SUMMARY OF IRRIGATION STUDIES CONDUCTED AT THE SWEET POTATO RESEARCH STATION, 2000–2005

Abstract

This report summarizes the results of irrigation studies conducted from 2000 to 2005 at the Sweet Potato Research Station, Chase, La. These studies investigated the role of various scheduling methods, soil moisture measurement devices, and irrigation delivery methods in sweetpotato production. The studies indicate that 15 to 20 inches of total rainfall and supplemental irrigation is required to produce 400 to 525 bu/acre of US#1 storage roots in Beauregard. Supplemental irrigation can be scheduled based on this benchmark, potentially reducing over-irrigation during dry periods. We have also found that during dry periods, irrigating every furrow can bring about 50% difference in US#1 yield vs. supplying irrigation to alternate furrows. During growing seasons characterized by optimum rainfall patterns, we did not detect any response in US#1 yield to various irrigation treatments. We evaluated several moisture measurement devices including granular matrix sensors, evaporation pan, time domain reflectometry (TDR)-based instrument, and tensiometers. We found the TDR-based device easy to use and convenient in terms of its portability. Based on studies conducted in 2001 and 2002, this device demonstrated potential as a management tool in sweetpotato production. For instance, a management allowable deficit (MAD) of 25% available moisture as measured using the TDR-based device can potentially result in the same yield as weekly irrigation and a MAD of 50% available moisture. When used properly, irrigation scheduling can reduce over-irrigation and contribute to overall efficiency in the use of production inputs.