Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2003
Publication Date: 4/5/2004
Citation: -- Interpretive Summary: Nitrogen is typically applied to cotton using two or three split applications. Subsurface drip irrigation (SDI) systems have the potential to apply nitrogen daily with each irrigation event. The response of cotton lint yield or grade to the application of nitrogen on a daily basis is unknown. Nitrogen fertilizer was applied daily to cotton through a SDI (subsurface drip irrigation) system and compared with split applications at recommended times in both a dryland and sprinkler irrigated areas. Cotton was planted following peanut during both study years (1999 and 2000). The SDI system was able to supply irrigation water at three irrigation levels. The first fertilizer treatment applied nitrogen starting at 40 days after planting. The second fertilizer treatment started at 50 days after planting. The total amount of nitrogen for each treatment was to be applied by 90 days after planting. Lateral spacing consisted of drip tubing placed underneath each row and in alternate furrows. Overall, lint yield was higher in both the irrigated treatments compared with the DRY regime. There were grade differences but these differences were not consistent from year to year with respect to nitrogen applied or irrigation system. Overall, the application of nitrogen on a daily basis through the SDI system had the same lint yield and grade compared with SP and both irrigation treatments had higher lint yield than the DRY. The lower nitrogen rate had essentially the same lint yield as the higher nitrogen rate when applied through the SDI (subsurface drip irrigation) system. Therefore, water and nitrogen can be applied daily through a subsurface drip irrigation system on cotton. irrigated systems. These practices should result in lower monetary input of water and nitrogen costs to the grower.
Technical Abstract: Nitrogen is typically applied to cotton (Gossypium hirsutum L.) in two or three split applications, however, with subsurface drip irrigation (SDI), nitrogen can be applied daily. The major objective was to show yield and grade response of cotton where nitrogen was applied daily through a SDI system at two nitrogen application strategies compared with accepted sprinkler (SP) and non-irrigated (DRY) regimens. The SDI system provided daily irrigation and nitrogen to a randomized block design with three irrigation levels (100%, IL1; 75%, IL2; and 50%, IL3), two nitrogen levels, N1 and N2, (67 and 101 kg ha-1), two drip tube lateral spacings, IR and AM (individual row = IR, alternate row middles = AM), with three replications per treatment. Nitrogen was applied in split applications to the SP and DRY areas in a randomized block design. Cotton was planted following peanut during the 1999 and 2000 growing seasons on a Tifton sandy loam soil (fine-loamy, kaolinitic, thermic Plinthic Kandiudults). In 1999, there was a 6% lint yield increase for N2 (total lint; 1484 kg ha-1), but there was no lint yield difference with nitrogen levels in 2000 (total lint; 1280 kg/ha). There was no yield difference with drip tube lateral spacing or irrigation level except at IL3 (50%) in 1999. Lint yield was higher in both the SDI and SP compared with the DRY regime. Differences within grade parameters were not consistent across years for micronaire, fiber strength, or fiber uniformity with respect to nitrogen applied or irrigation system. Overall, the application of nitrogen on a daily basis through the SDI system had the same lint yield and grade compared with SP and higher lint yield than the DRY. The lower nitrogen rate (N1) had the same yield as the higher nitrogen rate (N2) when applied through the SDI system which could result in less nitrogen applied and monetary savings to the grower.