Abstract
ABSTRACT In order to understand how soil microbial biomass was influenced by incorporated residues of summer cover crops and by water regimes, soil microbial biomass carbon (C) and nitrogen (N) were investigated in tomato field plots in which three leguminous and a non-leguminous cover crop had been grown and incorporated into the soil. The cover crops were sunn hemp (Crotalaria juncea L., cv ‘Tropic Sun’), cowpea (Vigna unguiculata L. Walp, cv ‘Iron clay’), velvetbean (Mucuna deeringiana (Bort) Merr.), and sorghum sudangrass (Sorghum bicolor × S. bicolor var. sudanense (Piper) Stapf) vs. a fallow (bare soil). The tomato crop was irrigated at four different rates, i.e., irrigation initiated only when the water tension had reached −5, −10, −20, or −30 kPa, respectively. The results showed that sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%, and microbial N by 58.3%, 100.0%, 297.3%, and 261.3%, respectively. A legume cover crop, cowpea, had no statistically significant greater effect on soil microbial C and N than the non-legume cover crop, sorghum sudangrass. The tropical legumes, velvetbean and sunn hemp, increased the microbial biomass N markedly. However, the various irrigation rates did not cause significant changes in either microbial N or microbial C. Soil microbial biomass was strongly related to the N concentration and/or the inverse of the C:N ratio of the cover crops and in the soil. Tomato plant biomass and tomato fruit yields correlated well with the level of soil microbial N and inversely with the soil C:N ratio. These results suggest that cover crops increase soil microbiological biomass through the decomposition of organic C. Legumes are more effective than non-legumes, because they contain larger quantities of N and lower C:N ratios than non-legumes.
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Claims 15
Claim · model-written summary
Sorghum sudangrass increased soil microbial biomass C by 68.9%.
- Taxon
- tomato
Solanum lycopersicumt0 - Treatment
- sorghum sudangrasse0
- Outcome
- microbial biomass Ce0
- Direction
- increasede0
- Value
- 68.9%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%”
t0“Tomato”
Claim · model-written summary
Cowpea increased soil microbial biomass C by 89.8%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- cowpeae0
- Outcome
- microbial biomass Ce0
- Direction
- increasede0
- Value
- 89.8%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%”
t0“Tomato”
Claim · model-written summary
Sunn hemp increased soil microbial biomass C by 116.8%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- sunn hempe0
- Outcome
- microbial biomass Ce0
- Direction
- increasede0
- Value
- 116.8%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%”
t0“Tomato”
Claim · model-written summary
Velvetbean increased soil microbial biomass C by 137.7%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- velvetbeane0
- Outcome
- microbial biomass Ce0
- Direction
- increasede0
- Value
- 137.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%”
t0“Tomato”
Claim · model-written summary
Sorghum sudangrass increased soil microbial N by 58.3%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- sorghum sudangrasse0
- Outcome
- microbial Ne0
- Direction
- increasede0
- Value
- 58.3%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sorghum sudangrass, cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%, and microbial N by 58.3%, 100.0%, 297.3%, and 261.3%”
t0“Tomato”
Claim · model-written summary
Cowpea increased soil microbial N by 100.0%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- cowpeae0
- Outcome
- microbial Ne0
- Direction
- increasede0
- Value
- 100.0%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cowpea, sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%, and microbial N by 58.3%, 100.0%, 297.3%, and 261.3%”
t0“Tomato”
Claim · model-written summary
Sunn hemp increased soil microbial N by 297.3%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- sunn hempe0
- Outcome
- microbial Ne0
- Direction
- increasede0
- Value
- 297.3%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sunn hemp, and velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%, and microbial N by 58.3%, 100.0%, 297.3%, and 261.3%”
t0“Tomato”
Claim · model-written summary
Velvetbean increased soil microbial N by 261.3%.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- velvetbeane0
- Outcome
- microbial Ne0
- Direction
- increasede0
- Value
- 261.3%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“velvetbean increased microbial biomass C by 68.9%, 89.8%, 116.8%, and 137.7%, and microbial N by 58.3%, 100.0%, 297.3%, and 261.3%”
t0“Tomato”
Claim · model-written summary
Cowpea did not produce significantly more soil microbial C and N than sorghum sudangrass.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- cowpeae0
- Outcome
- soil microbial C and Ne0
- Direction
- no statistically significant greatere0
- Comparator
- sorghum sudangrasse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cowpea, had no statistically significant greater effect on soil microbial C and N than the non-legume cover crop, sorghum sudangrass”
t0“Tomato”
Claim · model-written summary
Different irrigation rates did not significantly alter microbial N or C.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- various irrigation ratese0
- Outcome
- microbial N or microbial Ce0
- Direction
- did not cause significant changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“various irrigation rates did not cause significant changes in either microbial N or microbial C”
t0“Tomato”
Claim · model-written summary
Soil microbial biomass was related to cover crop and soil N concentration and inversely to C:N ratio.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- Soil microbial biomasse0
- Qualifier
- strongly relatede0
Not reportedSettingDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil microbial biomass was strongly related to the N concentration and/or the inverse of the C:N ratio of the cover crops and in the soil”
t0“Tomato”
Claim · model-written summary
Tomato plant biomass correlated with soil microbial N and inversely with soil C:N ratio.
- Taxon
- TomatoSolanum lycopersicume0
- Organ / stage
- plante0
- Outcome
- Tomato plant biomasse0
- Qualifier
- inverselye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tomato plant biomass and tomato fruit yields correlated well with the level of soil microbial N and inversely with the soil C:N ratio”
Claim · model-written summary
Tomato fruit yield correlated with soil microbial N and inversely with soil C:N ratio.
- Taxon
- TomatoSolanum lycopersicume0
- Organ / stage
- fruite0
- Outcome
- tomato fruit yieldse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tomato plant biomass and tomato fruit yields correlated well with the level of soil microbial N and inversely with the soil C:N ratio”
Claim · model-written summary
Cover crops were interpreted to increase soil microbial biomass through decomposition of organic C.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- cover cropse0
- Outcome
- soil microbiological biomasse0
- Qualifier
- decomposition of organic Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cover crops increase soil microbiological biomass through the decomposition of organic C”
t0“Tomato”
Claim · model-written summary
Legumes were interpreted as more effective because of more N and lower C:N ratios.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- Legumese0
- Outcome
- more effectivee0
- Qualifier
- larger quantities of N and lower C:N ratiose0
- Comparator
- non-legumese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Legumes are more effective than non-legumes, because they contain larger quantities of N and lower C:N ratios than non-legumes”
t0“Tomato”