Controlled mineralizing acetaldehyde condensation urea (CM-CDU) fertilizer can reduce nitrate leaching and N2O emission from an Andisol with continuous cropped komatsuna (Brassica napa L.)

Abstract

To reduce nitrogen (N) loss from vegetable fields with minimum labor, the effects of a single application of different types of controlled mineralizing acetaldehyde condensation urea (CM-CDU) fertilizer on crop yield and N uptake, nitrate leaching from the surface soil (0-20 cm) and N2O emission from the soil after two continuous croppings of a leafy vegetable (komatsuna, Brassica napa L.) were examined. The following four treatments were established in plastic containers filled with an Andisol: urea, CM-CDU-4, CM-CDU-10 at a rate of 30 g N m-2 and a control (no N fertilizer). The CM-CDU-4 and CM-CDU-10 treatments released 80% of N at 25°C in 30-60 and 90-140 days after fertilizer application, respectively. The yields for the two crops were 1.55, 1.55, 1.26 and 0.34 kg fresh weight m-2 in urea, CM-CDU-4, CM-CDU-10 and the control, respectively. The amount of total nitrate leaching was 3.4, 2.3, 1.2 and 0.3 g N m-2 from urea, CM-CDU-4, CM-CDU-10 and the control, respectively. The total amount of N2O emission from urea, CM-CDU-4, CM-CDU-10 and the control over two crops was 0.12, 0.06, 0.04 and 0.01 g N m-2, respectively. The emission factors were 0.7, 0.3 and 0.2 from the urea, CM-CDU-4 and CM-CDU-10 treatments, respectively. The N use efficiency of urea, CM-CDU-4 and CM-CDU-10 was 87, 85 and 59%, respectively. Among the examined fertilizers, we recommend CM-CDU-4 as best for komatsuna production after examining two continuous croppings with a single application. © 2009 Japanese Society of Soil Science and Plant Nutrition.