Nitrate content and nitrogen loss in drainwater.

Abstract

On cropped arable land, the nitrate content of drainage water showed a distinct maximum in spring (Mar.-May) and a minimum in autumn (Nov.). On grassland it was more constant during the year, except when N was applied in autumn or winter (liquid manure, f.y.m., liquid ammonia) when the situation was the same as for cropped arable land. An average content of 1-2 mg N/1. was found for grassland, and of 4-10 mg/1. for cropped arable land, depending on the clay content of the soil. From lysi-meter experiments it was found that on cropped arable land (350 mm drainage water per year) and from a soil profile of 100-125 cm with a clay content of 35% or more, little N was lost by leaching. On sandy soils (0-10% clay), however, about 60 kg N/ha could be lost yearly and 20% of the applied fertilizer N was leached out of the profile. On grassland, leaching losses depended on time of application of the N. A better distribution of the applied N during the growing season than on arable land and the high rate of N uptake by the grass greatly reduced the losses of applied N during the period Mar.-June, even on sandy soils. Later on, the losses could rise to a maximum of 40% for N applied in Nov.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)