Agricultural Water Management (Oct 2023)
Effect of sowing date on water uptake patterns of maize and soybean in intercropping systems using stable isotopes
Abstract
Intercropping is a beneficial agricultural approach that enhances crop productivity and water use efficiency. However, the relationship between sowing date and water uptake in intercropping is not yet well understood. A two-year field trial was conducted to explore the impacts of sowing date on water uptake patterns of maize and soybean across different seasons using stable isotopes δ18O and δ2H in plant and soil water along with MixSIAR modeling. Three sowing times with intercropping systems (two-row maize and four-row soybean) were used: M2S4 (maize sowed at the same time as soybean), M2s4 (soybean sowed 4 weeks later than maize), and m2S4 (maize sowed 4 weeks later than soybean). Maize water absorption depths in intercrop systems were 0–20 cm (47.2 %), 20–150 cm (56.5 %), and 70–200 cm (72.9 %) for M2S4, 0–20 cm (45.1 %), 70–200 cm (59.8 %), and 70–150 cm (59.2 %) for M2s4, and 0–20 cm (51.7 %), 20–150 cm (58.5 %), and 20–150 cm (63.1 %) for m2S4 at jointing, silking, and maturity stages, respectively. Soybean water uptake depth was 0–20 cm for intercrops with different sowing dates. Delayed sowing of intercropped soybean or maize had no effect on the soybean water uptake depth. With delayed soybean sowing, the main water absorption depth during the growth period of intercropped maize was first deeper and then shallower. With delayed maize sowing, the water absorption depth of intercropped maize became shallower in the late growth stage. Land (1.01–1.34) and water (0.93–1.33) equivalent ratios indicated variations in the impact of intercropping sowing dates on yield and water use efficiency with the greatest ratios observed in M2s4 intercrop. The M2s4 model is considered to be the optimal planting time for intercropping systems on the Loess Plateau.
