The soil nutrient balances of agricultural systems differ from those of natural ecosystems primarily due to the removal of nutrients in commercial products. In cropping systems, this removal can be a major factor in soil nutrient depletion. Other factors include nutrient removal in vegetative parts of crops and their residues, as well as losses through soil erosion, runoff, leaching, burning of crop residues, and gaseous losses (eg, denitrification and volatilization).Soil nutrient balances were calculated as net differences between four nutrient inputs (IN1, IN2, IN3 and IN4) and five nutrient outputs (OUT1, OUT2, OUT3, OUT4 and OUT5) flows that were independently quantified. Average erosion removal (OUT5), leaching (OUT3), and crop yields (OUT1) were the main causes of soil nutrient export in all socioeconomic groups at the study site. An average partial (farm management) nutrient balance of the reviewed articles indicated a relatively significant accumulation of nitrogen (N), while for potassium, it was slightly negative.

Keywords: Nutrient balance; soil; runoff; variability