1. Schwartzkopff, C.Potassium, calcium, magnesium-how they relate to plant growth. Usga Green Section Record, 1972, 1-2.
2. Savci, S. An agricultural pollutant: chemical fertilizer. International Journal of Environmental Science and Development,.(2012), 3(1), 77-80.
3. FAO,.ResourceSTAT-Fertilizer. Food and Agriculture Organization than 0.3 mg-N/L) throughout, however much higher nitrate concentrations (less than 1.0 mg/N/L to 28.0 mg-N/L)2009, 45-52.