Sunflower hulls degradation by co-composting with different nitrogen sources

Area of Science:

• Agricultural Science
• Environmental Science
• Waste Management

Background:

• Sunflower hulls are a lignocellulosic agricultural residue with potential for composting.
• Optimizing composting requires understanding the impact of co-substrates and temperature on decomposition.

Purpose of the Study:

• To evaluate the decomposition efficiency of sunflower hulls with various organic and inorganic nitrogen co-substrates.
• To determine the optimal amendment for composting sunflower hulls under thermophilic conditions.

Main Methods:

• Composting trials were conducted for 100 days under thermophilic conditions.
• Six treatments included sunflower hulls alone and with vetch, alfalfa, and/or ammonium nitrate.
• Key parameters measured included carbon fractions, nitrogen content, fiber components, pH, and C:N ratio.

Main Results:

• Sunflower hulls mixed with organic amendments (vetch, alfalfa) showed superior decomposition compared to inorganic amendment (ammonium nitrate).
• Organic co-substrates led to significant variations in fiber fractions and a greater decrease in dry matter.
• The carbon to nitrogen ratio decreased substantially with organic amendments, indicating efficient composting.

Conclusions:

• Organic amendments, particularly vetch and alfalfa, are more effective than ammonium nitrate for composting sunflower hulls.
• Thermophilic composting of sunflower hulls with organic co-substrates enhances decomposition and nutrient stabilization.