Testing methods for liquid fertilizers

The quality of liquid fertilizers directly impacts crop growth and soil environmental safety; consequently, testing technology plays a crucial role in ensuring product quality and sustainable agricultural development. Liquid fertilizer testing is applicable to scenarios such as production quality control, market regulation, import inspection, and self-testing by farmers.

Testing parameters fall into three main categories: nutrient content, safety indicators, and physicochemical properties. Nutrient content analysis primarily covers total nutrient levels, such as nitrogen, phosphorus, and potassium. Testing for harmful substances addresses heavy metals (e.g., lead, cadmium, mercury, and arsenic) and organic pollutants (e.g., polycyclic aromatic hydrocarbons and pesticide residues). Physicochemical property testing includes parameters such as pH value, density, solubility, and stability. Liquid fertilizers can be characterized by assessing specific gravity through weighing and evaluating low-temperature stability through freezing tests.

Core laboratory testing methods include spectrophotometry, atomic absorption spectroscopy (AAS), and inductively coupled plasma optical emission spectrometry (ICP-OES) for nutrient and elemental analysis. Gas chromatography-mass spectrometry (GC-MS) can be employed for organic pollutant analysis. Rapid testing can be performed using pH meters and conductivity meters.

The basic testing workflow comprises sample collection and pretreatment, laboratory analysis, and data analysis and reporting. Sample pretreatment involves preliminary inspection of received samples and the preparation of test samples through mixing and reduction.

With the advancement of precision agriculture, future liquid fertilizer testing technologies are expected to evolve towards greater speed, portability, and intelligence.