Abstract
Biochar is a porous carbonaceous solid material produced by pyrolysis. Application of biochar is considered as an efficient way of carbon (C) sequestration since the C in biochar is relatively resistant to microbial degradation. Furthermore, previous research in (sub-) tropical conditions suggests that it may enhance soil fertility and the yields of agricultural crops. To target the lack of knowledge about the effects of biochar in the boreal zone, softwood biochar was added to two boreal soils (a fertile Stagnosol and a nutrient deficient Umbrisol) in laboratory and field experiments in southern Finland in 2010 2012. The study focused on the effects of biochar on 1) the mineralisation of nitrogen (N) of organic fertilisers, 2) the physicochemical properties of soil, 3) earthworm abundance and behaviour, and 4) the yield formation of wheat, turnip rape and faba bean. Biochar application to soils caused an initial reduction in N availability, probably by N immobilisation due to increased microbial biomass. The effect was greater when the biochar application was combined with an organic fertiliser with a high C:N ratio than when one with a low C:N ratio was used. In the field experiments, however, the N immobilisation was moderate, as the N uptake of crops was not affected. Furthermore, signs of turnover of microbial biomass in the second year were seen in the Umbrisol field. Biochar application increased the contents of C and exchangeable potassium (K) in the soil, but had no significant effects on other soil chemical properties within the first two to three years of the experiments. Biochar effects on soil physical properties varied. In the Stagnosol with a sandy clay loam texture, the application slightly increased topsoil moisture content, but did not affect soil water retention or porosity. In the Umbrisol with a loamy sand texture, biochar increased the plant-available water content of the topsoil in the first year and soil porosity in the second year but did not affect the moisture content of the soil. In the laboratory, biochar did not affect the habitat choice of earthworms when the test lasted for 2 days, but after 2 weeks, biochar-treated soil was avoided. The avoidance effect was associated with a slight decline in soil water potential. This avoidance effect was not observed under field conditions, where there was even an indication of increased abundance and biomass of earthworms in biochar-amended soil. The effects of biochar application on the plant growth dynamics and N uptake of turnip rape and wheat were not significant, but the enhanced accumulation of biomass and N uptake of faba bean during the initial N immobilisation phase may be related to possibly enhanced biological N fixation. In dry years, biochar addition affected the yield formation of crops, as it was associated with decreased plant density and increased number of reproductive units (pods, siliques or ears) per plant. The latter was attributed to two additive mechanisms, the compensation for decreased plant density and relieved moderate water deficit. Biochar did not however affect the crop yield significantly, irrespective of the fertiliser treatments or the soil types studied. It can be concluded that the application of biochar in combination with inorganic fertilisers or with meat bone meal to boreal soils with near neutral pH and relatively high original SOM content may reduce deficits in both K and water, but should not be expected to significantly affect yields of faba bean, turnip rape and wheat during the first few years. As added biochar had no negative effects on crop yields or earthworms, it can be suggested that softwood biochar application is an agriculturally safe way of sequestering C. Considering the longevity of biochar in soils, future studies are needed for monitoring the long-term effects of biochar under field conditions.
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Claims 18
Claim · model-written summary
Biochar initially reduced soil nitrogen availability.
- Taxon
- wheat
Triticum aestivume1 - Treatment
- Biochar applicatione0
- Outcome
- N availabilitye0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biochar application to soils caused an initial reduction in N availability”
e1“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
The reduction in nitrogen availability was greater with high than low C:N organic fertilizer.
- Taxon
- wheatTriticum aestivume1
- Treatment
- biochar application was combined with an organic fertiliser with a high C:N ratioe0
- Outcome
- N availabilitye2
- Direction
- greatere0
- Comparator
- one with a low C:N ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect was greater when the biochar application was combined with an organic fertiliser with a high C:N ratio than when one with a low C:N ratio was used”
e1“yield formation of wheat, turnip rape and faba bean”
e2“reduction in N availability”
Claim · model-written summary
Field crop nitrogen uptake was unaffected by biochar.
- Taxon
- wheatTriticum aestivume2
- Treatment
- Biochar applicatione1
- Outcome
- N uptake of cropse0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the N uptake of crops was not affected”
e1“Biochar application to soils”
e2“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar increased soil carbon and exchangeable potassium content.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Biochar applicatione0
- Outcome
- contents of C and exchangeable potassium (K) in the soile0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biochar application increased the contents of C and exchangeable potassium (K) in the soil”
e1“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar did not significantly affect other soil chemical properties.
- Taxon
- wheatTriticum aestivume2
- Treatment
- Biochar applicatione1
- Outcome
- other soil chemical propertiese0
- Direction
- no significant effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no significant effects on other soil chemical properties within the first two to three years”
e1“Biochar application increased the contents”
e2“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar slightly increased Stagnosol topsoil moisture.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Biochar applicatione2
- Outcome
- topsoil moisture contente0
- Direction
- increasede0
- Setting
- Stagnosole0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the Stagnosol with a sandy clay loam texture, the application slightly increased topsoil moisture content”
e1“yield formation of wheat, turnip rape and faba bean”
e2“Biochar application increased the contents”
Claim · model-written summary
Biochar increased plant-available topsoil water in Umbrisol in year one.
- Taxon
- wheatTriticum aestivume1
- Treatment
- biochare0
- Outcome
- plant-available water content of the topsoile0
- Direction
- increasede0
- Setting
- Umbrisole0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the Umbrisol with a loamy sand texture, biochar increased the plant-available water content of the topsoil in the first year”
e1“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar increased Umbrisol soil porosity in year two.
- Taxon
- wheatTriticum aestivume2
- Treatment
- biochare0
- Outcome
- soil porositye0
- Direction
- increasede0
- Setting
- Umbrisole1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“biochar increased the plant-available water content of the topsoil in the first year and soil porosity in the second year”
e1“In the Umbrisol”
e2“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar did not significantly affect turnip rape growth dynamics or nitrogen uptake.
- Taxon
- turnip rapee0
- Treatment
- biochar applicatione0
- Outcome
- plant growth dynamics and N uptakee0
- Direction
- not significante0
Not reportedComparator
Verbatim
e0“The effects of biochar application on the plant growth dynamics and N uptake of turnip rape and wheat were not significant”
Claim · model-written summary
Biochar did not significantly affect wheat growth dynamics or nitrogen uptake.
- Taxon
- wheatTriticum aestivume0
- Treatment
- biochar applicatione0
- Outcome
- plant growth dynamics and N uptakee0
- Direction
- not significante0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effects of biochar application on the plant growth dynamics and N uptake of turnip rape and wheat were not significant”
Claim · model-written summary
Biochar enhanced faba bean biomass accumulation and nitrogen uptake during initial nitrogen immobilization.
- Taxon
- faba bean
Vicia fabae0 - Treatment
- Biochar applicatione1
- Outcome
- accumulation of biomass and N uptakee0
- Direction
- enhancede0
- Qualifier
- may be related to possibly enhanced biological N fixatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the enhanced accumulation of biomass and N uptake of faba bean during the initial N immobilisation phase may be related to possibly enhanced biological N fixation”
e1“Biochar application increased the contents”
Claim · model-written summary
In dry years biochar was associated with decreased crop density.
- Taxon
- wheatTriticum aestivume1
- Treatment
- biochar additione0
- Outcome
- plant densitye0
- Direction
- decreasede0
- Qualifier
- In dry yearse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In dry years, biochar addition affected the yield formation of crops, as it was associated with decreased plant density”
e1“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
In dry years biochar was associated with more reproductive units per plant.
- Taxon
- wheatTriticum aestivume1
- Treatment
- biochar additione0
- Outcome
- number of reproductive units (pods, siliques or ears) per plante0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In dry years, biochar addition affected the yield formation of crops, as it was associated with decreased plant density and increased number of reproductive units (pods, siliques or ears) per plant”
e1“yield formation of wheat, turnip rape and faba bean”
Claim · model-written summary
Biochar did not significantly affect faba bean yield.
- Taxon
- faba beanVicia fabae1
- Treatment
- Biochare0
- Outcome
- crop yielde0
- Direction
- did not however affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biochar did not however affect the crop yield significantly”
e1“yields of faba bean, turnip rape and wheat”
Claim · model-written summary
Biochar did not significantly affect turnip rape yield.
Not reportedComparator
Verbatim
e0“Biochar did not however affect the crop yield significantly”
e1“yields of faba bean, turnip rape and wheat”
Claim · model-written summary
Biochar did not significantly affect wheat yield.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Biochare0
- Outcome
- crop yielde0
- Direction
- did not however affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biochar did not however affect the crop yield significantly”
e1“yields of faba bean, turnip rape and wheat”
Claim · model-written summary
Biochar may reduce potassium and water deficits in boreal soils under the stated conditions.
- Taxon
- faba beanVicia fabae1
- Treatment
- application of biochar in combination with inorganic fertilisers or with meat bone meale0
- Outcome
- reduce deficits in both K and watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the application of biochar in combination with inorganic fertilisers or with meat bone meal to boreal soils with near neutral pH and relatively high original SOM content may reduce deficits in both K and water”
e1“yields of faba bean, turnip rape and wheat”
Claim · model-written summary
Softwood biochar was suggested as an agriculturally safe way to sequester carbon.
- Taxon
- faba beanVicia fabae1
- Outcome
- agriculturally safe way of sequestering Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“softwood biochar application is an agriculturally safe way of sequestering C”
e1“yields of faba bean, turnip rape and wheat”
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See all 13 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.