[Coupling effect of water and nitrogen for cotton under different furrow irrigation patterns].

ABSTRACT

A field plot experiment with general rotation design was conducted to study the coupling effect of water amount and nitrogen (N) application rate for cotton under alternative furrow irrigation (AFI), conventional furrow irrigation (CFI), and fixed separate furrow irrigation (FFI). When the water amount was 37.52-160.00 mm and N application rate was 56.2-95.2 kg N x hm(-2), cotton yield had significant positive correlations with them; when the two factors were in the ranges of 160.00-218.48 mm and 95.2-134.2 kg N x hm(-2), respectively, no significant change was observed in the cotton yield. Within the test ranges of water amount and N application rate, cotton yield had no significant difference between AFI and CFI, but was 9.15% higher under CFI than under FFI. The water use efficiency (WUE) of cotton was significantly negatively correlated with the water amount 37.52-160.00 mm and positively correlated with the N application rate 56.2-122.8 kg N x hm(-2), but had no significant change when the water amount was 160.00-218.48 mm and N application rate was 122.8-134.2 kg N x hm(-2). Within the test ranges of water amount and N application rate, the WUE had no significant difference between CFI and AFI, but was 9.01% higher under CFI than under FFI. The nitrogen use efficiency (NUE) of cotton had significant positive correlation with the water amount 37.52-160.00 mm but significant negative correlation with the N application rate 56.2-134.2 kg N x hm(-2), and had no significant difference between AFI and CFI but was 6. 34% was lower under FFI than under CFI. Appropriate measures for high-efficiently using water and nitrogen resources under different furrow irrigation patterns were put forward to optimize cotton yield, WUE and NUE.