Abstract
Replacing mineral nitrogen fertilizers with organic sources or service crops is often proposed to enhance resource nutrient use efficiency and reduce environmental impacts. However, in semi-arid irrigated systems, evidence of their agronomic performance is limited. A three-year field experiment in a wheat-wheat-rapeseed rotation compared five strategies: unfertilized control (0 N), full mineral fertilization (FM), pre-sowing slurry + mineral top-dressing (BAU), full slurry fertilization (FS), and a legume companion cover crop (CCC). In both wheat cropping seasons, CCC yielded less than FM, BAU and FS, and showed lower water use efficiency, with no benefits from biological N fixation. A non-significant trend of lower yields in CCC compared to 0 N was also observed in 2021 and 2022. FM and FS achieved equivalent yields at comparable N rates, indicating that slurry can fully replace mineral fertilizer for both pre-sowing and top-dressing applications without yield or nitrogen use efficiency penalties, while also increasing soil organic carbon in surface layers. These results highlight the need for critical evaluation of CCC in semi-arid irrigated systems, as they may not improve -and can even reduce- productivity and resource use efficiency. • A three-year field experiment compared fertilization and management strategies. • The companion cover crop reduced wheat yields compared to fertilized treatments. • Pig slurry achieved yields and NUE equivalent to mineral fertilizer. • Slurry fertilization increased surface SOC compared with mineral fertilization. • Companion crops compromised productivity without improving NUE, WUE or SOC stock.
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Claims 9
Claim · model-written summary
Companion cover cropping yielded less wheat than the three fertilized strategies.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- CCCe0
- Outcome
- yieldede0
- Direction
- lesse0
- Comparator
- FM, BAU and FSe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both wheat cropping seasons, CCC yielded less than FM, BAU and FS”
Claim · model-written summary
Companion cover cropping had lower wheat water use efficiency.
- Taxon
- wheatTriticum aestivume0
- Treatment
- CCCe0
- Outcome
- water use efficiencye0
- Direction
- lowere0
- Comparator
- FM, BAU and FSe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both wheat cropping seasons, CCC yielded less than FM, BAU and FS, and showed lower water use efficiency”
Claim · model-written summary
Companion cover cropping showed no benefit from biological nitrogen fixation in wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- CCCe0
- Outcome
- benefits from biological N fixatione0
- Direction
- no benefitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both wheat cropping seasons, CCC yielded less than FM, BAU and FS, and showed lower water use efficiency, with no benefits from biological N fixation”
Claim · model-written summary
Companion cover cropping showed a nonsignificant tendency toward lower wheat yield than no nitrogen in 2021 and 2022.
- Taxon
- wheatTriticum aestivume1
- Treatment
- CCCe0
- Outcome
- yieldse0
- Direction
- lowere0
- Qualifier
- 2021 and 2022e0
- Comparator
- 0 Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A non-significant trend of lower yields in CCC compared to 0 N was also observed in 2021 and 2022”
t0“crop productivity”
e1“In both wheat cropping seasons”
Claim · model-written summary
Full mineral and full slurry fertilization produced equivalent wheat yields at comparable nitrogen rates.
- Taxon
- wheatTriticum aestivume1
- Treatment
- FSe0
- Outcome
- yieldse0
- Direction
- equivalente0
- Qualifier
- comparable N ratese0
- Comparator
- FMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FM and FS achieved equivalent yields at comparable N rates”
e1“In both wheat cropping seasons”
Claim · model-written summary
Slurry replacement of mineral fertilizer incurred no wheat nitrogen use efficiency penalty.
- Taxon
- wheatTriticum aestivume1
- Treatment
- slurrye0
- Outcome
- nitrogen use efficiency penaltiese0
- Direction
- withoute0
- Comparator
- mineral fertilizere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“slurry can fully replace mineral fertilizer for both pre-sowing and top-dressing applications without yield or nitrogen use efficiency penalties”
e1“In both wheat cropping seasons”
Claim · model-written summary
Slurry fertilization increased surface soil organic carbon relative to mineral fertilization.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Slurry fertilizatione0
- Outcome
- surface SOCe0
- Direction
- increasede0
- Comparator
- mineral fertilizatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Slurry fertilization increased surface SOC compared with mineral fertilization”
e1“In both wheat cropping seasons”
Claim · model-written summary
Companion cropping did not improve nitrogen use efficiency or soil organic carbon stock.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Companion cropse0
- Outcome
- NUE, WUE or SOC stocke0
- Direction
- without improvinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Companion crops compromised productivity without improving NUE, WUE or SOC stock”
e1“In both wheat cropping seasons”
Claim · model-written summary
The authors recommend critical evaluation of companion cover crops in semi-arid irrigated systems.
- Taxon
- wheatTriticum aestivume1
- Outcome
- critical evaluation of CCCe0
- Setting
- semi-arid irrigated systemse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results highlight the need for critical evaluation of CCC in semi-arid irrigated systems”
e1“In both wheat cropping seasons”
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