Abstract
Abstract In the near future, composted bio‐solids are expected to play a major role in agriculture. In order to evaluate their contribution to plant growth and nutrition, a mixed sorghum–poultry manure compost was prepared using 15 N‐labeled materials. Four treatments were compared in a pot trial: fertilized with compost vs. unfertilized, both of them combined with (cultivated) and without (bare) plants of fibre sorghum ( Sorghum bicolor [L.] Moench.). Soil mineral nitrogen (N‐min), plant growth, and N uptake were monitored over a whole growing season (167 d after fertilizer treatment; DAT). Apparent soil mineralization (ASM) and apparent recovery fraction of nitrogen by the plant (ARF) were assessed, as well as the 15 N recovery fraction by the plant ( 15 NRF). Compost enhanced sorghum biomass at mid growth (+ 200% of dry weight compared to the unfertilized). However, the difference between the control and the fertilized plants progressively decreased towards the end of the season (+ 70%). Fertilized and unfertilized plants followed different growth patterns over time, although of the same sigmoid type. Conversely, N concentration in plant tissues followed a common dilution curve, indicating that fertilized sorghum efficiently used the supplied N, avoiding luxury consumption. Apparent soil mineralization approximately reached 45% of compost total N in pots without plants. Apparent recovery fraction attained 100% at about two third of the growing season (DAT 111), then declined to about 50% because of root and leaf decline. Compared to it, 15 NRF only reached ≈ 20% at mid growth (DAT 83), then declined to 12%. Despite the large difference in absolute values, ARF and 15 NRF exhibited a significant correlation, indicating a common trend in time. In contrast to 15 NRF, the amount of nutrient derived from fertilizer (Ndff) taken up by the plant decreased over the growth season, proving that compost contributed more to plant nutrition in the early (Ndff ≈ 50%) than in the late growing season (Ndff ≈ 25%). The large difference between ARF and 15 NRF suggests that sorghum exerted a strong nutrient demand on the soil and on the fertilizer. Both 15 NRF and ARF are considered valuable traits: the former better describes fertilizer behavior and actual supply of N, while the latter outlines the overall effect of fertilizer application on crop nutrition.
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Claims 16
Claim · model-written summary
Compost increased mid-growth sorghum dry biomass by 200% compared with unfertilized plants.
- Treatment
- Composte0
- Outcome
- sorghum biomasse0
- Direction
- enhancede0
- Value
- + 200% of dry weighte0
- Qualifier
- at mid growthe0
- Comparator
- the unfertilizede0
SorghumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compost enhanced sorghum biomass at mid growth (+ 200% of dry weight compared to the unfertilized).”
Claim · model-written summary
The compost biomass advantage declined to 70% by season end.
- Treatment
- fertilized plantse0
- Outcome
- difference between the control and the fertilized plantse0
- Direction
- decreasede0
- Value
- + 70%e0
- Qualifier
- towards the end of the seasone0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“difference between the control and the fertilized plants progressively decreased towards the end of the season (+ 70%)”
t0“sorghum”
Claim · model-written summary
Fertilized and unfertilized sorghum had different sigmoid growth patterns over time.
- Outcome
- different growth patterns over timee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilized and unfertilized plants followed different growth patterns over time, although of the same sigmoid type.”
t0“sorghum”
Claim · model-written summary
Plant tissue nitrogen concentration followed a shared dilution curve across treatments.
- Outcome
- N concentration in plant tissues followed a common dilution curvee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N concentration in plant tissues followed a common dilution curve”
t0“sorghum”
Claim · model-written summary
Apparent soil mineralization reached about 45% of compost nitrogen in pots without plants.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apparent soil mineralization approximately reached 45% of compost total N in pots without plants.”
t0“sorghum”
Claim · model-written summary
Apparent nitrogen recovery reached 100% around day 111.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apparent recovery fraction attained 100% at about two third of the growing season (DAT 111)”
t0“sorghum”
Claim · model-written summary
Apparent nitrogen recovery later declined to about 50%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“then declined to about 50% because of root and leaf decline.”
t0“Nitrogen release from a 15N‐labeled compost in a sorghum growth experiment”
Claim · model-written summary
15N recovery reached about 20% at day 83.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“15 NRF only reached ≈ 20% at mid growth (DAT 83)”
t0“sorghum”
Claim · model-written summary
15N recovery then declined to 12%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“then declined to 12%.”
t0“15N‐labeled compost in a sorghum growth experiment”
Claim · model-written summary
Apparent and labeled recovery fractions were significantly correlated over time.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ARF and 15 NRF exhibited a significant correlation, indicating a common trend in time.”
t0“sorghum”
Claim · model-written summary
Fertilizer-derived nutrient uptake declined over the growth season.
- Outcome
- amount of nutrient derived from fertilizer (Ndff) taken up by the plante0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the amount of nutrient derived from fertilizer (Ndff) taken up by the plant decreased over the growth season”
t0“sorghum”
Claim · model-written summary
Fertilizer-derived nutrient uptake was about 50% early in the season.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“early (Ndff ≈ 50%)”
t0“sorghum”
Claim · model-written summary
Fertilizer-derived nutrient uptake was about 25% late in the season.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“late growing season (Ndff ≈ 25%)”
t0“sorghum”
Claim · model-written summary
The authors inferred strong sorghum nutrient demand from the disparity between recovery metrics.
- Outcome
- strong nutrient demand on the soil and on the fertilizere0
- Qualifier
- large difference between ARF and 15 NRFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“large difference between ARF and 15 NRF suggests that sorghum exerted a strong nutrient demand on the soil and on the fertilizer”
Claim · model-written summary
The authors considered 15N recovery better for fertilizer behavior and actual nitrogen supply.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the former better describes fertilizer behavior and actual supply of N”
t0“sorghum”
Claim · model-written summary
The authors considered apparent recovery useful for overall fertilizer effects on crop nutrition.
- Outcome
- overall effect of fertilizer application on crop nutritione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the latter outlines the overall effect of fertilizer application on crop nutrition”
t0“sorghum”
The same questions in other papers
fertilization · growth · SorghumResults differ
103 papers in the same direction as this paper · 16 in the opposite direction
- negative
- negative
- no effect
116 papers more in this group
See all 120 papers →fertilization · control · SorghumResults agree
2 papers in the same direction as this paper
- positive
- positive
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.