Abstract
Abstract The carbon‐to‐nitrogen (C:N) ratio of organic amendments regulates nutrient cycling in soil through its influence on microbial activity. Where an organic amendment has a C:N ratio sparingly higher than that of soil microbes (C:N ratio 6.7—8.7), meeting microbial requirements of carbon and nitrogen may promote microbial biomass growth and nitrogen mineralization. Here we sought to understand the microbial response to the addition of organic amendments with varying C:N ratios and subsequent changes in nitrogen mineralization and plant nitrogen uptake. Dried insect larvae, beef feedlot manure and mixtures of beef feedlot manure with insect larvae or sugarcane residue were used as soil amendments to create a gradient of molar C:N ratios (C m :N m ) ranging from 6 to 28. An untreated control treatment with a C:N ratio of 17 was also included. Sorghum ( Sorghum bicolor L.) was grown in control and organic matter amended soils for 20 days after germination. The mixture of beef feedlot manure and insect larvae treatment (C m :N m = 9.7) had on average 68% higher microbial biomass compared with the other treatments. Beef feedlot manure with C m :N m ratio of 11 did not influence microbial biomass growth. The concentration of mineral nitrogen was highest in the insect larvae (C m :N m = 6) treatment, where 23% of the plant nitrogen was derived from the insect larvae as indicated by the δ 15 N of plant dry matter. We observed both carbon and nitrogen contents in the organic amendment determine microbial biomass growth and nitrogen mineralization in soil. The results presented here demonstrate that microbial response to organic amendments determines the availability of mineral nitrogen in soil.
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Claims 4
Claim · model-written summary
The manure and insect larvae mixture gave 68% higher microbial biomass than the other treatments.
- Treatment
- mixture of beef feedlot manure and insect larvaee0
- Outcome
- microbial biomasse0
- Direction
- highere0
- Value
- 68%e0
- Comparator
- other treatmentse0
SorghumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mixture of beef feedlot manure and insect larvae treatment (C m :N m = 9.7) had on average 68% higher microbial biomass compared with the other treatments.”
t0“Sorghum ( Sorghum bicolor L.) was grown in control and organic matter amended soils”
Claim · model-written summary
Beef feedlot manure with a C:N ratio of 11 did not influence microbial biomass growth.
- Treatment
- Beef feedlot manure with C m :N m ratio of 11e0
- Outcome
- microbial biomass growthe0
- Direction
- did not influencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Beef feedlot manure with C m :N m ratio of 11 did not influence microbial biomass growth.”
t0“Sorghum ( Sorghum bicolor L.) was grown in control and organic matter amended soils”
Claim · model-written summary
Mineral nitrogen concentration was highest with insect larvae amendment.
- Treatment
- insect larvae (C m :N m = 6) treatmente0
- Outcome
- concentration of mineral nitrogene0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The concentration of mineral nitrogen was highest in the insect larvae (C m :N m = 6) treatment”
t0“Sorghum ( Sorghum bicolor L.) was grown in control and organic matter amended soils”
Claim · model-written summary
In the insect larvae treatment, 23% of plant nitrogen came from insect larvae.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“23% of the plant nitrogen was derived from the insect larvae”
t0“Sorghum ( Sorghum bicolor L.) was grown in control and organic matter amended soils”
The same questions in other papers
fertilization · soil: biology · SorghumPositive and negative results
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