Effects of different long-term crop straw management practices on ammonia volatilization from subtropical calcareous agricultural soil

摘要

Ammonia (NH_(3)) volatilized from agricultural production and its secondary aerosols contribute greatly to air pollution. Different long-term crop straw management practices may significantly affect the soil fertility and soil nitrogen cycle, however, the effect on NH_(3) volatilization has not been well studied. Therefore, a one-year field experiment was conducted to evaluate the effect of straw incorporation on NH_(3) volatilization from subtropical calcareous agricultural soil from a longterm perspective, including four treatments: synthetic fertilizer (CK); synthetic fertilizer incorporation with 100% or 50% of the previous season’s crop straw (SI1 and SI2, respectively); and synthetic fertilizer incorporation with 50% burned crop straw (SI2B). Soil NH_(3) volatilizations were monitored through a wheat–maize rotation year by using a dynamic chamber method. The results demonstrated that NH_(3) volatilization primarily occurred within 38 days and 7–10 days following nitrogen fertilization events for the wheat and maize seasons, respectively. Different crop straw management practices mainly impacted the NH_(3) flux of the basal fertilization rather than the topdressing fertilization; long-term crop straw incorporation effectively lowered NH_(3) loss (35.1% for SI1 and 16.1% for SI2 compared to CK; and the inhibiting effect increased with increasing straw amount, possibly contributed by the high straw carbon/nitrogen ratio, and enhanced microbial activity, which contributed to inorganic nitrogen immobilization and lower ammonium content in the topsoil. However, SI2B significantly increased (29.9%) the annual NH_(3) flux compared with SI2, indicating that long-term 100% straw incorporation could be a promising straw management practice for mitigating NH_(3) loss and increasing soil fertility.