Abstract
Abstract Monoculture production of soybeans ( Glycine max (L.) Merr.) and grain sorghum ( Sorghum bicolor (L.) Moench) generally results in declining grain yields. To better understand biological and chemical interactions causing yield declines with continuous cropping, microbial biomass, crop root dry weight, soil organic matter, and total N content were measured in a cropping system experiment on a Sharpsburg silty clay loam (Typic Argiudoll). The cropping treatments included continuous soybeans, continuous sorghum, and sorghum‐soybean or soybean‐sorghum rotations. These treatments were initiated 5 y prior to taking the reported measurements. Fertilizer treatments consisted of no amendment (control), N (45 kg ha −1 on soybean plots and 90 kg ha −1 on sorghum plots), and manure applied at 15.8 Mg dry matter ha −1 yr −1 . In summer 1986, the microbial biomass C for the 0–30‐cm layer of soil averaged across fertility treatments was 1.37, 1.49, 1.43, and 1.58 Mg ha −1 for continuous soybeans, rotated soybeans, rotated sorghum and continuous sorghum, respectively. Soil microbial biomass C and soil organic matter contents for manured treatments were 11 to 14% and 6 to 16% greater, respectively than those of unfertilized controls. Root dry weights for the 0–30‐cm depth were 26 and 77% higher for soybeans and sorghum if the previous crop was sorghum instead of soybeans. In summer 1986, microbial biomass in the 0–15‐cm depth was correlated with root density and water‐filled pore space in sorghum plots and with bulk density in soybean plots. Previous crop, present crop, and fertilizer treatment affected dry matter partitioning between above‐ and below‐ground plant parts and microbial biomass. With sorghum as a previous crop, a higher proportion of the total production occurred below ground as roots and microbial biomass.
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Claims 12
Claim · model-written summary
Microbial biomass C (0-30 cm) averaged 1.37 Mg/ha under continuous soybeans.
- Taxon
- soybeans
Glycine maxe0 - Outcome
- microbial biomass Ce0
- Value
- 1.37e0
- Qualifier
- continuous soybeanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass C for the 0–30‐cm layer of soil averaged across fertility treatments was 1.37, 1.49, 1.43, and 1.58 Mg ha −1 for continuous soybeans, rotated soybeans, rotated sorghum and continuous sorghum”
Claim · model-written summary
Microbial biomass C (0-30 cm) averaged 1.49 Mg/ha under rotated soybeans.
- Taxon
- soybeansGlycine maxe0
- Outcome
- microbial biomass Ce0
- Value
- 1.49e0
- Qualifier
- rotated soybeanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass C for the 0–30‐cm layer of soil averaged across fertility treatments was 1.37, 1.49, 1.43, and 1.58 Mg ha −1 for continuous soybeans, rotated soybeans, rotated sorghum and continuous sorghum”
Claim · model-written summary
Microbial biomass C (0-30 cm) averaged 1.43 Mg/ha under rotated sorghum.
SorghumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass C for the 0–30‐cm layer of soil averaged across fertility treatments was 1.37, 1.49, 1.43, and 1.58 Mg ha −1 for continuous soybeans, rotated soybeans, rotated sorghum and continuous sorghum”
Claim · model-written summary
Microbial biomass C (0-30 cm) averaged 1.58 Mg/ha under continuous sorghum.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass C for the 0–30‐cm layer of soil averaged across fertility treatments was 1.37, 1.49, 1.43, and 1.58 Mg ha −1 for continuous soybeans, rotated soybeans, rotated sorghum and continuous sorghum”
Claim · model-written summary
Manure increased soil microbial biomass C by 11 to 14% compared with unfertilized controls.
- Treatment
- manured treatmentse0
- Outcome
- Soil microbial biomass Ce0
- Direction
- greatere0
- Value
- 11 to 14%e0
- Comparator
- unfertilized controlse0
Not reportedTaxon
Verbatim
e0“Soil microbial biomass C and soil organic matter contents for manured treatments were 11 to 14% and 6 to 16% greater, respectively than those of unfertilized controls”
Claim · model-written summary
Manure increased soil organic matter by 6 to 16% compared with unfertilized controls.
- Treatment
- manured treatmentse0
- Outcome
- soil organic matter contentse0
- Direction
- greatere0
- Value
- 6 to 16%e0
- Comparator
- unfertilized controlse0
Not reportedTaxon
Verbatim
e0“Soil microbial biomass C and soil organic matter contents for manured treatments were 11 to 14% and 6 to 16% greater, respectively than those of unfertilized controls”
Claim · model-written summary
Soybean root dry weight (0-30 cm) was 26% higher when the previous crop was sorghum rather than soybeans.
- Taxon
- soybeansGlycine maxe0
- Treatment
- the previous crop was sorghume0
- Outcome
- Root dry weightse0
- Direction
- highere0
- Value
- 26e0
- Comparator
- soybeanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root dry weights for the 0–30‐cm depth were 26 and 77% higher for soybeans and sorghum if the previous crop was sorghum instead of soybeans”
Claim · model-written summary
Sorghum root dry weight (0-30 cm) was 77% higher when the previous crop was sorghum rather than soybeans.
- Treatment
- the previous crop was sorghume0
- Outcome
- Root dry weightse0
- Direction
- highere0
- Value
- 77%e0
- Comparator
- soybeanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root dry weights for the 0–30‐cm depth were 26 and 77% higher for soybeans and sorghum if the previous crop was sorghum instead of soybeans”
Claim · model-written summary
In sorghum plots, microbial biomass (0-15 cm) was correlated with root density and water-filled pore space.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass in the 0–15‐cm depth was correlated with root density and water‐filled pore space in sorghum plots and with bulk density in soybean plots”
Claim · model-written summary
In soybean plots, microbial biomass (0-15 cm) was correlated with bulk density.
- Taxon
- soybeanGlycine maxe0
- Outcome
- microbial biomasse0
- Qualifier
- bulk densitye0
- Setting
- soybean plotse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microbial biomass in the 0–15‐cm depth was correlated with root density and water‐filled pore space in sorghum plots and with bulk density in soybean plots”
Claim · model-written summary
Previous crop, present crop and fertilizer treatment affected dry matter partitioning between above- and below-ground plant parts and microbial biomass.
Not reportedTaxonComparatorDirection
Verbatim
e0“Previous crop, present crop, and fertilizer treatment affected dry matter partitioning between above‐ and below‐ground plant parts and microbial biomass”
Claim · model-written summary
With sorghum as the previous crop, a higher proportion of total production occurred below ground as roots and microbial biomass.
- Treatment
- sorghum as a previous crope0
- Outcome
- proportion of the total production occurred below grounde0
- Direction
- highere0
Not reportedTaxonComparator
Verbatim
e0“With sorghum as a previous crop, a higher proportion of the total production occurred below ground as roots and microbial biomass”
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See all 18 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.