Effect of long-term conventional tillage and no-tillage systems on soil and water quality at the field scale.
No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces soil erosion and production costs relative to conventional tillage (CT). However, the impacts of no-tillage on the quantity and quality of tile drainage water are less well known. Accordingly, two adjacent field scale on-farm CT and NT sites were established to compare the impacts of the two tillage systems on tile drainage and NO3-N loss in tile drainage water. The effect of the two tillage systems on soil structure, hydraulic conductivity, and earthworm population were also investigated. The total NO3-N loss in tile drainage water over the 5-yr period (1995-1999) was 82.3 kg N ha(-1) for the long-term NT site and 63.7 kg N ha(-1) for the long-term CT site. The long-term NT site had 48% more tile drainage (6,975 kL ha(-1)) than the long-term CT site (4,716 kL ha(-1)). The average flow weighted mean (FWM) NO3-N concentration in tile drainage water over the 5-yr period was 11.8 mg N L(-1) for the NT site and 13.5 mg N L(-1) for the CT site. For both tillage systems, approximately 80% of tile drainage and NO3-N loss in tile drainage water occurred during the November to April non-growing season. Long-term NT improved wet aggregate stability, increased near-surface hydraulic conductivity and increased both the number and mass of earthworms relative to long-term CT. The greater tile drainage and NO3-N loss under NT were attributed to an increase in continuous soil macropores, as implied by greater hydraulic conductivity and greater numbers of earthworms.
Tan
C S
CS
Greenhouse and Processing Crops Research Centre, Agriculture and Agri-Food Canada, Harrow, ON.
Drury
C F
CF
Reynolds
W D
WD
Gaynor
J D
JD
Zhang
T Q
TQ
Ng
H Y
HY
D000383:Agriculture; D000818:Animals; D004784:Environmental Monitoring; D009566:Nitrates / Q000032:analysis; D009835:Oligochaeta; D011157:Population Dynamics; D012987:Soil; D014873:Water Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000517:prevention & control
D009566:Nitrates; D012987:Soil; D014873:Water Pollutants