Information
The effect of furrow length on rain and irrigation induced erosion on a vertisol in Australia
Level 1 General description
Purpose:
This study monitored runoff and sediment movement from irrigated furrows of different lengths and slope gradients, and the influence of rainfall and cultivation on a cotton farm within central Queensland.
Methods (brief)
The study was undertaken on Robert’s cotton farm within the Emerald Irrigation Area (EIA) in Emerald Queensland. Furrow lengths studied were 151 and 298 m long at a gradient of 1.3%. Runoff and soil loss was measured from six furrows over the 1986-87 cotton growing season.
Key findings (brief)
The critical erosion period was identified to be between pre-plant irrigation and canopy closure accelerated during storm events, particularly in the early season when soil cover was low. Sediment concentration from rainfall and irrigation declined when cultivation had ceased, soil in the furrows had consolidated and when the cotton canopy had sufficiently grown to provide surface cover.
Table 1. Mean annual runoff and soil loss concentrations exploring the impact of furrow length and slope gradient in Robert’s cotton farm. Study period 1986-87 growing season (September – March).
|
Treatment |
Slope length m |
Slope % |
LS1 |
Runoff mm |
Soil loss t/ha |
EMC 1
gm/L |
Normalised2 Soil loss t/ha |
Normalised3 EMC gm/L |
|
Short furrow |
151 |
1.3 |
0.2 |
16.55 |
0.876 |
5.3 |
4.38 |
26.5 |
|
Long furrow |
298 |
1.3 |
0.2 |
14.9 |
0.64 |
4.3 |
3.2 |
21.5 |
1 Soil loss divided by runoff, primary sediment source, no allowance for deposition.
2 USLE factor used to correct normalised data to an LS =1
3 EMC normalised to an LS =1
Location
Roberts farm located within the Emerald Irrigation Area Queensland Long 148° 10’ E., Lat 23° 32’ S.
Related studies
Denaro’s farm located within the Emerald Irrigation Area Queensland Long 148° 10’ E., Lat 23° 32’ S.