Effects of green waste compost on soil organic carbon fractions

  Objective  This paper aims to study the effects of green waste compost on soil organic carbon fractions, which provide a theoretical basis for accurately improving the soil fertility quality.

  Method  Taking Beijing sub-center forest soil as the research object, and the experiment consisted of four fertilization schedules, i.e. no fertilizer (NF), mineral NPK fertilizer (MF), green waste compost fertilizer (GF), mineral NPK fertilizer plus green waste compost fertilizer (MF+GF). The amount of N, P and K applied in each fertilization scheme was 10 N, 1.5 P₂O₅, 5 K₂O g/kg. Soil samples were collected after fertilization 1, 3, 6, 9, and 12 months, respectively, to determine soil organic carbon fractions.

  Result  Under different fertilization schemes, soil FAC, HMC and GRSPC content showed increasing first and then decreasing, and reached highest after fertilization 1 month, which were 0.98, 5.03 g/kg and 215.48 mg/kg. After fertilization 1 year, soil FAC, HAC, DOC, carbohydrates and GRSPC content showed highest under GF and MF+GF schemes. However, HMC content was the highest under MF scheme. The sensitivity of GRSPC was significantly higher than other organic carbon fractions under different fertilization schemes, which was 4.80%−229.03%. MF scheme was the least sensitive to soil organic carbon fractions. GF scheme significantly increased the sensitivity index of soil HAC, HMC and GRSPC, and MF+GF scheme increased the sensitivity index of soil DOC, FAC and carbohydrate. The relationship between soil GRSPC and TN, AP had highest linear correlation coefficients, which were 0.703 8 and 0.867 6, respectively. The relationship between soil carbohydrate and NO₃-N, AK had highest linear correlation coefficients, which were 0.524 6 and 0.586 9.

  Conclusion  Different fertilization schemes had impact on soil organic carbon fractions. GRSPC was the most sensitive index of organic carbon fractions, and had highest correlation with soil TN and AP, which could be used as an index to measure soil fertility during forestry fertilization management.