Irrigation and fertilizer effects on water use and yield of spring wheat in semi-arid regions

Controlled irrigation and fertilizing strategies under rainwater-harvesting technology in semi-arid areas were discussed. Effects of the amounts of applied water and fertilizer on water use and yield of spring wheat were determined. The experiment included four water treatments during the spring wheat growth period. The four treatments were (total water applied): rich water (RW), 400 mm; moderate water (MW), 300 mm; low water (LW), 100 mm, and natural water (NW), 212 mm. (In the first three situations, rainfall was excluded from irrigation plots while in the fourth only natural rainfall was utilized.) Four nutrition conditions were set up for each water treatment: high fertilizer (HF) 372 kg ha(-1), moderate fertilizer (MF) 248 kg ha(-1), low fertilizer (LF) 124 kg ha(-1) and without fertilizer application (CK). Each water-fertilizer treatment was replicated three times. Both soil water content and water use efficiency (WUE) (in terms of grain yield) increased with increasing applied water. The mean WUE were 6.37, 5.61, 5.08 and 4.40 kg ha(-1) mm(-1) in RW, MW, NW and LW, respectively. WUE increased increasing applied N and P fertilizer. Compared with LW treatment, MW and RW resulted in stronger seedlings, larger and deeper root system, and higher leaf area index (LAI). For RW, MW and NW, the maximum of root biomass increased 96.4, 56.6 and 21.6%, respectively, compared with that for LW. The value of LAI increased 95.6, 66.9 and 40.9%, respectively. The values of leaf area duration (LAD) in RW, MW and NW were remarkably higher than that in LW. Under RW, MW, NW and LW condition, the mean grain yield for the four fertilizer treatments were 3290, 2347, 1665 and 964 kg ha-1, respectively. The mean grain yield in RW, MW and NW increased 241, 143 and 73%, respectively, compared with that in LW. Yield components analysis indicates that the quality and quantity of spikelets and floscule played critical role in grain formation of spring wheat. Statistical analysis of experiment results indicates that the minimum coefficient of water-consumption (0.110 mm/(kg ha(-1))) occurred in RW, and the relevant optimal fertilizer application amount was 377 kg ha(-1). In various water-fertilizer treatments, WUE was the highest (8.733 kg ha(-1) mm(-1)) under rich water with high fertilization, while grain yield was consistently the highest (4514 kg ha(-1)). This indicates that rich water with high fertilizer is the most efficient way in the experiment. These results may offer help to controlled irrigation and fertilization in agricultural water management in semi-arid regions. (C) 2004 Elsevier B.V. All rights reserved.