Investigation of technology for composting mixed deer manure and straw.

Composting is an effective method for utilizing agricultural straw waste and livestock manure resources. Using deer manure and corn straw as raw materials, the changes in various indexes were studied during composting under different initial C/N ratios, initial moisture contents, and particle sizes of corn straw, and compost maturity was evaluated. Moisture content, total organic carbon content, and C/N ratio all declined during composting, while total nitrogen, total phosphorus, total potassium, pH, germination index, and electrical conductivity increased. The grey relational analysis method was used to evaluate maturity. The results showed that a mixture of stalk and deer manure with initial moisture content of 55%, initial C/N ratio of 30:1, and a straw particle size of 1.5-3.5 cm constituted the optimal experimental conditions. Taguchi analysis indicated that initial moisture content exerted the greatest influence on compost maturity, followed by initial C/N ratio and crushed straw particle size. This study provides an important reference for the utilization of compost derived from a mixture of livestock manure and straw.

Study of the potential of barnyard grass for the remediation of Cd- and Pb-contaminated soil.

In this study, the microwave digestion method was used to determine total cadmium (Cd) and lead (Pb) concentrations, the BCR method was used to determine different states of Cd and Pb, and atomic absorption spectroscopy (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES) were used to determine Cd and Pb concentrations in simulated soil and barnyard grass before and after planting barnyard grass to provide a theoretical basis for the remediation of Cd- and Pb-contaminated soil. The results showed that the bioconcentration factor changes with different Cd concentrations are relatively complex and that the removal rate increases regularly. The 100 mg kg-1 Cd treatment had the highest removal rate, which reached 36.66%. For Pb, the bioconcentration factor decreased and tended to reach equilibrium as the Pb concentration increased. The highest removal rate was 41.72% and occurred in the 500 mg kg-1 Pb treatment; however, this removal rate was generally lower than that of Cd. In addition, the reduction state had the highest change rate, followed by the residual, acid soluble and oxidation states. For Pb, the residual state has the highest change rate, followed by the acid soluble state, reduction state and oxidation state. In addition, a significant correlation was observed between the soil Pb and Cd concentrations and the concentrations of Pb and Cd that accumulated in the belowground biomass of the barnyard grass, but no significant correlation was observed between the soil Pb and Cd concentrations and the amounts of Pb and Cd that accumulated in the aboveground biomass of the barnyard grass. The highest transfer factor of Cd was 0.49, which occurred in the 5 mg kg-1 Cd treatment. The higher transfer factor of Pb was 0.48 in the 100 mg kg-1 Pb treatment. All of these factors indicate that the belowground biomass of barnyard grass plays a more important role in the remediation of Cd- and Pb-contaminated soils than the aboveground biomass of barnyard grass. Remediation should occur through phytostabilization. Thus, with its strong adaptability and lush growth, barnyard grass can be applied as a pioneer species for the phytoremediation of Cd- and Pb-contaminated soils.