Abstract
The implementation of alley cropping in orchards can be a sustainable strategy to increase farm productivity by crop diversification and contribute to climate change mitigation. In this research, we evaluated the short-term effect of alley cropping with reduced tillage on soil CO2 and N2O emissions and soil total organic carbon (TOC) in an almond orchard under Mediterranean rainfed conditions. We compared an almond monoculture with tillage in all plot surface (MC) with almond crop with reduced tillage and growth of Capparis spinosa (D1) and almond crop with reduced tillage and growth of Thymus hyemalis (D2). For two years, soil CO2 and N2O were measured, with soil sampling at the start and end of the experimental period. Results showed that CO2 emission rates followed the soil temperature pattern, while N2O emissions were not correlated with temperature nor moisture. Soil CO2 emissions were significantly higher in MC (87 mg m−2 h−1), with no significant differences between D1 and D2 (69 mg m−2 h−1). Some peaks in CO2 effluxes were observed after tillage operations during warm days. Soil N2O emission rates were not significantly different among treatments. Cumulative CO2 and CO2 equivalent (CO2e) emissions were significantly highest in MC. When CO2e emissions were expressed on a crop production basis, D2 showed the significantly lowest values (5080 g kg−1) compared to D1 (50,419 g kg−1) and MC (87,836 g kg−1), owing to the high thyme yield, additional to the almond yield. No production was obtained for C. spinosa, since at least two more years are required. TOC did not change with time in MC neither D1, but it significantly increased in D2 from 3.85 g kg−1 in 2019 to 4.62 g kg−1 in 2021. Thus, alley cropping can contribute to increase the agroecosystem productivity and reduce CO2 emissions. However, it is necessary to grow evergreen alley crops such as thyme to obtain short-term increases in soil organic matter. Thus, to estimate increases in TOC with alley cropping, the plantation density and the period required by the crop to cover most of the surface are essential factors at planning the cropping strategy.
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Claims 12
Claim · model-written summary
Soil CO2 emission rates followed soil temperature in the almond orchard.
- Taxon
- almond
Prunus dulcist0 - Outcome
- CO2 emission ratese0
- Setting
- soil temperaturee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“CO2 emission rates followed the soil temperature pattern”
Claim · model-written summary
N2O emissions were not correlated with temperature or moisture.
- Taxon
- almondPrunus dulcist0
- Outcome
- N2O emissionse0
- Direction
- not correlatede0
- Setting
- temperature nor moisturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“N2O emissions were not correlated with temperature nor moisture”
Claim · model-written summary
Monoculture had higher soil CO2 emission rates than alley crops.
- Taxon
- almondPrunus dulcist0
- Treatment
- MCe0
- Outcome
- Soil CO2 emissionse0
- Direction
- highere0
- Value
- 87 mg m−2 h−1e0
- Comparator
- D1 and D2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“Soil CO2 emissions were significantly higher in MC (87 mg m−2 h−1), with no significant differences between D1 and D2 (69 mg m−2 h−1)”
Claim · model-written summary
The two alley crops did not differ significantly in soil CO2 emissions.
- Taxon
- almondPrunus dulcist0
- Treatment
- D1e0
- Outcome
- no significant differencese0
- Direction
- no significant differencese0
- Value
- 69 mg m−2 h−1e0
- Comparator
- D2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“no significant differences between D1 and D2 (69 mg m−2 h−1)”
Claim · model-written summary
CO2 efflux peaks followed tillage on warm days.
- Taxon
- almondPrunus dulcist0
- Treatment
- tillage operationse0
- Outcome
- peaks in CO2 effluxese0
- Qualifier
- during warm dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“Some peaks in CO2 effluxes were observed after tillage operations during warm days”
Claim · model-written summary
Soil N2O emission rates did not differ significantly among treatments.
- Taxon
- almondPrunus dulcist0
- Treatment
- treatmentse0
- Outcome
- Soil N2O emission ratese0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“Soil N2O emission rates were not significantly different among treatments”
Claim · model-written summary
Cumulative CO2 and CO2e emissions were highest in monoculture.
- Taxon
- almondPrunus dulcist0
- Treatment
- MCe0
- Outcome
- Cumulative CO2 and CO2 equivalent (CO2e) emissionse0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“Cumulative CO2 and CO2 equivalent (CO2e) emissions were significantly highest in MC”
Claim · model-written summary
Production-adjusted CO2e emissions were lowest in the thyme alley crop.
- Taxon
- almondPrunus dulcist0
- Treatment
- D2e0
- Outcome
- valuese0
- Direction
- loweste0
- Value
- 5080 g kg−1e0
- Qualifier
- 50,419 g kg−1e0
- Comparator
- D1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“D2 showed the significantly lowest values (5080 g kg−1) compared to D1 (50,419 g kg−1) and MC (87,836 g kg−1)”
Claim · model-written summary
Capparis spinosa yielded no production during this period.
- Taxon
- C. spinosa
Capparis spinosae0 - Outcome
- No productione0
- Qualifier
- at least two more years are requirede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No production was obtained for C. spinosa, since at least two more years are required”
Claim · model-written summary
Soil organic carbon increased in the thyme alley crop from 2019 to 2021.
- Taxon
- almondPrunus dulcist0
- Treatment
- D2e0
- Outcome
- TOCe0
- Direction
- increasede0
- Value
- 4.62 g kg−1e0
- Comparator
- MCe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“TOC did not change with time in MC neither D1, but it significantly increased in D2 from 3.85 g kg−1 in 2019 to 4.62 g kg−1 in 2021”
Claim · model-written summary
Soil organic carbon did not change over time in monoculture or the Capparis alley crop.
- Taxon
- almondPrunus dulcist0
- Outcome
- TOCe0
- Direction
- did not changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“TOC did not change with time in MC neither D1”
Claim · model-written summary
The authors recommend evergreen alley crops such as thyme for short-term soil organic matter gains.
- Taxon
- almondPrunus dulcist0
- Outcome
- grow evergreen alley crops such as thymee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“almond orchard”
e0“it is necessary to grow evergreen alley crops such as thyme to obtain short-term increases in soil organic matter”