Simulation of the nitrogen balance in the soil and a winter wheat crop

A simulation model for winter wheat growth, crop nitrogen dynamics and soil nitrogen supply was tested against experimental data. When simulations of dry matter production agreed with measurements, nitrogen uptake was simulated accurately. The total amount of soil mineral nitrogen as well as the distribution of mineral nitrogen over the various soil layers were generally simulated well, except for experiments in which fertilizer was applied late in spring. In these experiments, applied nitrogen disappeared because it could not be accounted for by the model. Some explanations for this disappearance are briefly discussed.     

Effects of summer catch crop,residue management,soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems

Nitrogen nutrient management is crucially important in shallow-rooted vegetable production systems characterized by high input and high environmental risk. To investigate the effects of summer catch crop (sweet corn, common bean, garland chrysanthemum and edible amaranth), residue management, and soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems, we determined the rates of net nitrogen mineralization and nitrification in a 4-year field experiment on greenhouse cucumber double-cropping systems. Summer catch crop and its residue significantly increased the succeeding cucumber rhizosphere mineral nitrogen contents, when compared to conventional practices. In general, summer catch crop and its residue significantly increased the rates of both net nitrogen mineralization and net nitrogen nitrification at 4 or 40°C, and increased the rates of net nitrogen immobilization (negative mineralization) and net nitrogen nitrification at 15 or 28°C, in succeeding cucumber rhizosphere after four-year treatment. Soil temperature and water had more influence than catch crops and residue management on N mineralization. The effect of carbon on nitrogen mineralization was more pronounced than that of nitrogen, and the effect of microbial carbon on the different forms of inorganic N was more pronounced than that of organic carbon. When the effects of soil temperature and water content were eliminated, cumulative net nitrogen mineralization and nitrification in catch crop and residue management plots were 296–784 and 57–84% higher, respectively, than conventional practices plots. Catch crops and residue management influenced change of ammonium-N more significantly than that of nitrate-N. Additionally, there were complex relationships between fruit yield and soil N mineralization in catch crop- and residue management-induced systems.     

Effects of a catch crop and reduced nitrogen fertilization on nitrogen leaching in greenhouse vegetable production systems

Greenhouse vegetable cultivation has greatly increased productivity but has also led to a rapid accumulation of nitrate in soils and probably in plants. Significant losses of nitrate–nitrogen (NO₃-N) could occur after heavy N fertilization under open-field conditions combined with high precipitation in the summer. It is urgently needed to improve N management under the wide spread greenhouse vegetable production system. The objective of this study was to evaluate the effects of a summer catch crop and reduced N application rates on N leaching and vegetable crop yields. During a 2-year period, sweet corn as an N catch crop was planted between vegetable crops in the summer season under 5 N fertilizer treatments (0, 348, 522, 696, and 870 kg ha⁻¹) in greenhouse vegetable production systems in Tai Lake region, southern China. A water collection system was installed at a depth of 0.5 m in the soil to collect leachates during the vegetable growing season. The sweet corn as a catch crop reduced the total N concentration from 94 to 59 mg l⁻¹ in leached water and reduced the average soil nitrate N from 306 to 195 mg kg⁻¹ in the top 0.1-m soil during the fallow period of local farmers’ N application rate (870 kg ha⁻¹). Reducing the amount of N fertilizer and using catch crop during summer fallow season reduced total N leaching loss by 50 and 73%, respectively, without any negative effect on vegetable yields.     

Effects of applied nitrogen on soil nitrate-nitrogen content after harvest of winter barley

Seven field trials were conducted on winter barley to define relationships between rate of applied N, the amount of nitrate-N present in the soil after harvest and the ratio of soil nitrate-N to grain yield. Applying N up to the economic optimum rate (estimated from yield and N rate data from individual trials) was associated with small increases in soil nitrate-N after harvest (the mean increase was 4 kg N ha^–1). Where the optimum N rate was exceeded, soil nitrate-N levels increased to a greater extent. In every trial, the ratio of soil nitrate-N to yield showed a minimum at a fertilizer N rate below the economic optimum. However, the value of the ratio was always lower at the optimum N rate (mean value 6.0 kg N t^–1) than at the zero-N treatment (mean value 8.9 kg N t^–1) and the difference between the minimum value (mean 5.6 kg N t^–1) and that found at the optimum N rate was small.Overall, application of fertilizer N up to the economic optimum rate for practical purposes could be regarded as consistent with the objective of minimising the risk of nitrate leaching per hectare and per tonne of grain in the trials.     

海水对污泥沉降性能及脱氮除磷影响的试验

采用SBR工艺就添加海水改善生物处理系统污泥沉降性能及对生物脱氮除磷的影响进行了研究．结果表明,添加海水进入生物处理系统可以显著改善活性污泥的沉降性能,当海水与生活污水的体积比为1：4时,污泥沉降比由86％降为34％,污泥絮凝成团状结构,丝状菌含量下降,且对生物处理系统的氮、磷脱除效果没有显著影响。     

Effects of different manuring systems with and without biogas digestion on nitrogen cycle and crop yield in mixed organic dairy farming systems

Field trials were carried out between 2002 and 2005 to investigate the effects of biogas digestion in a mixed organic dairy farming system with arable land and grassland on nutrient cycling, nitrogen (N) uptake and crop yields within a cropping system comprising a whole crop rotation. Five treatments were carried out: (i) solid farmyard manure, (ii) undigested liquid slurry, (iii) digested liquid slurry, (iv) digestion of liquid slurry and field residues such as crop residues and cover crops, and (v) similar to iv, but with additional N inputs at the equivalent of 40 kg N ha⁻¹ farmland through digestion of purchased substrates. The term “manure” is used in the present study to mean all kind of aboveground organic residues left on the field (“immobile manures”, such as crop residues and green manures incorporated directly into the soil) or added as stable wastes or effluents of biogas digestion (“mobile manures”). The total aboveground biomass growth and the overall aboveground N uptake of non-legume maincrops were higher in the liquid slurry manure treatment than in the solid farmyard manure system (+5% and +9%, respectively). The digestion of the liquid slurry increased N uptake and crop yields only after soil incorporation of the slurry shortly after field spreading. The additional collection and digestion of field residues such as cover crops and crop residues, combined with a reallocation of the effluents, strongly increased the amounts of “mobile” manure, allowing a more focussed allocation of the available N. This led to an increase in the aboveground N uptake (+12%) and biomass yield (+4%) of the five non-legume crops, due to a better adapted allocation of nutrients in space and time. Results obtained with spring wheat showed that removal of cover crops in autumn, and their digestion, combined with subsequent use as manure in spring resulted in a better synchronisation of the crop N demand and the soil N availability, in comparison with a strategy where the biomass was left on the field as green (immobile) manure. The inclusion of external substrates led to a further increase of 8% in N uptake, but not to a significant increase in aboveground dry matter yields.     

Differential retention of carbon, nitrogen and phosphorus in grassland soil profiles with long-term manure application

Liquid hog manure (LHM) is a valuable source of nutrients for farm production. Long-term experimental plots that had received LHM applications of 0, 50, and 100 m³ ha^?1 annually for 20 years were analyzed for total soil C, N and P storage. Applications increased total soil N and P by 1,200 kg N ha^?1 and 850 kg P ha^?1 at 100 m^?3 LHM year^?1, compared to the control treatment. However, C storage did not increase with LHM rates and was lower in the 50 m³ ha^?1 LHM treatment (86 Mg C ha^?1) than in the 0 or 100 m³ ha^?1 treatments (100 Mg C ha^?1). In addition to the limited quantities and high decomposability of the C supplied by LHM, it is hypothesized that LHM stimulated the mineralization of both native soil C and fresh root-derived material. This priming effect was particularly apparent in deeper soil horizons where the decomposability of native C may be limited by the supply of fresh C. This study indicates that while LHM can be a significant source of crop nutrients, it has limited capacity for maintaining or increasing soil C.     

Response of wheat to nitrogen fertilization,a data set to validate simulation models for nitrogen dynamics in crop and soil

A data set originating from winter wheat experiments at three locations during two years is described. The purpose is to provide sufficient data for testing simulation models for soil nitrogen dynamics, crop growth and nitrogen uptake. Each experiment comprised three different nitrogen treatments, and observations were made at intervals of two or three weeks. The observations included measurements of soil mineral nitrogen content, soil water content, groundwater table, dry matter production and dry matter distribution, nitrogen uptake, nitrogen distribution and root length density.     

Effect of manure application on crop yield and soil chemical properties in a long-term field trial of semi-arid Kenya

The sustainability of cereal/legume intercropping was assessed by monitoring trends in grain yield, soil organic C (SOC) and soil extractable P (Olsen method) measured over 13 years at a long-term field trial on a P-deficient soil in semi-arid Kenya. Goat manure was applied annually for 13 years at 0, 5 and 10 t ha⁻¹ and trends in grain yield were not identifiable because of season-to-season variations. SOC and Olsen P increased for the first seven years of manure application and then remained constant. The residual effect of manure applied for four years only lasted another seven to eight years when assessed by yield, SOC and Olsen P. Mineral fertilizers provided the same annual rates of N and P as in 5 t ha⁻¹ manure and initially ,gave the same yield as manure, declining after nine years to about 80%. Therefore, manure applications could be made intermittently and nutrient requirements topped-up with fertilizers. Grain yields for sorghum with continuous manure were described well by correlations with rainfall and manure input only, if data were excluded for seasons with over 500 mm rainfall. A comprehensive simulation model should correctly describe crop losses caused by excess water.     

包裹型缓／控释肥对冬小麦产量、土壤无机氮和氮肥利用效率的影响

采用超大区田间试验,以不施氮、传统氯素管理方式和优化氮素管理方式为对照,研究冬小麦施用包裹型缓／控释肥（包裹肥料）对产量、土壤无机氮和氮肥利用效率的影响,并对冬小麦施用包裹型缓／控释肥效果进行评价,结果表明：与传统氮素管理方式相比,优化氮素管理方式和包裹肥料处理在分别节省了78％和67％的氮肥的条件下,获得了和传统氮素管理方式相似的冬小麦子粒产量;采用氮素优化管理模式和施用包裹肥料显著降低了土壤无机氮残留和氮素表观损失,从而显著提高了氮肥利用率;与优化氮素管理方式相比,施用包裹肥料可一次性基施,省时省力,提高了经济效益。     

Effects of mulch,N fertilizer,and plant density on wheat yield,wheat nitrogen uptake,and residual soil nitrate in a dryland area of China

Understanding mulching influences on nitrogen (N) activities in soil is important for developing N management strategies in dryland. A 3 year field experiment was conducted in the Loess Plateau of China to investigate the effects of mulching, N fertilizer application rate and plant density on winter wheat yield, N uptake by wheat and residual soil nitrate in a winter wheat-fallow system. The split plot design included four mulching methods (CK, no mulch; SM, straw mulch; FM, plastic film mulch; CM, combined mulch with plastic film and straw) as main plot treatments. Three N fertilizer rates (N0, 0 kg N ha⁻¹; N120, 120 kg N ha⁻¹; N240, 240 kg N ha⁻¹) were sub-plot treatments and two wheat sowing densities (LD, low density, seeding rate = 180 kg ha⁻¹; HD, high density, seeding rate = 225 kg ha⁻¹) were sub-subplot treatments. The results showed that wheat yield, N uptake, and N use efficiency (NUE) were higher for FM and CM compared to CK. However, soil nitrate-N contents in the 0–200 cm soil profile were also higher for FM and CM compared to CK after the 3 year experiment. Wheat grain yields were higher for SM compared to CK only when high levels of nitrogen or high planting density were applied. Mulching did not have a significant effect on wheat yield, nitrogen uptake and NUE when soil water content at planting was much high. Wheat yield, N uptake, and residual nitrate in 0–200 cm were significantly higher for N240 compared to N120 and N0. Wheat yield and N uptake were also significantly higher for HD compared to LD. When 0 or 120 kg N ha⁻¹ was applied, HD had more residual nitrate than LD while the reverse was true when 240 kg N ha⁻¹ was applied. After 3 years, residual nitrate-N in 0–200 cm soil averaged 170 kg ha⁻¹, which was equivalent to ~40% of the total N uptake by wheat in the three growing seasons.     

Effects of phosphorous oxychloride,phosphorous trichloride and dichlorophenylphosphine on the radical polymerisation of acrylonitrile under heterogeneous conditions

Summary The effects of C₆H₅PCl₂, POCl₃, and PCl₃ on the free radical polymerisation of acrylonitrile initiated bya,a-azobisisobutyronitrile were kinetically investigated in benzene and trichloroethylene solutions. With PCl₃ rates of polymerisation were unaffected but the degrees of polymerisation were found to decrease with increasing PCl₃. With C₆H₅PCl₂ and POCl₃ however both rates and degrees of polymerisation were adversely affected. Thus PCl₃ acts as a chain transfer agent while the other two phosphorous compounds function as degradative chain transfer agents.     

Effects of soil and crop management practices on yields,income and nutrients losses from upland farming systems in the Middle Mountains region of Nepal

On-farm runoff plots were established during 2004 and monitored for 4 years in the Pokhare Khola watershed (Nepal) in a completely randomized design with four replications of each three treatments: traditional Farmer Practice (FP) (Zea mays–Eleusine coracana), Reduced Tillage (RT; Z. mays–Vigna ungeuculata), and Commercial Vegetable with double dose of farm yard manure (CV; Z. mays–Capsicum species) to evaluate treatment effects on soil nutrient losses, nutrient balances and crop income on Bari land (rainfed terraces). Nutrient removal due to crop harvest was found to be significantly higher than nutrient loss through soil erosion, and CV treatment exhibited a significantly higher N uptake (123 kg ha⁻¹ year⁻¹) through crop harvest than other treatments. Moreover, the CV treatment produced significantly higher income per unit area of Bari land than the other treatments. Soil organic carbon and major nutrients losses (NPK) through soil erosion were minimal [25.5 kg ha⁻¹ year⁻¹ soil organic carbon (SOC) and 5.6:0.02:0.12 kg ha⁻¹ year⁻¹ nitrogen (N), phosphorus (P), potassium (K), respectively]. Result showed that no nutrients were lost through leaching. Nutrient losses due to soil erosion and runoff were lower than previously reported in the Middle Mountain region, indicating a need to re-evaluate the soil erosion and nutrient loss problems in this region. Interventions such as reduced tillage and double dose of FYM with vegetable production were found to be effective in maintaining soil fertility and increasing farm income compared to the traditional maize-millet production system. The nutrient balance calculations suggest that integrated nutrient management techniques such as residue incorporation and application of FYM with a minimum application of chemical fertilizer are potentially sustainable production approaches for the Mid-hills of Nepal.     

Effects of mulch and mineral fertilizer on crop, weevil and soil quality parameters in highland banana

The decline of cooking banana production in parts of East Africa hasbeen associated with a loss of soil fertility and increased pest pressure.Previous work indicated that the use of mineral fertilizers at recommendedratesis not financially viable on plantations where pest pressure is high. Theobjectives of this study were to determine the effects of half the recommendedrates of mineral fertilizers and organic mulch on banana yield, soil and foliarnutrient status, soil water and pest damage in the central region of Uganda.Thestudy was conducted in a four-year old banana plantation infested with weevils.Treatments consisted of mineral fertilizer alone, mulch alone, a combination ofmulch with fertilizer, and a control (no mulch from outside the plot, ormineralfertilizer applied). Fruit yield was generally low (mean of 7.4 Mgha^–1 yr^–1) and increases above thecontrol ranged from 1.1 to 2.0 Mg ha^–1 yr^–1. Banana yield was significantly higher in the solemulch treatment than in the control. However, there were no significantdifferences in yield among the treatments that received external inputs. Thus,there was no demonstrable yield advantage of combining mineral fertilizer withmulch. At the end of the trial, soil K concentrations in the two treatmentsthatwere mulched, were almost twice those of the control, but this difference wasnotstatistically significant. Concentrations of Ca and Mg did not differ withtreatment. Soil available P significantly increased when mineral fertilizer andorganic mulch were combined. Treatments that received organic mulch were lowerin foliar concentrations of N and Mg, and higher in K. Soil water content wasgreater in the surface soil layer in the treatments that received mulch,presumably due to less surface run-off and evaporation, since there was nochangein surface soil porosity. The effect of organic and inorganic amendments had noimpact on weevil damage, which remained above 5% at the end of the trial. Weconclude that where weevil damage is over 5% of the cross section near thecollar, banana production may not be economically increased through use ofeither mineral fertilizer and/or organic mulch.     

Long-term effects of crop rotations with and without perennial leys on soil carbon stocks and grain yields of winter wheat

A change from cultivated land to grassland generally increases soil organic matter (SOM) content and is a potential option to mitigate greenhouse gas emissions. We investigated the effects of two-year perennial grass and mixed grass/legume leys in a six-year crop rotation on topsoil (0–0.25 m depth) carbon content and on grain yields of winter wheat over a period of 31 years. Different nitrogen fertilisation regimes were included and no manure was added to the experimental plots. We used data from long-term crop rotation experiments at three sites in southern Sweden: Säby (59°49′ N/17°42′ E), Lanna (58°20′ N/13°07′ E) and Stenstugu (57°36′ N/18°26′ E). At Säby, the reduction in topsoil carbon content was smaller in the ley crop rotations than in the crop rotation with only annual crops. There were no statistically significant effects of crop rotation on topsoil carbon at the other two sites. At Lanna, the grain yield increase in winter wheat over time was higher in the mixed legume/grass ley crop rotation than in the other two rotations. Together, these effects of ley on topsoil carbon and winter wheat yield suggest that replacing annual crops with leys in the crop rotation could reduce losses of soil carbon without decreasing total yield of annual crops on a regional scale. We also applied the Introductory Carbon Balance Model (ICBM) to simulate topsoil carbon content at the three sites. Based on the results, measures to improve the model predictability are proposed.     

Long-term effects of fallow systems and lengths on crop production and soil fertility maintenance in West Africa

In the development of short fallow systems as alternatives to shifting cultivation in West Africa, a long-term trial was established at the International Institute of Tropical Agriculture (IITA) on an Alfisol in the forest-savanna transitional zone of southwestern Nigeria, comparing three fallow systems; natural regrowth fallow, cover crop fallow and alley cropping on soil productivity and crop yield sustainability. The natural fallow system consisted of natural regrowth of mainly Chromolaena odorata shrub as fallow vegetation. The cover crop fallow system consisted of Pueraria phaseoloides, a herbaceous legume as fallow vegetation. The alley cropping system consisted of woody hedgerows of Leucaena leucocephala as fallow vegetation. The fallow lengths were 0 (continuous cropping), 1, 2 and 3 years after 1 year of maize/cassava intercropping. Biomass produced from natural fallow and cover crop fallow was burnt during the land preparation. Fertilizer was not applied throughout the study. Without fertilizer application, maize yield declined from above 3.0 t ha^–1 to below 0.5 t ha^–1 during 12 years of cultivation (1989–2000) on a land cleared from a 23-year old secondary forest. Temporal change in cassava tuber yield was erratic. Mean maize grain yields from 1993–2000 except for 1999 were higher in cover crop fallow system (1.89 t ha^–1) than in natural fallow system (1.73 t ha^–1), while natural fallow system outperformed alley cropping system (1.46 t ha^–1). During the above 7 years, mean cassava tuber yield in cover crop system (7.7 t ha^–1) did not differ from natural fallow system (8.2 t ha^–1), and both systems showed higher cassava tuber than the alley cropping system (5.7 t ha^–1). The positive effect of fallowing on crop yields was observed for both crops in the three systems, however, insignificant effects were seen when fallow length exceeded 1 year for cover crop and alley cropping, and 2 years for natural fallow. Soil pH, organic carbon, available P and exchangeable Ca, Mg and K decreased considerably after 12 years of cultivation, even in a 3-year fallow subplot. After 12 years, soil organic carbon (SOC) within 0–5 cm depth in alley cropping (13.9 g kg^–1) and natural fallow (13.7 g kg^–1) was higher than in cover crop fallow (11.6 g kg^–1). Whereas significant increase in SOC with either natural fallow or alley cropping was observed only after 2 or 3 years of fallow, the SOC in the 1-year fallow alley cropping subplot was higher than that in continuous cropping natural fallow subplot. It can be concluded from our study that in transforming shifting cultivation to a permanent cropping, fallow with natural vegetation (natural fallow), herbaceous legumes (cover crop fallow) and woody legumes (alley cropping) can contribute to the maintenance of crop production and soil fertility, however, length of fallow period does not need to exceed 2 years. When the fallow length is reduced to 1 year, a better alternative to natural regrowth fallow would be the cover crop for higher maize yield and alley cropping for higher soil organic matter. For fallow length of 2 years, West African farmers would be better off with the natural fallow system.     

Microbial biomass carbon, nitrogen and phosphorus in the soil profiles of different vegetation covers established for soil rehabilitation in a red soil region of southeastern China

This study investigated the distribution of microbial biomass carbon (MB-C), nitrogen (MB-N) and phosphorus (MB-P) in the soil profiles of five different vegetation systems including bare area (Br), Bamboo (Bmb), Chinese Fir (CF), Citrus Orchard (Ctr) and Rice field (Rf). The MB-C levels in the Bmb system were higher than those in the other systems, and it decreased with increasing soil depth in all vegetation systems except the Bmb. The highest MB-N was detected in the top 20 cm of soil for the Bmb and in the 20~40 cm soil layer for the other vegetation systems such as Ctr, CF and Rf. The order of soil MB-P levels from highest to lowest was as follows: Bmb > CF > Ctr > Rf > Br. In all vegetation systems the level of MB-P decreased with increasing soil depth. Experimental results showed that the ratio of MB-C to TOC ranged from 0.75~2.7%, agreeing well with ranges previously reported by many others. Results also indicate that vegetation covers and management practices have a strong impact on the development and distribution of soil microbial properties in the soil profile.     

The effect of soil moisture on mineral nitrogen, soil electrical conductivity, and pH

Inorganic nitrogen in the soil is the source of N for non-legume plants. Rapid methods for monitoring changes in inorganic N concentrations would be helpful for N nutrient management. The effect of varying soil moisture content on soil mineral nitrogen, electrical conductivity (EC), and pH were studied in a laboratory experiment. Soil NO₃-N increased as soil water-filled pore space (WFPS) increased from 0 to 80 cm³ cm^–3. At soil moisture levels greater than 80 cm³ cm^–3, NO₃-N concentration declined rapidly and NH₄-N concentration increased, likely due to anaerobic conditions existing at higher WFPS levels. Soil pH did not change as soil moisture increased from 100 g kg^–1 to 400 g kg^–1 and increased from 6.2 to 6.6 at higher levels of soil moisture. Soil EC was correlated with soil mineral N concentration when measured in situ with a portable EC meter (R ²=0.85) or in the laboratory as 1:1 soil water slurries (R ²=0.92). Results suggest that EC can be used to rapidly detect changes in soil inorganic N status in soils where salts and free carbonates are not present in large amounts.     

Impact of planted fallows and a crop rotation on nitrogen mineralization and phosphorus and organic matter fractions on a Colombian volcanic-ash soil

Soil fertility replenishment is a critical factor that many farmers in the tropical American hillsides have to cope with to increase food crop production. The effect of three planted fallow systems (Calliandra houstoniana-CAL, Indigofera zollingeriana-IND, Tithonia diversifolia-TTH) and a crop rotation (maize/beans-ROT) on soil nitrogen mineralization, organic matter and phosphorus fractions was compared to the usual practice of allowing natural regeneration of native vegetation or natural fallow management (NAT). Studies were conducted on severely degraded Colombian volcanic-ash soils, 28 months after fallow establishment, at two on-farm experimental sites (BM1 and BM2) in the Cauca Department. Tithonia diversifolia had a significantly higher contribution to exchangeable Ca, K and Mg as well as B and Zn; the order of soil nutrient contribution was TTH > CAL > IND > NAT > ROT. On the other hand, lND had significantly higher soil NO₃⁻–N at both experimental farms as compared to all the other fallow system treatments. For the readily available P fraction, CAL and ROT had significantly higher H₂O–Po and resin-Pi, respectively, in the 0–5 cm soil layer; whereas TTH showed significantly higher values for both H₂O–Po and resin-Pi in the 5–10 cm soil layer. Significant effects were observed on the weights of the soil organic matter fractions which decreased in the order LL (Ludox light) > LM (Ludox intermediate) > LH (Ludox heavy). Indigofera zollingeriana showed greater C, N and P in the soil organic matter fractions than all the other fallow treatments, with NAT having the lowest values. It is concluded that planted fallows can restore soil fertility more rapidly than natural fallows.     

Effects and optimization of initial pH and sewage sludge compost content on leaching of lead and zinc in contaminated soil

We investigated the effects of initial pH (2≤pH₀≤6) and sewage sludge compost content (5≤[SSC]≤25 g/kg) on leaching characteristics of lead (Pb) and zinc (Zn) in contaminated field soil. pH₀ and [SSC] significantly affected the leaching of Pb and Zn in soils contaminated with them. The pH in the solution increased as reaction time and [SSC] increased. The leached amounts of Pb and Zn were highest at pH₀=2 and increased with reaction time. As [SSC] increased, the leached amount of Pb decreased (50.4 mg/kg at control condition ([SSC]=0 g/kg); 22.9 mg/kg at [SSC]=25 g/kg at pH₀=2) and the leached amount of Zn increased (20.1 mg/kg at [SSC]=0 g/kg; 31.7 mg/kg at [SSC]=25 g/kg at pH₀=2). The change increased as pH₀ decreased. Within the design boundaries, minimum leaching of Pb (14.7 mg/kg) occurred at pH₀=5.1 and [SSC]=25 g/kg, and minimum leaching of Zn (5.0 mg/kg) occurred at pH₀=5.1 and [SSC]=5 g/kg.