Nutrient Status and Contamination Risks from Digested Pig Slurry Applied on a Vegetable Crops Field.

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Pig slurry is a potential fertilizer but carries risks of nutrient loss, heavy metals, and pathogens.
• Anaerobic digestion reduces pathogens in pig slurry, making it a safer option for soil amendment.
• Assessing the long-term effects of digested pig slurry on soil properties and crop health is crucial.

Purpose of the Study:

• To investigate the nutrient content, heavy metal contamination, and hygienic risks of digested pig slurry.
• To evaluate the impact of digested pig slurry application on vegetable crop soil fertility and heavy metal accumulation over three years.
• To determine the changes in soil nutrient availability and microbial contamination after slurry application.

Main Methods:

• A three-year field study was conducted in Wuhan, China.
• Analysis of nutrient characteristics (N, P, K) and heavy metals (Cr, Zn, Cu, As, Hg, Cd, Pb) in digested pig slurry and soil.
• Monitoring of pathogen indicators (fecal coliforms, helminth eggs) in slurry and soil.
• Measurement of plant-available phosphorus and total phosphorus in soil.

Main Results:

• Digested pig slurry retained significant amounts of N, P, and K, with reduced levels of pathogens.
• Soil fertility improved, indicated by increased plant-available phosphorus due to higher total phosphorus and reduced low-availability fractions.
• While arsenic content increased slightly, other heavy metals (Hg, Zn, Cr, Cd, Pb, Cu) remained within permissible limits for vegetable soils.
• No pathogens were detected in the fertilized soil.
• High zinc accumulation was observed with repeated slurry applications, warranting concern.

Conclusions:

• Digested pig slurry is a viable fertilizer that improves soil fertility and reduces pathogen load.
• Careful monitoring of zinc accumulation is necessary for sustainable application of digested pig slurry.
• The study highlights the potential benefits and risks of using digested pig slurry in vegetable crop production.