H**2 treatments reduced average intake by 23, 33, 38, and 43%, respectively; compared with 212 mm of intake for the check. Because of furrow surface consolidation after the first irrigation, intake for all treatments was about 20% less during the second test 60 days later; when the check infiltrated 171 mm and traffic induced intake reductions were 16, 23, 28, and 36%, respectively; for L**1 L**2, H**1, and H**2 treatments. A better understanding of furrow traffic effects on irrigation intake helps irrigators to improve water application efficiency.