Effect of limiting vertical root growth on maize yield and nitrate migration in clay and sandy soils in Northeast China

Increasing rooting depth via subsoiling is suggested to increase nitrogen (N) uptake and reduce nitrate leaching in maize. In a two-year field experiment, this hypothesis was evaluated with two levels of N supply (120 and 240 kg N ha⁻¹) in two soils with different leaching potential (infertile sandy soil and fertile clay soil). Maize rooting depth was limited to either the 0–20 cm (D20) or 20–40 cm (D40) soil layer using a nylon net (30 μm), or was not limited (control). There was no water stress during the growing seasons for both soils. Compared to the control, root length with the D20 and D40 treatments was longer in the 0–20 and 20–40 cm soil layers, respectively. However, total root length per plant differed less among the treatments. In clay soil, the D20 treatment did not affect N uptake, shoot biomass, or maize yield, but increased nitrate leaching. In sandy soil, the D20 treatment greatly reduced plant N accumulation, shoot biomass, and grain yield, while nitrate leaching was similar across the three treatments. It is concluded that deeper roots in maize contribute to increase N uptake and grain yield in sandy soil, but only help to reduce nitrate leaching in clay soil.