• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.482-486
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• 2013

Assessment of nutrient balance in region unit is important to make a decision on nutrient management in agriculture. In this study, the nutrient demand in arable land and nutrient supply from livestock manure and chemical fertilizer were estimated from pig-concentrated areas. Three regions (H, I and J) were selected on the basis of pig numbers per unit area of arable land. In H and I regions, nitrogen amount from pig manure occupied about 50% of total livestock manure. Nutrient supply was three times higher compared to the nutrient demand in each of 3 regions. Soil available phosphate of higher pig-populated area in regional unit was higher than less populated livestock area. Therefore, livestock manure-derived regional management and monitoring of soil nutrient contents is necessary for the minimization and improvement of nutrient surplus.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.120-126
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• 2014

An accurate analysis of nutrient balance in different cropping systems is necessary for improving soil fertilities, causing higher crop yields and quality. This study was carried out to investigate the nutrient balance, changes in soil properties, and their effects on crop yield in long-term field cultivation under mono- and rotation-cropping systems (MCS and RCS, respectively). The analytical results of the soil properties showed that the application of mineral fertilizers alone in the MCS leads the reduction of soil CEC, exchangeable Ca, and microbial biomass C and N. Compared with the MCS of soybean, the RCS of soybean and barley significantly improved the soil properties, which increased crop yield. It might be due to the barley residue added to the RCS soil. Mean nutrient balances for 4 years were -55.9 kg N, +34.7 kg $P_2O_5$, and -0.3 kg $K_2O$ $ha^{-1}$ for the MCS and +19.7 kg N, +107.4 kg $P_2O_5$, and -48.6 kg $K_2O$ $ha^{-1}$ for the RCS, respectively. These nutrient imbalances mean that conventional fertilizer recommendations were inadequate for maintaining soil nutrient balance. From these results, we can conclude that the crop rotation may change comprehensive physical, chemical, and biological soil properties. These changes could affect the nutrient balance and then the crop yield.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.47-50
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• 2009

Nutrient losses, especially nitrogen and phosphorus, in agricultural runoff can contaminate surface and ground water, leading to eutrophication. Thus, erosion control is crucial to minimizing nutrient losses from agricultural land. Assessments of various erosion control practices were carried out under various cropping system, soil management practices, and slope conditions by means of a lysimeter study and under artificial rainfall. Soil and nutrient losses were monitored in a small agricultural field to evaluate the soil conservation practices. Nutrient losses occur in runoff and leachate (dissolved nutrient) and in sediments (particulate nutrient). Dissolved nitrates accounted for the majority (about 90%) of nitrate transport within the soil. Particulate phosphate in sediments represented the majority (60% to 67%) of phosphate transport. Recently, engineering and agronomic erosion-control practices haver been used to reduce erosion problems in fields on slopes. These practices reduced soil loss, runoff, and nutrient loss to 1/6, 1/2,and 1/3 their original levels, respectively. Bioavailable particulate phosphate in sediments represents a variable but longterm source of phosphate for algae. Dissolved nitrate and phosphate are immediately available for algal uptake, so reducing fluxes of these nutrients should also reduce the risk of eutrophication.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.157-164
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• 2021

Smart agriculture requires sensing systems which are fundamental for precision agriculture. Adequate and appropriate water and nutrient supply not only improves crop productivity but also benefit to environment. However, there is no available soil sensor to continuously monitor nutrient status in soil. Electrical conductivity (EC) of soil is affected by ion contents in soil and can be used to evaluate nutrient contents in soil. Comparison of various commercial EC sensors showed similar water content and EC values at water content less than 20%. Soil EC values measured by sensors decreased with decreasing soil water content and linearly correlated with soil water content. EC values measured by soil sensor were highly correlated with water soluble nutrient contents such as Ca, K, Mg and N in soil indicating that the soil EC sensor can be used for monitoring changes in plant available nutrients in soil.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.967-976
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• 2023

Biochar is emerging as a promising substance for achieving carbon neutrality and climate change mitigation. It can absorb several nutrients via ion bonding on its surface functional groups, resulting in slow dissociation of the bonds. Biochar, like organic fertilizers, contributes to sustainable nutrient management. The purpose of this study was to investigate the effects of nutrient-coated biochar amendments on leafy vegetables production and soil fertility. The nutrient-coated biochar was produced by soaking rice husk biochar in a nutrient solution containing nitrogen (N), phosphorus, and potassium for 24 hours. Nutrient-coated biochar and organic fertilizers were applied to soil at a rate of 120 kg·N·ha^-1. The growth components of the leafy vegetables showed that nutrient-coated biochar led to the highest fresh weight (FW) of both lettuce and kale (i.e., 146.67 and 93.54 g·plant^-1 FW, respectively). As a result, nutrient-coated biochar amendments led to superior yield compared to the control treatment and organic fertilization. The elemental composition of leafy vegetables revealed that soil amended with nutrient-coated biochar resulted in higher nutrient contents, which was attributed to the high nutrient contents supplied by the rice husk biochar. Soil amendment with nutrient-coated biochar positively enhanced the soil fertility compared to amendment with organic fertilizer. Therefore, nutrient-coated biochar is a promising substance for enhancing agronomic performance of leafy vegetables and improving soil fertility.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.98-102
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• 2012

Organic farming has rapidly increased in Gangwon province, but there is a concern about nutrient accumulation and nutrient imbalance in the soil of organic farming. This study was conducted to investigate the impact of continuous application of organic amendments on growth and yield of red pepper and soil characteristics compared with chemical fertilizers application for four years. Treatments of organic amendments including oil cake, rice straw compost, amino acid compost, rice bran compost, and mushroom media (spent substrate) compost resulted in comparable growth and yield of pepper to chemical fertilizers. Organic amendments improved soil physical and chemical characteristics. Especially, rice bran compost and oil cake significantly increased soil organic matter compared with chemical fertilizer application and mushroom media compost and rice straw compost significantly improved soil aggregate stability. On the other hand, available phosphate level in the soil amended with rice bran compost or mushroom media compost was relatively high compared with the other treatments due to relatively high phosphate levels in the composts. It is not easy to adjust nutrient composition in the organic materials. Therefore, the results obtained from the study imply that nutrient imbalance needs to be carefully considered in organic farming without use of chemical fertilizers.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.509-515
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• 2011

For this study the 4 sub-watersheds Okdong A, Hankang B, Jecheon A and Hankang C which are the main streams of the Han River within the mid-level region of Chungju Dam are selected and the analysis of soils has been carried out through the soil basic survey. When it comes to the soil erosion amount the soil nutrient load has been calculated by utilizing the RUSLE erosion equation. In case of the data related to the measurement of water flow and quality the information available from the "Water Information System" one of the websites run by the Ministry of Environment has been used to calculate the water pollution load. The correlation between the soil nutrient load and the water pollutant load has been analyzed through making comparison. According to the results related to the soil nutrient load of each sub-watershed the Hankang C shows the highest values TOC 29,986.92 ton/yr, TN 3,860.33 ton/yr and TP 973.97 ton/yr respectively. Even when it comes to the loads related to water quality the Hankang C shows also comparatively high values TOC 6,625.64 ton/yr, TN 7,335.01 ton/yrand TP 145.49 ton/yr respectively. The soil nutrient loads of the sub-watersheds are shown to increase towards the lower stream meaning the load increases in the order of Hankang CHankang B and Okdong A. When it comes to the water pollutant load the value goes up along down the water system meaning the load gets higher in the order of Hankang C, Hankang B and Okdong A while utilizing the mainstream within the mid-level region of Chungju Dam as the basis. The correlation study showed that the nutrient content of soil is proportional to the pollutant load in water with the strongest positive correlation with TOC.

• The Korean Journal of Ecology
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• v.27 no.2
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• pp.67-71
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• 2004

This study was carried out to evaluate soil carbon and nutrient storage of three adjacent coniferous plantations (Larix leptolepis, Pinus densiflora and Pinus rigitaeda) growing on a similar site with a same planting age (42-year old) in the Sambong Exhibition Forests, Hamyang-gun, Gyungsangnam-do. The soil carbon concentration among three plantations was not significantly different in 0∼10cm soil depth, but other two depths (10∼20cm and 20∼30cm) showed higher carbon concentration in P. densiflora plantation than the other two plantations. The exchangeable cation concentrations (Ca and Mg) in 0∼10cm depth were significantly lower in L. leptolepis plantation than in the other two plantations, while nitrogen and phosphorus concentrations were not significantly different among three plantations except for nitrogen at 10∼20cm depth in P. rigitaeda plantation. Soil carbon storage in 0∼20cm depth of three plantations was unaffected by the stand types. Soil nutrient storage was not significantly different at each depth except for nitrogen storage at 10∼20cm depth in P. rigitaeda plantation because of the variation of bulk density and coarse fragment. This result demonstrates that soil carbon and nutrient concentrations among the plantations on a similar soil condition can be altered significantly by tree species effects over 40 years after plantation establishment.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.537-546
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• 2016

The development of models for agriculture systems, especially for crop production, has supported the prediction of crop yields under various environmental change scenarios and the selection of better crop species or cultivar. Crop models could be used as tools for supporting reasonable nutrient management approaches for agricultural land. This paper outlines the simplified structure of main crop models (crop growth model, crop-soil model, and crop-soil-environment model) frequently used in agricultural systems and shows diverse application of their simulated results. Crop growth models such as LINTUL, SUCROS, could provide simulated data for daily growth, potential production, and photosynthesis assimilate partitioning to various organs with different physiological stages, and for evaluating crop nutrient demand. Crop-Soil models (DSSAT, APSIM, WOFOST, QUEFTS) simulate growth, development, and yields of crops; soil processes describing nutrient uptake from root zone; and soil nutrient supply capability, e.g., mineralization/decomposition of soil organic matter. The crop model built for the DSSAT family software has limitations in spatial variability due to its simulation mechanism based on a single homogeneous field unit. To introduce well-performing crop models, the potential applications for crop-soil-environment models such as DSSAT, APSIM, or even a newly designed model, should first be compared. The parameterization of various crops under different cultivation conditions like those of intensive farming systems common in Korea, shortened crop growth period, should be considered as well as various resource inputs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.108-115
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• 2002

The effects of long-term fertilization on soil properties and nutrient availability are not well documented for cassava cultivation in Vietnam. In 1990, a field research plots were established with 12 treatments to test the effect of different rates of nitrogen (N), phosphorus (P) and potassium (K) on soil properties in Acrisols at Thai Nguyen University in Northern Vietnam. In 1999, composite soil samples (0 to 20cm depth) were collected from eight selected plots for measurements of nutrient supply rates by ion exchange membrane probes and for growing corn and canola in a growth chamber with and without added lime. Generally, long-term nitrogen (N) fertilization increased available N supply rates but decreased available potassium (K) and magnesium (Mg). Long-term phosphorus(P) applications increased canola N, calcium (Ca) and Mg uptake. Canola P uptake increased with increased P rates only when lime was added. Long-term K applications increased canola N, K, Ca, Mg uptake but only significantly increased corn N uptake. Liming significantly increased uptake of N, P, K, Ca, Mg and S for both corn and canola. However, N $H_{4-}$N, K and Mg soil supply rates were reduced when lime was added, due to competition between Ca from the added lime and other nutrients.