Abstract
Compost use in agriculture has gained popularity in recent decades as public concern over the environmental impact of synthetic inputs in agriculture has increased. Compost application has been associated with improvements to soil physical and chemical properties. Thesis research focused on compost production and utilization in an organic farming system in North Carolina and in a smallholder subsistence farming system in semi-arid West Africa. Part 1: An experiment was conducted at the Center for Environmental Farming Systems (CEFS) in Goldsboro, NC, to compare methods of composting separated solid swine waste and various rates of wheat straw. Straw was chopped (<10 cm) or unchopped and mixed with manure at five different rates and placed in piles (1m³) for composting. Sub-samples of each mixture were stocked with earthworms (Eisenia fetida) for vermicomposting. After 3 weeks, additional sub-samples were removed from piles and stocked with worms. At Weeks 3, 6, and 10, chop significantly affected C and N concentrations and C:N ratios in both vermicomposting treatments, generally in high-straw mixtures. By Week 13, chop was no longer significant. Overall, worms were not able to degrade straw fractions of mixtures that were not pre-composted. Part 2: An experiment was conducted at a site in the North Carolina Piedmont (Pittsboro) and another in the Coastal Plain (Goldsboro) to evaluate the integration of compost with cover crops, both common sources of fertility in organic farming systems. Treatments were: poultry litter compost (COMP), crimson clover (CLOV), clover + compost (MIX), and a control fertilized with soymeal (SOY). COMP and CLOV plots were also amended with soymeal to equalize N rates across treatments. Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP) or biomass (DM) accumulation at 5 WAP at either site. At Goldsboro, CLOV yielded 22% more DM at harvest than COMP and 31% more marketable ears. Total yield of COMP plots was 22% less than CLOV while marketable yield was 20 to 31% less than CLOV, MIX, or SOY treatments. Release of plant available nitrogen (PAN) from decomposing clover (C:N 11.1) may have been slower than from compost (C:N 8.1) or soymeal (C:N 6.2), coinciding with the period of maximum uptake by corn plants. Soil inorganic N (SIN) concentration was greater at Pittsboro, likely due to method of incorporation (roto-tilled vs. disked) and soil type. In a lab incubation of both soils (and which did not include soymeal), SIN in Goldsboro MIX treatments was greater than the sum of CLOV and COMP SIN, suggesting a priming effect, likely masked by soymeal in the field experiment. Part 3: The Jóór (Dior) soils of Senegal's Peanut Basin are inherently low in OM, limiting yields of millet and other crops and threatening the food security of smallholders. A series of focus groups and interviews were conducted in eight villages to characterize the site-specific fertility management practiced by farmers in the Peanut Basin. On-site measurements revealed little significant difference between the effects of compost and manure on peanut and millet growth, but significant increases over unamended areas. Similarly, chemical analysis revealed increased cation exchange capacity and nutrient concentrations in soils amended with compost or manure. Similarities in the chemical characteristics of compost and traditional pile manure (sëntaare) suggest that development workers could emphasize improved pile management rather than promoting more labor-intensive composting.
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Claims 17
Claim · model-written summary
Chopping straw significantly affected C and N concentrations and C:N ratios in vermicomposting treatments, generally in high-straw mixtures.
- Treatment
- chope1
- Outcome
- C and N concentrations and C:N ratiose1
- Qualifier
- generally in high-straw mixturese1
Not reportedTaxon
Verbatim
e1“At Weeks 3, 6, and 10, chop significantly affected C and N concentrations and C:N ratios in both vermicomposting treatments, generally in high-straw mixtures”
Claim · model-written summary
Earthworms were not able to degrade straw fractions of mixtures that were not pre-composted.
Not reportedTaxon
Verbatim
e1“Overall, worms were not able to degrade straw fractions of mixtures that were not pre-composted”
Claim · model-written summary
Compost, cover-crop and soymeal treatments did not affect sweet corn height or biomass accumulation at either site.
- Taxon
- sweet corne1
- Treatment
- poultry litter compost (COMP), crimson clover (CLOV), clover + compost (MIX)e2
- Outcome
- sweet corn heighte1
- Direction
- did not affecte1
- Qualifier
- at 5 or 7 weeks after planting (WAP) or biomass (DM) accumulation at 5 WAP at either sitee1
- Comparator
- a control fertilized with soymeal (SOY)e2
Verbatim
e1“Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP) or biomass (DM) accumulation at 5 WAP at either site”
e2“Treatments were: poultry litter compost (COMP), crimson clover (CLOV), clover + compost (MIX), and a control fertilized with soymeal (SOY)”
Claim · model-written summary
At Goldsboro, crimson clover yielded 22% more dry matter at harvest than poultry litter compost.
Verbatim
e1“Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP)”
e2“At Goldsboro, CLOV yielded 22% more DM at harvest than COMP and 31% more marketable ears”
Claim · model-written summary
At Goldsboro, crimson clover yielded 31% more marketable ears than poultry litter compost.
Verbatim
e1“Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP)”
e2“At Goldsboro, CLOV yielded 22% more DM at harvest than COMP and 31% more marketable ears”
Claim · model-written summary
Total yield of poultry litter compost plots was 22% less than crimson clover.
Verbatim
e1“Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP)”
e2“Total yield of COMP plots was 22% less than CLOV while marketable yield was 20 to 31% less than CLOV, MIX, or SOY treatments”
Claim · model-written summary
Marketable yield of poultry litter compost was 20 to 31% less than crimson clover, clover + compost or soymeal treatments.
Verbatim
e1“Treatment differences did not affect sweet corn height at 5 or 7 weeks after planting (WAP)”
e2“Total yield of COMP plots was 22% less than CLOV while marketable yield was 20 to 31% less than CLOV, MIX, or SOY treatments”
Claim · model-written summary
Release of plant available nitrogen from decomposing clover may have been slower than from compost or soymeal (hypothesis).
- Treatment
- decomposing clovere1
- Outcome
- Release of plant available nitrogen (PAN)e1
- Direction
- slowere1
- Comparator
- compost (C:N 8.1) or soymeal (C:N 6.2)e1
Not reportedTaxon
Verbatim
e1“Release of plant available nitrogen (PAN) from decomposing clover (C:N 11.1) may have been slower than from compost (C:N 8.1) or soymeal (C:N 6.2), coinciding with the period of maximum uptake by corn plants”
Claim · model-written summary
Soil inorganic N concentration was greater at Pittsboro, likely due to method of incorporation and soil type.
- Outcome
- Soil inorganic N (SIN) concentratione1
- Direction
- greatere1
- Qualifier
- likely due to method of incorporation (roto-tilled vs. disked) and soil typee1
- Setting
- Pittsboroe1
Not reportedTaxon
Verbatim
e1“Soil inorganic N (SIN) concentration was greater at Pittsboro, likely due to method of incorporation (roto-tilled vs. disked) and soil type”
Claim · model-written summary
In lab incubation, soil inorganic N in Goldsboro MIX treatments was greater than the sum of CLOV and COMP, suggesting a priming effect.
- Treatment
- MIXe1
- Outcome
- SINe1
- Direction
- greatere1
- Qualifier
- suggesting a priming effecte1
- Comparator
- the sum of CLOV and COMP SINe1
- Setting
- lab incubatione1
Not reportedTaxon
Verbatim
e1“In a lab incubation of both soils (and which did not include soymeal), SIN in Goldsboro MIX treatments was greater than the sum of CLOV and COMP SIN, suggesting a priming effect, likely masked by soymeal in the field experiment”
Claim · model-written summary
Compost and manure produced little significant difference in peanut growth.
- Taxon
- peanut
Arachis hypogaeae1 - Treatment
- composte1
- Outcome
- growthe1
- Direction
- little significant differencee1
- Comparator
- manuree1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“On-site measurements revealed little significant difference between the effects of compost and manure on peanut and millet growth, but significant increases over unamended areas”
Claim · model-written summary
Compost and manure produced little significant difference in millet growth.
Verbatim
e1“On-site measurements revealed little significant difference between the effects of compost and manure on peanut and millet growth, but significant increases over unamended areas”
Claim · model-written summary
Compost and manure significantly increased peanut growth over unamended areas.
- Taxon
- peanutArachis hypogaeae1
- Treatment
- compost and manuree1
- Outcome
- growthe1
- Direction
- increasese1
- Comparator
- unamended arease1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“On-site measurements revealed little significant difference between the effects of compost and manure on peanut and millet growth, but significant increases over unamended areas”
Claim · model-written summary
Compost and manure significantly increased millet growth over unamended areas.
Verbatim
e1“On-site measurements revealed little significant difference between the effects of compost and manure on peanut and millet growth, but significant increases over unamended areas”
Claim · model-written summary
Compost or manure increased cation exchange capacity and nutrient concentrations in amended soils.
- Treatment
- compost or manuree1
- Outcome
- cation exchange capacity and nutrient concentrationse1
- Direction
- increasede1
Not reportedTaxonComparator
Verbatim
e1“Similarly, chemical analysis revealed increased cation exchange capacity and nutrient concentrations in soils amended with compost or manure”
Claim · model-written summary
Chemical characteristics of compost and traditional pile manure were similar.
Not reportedTaxon
Verbatim
e1“Similarities in the chemical characteristics of compost and traditional pile manure (sëntaare) suggest that development workers could emphasize improved pile management rather than promoting more labor-intensive composting”
Claim · model-written summary
Development workers could emphasize improved pile management rather than promoting more labor-intensive composting (recommendation).
Not reportedTaxon
Verbatim
e1“Similarities in the chemical characteristics of compost and traditional pile manure (sëntaare) suggest that development workers could emphasize improved pile management rather than promoting more labor-intensive composting”
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