Cr. Camp et al., SUBSURFACE DRIP IRRIGATION LATERAL SPACING AND MANAGEMENT FOR COTTON IN THE SOUTHEASTERN COASTAL-PLAIN, Transactions of the ASAE, 40(4), 1997, pp. 993-999
The cost of drip irrigation can be reduced by using both wider lateral
spacings and the same laterals for multiple years, as with subsurface
placement. Multiple, low-rate fertilizer and water applications may r
educe N fertilizer needs by improving efficiency and limiting the pote
ntial for leaching. The combination of these technologies may make dri
p irrigation of cotton profitable. Four years of continuous cotton and
two years of cotton rotated with peanut were evaluated. Two subsurfac
e drip irrigation lateral spacings (every row, 1 m, and alternate furr
ow, 2 m) and three sidedress-nitrogen methods (STD, single application
of 112 kg/ha; INC, 112 kg/ha in five equal applications; and GOS, app
lications determined by GOSSYM/COMAX) were evaluated for cotton during
1991-1994. Two of the sidedress-nitrogen methods (STD and GOS) were e
valuated for a rainfall-only treatment Lint yields did not differ betw
een the lateral spacings in any year Yields for irrigated treatments w
ere 16 and 65% greater than rainfall-only yields in 1992 and 1993, res
pectively. The GOSSYM/COMAX-managed nitrogen treatment received 30% le
ss nitrogen fertilizer than other treatments, but had similar lint yie
ld. Several fiber physical properties were affected by irrigation and
nitrogen, but these effects were small and inconsistent. For continuou
s cotton, or cotton rotated with peanut, the wider lateral spacing is
preferred to the every-row spacing because of its lower initial cost (
a:bout 30%). The combination of lower system cost, longer system life,
and lower N-fertilizer requirements could make subsurface drip irriga
tion of cotton profitable for southeastern Coastal Plain soils, and re
duce the potential for ground water contamination.