Abstract
Water stored deep in the soil profile is valuable to crop yield but its availability and conversion to grain vary with preceding management and seasonal rainfall distribution. We investigated the value of subsoil water to wheat on the Red Kandosol soils in southern New South Wales, Australia, using the APSIM Wheat model, carefully validated for the study area. Simulation treatments over 106 years of historic climate data involved a factorial combination of (1) a preceding crop of either lucerne (Dry treatment) or a low-yielding wheat crop (Wet treatment) and (2) restriction of wheat root depth to either 1.2 or 1.8 m. Root access to the subsoil (1.2–1.8 m) increased wheat yield by an average of 0.6 and 0.3 t/ha for the Wet and Dry treatments, respectively, at Cootamundra (mean annual rainfall 624 mm) and by 0.5 and 0.1 t/ha at Ardlethan (mean annual rainfall 484 mm). The differences were principally related to the frequency with which the subsoil failed to wet up, which occurred in 8% and 39% of years at Cootamundra in Wet and Dry treatments, respectively, but in 21% and 79% of years at Ardlethan. In seasons where water from the subsoil was used, the mean value of the water for grain yield, expressed as marginal water-use efficiency (MWUE), was 30–36 kg/ha.mm at both sites. High MWUE (>60 kg/ha.mm) generally occurred in seasons of above-average rainfall when subsoil water facilitated extra post-anthesis water extraction, including that from upper soil layers, to realise the high yield potential. Low MWUE (<10 kg/ha.mm) occurred when re-translocation of pre-anthesis assimilate to grain in the 1.2 m treatment compensated for reduced subsoil water extraction and no yield difference between 1.2 and 1.8 m treatments was observed. Counter-intuitively, the results suggest that subsoil water will be of more value in higher rainfall environments due to its more frequent occurrence, and in above-average seasons due to more efficient conversion to grain.
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Claims 14
Claim · model-written summary
At Cootamundra, deeper root access increased wheat yield by 0.6 t/ha under Wet treatment.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- Root access to the subsoil (1.2–1.8 m)e0
- Outcome
- wheat yielde0
- Direction
- increasede0
- Value
- 0.6e0
- Qualifier
- Wete0
- Setting
- Cootamundrae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Root access to the subsoil (1.2–1.8 m) increased wheat yield by an average of 0.6 and 0.3 t/ha for the Wet and Dry treatments, respectively, at Cootamundra”
Claim · model-written summary
At Cootamundra, deeper root access increased wheat yield by 0.3 t/ha under Dry treatment.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Root access to the subsoil (1.2–1.8 m)e0
- Outcome
- wheat yielde0
- Direction
- increasede0
- Value
- 0.3 t/hae0
- Qualifier
- Drye0
- Setting
- Cootamundrae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Root access to the subsoil (1.2–1.8 m) increased wheat yield by an average of 0.6 and 0.3 t/ha for the Wet and Dry treatments, respectively, at Cootamundra”
Claim · model-written summary
At Ardlethan, deeper root access increased wheat yield by 0.5 t/ha under Wet treatment.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Root access to the subsoil (1.2–1.8 m)e1
- Outcome
- wheat yielde1
- Direction
- increasede1
- Value
- 0.5e0
- Qualifier
- Wete2
- Setting
- Ardlethane0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“by 0.5 and 0.1 t/ha at Ardlethan”
e1“Root access to the subsoil (1.2–1.8 m) increased wheat yield”
e2“for the Wet and Dry treatments, respectively”
Claim · model-written summary
At Ardlethan, deeper root access increased wheat yield by 0.1 t/ha under Dry treatment.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Root access to the subsoil (1.2–1.8 m)e1
- Outcome
- wheat yielde1
- Direction
- increasede1
- Value
- 0.1 t/hae0
- Qualifier
- Drye2
- Setting
- Ardlethane0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“by 0.5 and 0.1 t/ha at Ardlethan”
e1“Root access to the subsoil (1.2–1.8 m) increased wheat yield”
e2“for the Wet and Dry treatments, respectively”
Claim · model-written summary
At Cootamundra, subsoil failed to wet in 8% of years with Wet treatment.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- subsoil failed to wet upe0
- Value
- 8%e0
- Qualifier
- Wete0
- Setting
- Cootamundrae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“the subsoil failed to wet up, which occurred in 8% and 39% of years at Cootamundra in Wet and Dry treatments, respectively”
Claim · model-written summary
At Cootamundra, subsoil failed to wet in 39% of years with Dry treatment.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- subsoil failed to wet upe0
- Value
- 39%e0
- Qualifier
- Drye0
- Setting
- Cootamundrae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“the subsoil failed to wet up, which occurred in 8% and 39% of years at Cootamundra in Wet and Dry treatments, respectively”
Claim · model-written summary
At Ardlethan, subsoil failed to wet in 21% of years with Wet treatment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“but in 21% and 79% of years at Ardlethan”
e1“in Wet and Dry treatments, respectively”
Claim · model-written summary
At Ardlethan, subsoil failed to wet in 79% of years with Dry treatment.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“but in 21% and 79% of years at Ardlethan”
e1“in Wet and Dry treatments, respectively”
Claim · model-written summary
In seasons using subsoil water, marginal water-use efficiency was 30–36 kg/ha.mm at both sites.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- marginal water-use efficiency (MWUE)e0
- Value
- 30–36 kg/ha.mme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“In seasons where water from the subsoil was used, the mean value of the water for grain yield, expressed as marginal water-use efficiency (MWUE), was 30–36 kg/ha.mm at both sites”
Claim · model-written summary
High MWUE above 60 kg/ha.mm generally occurred in above-average rainfall seasons.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- MWUEe0
- Direction
- Highe0
- Value
- >60 kg/ha.mme0
- Qualifier
- above-average rainfalle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“High MWUE (>60 kg/ha.mm) generally occurred in seasons of above-average rainfall”
Claim · model-written summary
In high-rainfall seasons subsoil water facilitated extra post-anthesis water extraction, including upper layers.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- extra post-anthesis water extractione0
- Qualifier
- subsoil watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“subsoil water facilitated extra post-anthesis water extraction, including that from upper soil layers, to realise the high yield potential”
Claim · model-written summary
Low MWUE below 10 kg/ha.mm occurred where assimilate re-translocation compensated for reduced subsoil extraction.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- MWUEe0
- Direction
- Lowe0
- Value
- <10 kg/ha.mme0
- Qualifier
- 1.2 m treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Low MWUE (<10 kg/ha.mm) occurred when re-translocation of pre-anthesis assimilate to grain in the 1.2 m treatment compensated for reduced subsoil water extraction”
Claim · model-written summary
Yield did not differ between 1.2 and 1.8 m treatments in low-MWUE seasons.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- 1.8 m treatmentse0
- Outcome
- yielde0
- Direction
- no yield differencee0
- Comparator
- 1.2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“no yield difference between 1.2 and 1.8 m treatments was observed”
Claim · model-written summary
The authors infer subsoil water has greater value in higher rainfall environments and above-average seasons.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- subsoil water will be of more valuee0
- Direction
- more valuee0
- Qualifier
- higher rainfall environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“subsoil water will be of more value in higher rainfall environments due to its more frequent occurrence, and in above-average seasons due to more efficient conversion to grain”
The same questions in other papers
tillage · yield · Triticum aestivum (wheat)Positive and negative results
1,115 papers in the same direction as this paper · 257 in the opposite direction · 41 reporting no difference from an alternative
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