Abstract
Abstract Prospects for improving the productivity of species mixtures in transitions between phases by changing row configuration at sowing were examined in two series of field experiments in rain‐fed, semi‐arid environments in south‐eastern Australia. The first series explored how the choice of cover crop and use of alternate drill row configurations affected establishment and yields of sward components in the transition from a cropping into a pasture phase. Cover‐crop species included wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), canola ( Brassica napus L.) and lupins ( Lupinus augustifolius L.), each sown in mixed or alternate drill rows with lucerne ( Medicago sativa L.) and subterranean clover ( Trifolium subterraneum L.). The second series of experiments examined the productivity implications when returning from the pasture phase back into cropping following 10 contrasting pastures sown to various combinations of lucerne, subterranean clover or phalaris ( Phalaris aquatica L.) sown in mixed, alternate (1:1) or double skip (1:2) row configurations in the absence of cover crops. All experiments were sown on a 0.25‐m row spacing. In the transition into the pasture phase, grain yields of cover crops in the mixed drill row treatment were similar to those achieved by crops grown in the absence of pasture species but were reduced by an average of 24% in the alternate drill row configuration. Canola and lupin crop biomass were lower, compared with wheat and barley, leading to increased pasture yields in year 1, highlighting an opportunity for increased use of these species as cover/companion crops in semi‐arid environments. Pasture yields beyond year 1 were reduced by ~20% in the alternate drill row treatments compared with where species were sown in mixed drill rows, with greater yield differences under more favourable growing conditions. This response largely reflected yield reductions in lucerne where it was concentrated in fewer drill rows. The alternate drill row configuration increased the abundance of subterranean clover in year 1, but this species remained a minor component of all swards beyond the establishment year. In the transition into the cropping phase, effects on grain quality could only be attributed to row configuration of the previous pasture to the extent that row configuration changed pasture composition. Grain size was smallest and protein concentration highest where previous pastures contained both lucerne and subterranean clover without phalaris. Taken together, there was little advantage in total productivity attributable to spatially separating species in drill rows at sowing.
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Claims 12
Claim · model-written summary
Grain yields of cover crops in mixed drill rows were similar to crops grown without pasture species.
Verbatim
e1“grain yields of cover crops in the mixed drill row treatment were similar to those achieved by crops grown in the absence of pasture species”
Claim · model-written summary
Alternate drill rows reduced cover-crop grain yields by an average of 24% relative to mixed drill rows.
Verbatim
e1“grain yields of cover crops in the mixed drill row treatment were similar to those achieved by crops grown in the absence of pasture species”
e2“but were reduced by an average of 24% in the alternate drill row configuration”
Claim · model-written summary
Canola and lupin crop biomass was lower than wheat and barley biomass.
- Taxon
- Canola
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Brassica napus var. napuse3 - Outcome
- crop biomasse3
- Direction
- lowere3
- Comparator
- wheat and barleye3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e3“Canola and lupin crop biomass were lower, compared with wheat and barley”
Claim · model-written summary
Canola and lupin as cover crops led to increased pasture yields in year 1.
- Taxon
- CanolaBrassica napus var. napuse3
- Outcome
- pasture yields in year 1e4
- Direction
- increasede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Canola and lupin crop biomass were lower, compared with wheat and barley”
e4“leading to increased pasture yields in year 1”
Claim · model-written summary
Canola and lupin should be used more as cover or companion crops in semi-arid environments.
- Taxon
- CanolaBrassica napus var. napuse3
- Outcome
- increased use of these species as cover/companion cropse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Canola and lupin crop biomass were lower”
e5“highlighting an opportunity for increased use of these species as cover/companion crops”
Claim · model-written summary
Pasture yields beyond year 1 were reduced by about 20% in alternate drill row treatments compared with mixed drill rows, with greater differences in more favourable conditions.
Verbatim
e6“Pasture yields beyond year 1 were reduced by ~20% in the alternate drill row treatments compared with where species were sown in mixed drill rows”
e7“greater yield differences under more favourable growing conditions”
Claim · model-written summary
Yield reductions in lucerne were concentrated in the fewer drill rows of the alternate configuration.
- Taxon
- lucerne
Medicago sativae1 - Outcome
- yield reductions in lucernee1
- Qualifier
- concentrated in fewer drill rowse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“yield reductions in lucerne where it was concentrated in fewer drill rows”
Claim · model-written summary
The alternate drill row configuration increased subterranean clover abundance in year 1.
- Taxon
- subterranean clover
Trifolium subterraneume1 - Treatment
- alternate drill row configuratione1
- Outcome
- abundance of subterranean clovere1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The alternate drill row configuration increased the abundance of subterranean clover in year 1”
Claim · model-written summary
Subterranean clover remained a minor component of all swards beyond the establishment year.
- Taxon
- subterranean cloverTrifolium subterraneume1
- Outcome
- minor component of all swardse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The alternate drill row configuration increased the abundance of subterranean clover in year 1”
e2“this species remained a minor component of all swards beyond the establishment year”
Claim · model-written summary
Grain size was smallest where previous pastures contained lucerne and subterranean clover without phalaris.
Verbatim
e1“Grain size was smallest and protein concentration highest where previous pastures contained both lucerne and subterranean clover without phalaris”
Claim · model-written summary
Protein concentration in grain was highest where previous pastures contained lucerne and subterranean clover without phalaris.
Verbatim
e1“Grain size was smallest and protein concentration highest where previous pastures contained both lucerne and subterranean clover without phalaris”
Claim · model-written summary
Spatially separating species in drill rows at sowing gave little advantage in total productivity.
Verbatim
e0“Prospects for improving the productivity of species mixtures”
e1“there was little advantage in total productivity attributable to spatially separating species in drill rows at sowing”