Abstract
We investigated if subsoil constraints to root development imposed by coarse sand were affected by drought and biochar application over two seasons. Biochar was applied to the subsoil of pots at 20-50 cm depth in concentrations of 0, 1, 2, and 3% (B0, B1, B2, and B3). Maize was grown in the same pots one week and 12 months after biochar application. The maize plants were fully irrigated until flowering; thereafter, half of them were subjected to drought. A new method for observing root growth dynamics and root length density in situ, the Rootsnap sensor system, was developed. The sensors were installed at 50 cm depth just below the layer of biochar-amended subsoil. Using data from a smaller experiment with grass, the calculated root length densities from the sensors were compared with data from scanning of manually washed roots. In year 2, we investigated the effect of aged biochar on root growth using only the root wash and scanning method. The Rootsnap sensor revealed that the arrival time of the first root in B3 at the 50 cm depth averaged 47 days after planting, which was significantly earlier than in B0, by 9 days. The tendency for faster root proliferation in biochar-amended subsoil indicates that biochar reduced subsoil mechanical impedance and allowed roots to gain faster access to deep soil layers. A linear regression comparing root length density obtained from the Rootsnap sensor with the scanning method yielded an r2 of 0.50. Our analysis using the scanning method further showed that under drought stress, maize roots responded with reduced root diameter and increased root length density at 50-70 cm depth in the first and second year, respectively. The trend under full irrigation was less clear, with significant decrease in root length density for B1 and B2 in year 2. Overall, reduction in subsoil mechanical impedance observed as early arrival of roots to the subsoil may prevent or delay the onset of drought and reduce leaching of nutrients in biochar-amended soil with positive implications for agricultural productivity.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 7
Claim · model-written summary
At 50 cm, first roots arrived 9 days earlier with B3 than B0, averaging 47 days after planting.
Verbatim
e0“The Rootsnap sensor revealed that the arrival time of the first root in B3 at the 50 cm depth averaged 47 days after planting, which was significantly earlier than in B0, by 9 days.”
Claim · model-written summary
Biochar may reduce subsoil mechanical impedance and speed root access to deep layers.
- Treatment
- biochare0
- Outcome
- faster access to deep soil layerse0
- Direction
- fastere0
- Qualifier
- reduced subsoil mechanical impedancee0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“biochar reduced subsoil mechanical impedance and allowed roots to gain faster access to deep soil layers”
t0“Maize”
Claim · model-written summary
Rootsnap and scanning root length density estimates had a regression r2 of 0.50.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A linear regression comparing root length density obtained from the Rootsnap sensor with the scanning method yielded an r2 of 0.50.”
t0“Maize”
Claim · model-written summary
Under drought, maize root diameter was reduced at 50-70 cm in the first year.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under drought stress, maize roots responded with reduced root diameter and increased root length density at 50-70 cm depth in the first and second year, respectively.”
Claim · model-written summary
Under drought, maize root length density increased at 50-70 cm in the second year.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under drought stress, maize roots responded with reduced root diameter and increased root length density at 50-70 cm depth in the first and second year, respectively.”
Claim · model-written summary
Under full irrigation, B1 significantly decreased root length density in year 2.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under full irrigation was less clear, with significant decrease in root length density for B1 and B2 in year 2”
t0“Maize”
Claim · model-written summary
Under full irrigation, B2 significantly decreased root length density in year 2.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under full irrigation was less clear, with significant decrease in root length density for B1 and B2 in year 2”
t0“Maize”