Phosphorus Budget for a Forested-Agricultural Watershed in Korea

Abstract

Despite increased attention to the need for sustainable agriculture, fertilizer application rates above crop requirements remain common agricultural practices in South Korea, causing eutrophication of freshwater and coastal ecosystems. The aim of this study is to quantify phosphorus (P) inputs, outputs, and retention in a forested-agricultural watershed. The P budget showed that the combined use of chemical fertilizer and organic compost was the largest source of P (97.6% of the total) followed by atmospheric wet deposition (2.1% of the total P), whereas forest export (0.2% of the total) and sewage treatment plants (STPs) (0.1% of the total) were negligible. The P outputs were crop harvesting and hydrologic export to surface water. The P balance showed that P inputs are higher than the P outputs; approximately 87% of the total P input was retained in the soils within the watershed. However, P concentrations in drainage water were still high enough to cause eutrophication of downstream reservoirs. The results provide important details on the proportion of P export and retention in the watershed. This will help efforts to improve water quality and design better management strategies for agricultural nonpoint source pollution.

Rational budgeting approach as a nutrient management tool for mixed crop-swine farms in Korea

“…Data obtained from farm census and lab estimation together with data collected from the published literature were used to construct the farm nutrient budgets [6,7,[9][10][11][12][13][14][15][16][17][18][19][20][21]. Nutrient fluxes were used to convert the different components of the nutrient budgets from their original reported unit to common units (Table 2).…”

“…Nutrient fluxes were used to convert the different components of the nutrient budgets from their original reported unit to common units (Table 2). Most of the fluxes used in this study were derived from the studies focused on Korea [6,7,[9][10][11][12][13][14]. Seed nutrient inputs fluxes were obtained from Kremer [15].…”

“…P lc = (AH×D l ×C P ×LC P ) (12) where N lc and P lc are the nutrient inputs from liquid compost (kg/yr); AH is the number of animals (head); D l is unit discharge coefficient for liquid fraction (kg/head/yr); C N and C P are the nutrient content in liquid fraction after separation (g/kg) and LC N and LC P are nutrient loading fluxes. v) Nutrient inputs from atmospheric deposition Values from previously published literature were used to estimate the N and P inputs from atmospheric deposition [9,11] and expressed as:…”

“…Annual P inputs from seeds to the farms (1, 2, and 3) were calculated as 0.5, 3.0, and 2.0 kg/yr, respectively. Atmospheric deposition of P was estimated as 0.59 kg/ha/yr [9], which equivalent to 0.4, 1.9, and 1.4 kg/yr of P inputs to farm 1, 2 and 3, respectively.…”

Evaluation of Struvite Recovered from Swine Wastewater as an Alternative Phosphorus Source in Broiler Feed

“…There is no substitution of P as a fertilizer and feed additive in agricultural production systems, and therefore, ensuring a substantial amount of P will be necessary for future food security [1][2][3]. Most of the P used in livestock feed and applied as fertilizers are either lost in wastewater or by leaching and runoff [4,5]. P concentration in livestock wastewater is generally high (600 to 1400 mg/L) [6] and therefore P recovery from livestock wastewater seems necessary.…”