Mineralizable Nitrogen of Organic Wastes and Soil Chemical Changes under Laboratory Conditions

This study looks at the ability of organic wastes from different sources to efficiently promote chemical attributes and enhance nitrogen (N) concentrations in an Oxisol Ustox with a sandy texture. This experiment was performed in a randomized design using wastes from pulp mill sludge, petrochemical complex, sewage treatment plant, dairy factory sewage treatment plant, and pulp fruit industry, on 10 different days. Results showed that addition of the wastes to the soil amended their chemical attributes. The different characteristics of the organic wastes seem to have influenced the N mineralization rates during the 112 days. There was a close relationship between the N mineralization and organic waste C/N ratio: blank soil (SP) (Nma = 3.17) < Treated pulp mill sludge (PMS) (Nma = 30.49, C/N 63.6:1) < Organic compost from the fruit pulp industry (FPW) (Nma = 67.6, C/N 11.9:1) < Treated urban sewage sludge (USS) (Nma = 76.22, C/N 7.2:1) = Petrochemical complex sludge (PS) (Nma = 84.0, C/N 7.7:1) < Treated dairy industry sewage sludge (DSS) (Nma = 102.17, C/N 8.4:1).     

Leaching of Saline Calcareous Soil under Laboratory Conditions

Eurasian Soil Science - Soil salinity is a major problem in Kerman pistachio (Pistacia vera) orchards which caused low pistachio’s productivity in recent years. Farmers excessively use gypsum...     

Adopting a Robotic pH Instrument for Soil and Soil-Buffer pH Measurements in a Soil Test Laboratory

Optimum software settings were evaluated to minimize time of analysis without sacrificing data quality on an AS-3010D LabFit robotic instrument. There was little to no difference between soil and soil-buffer pH values measured via manual methods and LabFit analysis with four software settings. A setting for routine laboratory analysis was determined by evaluating r² values from a comparison of LabFit versus manual measurements. Settings for routine analysis were adopted as follows: 5 s for sample delay time, 60 s for maximum sample time, 10 readings for stability, 0.02 for pH stability, 0 s for buffer run delay, and probe rinsing after every 40 samples. These settings were evaluated on 2933 Kentucky soil samples where robotic versus routine analysis of soil and soil-buffer pH resulted in r² values of 0.94 and 0.82 for soil pH and soil-buffer pH, respectively. The results validated the utility of robotic instruments for soil pH analysis.     

Effectiveness of Pyrites in Reclaiming Sodic Clay Soil under Laboratory Conditions

In a laboratory experiment pyrites at the rate equivalent to 75% of gypsum requirement was surface applied and mixed with a sodic black clay soil (Vertisol) at 15, 30, 45 and 60% soil moisture content. The soil samples were then incubated for 60, 120, 240 and 360 hours. A separate set of similarly treated soil packed in permeameters was used to estimate saturated hydraulic conductivity. After incubation, FeS₂ was oxidised, soil pH and percentage of exchangeable sodium (ESP) decreased and water soluble sulphate and calcium increased with soil moisture content up to 45% and with time of incubation up to 120 hours. The surface application of pyrites proved superior as compared to mixed with soil. Leaching of the soil following incubation with three pore volumes of demineralised water removed most of the water soluble sodium and thus improved the effectiveness of the pyrites in lowering down the soil ESP. The saturated hydraulic conductivity also increased as a result of improved physico-chemical properties of the soil.     

Leaching of Nitrate,Ammonium, and Phosphate From Compost Amended Soil Columns

Compost amendment to agricultural soils has been reported to reduce disease incidence, conserve soil moisture, control weeds, or improve soil fertility. Application rate and placement of compost largely depends on the proposed beneficial effects and the rate may vary from 25 to 250 Mg ha^?1 (N content up to 4 percent). Application of high rates of compost with high N or P levels may result in excessive leaching of nitrate, ammonium, and phosphate into the groundwater. Leaching could be a serious concern on the east coast of Florida with its inherent high annual rainfall, sandy soils and shallow water table. In this study, five composts (sugarcane filtercake, biosolids, and mixtures of municipal solid wastes and biosolids) were applied on the surface of an Oldsmar sand soil (in 7.5 cm diameter leaching columns) at 100 Mg ha^?1 rate and leached with deionized water (300 ml day^?1, for five days; equivalent to 34 cm rainfall). The concentrations of NO₃-N, NH₄-N, and PO₄-P in leachate reached as high as 246, 29, and 7 mg L^?1, respectively. The amount of N and P leached accounted for 3.3-15.8 percent of total N and 0.2-2.8 percent of total P in the compost. The leaching peaks of NO₃-N occurred following the application of only 300-400 ml water (equivalent to 6.8-9.1 cm rainfall).     

Mineralization of Three Organic Manures Used as Nitrogen Source in a Soil Incubated under Laboratory Conditions

Abstract

The rate and timing of manure application when used as nitrogen (N) fertilizer depend on N‐releasing capacity (mineralization) of manures. A soil incubation study was undertaken to establish relative potential rates of mineralization of three organic manures to estimate the value of manure as N fertilizer. Surface soil samples of 0–15 cm were collected and amended with cattle manure (CM), sheep manure (SM), and poultry manure (PM) at a rate equivalent to 200 mg N kg^?1 soil. Soil without any amendment was used as a check (control). Nitrogen‐release potential of organic manures was determined by measuring changes in total mineral N [ammonium‐N+nitrate‐N (NH₄ ⁺–N+NO₃ ^?–N)], NH₄ ⁺–N, and accumulation of NO₃ ^?–N periodically over 120 days. Results indicated that the control soil (without any amendment) released a maximum of 33 mg N kg^?1soil at day 90, a fourfold increase (significant) over initial concentration, indicating that soil had substantial potential for mineralization. Soil with CM, SM, and PM released a maximum of 50, 40, and 52 mg N kg^?1 soil, respectively. Addition of organic manures (i.e., CM, SM, and PM) increased net N released by 42, 25, and 43% over the control (average). No significant differences were observed among manures. Net mineralization of organic N was observed for all manures, and the net rates varied between 0.01 and 0.74 mg N kg^?1 soil day^?1. Net N released, as percent of organic N added, was 9, 10, and 8% for CM, SM, and PM. Four phases of mineralization were observed; initial rapid release phase in 10–20 days followed by slow phase in 30–40 days, a maximum mineralization in 55–90 days, and finally a declined phase in 120 days. Accumulation of NO₃ ^?–N was 13.2, 10.6, and 14.6 mg kg^?1 soil relative to 7.4 mg NO₃ ^?–N kg^?1 in the control soil, indicating that manures accumulated NO₃ ^?–N almost double than the control. The proportion of total mineral N to NO₃ ^?–N revealed that a total of 44–61% of mineral N is converted into NO₃ ^?–N, indicating that nitrifiers were unable to completely oxidize the available NH₄ ⁺. The net rates of mineralization were highest during the initial 10–20 days, showing that application of manures 1–2 months before sowing generally practiced in the field may cause a substantial loss of mineralized N. The rates of mineralization and nitrification in the present study indicated that release of inorganic N from the organic pool of manures was very low; therefore, manures have a low N fertilizer effect in our conditions.     

水稻秸秆施用后土壤溶解性有机碳的变化与土壤CO_2排放

为了进一步认识水稻秸秆还田后土壤有机碳固定机制,以浙江两种典型水稻土淡涂泥、青紫泥为研究对象,并以不加秸秆为对照,研究秸秆施用下土壤溶解性有机碳(Dissolved Organic Carbon,DOC)含量以及CO_2产生速率的动态变化,以及秸秆分解产生DOC在土壤中的吸附作用。结果表明,添加秸杆显著增加了土壤CO_2排放,总矿化碳量表现为10%>5%>2%>CK;土壤CO_2产生速率的变化与DOC含量变化具有高度一致性,都表现为先快速上升-急剧下降-缓慢下降-趋于稳定的变化模式,两者呈显著正相关(P<0.01),但在石英砂处理中两者则无明显相关性。DOC吸附实验表明随着秸秆分解时间延长,所产生的DOC在土壤中的吸附作用增强。pH和本底DOC较低的青紫泥对DOC具有更强的吸附作用,其CO_2排放速率和总矿化碳量均显著低于淡涂泥,青紫泥更有利于秸秆还田有机碳的保留和稳定。该结果表明秸秆分解前期产生DOC主要以CO_2形式释放,分解后期产生DOC更倾向于土壤有机碳固定,增加土壤对DOC的吸附作用有利于土壤固碳。     

Nutrient Availability in a Calcareous Soil Amended with Different Types of Biomass Ash

An incubation experiment was conducted to evaluate the effects that three types of biomass ash, each applied at two doses, exert on the nutrient availability in a calcareous soil. The application of the ash from dry olive cake or greenhouse vegetable wastes significantly increased soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable phosphorus (P), potassium (K), sodium (Na), copper (Cu) and zinc (Zn) as well as exchangeable and non-exchangeable K and Na. Wood ash was effective only for increasing soil ABDTPA-extractable Zn and Cu. By contrast, the three types of biomass ash hardly increased soil ABDTPA-extractable Fe or Mn. The high content in carbonate of the soil appears to minimize the potential of the ash to increase the micronutrients availability, which shortened with longer incubation time. Soil ABDTPA-extractable heavy metals were not detected in the different treatments tested. Other parameters of the soil, as pH and organic carbon, were scarcely affected by the ash, while conductivity and dehydrogenase activity increased.     

Nitrogen Inputs with Different Substrate Quality Modified pH,Eh, and N Dynamics of a Paddy Soil Incubated under Waterlogged Conditions

Synthetic fertilizer, livestock manure, and green manure are the typical nitrogen (N) sources in agriculture. This study was conducted to investigate the effects of different N sources on soil chemical environment and N dynamics. Changes in pH, redox potential (Eh), and concentration and δ¹⁵N of dissolved N [ammonium (NH₄⁺), nitrate (NO₃^?), organic N, and total N] of soils treated with urea (U), pig manure compost (PMC), and hairy vetch (HV) were investigated in an incubation experiment under waterlogged conditions. The patterns of pH, Eh, and N concentration reflected both a greater mineralization potential of N derived from U than that from HV and PMC and easier decomposability of HV than PMC. The δ¹⁵N further suggested that nitrification was more active for U than for HV- and PMC-treated soils and that N loss via NH₃ volatilization and denitrification would be greater for HV than U and PMC treatments.     

Temporal Changes in Cadmium, Thallium, and Vanadium Mobility in Soil and Phytoavailability under Field Conditions

A field study was conducted over a 30 mo period to examine movement of Cd, Tl, and V through the profile of a Coastal Plain soil (Typic Kandiudult) and the availability of these trace metals to bush bean (Phaseolus vulgaris L.) plants. The metals were applied to field plots as dissolved salts and mixed into the surface 7.5 cm. The greatest concentration of all three metals was observed in the surface soils, with a steep decrease occurring down to the 7.5 to 15 cm depth. Thallium was the most mobile of the three metals; approximately 15% of the applied Tl and <3% of the applied Cd and V moved below the surface 7.5-cm region during the 30-mo experiment. Extractable concentrations of all three metals in the surface soils decreased significantly (P ≤0.05) during the initial 18 mo after treatment. No further decrease occurred between 18 and 30 mo. The presence of Al- and Fe-oxides and small amounts of clay minerals and organic matter in this highly-weathered, low cation-exchange soil were likely responsible for the retention of the trace metals. Bioavailability, as measured by concentrations and total amounts of metals in root and aboveground tissues of plants, did not change significantly between 18 and 30 mo. These data suggest that bioavailability of Cd, Tl, and V decreased over time as a result of transformation of these elements into unavailable forms and not to leaching. These changes in bioavailability occurred soon after application, becoming negligible after 18 mo.     

Solubility and Phytoavailability of Phosphorus and Lead in a Contaminated Soil Amended with Two Phosphorus Fertilizers

Application of some chemical amendments such as diammonium phosphate (DP) and triple superphosphate (TP) to contaminated soils is an effective technique to stabilize Pb and decrease its uptake by plants. A calcareous soil was spiked with the rates of 0, 250, 500, and 750 mg of lead (Pb) kg^?1 soil as Pb acetate, treated with 760 mg of P kg^?1 soil as DP and TP, and incubated for 120 days. The results showed that available phosphorus (P) increased immediately after addition of DP or TP to soil, but it declined sharply after only a few days of incubation time. Pot experiment was conducted on sorghum and spinach. The accumulation of Pb was significantly (P ≤ 0.05) lower in sorghum than in spinach, and also was lower in soil amended with DP than TP. The decreased Pb accumulation in the plants by application of both amendments was mainly attributed to the formation of chloropyromorphite.     

The Ecological Dose of Nickel in a Semiarid Soil Amended with Sewage Sludge Related to the Unamended Soil

Nickel pollution may affect microbial communitydevelopment and its activity in soil and, therefore, itsfertility, while organic amendment may affect Ni mobilityand bioavailability. The aim of this research was toascertain the extent to which the addition of sewage sludgeto soil may affect Ni toxicity and to establish theecological dose of this heavy metal. Unamended and amendedsoils with sewage sludge were spiked with differentconcentrations of Ni (0–8000 mg kg^-1) and then incubatedfor 3 hours, 12 days and 40 days. Soil dehydrogenaseactivity, ATP content, microbial respiration and microbialbiomass C were measured in the samples containing differentNi concentrations. A mathematical model which describe theinhibition of these soil parameters were used to calculatethe ecological dose of Ni: ED₅₀. Soil microbialbiomass C measurements of all treatments better fitted themodel (r² = 0.95–0.69 with p < 0.05) than the otherparameters studied; but the ED₅₀ values predicted by the modelhad a high coefficient of variation. For both ATP contentand microbial biomass C, the ED₅₀ values calculatedfor the amended soil were higher than for the unamendedsoil and so that the effect of Ni toxicity on theseparameters of microbial activity may be considered lower inthe former. In this study, an increase in ED₅₀ valueswith the time elapsed was also observed.     

Nitrate Dynamic in a Tropical Mollisol Amended with Organic Manures,Planted with Sweet Corn,and Monitored with SPAD Readings

Two field experiments were conducted to evaluate the use of relative chlorophyll content (RCC) in sweet corn leaves as an indicator of nitrate concentration in soil. Study objectives were (1) to evaluate the effect of manure types (chicken and dairy), rates (0, 168, 336, and 672 kg ha^?1 equivalent N), and application frequency (one and two applications) of organic amendments on (a) nitrate nitrogen (NO₃-N) concentration within and below the crop root zone and (b) the RCC of sweet corn leaves and (2) to quantify the relationship between RCC and NO₃-N concentrations. The results showed a significant increase in NO₃-N concentrations within and below the root zone and plant leaf RCC under chicken manure treatments. Manure application rates and frequency had a significant effect on both NO₃-N concentration within and below the root zone and leaf RCC. It appears that leaf RCC can be used as an indicator of NO₃-N availability for sweet corn cultivated under the study conditions.     

Methanogenic Characteristics of Flooded Rice Soils in Response to Glucose Amendment

Extract

It was reported that flooded rice soil was an important source of atmospheric CH₄ (Cicerone and Shetter 1981; Sciler et al. 1984). In flooded rice soils, CH₄ is produced under strict anaerobic conditions by methanogenic bacteria (Jones et al. 1987; Jones 1991). Rice plants carry the produced CH₄ from anoxic sediment and release it to the atmosphere (Cicerone and Shetter 1981; Nouchi et al. 1990). More than 90% of emitted CH₄ is released through rice plants and the emission pattern usually shows large seasonal variations (Cicerone et al. 1983; Sciler et al. 1984; Inubushi et al. 1989). Since the number of methanogens did not change throughout the rice growth season (Schutz et al. 1989; Mayer and Conrad 1990), seasonal variations of CH₄ emission could be ascribed to the activities of methanogens and the amount of available substrates. However, the changes in the methanogenic activities in response to available substrates especially in relation to the growth period of rice plants are poorly documented.     

Nutrient Uptake and Leaching from Soil Amended with Cattle Manure and Nitrapyrin

We investigated whether nitrification inhibitor nitrapyrin can reduce nutrient leaching and increase nutrient uptake by corn (Zea mays L.) in cattle manure amended soil. Amendments included non-amended check (CK), urea (Urea), REG (manure from cattle fed barley grain), and DDGS (manure from cattle fed 60% dried distillers grains with solubles), co-applied with or without nitrapyrin and leached or unleached with water. Nitrapyrin reduced (P < 0.01) leaching of nitrate by 56, 32, and 24% from DDGS, REG, and Urea treatments, respectively, and also reduced (P < 0.05) leaching of phosphate (58%), potassium (39%), calcium (39%), and magnesium (39%) from DDGS treatment. While nitrapyrin reduces the rate of ammonium conversion to nitrate, higher magnesium and phosphate levels in DDGS-amended soil favor struvite formation and reduce their leaching. Corn biomass and nutrient uptake were higher (P < 0.01) in DDGS and Urea than CK and REG treatments, but remained unaffected by nitrapyrin. The benefits of nitrapyrin should be further investigated under field conditions.

Abbreviations: DCD, dicyandiamide; DDGS, dried distillers grains with solubles; NI, nitrification inhibitor; TP, total P; TN, total N.     

铬渣钙镁磷肥改土对地下水潜在影响

报道了施用铬渣钙镁磷肥改良镉污染土壤对土壤渗漏水影响试验，结果表明在铬渣钙镁磷肥用量分别为６．６７、１３．３４和２６．６８ｇ／ｋｇ土时，土壤渗滤液未受Ｃｄ和Ｃｒ的污染，Ｐ的含量亦不会对地下水产生明显不良影响。     

Phosphorus Adsorption and Bioavailability in a Paddy Soil Amended with Pig Manure Compost and Decaying Rice Straw

Phosphorus (P) availability in soil is closely related not only to soil P content but also to soil physicochemical and biological properties, which are closely associated with P sorption and biochemical transformation. The aims of this study were to determine the effects of pig manure compost (PMC) or decaying rice straw (DRS) added to a paddy soil on soil pH, soil organic carbon (SOC), dissolved organic carbon (DOC), acid phosphatase, microbial biomass P, soil test P (Olsen P), and P uptake by rice (Oryza sativa L. cv. ‘Liaoyan’). Phosphorus adsorption characterization affected by PMC‐ or DRS‐derived DOC was also studied. Compared with the control, both PMC and DRS treatments increased soil pH, SOM, DOC, microbial biomass P, and Olsen P, and the activity of acid phosphatase during the 110‐day incubation period. Phosphorus adsorption in soil decreased with DOC extracted from PMC and DRS and was well fit by the Langmuir equation. The Olsen P in the PMC‐ and DRS‐treated soil was correlated with both DOC content and acid phosphatase activity. Both PMC and DRS treatments significantly increased dry‐matter yield and P uptake in rice shoot. In conclusion, the increased P availability in the paddy soil was not only a result of direct P supplied following organic manure incorporation, but also an indirect result of reduction in P sorption on the solid phase of the paddy soil by DOCs which were derived from DRS or PMC.     

Changes in Biological Properties in Soil Amended with Rock Phosphate and Waste Mica Enriched Compost using Biological Amendments and Chemical Fertilizers Under Wheat-Soybean Rotation

The main aim of this research work is to prepare an enriched compost using rice straw mixed with rock phosphate, waste mica and Aspergillus awamori and to study their effect on changes in microbial properties in soils with and without chemical fertilizers under wheat-soybean rotation. Data revealed that significant increase in microbial biomass carbon (MBC), dehydrogenase activity, phosphatase activities, and microbial biomass phosphorus (MBP) in soil were maintained in enriched compost than ordinary compost after both the crops. Significant increase in MBC, dehydrogenase activity, phosphatase activities, and MBP were found in surface soil. The maximum microbial activities were observed in the treatment receiving 50% recommended dose of fertilizer (RDF) + enriched compost at 5 t ha^?1 indicating that integrated use of chemical fertilizers and enriched compost significantly improved the biological properties of soil under wheat–soybean rotation thereby enhanced soil fertility and crop production.