Abstract
Boron (B) is a trace element essential to crop growth in small soil concentrations (0.2-1.5ppm), yet may produce plant toxicity symptoms readily as the amount in the soil solution increases over 2ppm. Boron is present in significant amounts in recycled materials such as municipal solid waste (MSW) and coal fly ash, and therefore composts containing these ingredients may potentially exceed agronomic B levels, especially when used at heavy rates. Boron requirements and expression of toxicity vary widely among varying plant types. Furthermore, boron behavior in organic soils (high organic matter) is more dependent on pH than in mineral soils, thus boron effects from compost-based media may be very variable and difficult to predict. Our study examined commercial compost made with coal fly-ash used to prepare growing media for cultivars of varying sensitivity (corn, beans, cucumber, peas). We examined total vs. extractable boron content and relate final visual symptoms of B-toxicity to yields and tissue concentrations. Visual toxicity effects included tip burn (corn), leaf mottling and necrosis (beans and peas) and leaf mottling and cupping (cucumbers). Fly ash added to compost increased hot-water soluble (HWS) B in proportion to rate and in dependence on pH, with 30% and 10% of total-B expressed as HWS-B at a media pH of 6 and 7.5, respectively. Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively. Economic yield depressions in compost media are evident for all crops and appeared at levels of HWS-B in compost media exceeding 5 ppm. The study underscores the need for careful management of exogenous factors that may be present in composts and suggests detailed understanding of media-pH and cultivar preferences may be required in preparation of growing media in order to reduce potential negative growth effects.
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Claims 12
Claim · model-written summary
Corn showed tip burn as a boron toxicity symptom.
- Taxon
- corn
Zea mays subsp. mayse0 - Outcome
- tip burne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Visual toxicity effects included tip burn (corn), leaf mottling and necrosis (beans and peas) and leaf mottling and cupping (cucumbers).”
Claim · model-written summary
Beans and peas showed leaf mottling and necrosis.
Verbatim
e0“Visual toxicity effects included tip burn (corn), leaf mottling and necrosis (beans and peas) and leaf mottling and cupping (cucumbers).”
Claim · model-written summary
Cucumbers showed leaf mottling and cupping.
- Taxon
- cucumbers
Cucumis sativuse0 - Outcome
- leaf mottling and cuppinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Visual toxicity effects included tip burn (corn), leaf mottling and necrosis (beans and peas) and leaf mottling and cupping (cucumbers).”
Claim · model-written summary
Fly ash raised hot-water soluble B proportional to rate and dependent on pH.
Not reportedTaxon
Verbatim
e0“Fly ash added to compost increased hot-water soluble (HWS) B in proportion to rate and in dependence on pH, with 30% and 10% of total-B expressed as HWS-B at a media pH of 6 and 7.5, respectively.”
Claim · model-written summary
At media pH 6, 30% of total B was hot-water soluble.
Not reportedTaxon
Verbatim
e0“Fly ash added to compost increased hot-water soluble (HWS) B in proportion to rate and in dependence on pH, with 30% and 10% of total-B expressed as HWS-B at a media pH of 6 and 7.5, respectively.”
Claim · model-written summary
At media pH 7.5, 10% of total B was hot-water soluble.
Not reportedTaxon
Verbatim
e0“Fly ash added to compost increased hot-water soluble (HWS) B in proportion to rate and in dependence on pH, with 30% and 10% of total-B expressed as HWS-B at a media pH of 6 and 7.5, respectively.”
Claim · model-written summary
33% fly ash compost significantly reduced bean biomass by 45%.
- Taxon
- beane0
- Treatment
- addition of 33% fly-ash composte0
- Outcome
- Biomasse0
- Direction
- reducede0
- Value
- 45 to 55%e0
- Qualifier
- 28ppm total-Be0
Not reportedComparator
Verbatim
e0“Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively.”
Claim · model-written summary
33% fly ash compost significantly reduced cucumber biomass by 55%.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- addition of 33% fly-ash composte0
- Outcome
- Biomasse0
- Direction
- reducede0
- Value
- 45 to 55%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively.”
Claim · model-written summary
Fly ash compost increased bean tissue B about sixfold.
- Taxon
- beane0
- Treatment
- addition of 33% fly-ash composte0
- Outcome
- plant tissue-Be0
- Direction
- increasede0
- Value
- 6- to 4-folde0
Not reportedComparator
Verbatim
e0“Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively.”
Claim · model-written summary
Fly ash compost increased cucumber tissue B about fourfold.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- addition of 33% fly-ash composte0
- Outcome
- plant tissue-Be0
- Direction
- increasede0
- Value
- 6- to 4-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively.”
Claim · model-written summary
All tested crops had depressed economic yields when compost HWS-B exceeded 5 ppm.
Verbatim
e0“Economic yield depressions in compost media are evident for all crops and appeared at levels of HWS-B in compost media exceeding 5 ppm.”
t0“cultivars of varying sensitivity (corn, beans, cucumber, peas)”
Claim · model-written summary
Authors recommend managing compost factors and accounting for pH and cultivar preferences.
Verbatim
e0“The study underscores the need for careful management of exogenous factors that may be present in composts and suggests detailed understanding of media-pH and cultivar preferences may be required in preparation of growing media in order to reduce potential negative growth effects.”
t0“cultivars of varying sensitivity (corn, beans, cucumber, peas)”
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