Abstract
Abstract The resource pool diversity hypothesis (RPDH) posits that organic systems that include diverse crop rotations, green manure and organic fertilizers have a greater diversity of resource pools that can alleviate weed–crop competition compared to conventional systems. To test the RPDH, wheat ( Triticum aestivum ) and wild oats ( Avena sterilis ) in winter, and maize ( Zea mays ) and Palmer amaranth ( Amaranthus palmeri ) in summer, were grown in pots in soils from organic (ORG) and conventional (CONV) fields, with contrasting number of estimated resource pools. A replacement series design with proportions of crop: weed of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 was used. Half of the pots received an organic‐mineral fertilizer (F) and the other half did not (NF). Aerial biomass of all plants was measured. Relative Crowding Coefficient (RCC) and the product of RCC (RCCP) for each crop and weed biomass were estimated by modelling the biomass across crop: weed proportions. RCCP larger than one was used as an indicator of overyielding. In the winter experiment, wheat always outcompeted wild oats and we did not detect overyielding across fields with different number of pools, system or fertilizer. In the summer experiment, we found overyielding in ORG NF fields. Functionally different species like maize and Palmer amaranth may have been extracting nutrients from diverse pools in organic NF fields whereas with the addition of fertilizer, Palmer amaranth outcompeted maize. Biomass of monoculture crop and weed in both experiments were positively correlated with number of estimated pools, even if none of the competition indexes were. Our results provide some support for the RPHD in species that are functionally different but also question the definition and nature of the nutrient pools, as well as emphasize the need for more research in the area.
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Claims 6
Claim · model-written summary
Wheat outcompeted wild oats in the winter experiment.
- Taxon
- wheat
Triticum aestivume0 - Outcome
- outcompeted wild oatse0
AvenaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the winter experiment, wheat always outcompeted wild oats”
Claim · model-written summary
No overyielding was detected in winter across field resource pools, system or fertilizer.
- Taxon
- wheatTriticum aestivume1
- Outcome
- overyieldinge0
- Direction
- did not detecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we did not detect overyielding across fields with different number of pools, system or fertilizer”
t0“weed–crop competition”
e1“wheat ( Triticum aestivum ) and wild oats ( Avena sterilis ) in winter, and maize ( Zea mays ) and Palmer amaranth ( Amaranthus palmeri ) in summer”
Claim · model-written summary
Summer organic fields without fertilizer showed overyielding.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the summer experiment, we found overyielding in ORG NF fields”
e1“wheat ( Triticum aestivum ) and wild oats ( Avena sterilis ) in winter, and maize ( Zea mays ) and Palmer amaranth ( Amaranthus palmeri ) in summer”
Claim · model-written summary
With fertilizer addition, Palmer amaranth outcompeted maize.
- Treatment
- addition of fertilizere0
- Interactor
- Palmer amaranthe0weed
- Outcome
- Palmer amaranth outcompeted maizee0
- Direction
- outcompetede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with the addition of fertilizer, Palmer amaranth outcompeted maize”
Claim · model-written summary
Monoculture crop and weed biomass in both experiments correlated positively with estimated pool number.
- Taxon
- wheatTriticum aestivume1
- Outcome
- Biomass of monoculture crop and weede0
- Direction
- positively correlatede0
- Setting
- number of estimated poolse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biomass of monoculture crop and weed in both experiments were positively correlated with number of estimated pools”
e1“wheat ( Triticum aestivum ) and wild oats ( Avena sterilis ) in winter, and maize ( Zea mays ) and Palmer amaranth ( Amaranthus palmeri ) in summer”
Claim · model-written summary
Competition indexes did not correlate with estimated pool number.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“none of the competition indexes were”
e1“Biomass of monoculture crop and weed in both experiments were positively correlated with number of estimated pools”
e2“wheat ( Triticum aestivum ) and wild oats ( Avena sterilis ) in winter, and maize ( Zea mays ) and Palmer amaranth ( Amaranthus palmeri ) in summer”
The same questions in other papers
fertilization · organism · Zea mays (maize)Results differ
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