SOIL TYPES AND RAINFALL
Paddock History – 2009 Wheat, 2010 Oats Hay
Soil Type – Red Brown Earth
APSIM Classification: Red / Brown Clay Loam over Clay on Rock
Drained Upper Limit (DUL – the total amount of water the soil contains to 150cm when the
soil is fully wet) – 511 mm
Crop Lower Limit (CLL – the amount of water that a wheat crop cannot extract from the
soil to 150cm) – 348 mm
Plant Available Water Capacity (PAWC – the total amount of water that could be available
to a wheat crop if the soil was fully wet to 150cm) – 163 mm
Actual Plant Available Water at 14/06/2011 – 97mm
1|Trial Results 2011
MNHRZ Trial Site 2011 - Red Soil
Volumetric Water (%)
0
10
20
30
40
50
60
0
20
Depth (cm)
40
60
80
100
120
DUL
CLL
Actual 14/6/2011
The soil was tested in accordance with Yield Prophet protocol on the 14th of June, 2011. PAW was 97mm, a
relatively high level of moisture to have in the soil for this time of year and as the season progressed, it
became evident just how beneficial to the crop this stored water was. The high level of soil water in June
was a result of large summer rainfall events, which were then followed by reasonably large events in March.
Soil Nitrogen was
comparatively high at 129 kg/ha 0-90cm,which was also associated with the large
summer rains resulting in increased organic matter mineralisation.
Chemical analysis from the trial site revealed very few limitations to root growth deeper in the profile. There
were low EC (salt – mainly sodium chloride) and Chloride levels and satisfactory pH levels. Subsoil pH was
dominated by fine calcium carbonate. There are areas in the paddock surrounding the trial site which are
sodic at the surface and mildly saline at depth. Whilst not present at the trial site itself, it gives an indication
that subsoil conditions and hence limitations to root growth are likely to vary considerably across this
paddock and many mid north paddocks.
2|Trial Results 2011
Soil Test Result – Yield Prophet requirements
DEPTH
0-10cm
10-40cm
40-70cm
70-90cm
NITRATE
(mg/kg)
AMMONIUM
(mg/kg)
CONDUCTIVITY
(dS/m)
pH
(CaCl2)
CHLORIDE
(mg/kg)
20
14
4
4
2
1
1
0.1
0.42
0.42
0.5
0.26
6.9
7.5
7.7
7.7
7.6
31
5.6
13.6
Organic Carbon (0-10cm) – 2.0%
Total N (0-90cm) – 129 kg/ha
Yield Prophet Performance 2011
Based on Scout sown on 05/05/2011 at 300 seeds/m 2, with 100 kg N/ha applied at seeding
Yield Prophet Predicted Final Yield – 5.4 t/ha
Actual Final Yield – 4.97 t/ha
Yield Prophet over- stated predicted yield by 8%. With yield prediction this close to what was actually
achieved, it can be considered a useful tool for input planning, budgeting, and grain marketing.
3|Trial Results 2011
Rainfall MNHRZ Trial Site 2011
Day
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
1
Nov
Dec
11.0
2
1.5
2.5
3
8.5
4
3.5
5
6
7
8
8.0
9
27.0
10
2.0
3.0
11
3.0
13
2.0
9.0
1.5
13.0
10.0
2.0
5.0
1.0
2.0
0.5
7.5
7.5
2.5
2.0
8.5
2.0
3.5
1.0
13.5
1.0
12
14
Oct
2.0
4.0
2.0
3.0
1.0
2.5
2.0
2.5
5.5
1.0
5.0
2.0
2.0
18.0
18
2.0
2.0
7.0
36.0
0.5
1.0
21
20.0
22
7.0
2.0
23
2.0
1.0
24
7.5
25
1.0
1.5
3.5
4.0
4.0
2.0
17
20
1.5
1.5
16
19
3.5
0.5
0.5
15
2.0
25.0
3.5
1.0
0.5
2.5
1.5
4.0
17.5
3.0
7.5
3.0
2.0
15.5
3.5
0.5
7.0
1.5
3.5
26
4.0
5.0
27
1.5
1.5
28
2.0
29
21.0
30
2.0
8.0
1.5
2.0
31
Totals
9.0
36.0
76.0
11.0
41.0
36.5
53.5
67.0
37.5
56.0
26.5
32.0
2011 Annual Rainfall Total – 482.0mm, Annual Rainfall Long Term Average – 529mm
2011 April – October Rainfall – 302.5mm (Decile 2), April – October Rainfall Long Term Average 400mm
The in season rainfall for the site in 2011 was in the lowest 20% of years on record. However, due to above
average summer rainfall and the accumulation of subsoil moisture that resulted from it, crops generally
finished well , with many yields as high as the previous year. This result highlights the importance of stored
4|Trial Results 2011
subsoil moisture to grain production – even in the high rainfall zones. Once again, the season started early,
largely with the assistance of excellent rains that were received in March. This basically allowed seeding to
commence as soon as growers were organised to do so, with the light rains that fell in April. These rains
were very marginal for canola establishment and many crops suffered from poor germination and required
re-sowing. Slightly drier conditions present at the start to the middle of May put a stop to seeding for many
farmers. Good follow up rainfall in late May / early June allowed most to finish seeding. Following reasonable
winter rainfall there were still good reserves of PAW (100mm+) going into spring. A dry period from the final
week of August until the final week of September meant that this reserve was called upon heavily to meet
crop growth requirements. Yield Prophet during this period predicted that crop water use averaged
2.5mm/day. Clearly, without the rains late in September and reasonable follow up rain in October, the crop
was destined to finish poorly. On reflection, grain yields for the season were very good considering the April
to October rainfall for the site was Decile 2. Once again at this site the results highlight the contribution of
stored PAW to crop production. They also show the importance of the nutritional needs of the crop targeted
to crop yield based on PAW.
Harvest progressed well for most people, with a generally earlier finish to harvest than average and very little
weather damage. This was a welcome respite for everyone following the trying conditions of the 2010
harvest.
Once again, some management strategies produced handsome rewards. Understanding the complex
relationships that occur in crop production is a goal of the Mid North High Rainfall Zone Group. Trial results
and successful strategies are summarised in the Mid North High Rainfall Zone 2011 Trial Results. We hope
that you enjoy them.
Mid North High Rainfall Zone Trial Site Committee.
5|Trial Results 2011