[Research of potassium flow and circulation based on substance flow analysis]

Area of Science:

• Agricultural Science
• Environmental Science
• Resource Management

Background:

• Potassium consumption is dominated by crop production in China.
• China has a low degree of self-sufficiency in potassium due to deficient domestic resources.
• Understanding potassium flow is crucial for sustainable agriculture and environmental protection.

Purpose of the Study:

• To analyze key links in potassium issues within crop production and consumptive use in China for 2009.
• To quantify potassium losses from agricultural and domestic sources into the hydrologic cycle.
• To assess the national farmland nutrient balance regarding potassium.

Main Methods:

• Substance flow analysis was employed to track potassium.
• Data from 2009 was used to analyze crop production and consumptive use.
• Quantification of potassium input/output balance in farmland and losses to water systems was performed.

Main Results:

• A national farmland nutrient deficit of 50.4 kg/hm² was identified.
• Approximately 2.31 million tons of potash fertilizer (40.97% of total chemical fertilizer) were lost to the hydrologic cycle.
• Domestic wastewater contributed significantly to potassium entering water systems (671 thousand tons from urban, 547 thousand tons from rural areas).
• Wastewater treatment plants discharged 505 thousand tons of potassium annually (75.25% of urban emissions).

Conclusions:

• Farmland nutrient balance in China shows a significant potassium deficit.
• Substantial amounts of potash fertilizer are lost to water bodies, impacting the environment.
• Domestic wastewater is a major pathway for potassium entering aquatic ecosystems, necessitating improved management strategies.