Abstract
Results from monocropped barley treatments in long-term rotation (RTN) and continuous barley (CB) trials at two sites were examined for fertilizer effects on yield means and long-term yield trends. In RTN trials, mean responses to fertilizer (N[ratio ]P 2 O 5 ) applied annually at rates of 20[ratio ]60 at the drier and 40[ratio ]60 at the wetter site were almost double those from biennial application, confirming the need for annual fertilization in monocropped barley systems. In CB trials, with N and P applied annually in nine factorial combinations, at rates up to 120[ratio ]90, responses to each nutrient were curvilinear and dependent on the presence of the other nutrient. Trend analysis showed a decline in grain yields over time where NP fertilizer had not been applied or applied only at low annual rates (< 60[ratio ]45 or < 60[ratio ]90, according to site); but straw yields, at worst, remained approximately stable in the absence of fertilizer and generally increased strongly with higher NP rates. Uncertainties in the interpretation of trend-analysis results indicate the need for methodology improvements, to include (i) additional single-value parameters of the growth environment, to improve the model's ability to account for seasonal variability, and (ii) a more flexible, non-linear function for time. It was concluded that barley monocropping is not necessarily non-sustainable in the medium term, provided adequate annual fertilization is maintained; but risks of pest or disease build-up, in addition to the superiority of legume-barley systems in biomass and crude protein output demonstrated in preceding papers, undoubtedly favour the introduction of some forage legumes into long-term barley sequences. The most practicable (and acceptable) systems may well be ones in which continuous barley is interrupted by a legume, or even a bare fallow, every third or fourth year. Above all, farmers should be helped to experiment with different forage legumes, barley–legume sequences, and modes of legume harvest, to optimize outputs in relation to their evolving and individual enterprise needs.
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Claims 12
Claim · model-written summary
Annual fertilizer produced almost double the mean barley yield response of biennial application.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- applied annuallye0
- Outcome
- mean responses to fertilizere0
- Direction
- almost doublee0
- Comparator
- biennial applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“mean responses to fertilizer (N[ratio ]P 2 O 5 ) applied annually at rates of 20[ratio ]60 at the drier and 40[ratio ]60 at the wetter site were almost double those from biennial application”
t0“barley”
Claim · model-written summary
In continuous barley trials, nitrogen response was curvilinear and depended on phosphorus.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- N and P applied annuallye0
- Outcome
- responses to each nutriente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In CB trials, with N and P applied annually in nine factorial combinations, at rates up to 120[ratio ]90, responses to each nutrient were curvilinear and dependent on the presence of the other nutrient”
t0“barley”
Claim · model-written summary
Grain yield declined over time where NP fertilizer was absent or applied at low rates.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- NP fertilizer had not been applied or applied only at low annual ratese0
- Outcome
- grain yieldse0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a decline in grain yields over time where NP fertilizer had not been applied or applied only at low annual rates (< 60[ratio ]45 or < 60[ratio ]90, according to site)”
t0“barley”
Claim · model-written summary
Straw yields remained approximately stable without fertilizer.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- absence of fertilizere0
- Outcome
- straw yieldse0
- Direction
- remained approximately stablee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“straw yields, at worst, remained approximately stable in the absence of fertilizer”
t0“barley”
Claim · model-written summary
Higher NP fertilizer rates generally increased straw yields strongly.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- higher NP ratese0
- Outcome
- straw yieldse0
- Direction
- increased stronglye0
- Comparator
- absence of fertilizere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“straw yields, at worst, remained approximately stable in the absence of fertilizer and generally increased strongly with higher NP rates”
t0“barley”
Claim · model-written summary
The authors recommend improved trend analysis using growth-environment parameters.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- additional single-value parameters of the growth environmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“include (i) additional single-value parameters of the growth environment, to improve the model's ability to account for seasonal variability”
t0“barley”
Claim · model-written summary
The authors recommend a more flexible nonlinear time function for trend analysis.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- a more flexible, non-linear function for timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a more flexible, non-linear function for time”
t0“barley”
Claim · model-written summary
Barley monocropping was judged potentially sustainable in the medium term with adequate annual fertilization.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- barley monocropping is not necessarily non-sustainable in the medium terme0
- Qualifier
- adequate annual fertilizatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“barley monocropping is not necessarily non-sustainable in the medium term, provided adequate annual fertilization is maintained”
Claim · model-written summary
The authors favor introducing forage legumes into long-term barley sequences.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- introduction of some forage legumes into long-term barley sequencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“favour the introduction of some forage legumes into long-term barley sequences”
Claim · model-written summary
The authors suggest interrupting continuous barley with a legume every third or fourth year.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- continuous barley is interrupted by a legumee0
- Qualifier
- every third or fourth yeare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“continuous barley is interrupted by a legume, or even a bare fallow, every third or fourth year”
Claim · model-written summary
The authors suggest interrupting continuous barley with bare fallow every third or fourth year.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- a bare fallowe0
- Qualifier
- every third or fourth yeare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“continuous barley is interrupted by a legume, or even a bare fallow, every third or fourth year”
Claim · model-written summary
The authors recommend that farmers experiment with forage legumes and barley–legume sequences.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- experiment with different forage legumes, barley–legume sequences, and modes of legume harveste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“farmers should be helped to experiment with different forage legumes, barley–legume sequences, and modes of legume harvest”
t0“barley”
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