Abstract
In view of the high cost of chemical fertilizers, use of natural fertilizer sources for increasing crop production on a sustainable basis has become imperative. A pot experiment was conducted in silty clay loam, mixed, hyperthermic typic calciustepts, and Tarnab soil series to study the effect of different levels of humic acid (HA) derived from lignitic coal on the growth of maize (Zea maysL. Kissan). HA was sprayed on soil at the rate of 0, 50, 100, 150, 200, 250, and 300 mg kg−1 soil along with uniform dose of nitrogen–phosphorus–potassium (NPK) (120–90–60 kg ha−1). The addition of 50 and 100 mg kg−1 HA caused significant increase of 20 and 23% in shoot and 39 and 32% in root dry weight of maize plants as compared to control. The increasing levels of HA above 50 and 100 mg kg−1 produced no significant effect on maize yield. Soil organic matter content was improved slightly (7 to 14%) and pH values were decreased by 0.2 to 0.3 unit by the HA treatments. Addition of HA increased soil N concentration and plant N accumulation significantly over control with no significant differences within the treatments of different levels of HA applied. Soil P concentration improved significantly by the addition of 200 mg kg−1 HA whereas plant P accumulation was not significantly affected by the application of different levels of HA. Micronutrients [zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu)] concentrations of soil and their accumulations by maize plants increased nonsignificantly over control by the application of HA. Laboratory incubation experiment conducted to study the effect of HA on soil biological and physicochemical properties showed that the addition of 0.5 and 1.0 kg ha−1 HA promoted CO2 evolution, increased bacterial population by 355% to 476%, fungi 610 to 716%, and cation exchange capacity of the soil by 13.8 to 28.9%. Results suggest that increases in growth of maize due to HA addition may be associated with the improved biochemical environment of the soil.
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Claims 15
Claim · model-written summary
Addition of 50 and 100 mg kg−1 HA significantly increased shoot dry weight of maize by 20 and 23% relative to control.
- Organ / stage
- shoote1
- Treatment
- addition of 50 and 100 mg kg−1 HAe1
- Outcome
- dry weighte1
- Direction
- increasee1
- Value
- 20 and 23%e1
- Comparator
- controle1
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“The addition of 50 and 100 mg kg−1 HA caused significant increase of 20 and 23% in shoot and 39 and 32% in root dry weight of maize plants as compared to control”
Claim · model-written summary
Addition of 50 and 100 mg kg−1 HA significantly increased root dry weight of maize by 39 and 32% relative to control.
- Organ / stage
- roote1
- Treatment
- addition of 50 and 100 mg kg−1 HAe1
- Outcome
- root dry weighte1
- Direction
- increasee1
- Value
- 39 and 32%e1
- Comparator
- controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“The addition of 50 and 100 mg kg−1 HA caused significant increase of 20 and 23% in shoot and 39 and 32% in root dry weight of maize plants as compared to control”
Claim · model-written summary
HA above 50 and 100 mg kg−1 had no significant effect on maize yield.
- Treatment
- increasing levels of HA above 50 and 100 mg kg−1e2
- Outcome
- maize yielde2
- Direction
- no significant effecte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e2“The increasing levels of HA above 50 and 100 mg kg−1 produced no significant effect on maize yield”
Claim · model-written summary
HA treatments improved soil organic matter content slightly, by 7 to 14%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e2“Soil organic matter content was improved slightly (7 to 14%)”
e3“pH values were decreased by 0.2 to 0.3 unit by the HA treatments”
Claim · model-written summary
HA treatments decreased soil pH by 0.2 to 0.3 unit.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e3“pH values were decreased by 0.2 to 0.3 unit by the HA treatments”
Claim · model-written summary
Addition of HA significantly increased soil N concentration and plant N accumulation over control.
- Treatment
- Addition of HAe4
- Outcome
- soil N concentration and plant N accumulatione4
- Direction
- increasede4
- Comparator
- controle4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e4“Addition of HA increased soil N concentration and plant N accumulation significantly over control with no significant differences within the treatments of different levels of HA applied”
Claim · model-written summary
Different levels of HA applied showed no significant differences in soil N concentration and plant N accumulation.
- Treatment
- different levels of HA appliede4
- Outcome
- soil N concentration and plant N accumulatione4
- Direction
- no significant differencese4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e4“Addition of HA increased soil N concentration and plant N accumulation significantly over control with no significant differences within the treatments of different levels of HA applied”
Claim · model-written summary
Addition of 200 mg kg−1 HA significantly improved soil P concentration.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e5“Soil P concentration improved significantly by the addition of 200 mg kg−1 HA”
Claim · model-written summary
Plant P accumulation of maize was not significantly affected by different levels of HA.
- Treatment
- application of different levels of HAe6
- Outcome
- plant P accumulatione6
- Direction
- not significantly affectede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e6“whereas plant P accumulation was not significantly affected by the application of different levels of HA”
Claim · model-written summary
Application of HA nonsignificantly increased soil micronutrient concentrations and their accumulation by maize.
- Treatment
- application of HAe7
- Outcome
- concentrations of soil and their accumulations by maize plantse7
- Direction
- increasede7
- Qualifier
- zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu)e7
- Comparator
- controle7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e7“Micronutrients [zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu)] concentrations of soil and their accumulations by maize plants increased nonsignificantly over control by the application of HA”
Claim · model-written summary
Addition of 0.5 and 1.0 kg ha−1 HA promoted soil CO2 evolution in a laboratory incubation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“the addition of 0.5 and 1.0 kg ha−1 HA promoted CO2 evolution, increased bacterial population by 355% to 476%, fungi 610 to 716%, and cation exchange capacity of the soil by 13.8 to 28.9%”
Claim · model-written summary
Addition of 0.5 and 1.0 kg ha−1 HA increased soil bacterial population by 355% to 476%.
- Treatment
- the addition of 0.5 and 1.0 kg ha−1 HAe1
- Outcome
- bacterial populatione1
- Direction
- increasede1
- Value
- 355% to 476%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“the addition of 0.5 and 1.0 kg ha−1 HA promoted CO2 evolution, increased bacterial population by 355% to 476%, fungi 610 to 716%, and cation exchange capacity of the soil by 13.8 to 28.9%”
Claim · model-written summary
Addition of 0.5 and 1.0 kg ha−1 HA increased soil fungi by 610 to 716%.
- Treatment
- the addition of 0.5 and 1.0 kg ha−1 HAe1
- Outcome
- fungie1
- Direction
- increasede1
- Value
- 610 to 716%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“the addition of 0.5 and 1.0 kg ha−1 HA promoted CO2 evolution, increased bacterial population by 355% to 476%, fungi 610 to 716%, and cation exchange capacity of the soil by 13.8 to 28.9%”
Claim · model-written summary
Addition of 0.5 and 1.0 kg ha−1 HA increased cation exchange capacity of the soil by 13.8 to 28.9%.
- Treatment
- the addition of 0.5 and 1.0 kg ha−1 HAe1
- Outcome
- cation exchange capacity of the soile1
- Direction
- increasede1
- Value
- 13.8 to 28.9%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e1“the addition of 0.5 and 1.0 kg ha−1 HA promoted CO2 evolution, increased bacterial population by 355% to 476%, fungi 610 to 716%, and cation exchange capacity of the soil by 13.8 to 28.9%”
Claim · model-written summary
Increased growth of maize due to HA addition may be associated with the improved biochemical environment of the soil.
- Treatment
- HA additione2
- Outcome
- growth of maizee2
- Direction
- increasese2
- Qualifier
- may be associated with the improved biochemical environment of the soile2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“MAIZE PLANTS”
e2“Results suggest that increases in growth of maize due to HA addition may be associated with the improved biochemical environment of the soil”
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