Yield response of corn and grain sorghum to row offsets on subsurface drip laterals

Subsurface drip irrigation (SDI) is a micro-irrigation system that could be adopted by producers in the semi-arid regions around the world for efficient use of water. Yet, several crop management issues related to SDI system need to be addressed to assess the feasibility of SDI. One such issue is the impact of crop row placement on crop performance, irrigation water use efficiency and yield under SDI. A study was conducted in the Southern U.S. Great Plains, in which drip tape laterals were buried 30 cm deep at 153 cm spacing, with two crop rows planted at 76 cm spacing, and irrigated with one tape. Corn (Zea mays L.) and grain sorghum (Sorghum bicolor L.) rows were offset from equidistance from the drip tape by 0, 8, 15, 23, and 38 cm using high precision guidance system (real time kinematics). This resulted in 5 treatments and 4 replications. This treatment structure was imposed on three irrigation (high, medium and low) regimes. Analysis of Variance showed no interaction between offset treatments and irrigation or year in corn and grain sorghum yields. The row offset did not impact the overall yield as the yield loss in row farther from the tape was compensated by the increased yield in row moved closer to the tape. The yield distribution ranged from 50% in both rows for 0 cm offset to 59% in row closer to the tape for 38 cm offset. The findings of this study suggests that while driver accuracy is important to maintain equal yields in neighboring crop rows, the overall yields are affected more by irrigation and climatic conditions and not by the row offsets with respect to SDI tape. This data suggests that SDI can be successful regardless of access to high precision guidance systems.