Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2006
Publication Date: 7/9/2006
Citation: Colaizzi, P.D., Evett, S.R., Howell, T.A. 2006. SDI bed design comparison for soybean emergence and yield. In: Proceedings of the ASABE Annual International Meeting, July 9-12, 2006, Portland, Oregon. 2006 CDROM.
Interpretive Summary: Crop establishment is a serious limitation for subsurface drip irrigation (SDI) for many soils, including those common in the Southern Great Plains. We evaluated crop emergence and final yield for an alternative SDI design where laterals (lines of drip irrigation tubing) were installed in the center of wide beds with twin crop rows in each bed. This design is different from the traditional design where crop rows are evenly spaced and laterals are installed in alternate furrows (between two crop rows), but results in the same number of crop rows and SDI laterals. We hypothesized that the wide bed design would result in better crop establishment and final crop yield because the laterals were closer to the seed bed. In the 2005 growing season for soybeans, the wide bed design did result in a greater number of plants emerged but did not increase crop yields. We also varied the lateral installation depth for each SDI design at 15-, 22-, and 30-cm, which may be a trade-off between crop response and avoidance of mechanical or animal damage to laterals. Although the shallower installation depths tended to result in greater crop emergence, especially for the traditional standard bed design, lateral depth did not cause yield to be different. Furthermore, it had more frequent mechanical and rodent damage. The greater yield for sparser plant populations may have resulted from greater water and nutrient availability per plant. Although these results suggest that growers may not want to change their current SDI designs, this study will continue for additional seasons and different crops, which may have vastly different responses than the single season of soybean data presented here.
Technical Abstract: Subsurface drip irrigation (SDI) is gaining popularity with producers in the Southern and Central Great Plains region of the United States. Drip laterals are commonly installed in alternate furrows because it is cost prohibitive to install laterals in every bed for low value crops; however, crop germination can be difficult if preseason precipitation is inadequate. We evaluated soybean emergence and grain yield with laterals installed in wide beds containing two seed rows and compared this to laterals installed in alternate furrows and in every bed. The wide bed design requires the same number of laterals as the alternate furrow design, but the seed row is closer to the lateral. For each bed design, lateral burial depth was 15-, 22-, and 30-cm, and irrigation rates were 33, 66, and 100% of full crop evapotranspiration (ETc). The wide bed design generally resulted in greater plant emergence early in the season than standard beds; however, bed design and lateral installation depth did not usually result in significant differences in final grain yield. This implied that for sparse plant populations, greater water and nutrient availability per plant may have been compensating factors for final yield. This paper reports data for a single soybean crop season, and this experiment will continue for additional seasons and different crops.