Information
Runoff, soil loss, and nutrient transport from cropping systems on red ferrosols in tropical north Australia (Kairi Research Station)
Level 1 general description
Purpose
This study investigated the effects of different tillage practices on runoff, soil erosion, nutrient loss and crop production over 3 years on red ferrosols to identify sustainable cropping practices and production benefits. Furthermore, the cropping model system PERFECT was tested against the observed data to determine its accuracy, whilst also providing information regrading long-term runoff and soil erosion rates.
Methods (brief)
The study was undertaken on the Kairi research station (Atherton Tablelands) approximately 90 km from Cairns in North Queensland. The study incorporated 12 plots in order to determine the effects of four tillage practices (treatments) on runoff, erosion, nutrient loss and crop yields. Each treatment included triplicate replication.
Key findings
Results showed the importance of cover in reducing runoff, soil loss, and nutrient loss. Runoff ranged from 13% of incident rainfall for the conventional cultivation to 29% under bare conditions during the highest rainfall year, and was well correlated with event rainfall and rainfall energy. Soil loss ranged from 30 t/ha.year under bare conditions to <6 t/ha.year under cropping. Nutrient losses of 35 kg N and 35 kg P/ha.year under bare conditions and 17 kg N and 11 kg P/ha.year under cropping were measured.
The cropping systems model PERFECT was calibrated using runoff, soil loss, and soil water data. Runoff and soil loss showed good agreement with observed data in the calibration, and soil water and yield had reasonable agreement. Long term runs using historical weather data showed the episodic nature of runoff and soil loss events in this region and emphasise the need to manage land using protective measures such as conservation cropping practices
Table 1. Mean annual runoff and erosion (1998-2001) and, total nitrogen and phosphorus (1999-2001) under bare (B), conventional tillage (CT), reduced tillage (RT) and grass (G) treatments for cropping lands – Kairi research station, North Queensland. AAR 1402mm (Cogle et al 2011)
|
Tillage |
Slope (%) |
Runoff (mm) |
Erosion (t/ha) |
Total Nitrogen (kg/ha) |
Total Phosphorus (kg/ha) |
EMC1 gm/L |
|
B |
6 |
304 |
18.7 |
23.3 |
23.3 |
6.2 |
|
CT |
6 |
135 |
4.1 |
11.0 |
7.8 |
3.0 |
|
RT |
6 |
99 |
2.9 |
6.7 |
6.1 |
2.9 |
|
G |
6 |
43 |
0.6 |
2.7 |
6.7 |
1.4 |
1 Soil loss divided by runoff, primary sediment source, no allowance for deposition.
Location
Kairi research station (Atherton Tablelands). Lat 17.20S, Long 145.57E