EFFECT OF CONTROLLED DRAINAGE AND SUBIRRIGATION ON SUBSURFACE TILE DRAINAGE NITRATE LOSS AND CROP YIELD AT THE FARM SCALE

Abstract

An on-farm evaluation of controlled drainage and subirrigation systems can raise farmer awareness and acceptance of these innovative technologies. A four hectare field experiment was established on sandy-loam soil near Harrow in Essex County, Ontario. The field was modified to allow the implementation of two water table-management treatments, controlled drainage with subirrigation (CDS) and free outlet tile drainage (DR). Volume of tile drainage, nitrate concentration and loss in the tile drainage water and crop yields were measured. The objectives of the study were to provide on-farm demonstrations of controlled drainage and subirrigation systems, and to determine their effect on crop yields and environmental benefits.The CDS system reduced flow weighted mean nitrate concentration in tile drainage water by 38% and total nitrate loss by 37% compared to the DR system from May 1995 to April 1997. The CDS system increased marketable tomato yields by 11% in 1995. The average marketable tomato yields were 58.4 t ha−1 for DR system and 64.9 t h−1 for CDS system. The CDS system also increased corn yields by 64% in 1996. The average corn yields were 6.7 t ha−1 for DR system and 11.0 t ha−1 for CDS system. Thus, the CDS system effectively reduced total nitrate loss and improved yields of both processing tomatoes and grain corn on a sandy loam soil.