Deep Nitrogen Application Increase Maize Root Growth

Root system establishment is impaired by soil acidity and Al toxicity. Liming has been recommended to deal with soil acidity, but as lime moves slowly through the soil profile, subsoil acidity may not be ameliorated, especially under no-tillage. However, it has been observed that roots of many plant species respond with an increased localized root growth proliferation in nutrient-rich patches, but the interaction of liming and nutrient rich patches on root growth is not well understood. In the present study, maize initial development root growth and nutrition were evaluated as affected by nitrogen fertilizer application site and limestone distribution in the soil profile. The study was performed on glass walled pots. Nitrogen was placed 5.0 and 15.0 cm deep and lime was applied on the soil surface or incorporated down to 20.0 cm, plus a control without limestone. Root growth was evaluated every three days up to 21 days after plant emergence, when the experiment was terminated. There was no effect of liming on plant growth or N concentration in maize shoots and roots, but soil ammonium and nitrate were increased by liming, mainly when it was incorporated. Plant dry matter production, root length, surface and volume were increased, and a higher root growth rate was observed when N was placed 15 cm deep. Root growth was greater in the first 10 cm of the soil profile, and decreased with depth. The application of N fertilizer 15 cm deep in the soil profile stimulate the initial growth of the root system, as well as root growth in the subsoil, which is important for the crop establishment.