Scorecard to assess the potential drought resistance of a pastoral farm

Land owner: Land use:

Site location: GPS ref:

Soil type: Date:

Drainage class: Soil Classification:

Textual group (upper 1m) c Sandy c Loamy c Silty c Clayey c Other

Moisture condition: c Dry c Slightly moist c Moist c Very moist c Wet

Seasonal weather c Dry c Wet c Cold c Warm c Average

conditions:

Indicators of Drought Resistance

/ Drought Resistance Score (DRS)
0 = Poor resistance
1 = Moderate resistance
2 = Good resistance
1.  Percent cover by drought resistant pasture species
2.  Residual pasture levels
3.  Rooting depth
4.  Root density
5.  Soil structure
6.  6. Soil porosity
7.  Soil Ca levels
8.  8. Soil Mg levels
9.  Soil K levels
10. Soil Na levels
11. Fe levels
12. Zn levels
13. B levels
14. Brix levels of pasture
15. Mycorrhizal colonisation
16. Active to total fungal ratio
17. Soil organic C levels
18. Amount & form of fertiliser & N applied
DROUGHT RESISTANCE INDEX (Sum of the DRS’s)

Drought Resistance Assessment

/

Drought Resistance Index (DRI)

Poor / < 15
Moderate / 15–26
Good / > 26
Notes:
Total available water holding capacity (TAWC): Depth of soil x moisture holding capacity.
Approx. moisture holding capacity for a:
Loamy sand = 1.1 mls/cm of soil
Sandy loam = 1.4 mls/cm of soil
Silt loam = 1.7 mls/cm of soil
Silty clay loam = 1.5 mls/cm of soil
e.g. A soil with a 100 cm depth of sandy loam would have a TAWC of 100 x 1.4 = 40 mls.
If the evapotranspiration (ET) = 5 mls/day, there are 8 days of TAW available

1. Percent cover by drought resistant pasture species:

e.g. tall fescue, prairie grass, cocksfoot, phalaris, red clover, spear head clover, lucerne, chicory, plantain

DRS for pasture species / 0 / 0.5 / 1.0 / 1.5 / 2.0
Percentage cover by drought resistant pasture species / <30 / 30−50 / 50−70 / 70−90 / >90

2. Pasture residual levels

DRS for residual levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
Residual levels (kg/ha) / <1100 / 1100−1300 / 1300−1500 / 1500−1700 / 1700

3. Root length

DRS for root length / 0 / 0.5 / 1.0 / 1.5 / 2.0
Root length (mm) / <200 / 200−400 / 400−600 / 600−800 / >800


4. Root density

DRS for root density / 0 / 0.5 / 1.0 / 1.5 / 2.0
Root density / / /

5. Soil structure

DRS for soil structure / 0 / 0.5 / 1.0 / 1.5 / 2.0
Soil
structure / / /

Photos courtesy of Ball et al. 2007. Soil Use and Management, 23, 329–337.

6. Soil porosity

DRS for soil porosity / 0 / 0.5 / 1.0 / 1.5 / 2.0
Soil porosity / / /

7. Soil Ca levels

DRS for calcium levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
% BS Ca – heavy soils
– light soils
% Ca in pasture / <35
25
<0.3 / 35−45
25−35
0.3–0.49 / 45−55
35−50
0.5–0.99 / 60−68
50−60
1.0–1.49 / 68−70
60−65
1.5–2.0

8. Soil Mg levels

DRS for magnesium levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
% BS Mg – heavy soils
– light soils
% Mg in pasture / <3
<5
<0.1 / 3−5.9
5−8.99
0.1–0.19 / 6−8.99
9−14.9
0.2–0.29 / 9−11.9
15−19.9
0.3–0.39 / 12
20
0.4–0.5

9. Soil K levels

DRS for potassium levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
% BS K in soils
% K in pasture / <2
<1 / 2−2.9
1–1.49 / 3−3.9
1.5–1.99 / 4−4.9
2–2.49 / 5
2.5–3

10. Soil Na levels

DRS for sodium levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
% BS Na in soil
% Na in pasture / <0.3
<0.05 / 0.3−0.49
0.05–0.09 / 0.5−0.99
0.1–0.14 / 1.0−1.49
0.15–0.19 / 1.5–2
0.2–0.3

11. Soil Fe levels

DRS for iron levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
Fe levels in light soils (ppm)
Fe levels in heavy soils (ppm)
Fe levels in the pasture (mg/kg) / 150
<200
<50 / 150−199
200−249
50−99 / 200−249
250−299
100−149 / 250−299
300−359
150−199 / 300
360
200

12. Soil Zn levels

DRS for zinc levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
Zn levels in light soils (ppm)
Zn levels in heavy soils (ppm)
Zn levels in the pasture (mg/kg) / <2
<8
<10 / 2−4
8−10.9
10−20 / 4−6
11−13.9
20−30 / 6−8
14−16.9
30−44.9 / >8
17
45

13. Soil B levels

DRS for boron levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
B levels in the soil (ppm)
B levels in the pasture (mg/kg) / <0.5
<5 / 0.5−1
5−9.9 / 1−1.5
10−19 / 1.5−2
20−29 / >2
30−40

14. Brix level of pasture

DRS for brix levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
Pasture Brix level / ≤3 / 3−6 / 6−9 / 9−12 / ≥12

15. Mycorrhizal colonisation

DRS for mycorrhizal colonisation / 0 / 0.5 / 1.0 / 1.5 / 2.0
% Colonisation / ≤40 / 41‒53 / 54‒66 / 67‒79 / ≥80

16. Active to total fungal ratio

DRS for active to total fungal ratio / 0 / 0.5 / 1.0 / 1.5 / 2.0
Active:total fungal ratio / ≤0.1 / 0.11‒0.129 / 0.13‒0.139 / 0.14‒0.149 / ≥0.15

17. Soil organic carbon levels

DRS for soil organic C levels / 0 / 0.5 / 1.0 / 1.5 / 2.0
Soil organic C levels (%)
/ <2 / 2−4 / 4−6 / 6−8 / >8

18. The amount and form of fertiliser & N applied

DRS = 0 if applying high amounts of soluble, salt-based phosphatic & potassic fertilisers with >50 kg P/ha; 120 kg N/ha/yr is applied as urea or in other forms of soluble, salt-based nitrogenous fertilisers

DRS = 1 if applying moderate amounts of soluble, salt-based phosphatic & potassic fertilisers with 30−40 kg P/ha; 60−90 kg N/ha/yr is applied as urea or in other forms of soluble, salt-based nitrogenous fertilisers

DRS = 2 if ‘smart’ conditioner fertilisers are used or if applying low amounts of soluble, salt-based phosphatic & potassic fertilisers with ≤ 20 kg P/ha/yr; ≤ 30 kg N/ha/yr is applied as urea or in other forms of soluble, salt-based nitrogenous fertilisers, or if N is applied as a foliar spray in low amounts with a form of carbon.

Notes: