Abstract
Broadleaf break crops improve cereal yield through disease and weed control, increased nitrogen (N) availability and other mechanisms. In the rainfed farming systems of Australia the magnitude of the yield benefit is highly variable, yet is a major driver for adoption of break crops which are often less profitable and more risky than cereals. Declining area of break crops throughout Australia has re-ignited interest in better understanding the circumstances in which break-crop benefits can be maximised from a farming systems perspective. We compiled and analysed a database of 167 crop sequence experiments conducted throughout Western Australia in the period 1974–2007 to evaluate the impact on wheat (Triticum aestivum L.) grain yield from the use of narrow-leafed lupin (Lupinus angustifolius L.), field pea (Pisum sativum L.), canola (Brassica napus L.) or oats (Avena sativa L.), or following a long fallow where no crop had been sown the previous year. Adjusted for the years in which each was represented the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow, though direct comparisons between break crops could not be made as few experiments (3) included all species. For all break crops, the mean wheat yield increase was independent of the level of wheat yield, representing a step-change rather than a proportional improvement in yield. Analysis of the larger number and spread of lupin experiments revealed that break-crop benefits increased in higher rainfall areas, following higher yielding lupin crops (>1.5 t/ha), and that the break-crop benefit in terms of yield and water-use efficiency increased significantly after 1991. These observations were often related to the level and/or effectiveness of diseases or grass weed control in the break crop; however, increased contribution of fixed N was also likely with better legume crops. For both lupin and field pea, the magnitude of the break-crop response declined as rate of N fertiliser applied to subsequent wheat crop increased, although non-N related benefits (disease and weed control) tended to dominate wheat response to lupin after 1989. Significant break-crop benefits from lupins (+0.40 t/ha) persisted to a third wheat crop (n = 29) but effects were inconsistent beyond that point. The magnitude, persistence and reliability of the break-crop benefits revealed in this study provide a more accurate framework to assess their likely benefit within the farming system. Further information is required to define the key ‘trigger points’ for the major drivers of the response – water, N, weeds and disease – at which the benefits outweigh the higher risk of these crops and would influence the decision to include them within the system.
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Claims 14
Claim · model-written summary
Wheat after lupin yielded 0.60 t/ha more than wheat after wheat.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- lupine0
- Outcome
- yield benefite0
- Direction
- benefite0
- Value
- 0.60e0
- Comparator
- wheat after wheate0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow”
e1“wheat (Triticum aestivum L.) grain yield”
Claim · model-written summary
Wheat after field pea yielded 0.45 t/ha more than wheat after wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- field peae0
- Outcome
- yield benefite0
- Direction
- benefite0
- Value
- 0.45e0
- Comparator
- wheat after wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow”
Claim · model-written summary
Wheat after canola yielded 0.40 t/ha more than wheat after wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- canolae0
- Outcome
- yield benefite0
- Direction
- benefite0
- Value
- 0.40e0
- Comparator
- wheat after wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow”
Claim · model-written summary
Wheat after oats yielded 0.35 t/ha more than wheat after wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- oatse0
- Outcome
- yield benefite0
- Direction
- benefite0
- Value
- 0.35e0
- Comparator
- wheat after wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow”
Claim · model-written summary
Wheat after fallow yielded 0.30 t/ha more than wheat after wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- fallowe0
- Outcome
- yield benefite0
- Direction
- benefite0
- Value
- 0.30 t/hae0
- Comparator
- wheat after wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow”
Claim · model-written summary
Mean wheat yield increases after break crops were independent of wheat yield level.
- Taxon
- wheatTriticum aestivume0
- Treatment
- break cropse0
- Outcome
- mean wheat yield increasee0
- Direction
- independente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For all break crops, the mean wheat yield increase was independent of the level of wheat yield, representing a step-change rather than a proportional improvement in yield.”
Claim · model-written summary
Lupin break-crop benefits to wheat increased in higher-rainfall areas.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- lupin cropse0
- Outcome
- break-crop benefitse0
- Direction
- increasede0
- Setting
- higher rainfall arease0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“break-crop benefits increased in higher rainfall areas, following higher yielding lupin crops (>1.5 t/ha)”
t0“wheat”
Claim · model-written summary
Lupin break-crop benefits to wheat increased following lupin crops yielding over 1.5 t/ha.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- lupin cropse0
- Outcome
- break-crop benefitse0
- Direction
- increasede0
- Qualifier
- >1.5 t/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“break-crop benefits increased in higher rainfall areas, following higher yielding lupin crops (>1.5 t/ha)”
t0“wheat”
Claim · model-written summary
Lupin break-crop yield and water-use-efficiency benefits increased significantly after 1991.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- break-crope0
- Outcome
- yield and water-use efficiencye0
- Direction
- increasede0
- Qualifier
- after 1991e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the break-crop benefit in terms of yield and water-use efficiency increased significantly after 1991”
t0“wheat”
Claim · model-written summary
Greater nitrogen fertilizer to subsequent wheat reduced the response after lupin.
- Taxon
- wheatTriticum aestivume0
- Treatment
- lupine0
- Outcome
- break-crop responsee0
- Direction
- declinede0
- Qualifier
- rate of N fertiliser applied to subsequent wheat crop increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For both lupin and field pea, the magnitude of the break-crop response declined as rate of N fertiliser applied to subsequent wheat crop increased”
Claim · model-written summary
Greater nitrogen fertilizer to subsequent wheat reduced the response after field pea.
- Taxon
- wheatTriticum aestivume0
- Treatment
- field peae0
- Outcome
- break-crop responsee0
- Direction
- declinede0
- Qualifier
- rate of N fertiliser applied to subsequent wheat crop increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For both lupin and field pea, the magnitude of the break-crop response declined as rate of N fertiliser applied to subsequent wheat crop increased”
Claim · model-written summary
Non-nitrogen benefits tended to dominate wheat response to lupin after 1989.
- Taxon
- wheatTriticum aestivume0
- Outcome
- wheat response to lupine0
- Direction
- dominatee0
- Qualifier
- after 1989e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“non-N related benefits (disease and weed control) tended to dominate wheat response to lupin after 1989”
Claim · model-written summary
Lupin benefits of +0.40 t/ha persisted to a third wheat crop.
- Taxon
- wheatTriticum aestivume0
- Treatment
- lupinse0
- Outcome
- break-crop benefitse0
- Direction
- persistede0
- Value
- +0.40 t/hae0
- Qualifier
- a third wheat crope0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant break-crop benefits from lupins (+0.40 t/ha) persisted to a third wheat crop (n = 29)”
Claim · model-written summary
Lupin break-crop effects were inconsistent beyond the third wheat crop.
- Taxon
- wheatTriticum aestivume0
- Treatment
- lupinse1
- Outcome
- effectse0
- Direction
- inconsistente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“persisted to a third wheat crop (n = 29) but effects were inconsistent beyond that point”
e1“break-crop benefits from lupins”
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