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

Abstract

Ammonia (NH3) 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 NH3 volatilization has not been well studied. Therefore, a one-year field experiment was conducted to evaluate the effect of straw incorporation on NH3 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 NH3 volatilizations were monitored through a wheat–maize rotation year by using a dynamic chamber method. The results demonstrated that NH3 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 NH3 flux of the basal fertilization rather than the topdressing fertilization; long-term crop straw incorporation effectively lowered NH3 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 NH3 flux compared with SI2, indicating that long-term 100% straw incorporation could be a promising straw management practice for mitigating NH3 loss and increasing soil fertility.

Keywords

• ammonia volatilization
• crop straw incorporation
• straw burning
• calcareous soil