Importance of Crop Drive-Rows in Soil Carbon Sequestration: a Regional Study of Grape, Apple and Cherry Cropping Systems
Abstract
Unlike many annual crops, vineyards and orchards are unique in having relatively permanent plant structures, with woody perennial plants arranged in rows separated by drive rows. Drive rows can be deliberately planted with cover crops or contain unmanaged, natural vegetation. The contrast between the crop and drive row vegetation creates spatially distinct soil carbon (C) storage profiles across the landscape; the importance of which for climate change adaptation and C sequestration is only just beginning to be recognised. Here we describe an extensive regional study of 99 sites along a semi-arid, 200 km-long valley in British Columbia, Canada. We analysed soil samples from 34 apple orchards irrigated using either drip or micro-spray systems, 22 cherry sites irrigated with micro-spray and 24 vineyards irrigated by drip, stratified across a range of soil textures. Soils ranged from silty clays to gravelly loamy sands, and were sampled in 3 depth increments to 60 cm, in both crop and drive rows. The soil samples were analysed for organic C and 13C content, both before and after separation into a range of particle and density fractions. Across the four cropping systems (fruit crop / irrigation combination), drive rows contained significantly more C than crop rows, with the most pronounced differences at the surface and decreasing with depth. Cropping system also influenced soil C content: cherry orchards contained the most carbon and vineyards the least. We found little impact of irrigation type, with no difference between apples irrigated using drip or micro-spray. Stable isotope and particle/density fractionation of the soils provided a mechanistic understanding of the C turnover in these systems. Relatively unprocessed, 'new' carbon, with a depleted 13C content was responsible for the higher soil C content in surface soils of drive rows compared to crop rows, most likely due to inputs from shallow rooted grasses. Much of this carbon was associated with the light soil fractions between 2 - 0.2 mm, while <0.05 mm fractions contained more processed and presumably older carbon as indicated by 13C enrichment. Our work seeks to better understand and optimise sustainable management practices that promote soil C retention using the drive-rows, thereby improving soil conditions and also mitigating rising atmospheric CO2levels.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B43B..07M
- Keywords:
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- 0402 Agricultural systems;
- BIOGEOSCIENCES;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0495 Water/energy interactions;
- BIOGEOSCIENCES