Different management and movement in the agricultural nutrient balances of Korea and the Netherlands: Highest nutrient surplus countries among OECD members.

Korea and the Netherlands historically developed highly fertilized cropping systems, resulting in the highest nitrogen (N) and phosphorus (P) surpluses among Organization for Economic Cooperation and Development (OECD) countries. However, their nutrient balances changed differently over the past three decades. The Netherlands reduced its N and P balances dramatically, from 328 to 166 kg ha^-1 and 35 to 4 kg ha^-1, respectively, while Korea's balances remained unchanged with the highest levels in 2019 (230 kg N ha^-1 and 46 kg P ha^-1). To find solutions for Korea's persistent nutrient surpluses, changes in nutrient balances and related parameters were compared using OECD statistics. Despite Korea's efforts to reduce chemical fertilizer use, a 33% decline in agricultural land area and increased manure production offset the reduction. Conversely, the Netherlands rapidly decreased nutrient balances by reducing N and P inputs by 35% and 52%, respectively. Nutrient outputs in the Netherlands, primarily driven by forage harvest, were over twice as high as in Korea, helping lower its balances despite minor output declines. By the late 2010s, Dutch P input and output were nearly equilibrated, indicating no P surplus. As a result, the Netherlands has improved its nutrient use efficiency substantially, which inversely correlates with nutrient balance, but Korea has not shown considerable changes. Therefore, to address Korea's nutrient balances, nutrient inputs should be reduced while increasing outputs. Determining the level of nutrient inputs, coupled with advanced agronomic practices and technologies to improve nutrient use efficiency, is essential for achieving reductions in nutrient balances while enhancing crops and forage production.