How Can Organic Amendments Help to Bind Sulfadiazine in the Soil? – An Iranian Soil Study

ABSTRACT

Veterinary antibiotics can enter the environment especially agricultural soils via animal manure application in which Sulfadiazine (SDZ) is considered as one of the most used antibiotic. After soil application, it may be transported into subsurface water. The sorption behavior of SDZ is not only influenced by the soil type but also by soil organic matters as well. Hence, an experiment was executed aimed to study sorption/desorption processes of SDZ under experimental conditions in three various soils treated by different bio fertilizers including rice husk compost (RHC), rice husk biochar (RHB) and Micrococcus yunnanensis (My) bacterium. Sorption/desorption data of soils with and without bio-fertilizers were well fitted with Freundlich model (R² = 0.97). Results showed that bio-amended soils had higher values of k_d sorption ranged from 1.16 to 52.4 without and with bio-fertilizers application respectively, proposing low sorption of SDZ with substantial risk of leaching without bio-fertilizers application. Also for the desorption cycle values of K_d increased from 1.03 to 39.1 without and with bio-fertilizers application, respectively. Furthermore, there was a hysteresis effect using organic matter. As a result of bio-fertilizers application, a significant value of SDZ was strongly adsorbed on the soil particles which was not desorb through desorption process.     

Sorption and desorption of diuron and norflurazon in Florida citrus soils

The potential for surface and groundwater contamination of soil applied herbicides is partly dependent on soil properties. Sorption and desorption of diuron and norflurazon were studied in seven soils representative of the southern citrus-belt of Florida using the batch-equilibrium technique. Sorption of herbicides was influenced by soil properties. Sorption coefficients (K _d) ranged from 0.84 to 3.26 mL g^?1 for diuron and 0.63 to 2.20 mL g^?1 for norflurazon indicating weak to moderate binding of herbicides to soil. For norflurazon, K _dwas significantly related to organic C content, soil pH, and cation exchange capacity. For diuron, absence of a significant relationship between K _dand selected soil properties suggests that the soil properties other than those studied may play a role in determining sorption on these soils. Desorption studies showed that higher amounts of diuron and norflurazon was desorbed by water than by 0.5 M CaCl₂. An inverse relationship was apparent between herbicides sorbed and that which was desorbed among the soils studied. The soil which exhibited higher sorption had lower desorption and the soil which exhibited lower sorption had higher desorption.     

Impact of biochar coated with magnesium (hydr)oxide on phosphorus leaching from organic and mineral soils

Purpose

Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated.

Materials and methods

Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching.

Results and discussion

Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha^?1)?>?organic 1 (1.0 kg ha^?1)?>?sand (0.3 kg ha^?1)?>?loam (0.2 kg ha^?1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)₂) in water. The Langmuir maximum adsorption capacity (Q_max) of the coated biochar was 65.4 mg P g^?1. Lysimeters produced mixed results, with a 74% (P?<?0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam.

Conclusions

The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.

     

Environmental Behaviour of Metolachlor and Diuron in a Tropical Soil in the Central Region of Brazil

The environmental behaviour of metolachlor and diuron was studied in the Central-western region of Brazil, by means of a field study where six experimental plots were installed. The soil was classified as a Latosol, and the soil horizons were characterized. Sorption of metolachlor and diuron was evaluated in laboratory batch experiments. Metolachlor and diuron were applied to the experimental plots on uncultivated soil in October 2003. From this date to March 2004, the following processes were studied: leaching, runoff and dissipation in top soil. K _oc of metolachlor varied from 179 to 264 mL g^?1 in the soil horizons. K _oc of diuron in the Ap horizon was 917 mL g^?1, decreasing significantly in the deeper horizons. Field dissipation half-lives of metolachlor and diuron were 18 and 15 days, respectively. In percolated water, metolachlor was detected in concentrations ranging from 0.02 to 2.84 μg L^?1. In runoff water and sediment, metolachlor was detected in decreasing concentrations throughout the period of study. Losses of 0.02% and 0.54% of the applied amount by leaching and runoff, respectively, were observed confirming the high mobility of this herbicide in the environment. In percolated water, diuron was detected with low frequency but in relatively high concentrations (up to 6.29 μg L^?1). In runoff water and soil, diuron was detected in decreasing concentrations until 70 days after application, totalizing 13.9% during the whole sampling period. These results show the importance of practices to reduce runoff avoiding surface water contamination by these pesticides, particularly diuron.     

Biochar mediated alterations in herbicide breakdown and leaching in soil

Biochar application to soil has been proposed as a mechanism for improving soil quality and the long term sequestration of carbon. The implications of biochar on pesticide behavior, particularly in the longer term, however, remains poorly understood. Here we evaluated the influence of biochar type, time after incorporation into soil, dose rate and particle size on the sorption, biodegradation and leaching of the herbicide simazine. We show that typical agronomic application rates of biochar (10-100 t ha⁻¹) led to alterations in soil water herbicide concentrations, availability, transport and spatial heterogeneity. Overall, biochar suppressed simazine biodegradation and reduced simazine leaching. These responses were induced by a rapid and strong sorption of simazine to the biochar which limits its availability to microbial communities. Spatial imaging of ¹⁴C-labeled simazine revealed concentrated hotpsots of herbicide co-localized with biochar in the soil profile. The rate of simazine mineralization, amount of sorption and leaching was inversely correlated with biochar particle size. Biochar aged in the field for 2 years had the same effect as fresh biochar on the sorption and mineralization of simazine, suggesting that the effects of biochar on herbicide behavior may be long lasting. We conclude that biochar application to soil will reduce the dissipation of foliar applied pesticides decreasing the risk of environmental contamination and human exposure via transfer in the food chain, but may affect the efficacy of soil-applied herbicides.     

生物质炭对坡耕地紫色土中抗生素吸附-解吸及迁移的影响

以磺胺嘧啶、磺胺二甲基嘧啶和氟苯尼考为目标抗生素，一方面，通过室内批量平衡实验研究施用生物炭（投加量0、2.145kg/m2和28.65kg/m2，经三年田间老化）对石灰性紫色土中抗生素等温吸附-解吸特征的影响；另一方面，利用长20米、宽5米的坡耕地（6?）野外小区，开展面施2.145kg/m2生物炭和在坡底构建一定宽度(40cm)和深度(40cm)含28.65kg/m2生物炭可渗透反应土墙试验，研究两种不同生物炭施用方式对暴雨条件下抗生素迁移行为的影响。结果表明：生物炭的添加显著增强紫色土对抗生素的吸附与固持作用，其等温吸附和解吸行为均能被Freundlich方程较好地拟合；不论施炭与否，磺胺嘧啶和磺胺二甲基嘧啶都表现为非线性吸附，而对于K_ow值最低的氟苯尼考，生物炭的施用则为其引入了新的非线性吸附机制；耕作层面施生物炭能更有效地阻控抗生素向深层土壤的垂向淋失迁移; 在坡底修建生物炭可渗透反应土墙（顶端构筑为地埂-边沟）则能更大幅度地削减抗生素随地表径流的输出负荷，其中以对正辛醇-水分配系数最低的氟苯尼考的削减率最小。     

The Effect of the Organic Matter Composition on POP Accumulation in Soil

The effect of different humic fractions on polychlorinated biphenyl (PCB) contamination in soils was tested in the field by means of 53 soil samples from a high-altitude grassland plateau in the Italian Alps. Three humic fractions (humin, humic acids, and fulvic acids) were characterized in parallel by quantifying 12 PCB congeners to establish a direct relationship between PCB levels and humic fraction concentrations. Humin (the most hydrophobic fraction) appears to be the most closely correlated with the amount of PCBs in soil (R ²?=?0.83), while fulvic acid shows the lowest correlation (R ²?=?0.49). The idea of preferential sorption of hydrophobic compounds in the humin fraction is discussed, and the humin carbon content (f _huminC) is proposed as an improved parameter for evaluating the potential for POP accumulation in soils, replacing total organic carbon (f _oc). Congener studies revealed that penta- and hexa-substituted-CBs show the optimal combination of physicochemical properties for equilibrating with the humin content in soil. Moreover, f _huminC/f _oc is conceptually equivalent to the empirical coefficients used in predictive K _sa equations. In our samples, the f _huminC/f _oc was 0.55, a value in between the empirical coefficients proposed in the literature. In predictive equations, the use of f _huminC instead f _oc avoids the necessity of using an empirical parameter for a ??generic?? condition by introducing an experimental parameter (f _huminC) that takes into account local conditions (organic matter composition).     

Biochar and biochar with N fertilizer as a potential tool for improving soil sorption of nutrients

Purpose

Biochar usually has a large specific surface area, and due to this, it increases the sorption capacity of the soil where it was applied. The objectives of this study were to (i) quantify the effects of biochar and biochar in combination with N fertilizer on the soil sorption parameters and (ii) quantify the effects of soil organic matter on the sorption parameters after application of biochar with and without N fertilizer.

Materials and methods

The experiment was established on Haplic Luvisol at the locality of Dolná Malanta (Slovakia) in 2014. The soil samples were collected once a month from the depth 0–0.2 m during 2014 to 2016. The field experiment included three rates of biochar application (B0?=?no biochar, B10?=?biochar at the rate of 10 t ha^?1, B20?=?biochar at the rate of 20 t ha^?1) and three levels of N fertilization (N0?=?no nitrogen, N40?=?nitrogen at the rate of 40 kg ha^?1, N80?=?nitrogen at the rate of 80 kg ha^?1).

Results and discussion

Overall, the decrease of the average values of hydrolytic acidity due to biochar and biochar combined with N fertilization resulted on average in an increase of sum of basic cation (SBC), cation exchange capacity (CEC), and sorption capacity of soil organic matter (CEC_SOM) in all treatments. However, this effect was the most intensive in B10N40. Despite the fact that the average values of sorption parameters improved, its dynamics during the investigated period were different. A significant decrease in CEC was observed from 2014 to 2016 in all treatments, except B0N0 and B10N0. A stable trend in CEC_SOM was observed only in B10N40. Humic substances and humic acids had a statistically significant positive effect on the SBC, CEC, and CEC_SOM only in B20N0 treatment. Negative correlations between the above mentioned parameters were observed in B10N80 treatment.

Conclusions

We conclude that the application of biochar and biochar combined with N fertilization had a positive influence on sorption parameters. However, its effects on SBC, CEC, and CEC_SOM decreased over time after its application.

     

Effects of soil-cation composition on reactions of four herbicides in a candler fine sand

Sorption, persistence and transport of herbicides in soils depend on the relative saturation of soils with cations from various soil amendments. Current research was conducted to study the effect of preequilibration of a Candler fine sand (Hyperthermic uncoated typic Quartzipsamments; 0–30 cm depth) with AlCl₃, CaCl₂, CuCl₂, FeCl₃, or KCl salt solutions on sorption in bromacil, simazine, norflurazon, and diuron herbicides commonly used in Florida citrus groves. Preequilibration of the soil with either FeCl₃, or AlCl₃ significantly decreased the sorption and therefore increased internal leaching potential, of all four herbicides as compared to their sorption in untreated soil. This decrease in sorption was much greater for bromacil and simazine (24 to 35%) than for norflurazon and diuron (7 to 8%). The desorption of bromacil and diuron in 1M NH₄OAc was also significantly lower in soils preequilibrated with FeCl₃ or AlCl₃ than the untreated soil. However, the reverse was true in the case of simazine and norflurazon. Preequilibration of the soil with CuCl₂, KCl, and CaCl₂ resulted in a significant decrease in sorption of norflurazon, diuron, and simazine but did not affect bromacil sorption. Accordingly, the species of adsorbed cation had varying effects on the sorption/desorption of each of the herbicides and varied their leaching potential.     

Soil organic carbon storage and quality are impacted by corn cob biochar application on a tropical sandy loam

Purpose

Humic substances, which are integral components of total organic carbon (TOC), influence soil quality. The study aimed to investigate whether humic and non-humic fractions exhibit early, consistent, and measurable changes and affect TOC sensitivity and storage in a tropical sandy loam soils amended with corn cob biochar.

Materials and methods

There were four treatments with four replicates established in a randomized complete block design. Composite soil samples were taken from plots without biochar (CT), from plots incorporated with 15 t biochar ha^?1 (BC-15), and 30 t biochar ha^?1 without or with phosphate fertilizer (BC-30 and BC-30+P). The TOC, and humin, humic acid (HA), and fulvic acid (HA) fractions of soil organic carbon were determined for each treatment. The optical densities (400–700 nm) were measured on the soil-free extracts by spectrophotometry; the densities measured at 465 and 665 nm were used to calculate the E₄₆₅/E₆₆₅ ratios.

Results and discussion

The BC-30 and BC-30+P plots recorded the highest TOC, humin, humic acid (HA), and fulvic acid (FA) contents with respect to the lowest in the CT. The total exchangeable carbon stratification was significantly higher in all the biochar-treated plots relative to the CT. Spectral analysis showed higher values of E₄₆₅/E₆₆₅ (5.02 and 5.15) in the CT and BC-15-treated soils, respectively, compared with the BC-30 and BC-30+P-amended soils with E₄₆₅/E₆₆₅ ratios of 2.76 and 2.98, respectively.

Conclusions

Corn cob biochar applied to a tropical sandy loam:

? increased the concentrations of HA and FA and led to increased stratification of TOC, with a stronger effect on HA compared with FA;

? significantly lowered E₄₆₅/E₆₆₅ at the high biochar application rate of 30 t ha^?1, implying the dominance of high molecular weight humic acid-like substances, and increased degree of aromaticity of the TOC.

     

Long-term effects of bone char and lignocellulosic biochar-based soil amendments on phosphorus adsorption–desorption and crop yield in low-input acidic soils

Although the addition of biochar has been shown to reduce the phosphorus (P) adsorption capacity of soil, quantitative evidence of this has mainly been provided by incubation experiments and it is therefore essential to conduct long-term field trials to draw general conclusions. It is largely unknown whether bone char has a greater effect than lignocellulosic biochar on P adsorption–desorption processes and crop yield. The aim of this study was to determine the long-term (8 years) effect of bone char and biochar on P adsorption–desorption and crop yield in low-input acidic soils. The results showed that bone char decreased the maximum P adsorption capacity (Q_m) by 10% and increased the desorption capacity (D_s) by 150% compared with the control (i.e. without a soil amendment). The desorption ratio was highest for the bone char treatment (10.3%) and three times more than the control. Plant-available P was seven times greater under bone char than the control. There was no variation in adsorption–desorption characteristics, desorption ratio and plant-P available content between bone char and lignocellulosic biochar treatments. The average yield increment following the application of bone char and biochar was 1.7 and 1.4 Mg ha⁻¹ for maize and 1.8 and 1.9 Mg ha⁻¹ for soya bean, respectively. Despite the low application rate (4 t ha⁻¹ year⁻¹), these findings demonstrated that the long-term application of bone char and biochar-based amendments enhanced P availability in low-input cropping systems, mainly by altering the P adsorption and desorption capacity of soils.     

Effect of straw biochar application on soil carbon,greenhouse gas emissions and nitrogen leaching: A vegetable crop rotation field experiment

Intensive vegetable crop systems are rapidly developing, with consequences for greenhouse gas (GHGs) emissions, nitrogen leaching and soil carbon. We undertook a field trial to explore the effect of biochar application (0, 10, 20 and 40 t ha⁻¹) on these factors in lettuce, water spinach and ice plant rotation. Our results show that the 20 and 40 t ha⁻¹ soil treatments resulted in the SOC content being 26.3% and 29.8% higher than the control (0 t ha⁻¹), respectively, with significant differences among all treatments (p < .05). Biochar application caused N₂O emissions to decrease during the lettuce and water spinach seasons, by 1.5%–33.6% and 12.4%–40.5%, respectively, compared the control, with the 20 t ha⁻¹ application rate resulting in the lowest N₂O emissions. Biochar also decreased the dissolved nitrogen (DN) concentration in leachate by 9.8%–36.2%, following a 7.3%–19.9% reduction in dissolved nitrogen in the soil. Similarly, biochar decreased the nitrate (NO₃⁻) concentrations in leachate by 3.9%–30.2%, following a 3.8%–16.7% reduction in the soil nitrate level. Overall, straw biochar applied at rate of 20 t ha⁻¹ produced the lowest N₂O emissions and N leaching, while, increasing soil carbon.     

Effects of biochar compared to organic and inorganic fertilizers on soil quality and plant growth in a greenhouse experiment

Our contemporary society is struggling with soil degradation due to overuse and climate change. Pre‐Columbian people left behind sustainably fertile soils rich in organic matter and nutrients well known as terra preta (de Indio) by adding charred residues (biochar) together with organic and inorganic wastes such as excrements and household garbage being a model for sustainable agriculture today. This is the reason why new studies on biochar effects on ecosystem services rapidly emerge. Beneficial effects of biochar amendment on plant growth, soil nutrient content, and C storage were repeatedly observed although a number of negative effects were reported, too. In addition, there is no consensus on benefits of biochar when combined with fertilizers. Therefore, the objective of this study was to test whether biochar effects on soil quality and plant growth could be improved by addition of mineral and organic fertilizers. For this purpose, two growth periods of oat (Avena sativa L.) were studied under tropical conditions (26°C and 2600 mm annual rainfall) on an infertile sandy soil in the greenhouse in fivefold replication. Treatments comprised control (only water), mineral fertilizer (111.5 kg N ha^–1, 111.5 kg P ha^–1, and 82.9 kg K ha^–1), compost (5% by weight), biochar (5% by weight), and combinations of biochar (5% by weight) plus mineral fertilizer (111.5 kg N ha^–1, 111.5 kg P ha^–1, and 82.9 kg K ha^–1), and biochar (2.5% by weight) plus compost (2.5% by weight). Pure compost application showed highest yield during the two growth periods, followed by the biochar + compost mixture. biochar addition to mineral fertilizer significantly increased plant growth compared to mineral fertilizer alone. During the second growth period, plant yields were significantly smaller compared to the first growth period. biochar and compost additions significantly increased total organic C content during the two growth periods. Cation‐exchange capacity (CEC) could not be increased upon biochar addition while base saturation (BS) was significantly increased due to ash addition with biochar. On the other hand, compost addition significantly increased CEC. Biochar addition significantly increased soil pH but pH value was generally lower during the second growth period probably due to leaching of base cations. Biochar addition did not reduce ammonium, nitrate, and phosphate leaching during the experiment but it reduced nitrification. The overall plant growth and soil fertility decreased in the order compost > biochar + compost > mineral fertilizer + biochar > mineral fertilizer > control. Further experiments should optimize biochar–organic fertilizer systems.     

源于松针的可溶性有机物对土壤多环芳烃吸附和解吸行为的影响研究

Study of the relationship between plant litter-derived dissolved organic matter（DOM） and organic pollutant transport in soil is important for understanding the role of forest litter carbon cycling in influencing pollutant behaviour and fate in forest soil.With the aim of providing insight into the capacity of plant litter-derived DOM to influence sorption and desorption of selected polycyclic aromatic hydrocarbons（PAHs） on soil, batch experiments were carried out with application of a sorption-desorption model incorporating DOM effects. Freshly fallen pine（Pinus elliottii） needles were used as the source of organic matter. Input of the pine needle litter-derived DOM was found to significantly decrease desorption hysteresis as well as soil adsorption capacity of phenanthrene（PHE） and fluoranthene（FLA）. Addition of 1 728 mg L-1dissolved organic carbon（DOC） lowered the organic carbon-normalized sorption distribution coefficient of PHE from 7 776 to 2 541 L kg-1C and of FLA from 11 503 to 4 368 L kg-1C. Decreases of the apparent sorption-desorption distribution coefficients of PHE and FLA with increased DOC concentration indicated that DOM favored desorption of PAHs from soil. Increases in the fraction of apparently dissolved PAHs were attributable to the dissolved PAH-DOM complexes, accounting for the dissolved proportions of 39% to 69% for PHE and 26% to 72% for FLA in the sorption and desorption processes as the concentration of the added DOM solution rose from 0 to 1 728 mg L-1. Our results suggest that pine needle litterderived DOM can have a substantial effect of inhibiting PAHs sorption and promoting PAHs desorption, thus leading to enhanced leaching in soil, which should be taken into account in risk assessment of PAHs accumulated in forest soil.     

Eucalyptus biochar application enhances Ca uptake of upland rice,soil available P,exchangeable K,yield, and N use efficiency of sugarcane in a crop rotation system

It was hypothesized that the application of eucalyptus biochar enhances nutrient use efficiencies of simultaneously supplied fertilizer, as well as provides additional nutrients (i.e., Ca, P, and K), to support crop performance and residual effects on subsequent crops in a degraded sandy soil. To test this hypothesis, we conducted an on‐farm field experiment in the Khon Kaen province of Northeastern Thailand to assess the effects of different application rates of eucalyptus biochar in combination with mineral fertilizers to upland rice and a succeeding crop of sugarcane on a sandy soil. The field experiment consisted of three treatments: (1) no biochar; (2) 3.1 Mg ha^?1 biochar (10.4 kg N ha^?1, 3.1 kg P ha^?1, 11.0 kg K ha^?1, and 17.7 kg Ca ha^?1); (3) 6.2 Mg ha^?1 biochar (20.8 kg N ha^?1, 6.2 kg P ha^?1, 22.0 kg K ha^?1, and 35.4 kg Ca ha^?1). All treatments received the same recommended fertilizer rate (32 kg N ha^?1, 14 kg P ha^?1, and 16 kg K ha^?1 for upland rice; 119 kg N ha^?1, 21 kg P ha^?1, and 39 kg K ha^?1 for sugarcane). At crop harvests, yield and nutrient contents and nitrogen (N) use efficiency were determined, and soil chemical properties and pH₀ monitored. The eucalyptus biochar material increased soil Ca availability (117 ± 28 and 116 ± 7 mg kg^?1 with 3.1 and 6.2 Mg ha^?1 biochar application, respectively) compared to 71 ± 13 mg kg^?1 without biochar application, thus promoting Ca uptake and total plant biomass in upland rice. Moreover, the higher rate of eucalyptus biochar improved CEC, organic matter, available P, and exchangeable K at succeeding sugarcane harvest. Additionally, 6.2 Mg ha^?1 biochar significantly increased sugarcane yield (41%) and N uptake (70%), thus enhancing N use efficiency (118%) by higher P (96%) and K (128%) uptake, although the sugar content was not increased. Hence, the application rate of 6.2 Mg ha^?1 eucalyptus biochar could become a potential practice to enhance not only the nutrient status of crops and soils, but also crop productivity within an upland rice–sugarcane rotation system established on tropical low fertility sandy soils.     

Sorption of s-Triazine Herbicides in Organic Matter Amended Soils: Fresh and Incubated Systems

Fresh amendment of soil with sewage sludge and composted sewage sludge resulted in increased sorption of three s-triazine herbicides: atrazine, ametryn and terbuthylazine. The extent of increased sorption (as evaluated by sorption coefficients K_d or K_f) was a function of soil type, such that sorption in amended organic carbon-poor soil (0.4% OC) was more enhanced than in amended organic carbon-rich soil (1.55% OC). Despite significant differences between the organic amendments in terms of humic and fulvic acid content, humin content, soluble organic matter content, total organic matter content, and H/C and O/C atomic ratios, organic matter composition had no discernible effect on either sorption distribution coefficients or on isotherm linearity in amended soils. Soils amended with composted sludge had the same sorption potential as did soils amended with the analogous uncomposted sludge. After incubating soil-sludge mixtures for a year at room temperature, organic matter content decreased to original pre-amendment levels. Sorption coefficients for the three compounds similarly decreased to initial pre-amendment values. Organic carbon normalized sorption coefficients (K_oc) were essentially identical in the soils, amended soils, and incubated amended soils, indicating that sludge and compost derived organic matter does not have a significantly different sorption capacity as compared with the original soils, despite compositional differences.     

N-Source Effects on Temporal Distribution of NO3-N Leaching Losses to Subsurface Drainage Water

Understanding the temporal distribution of NO₃-N leaching losses from subsurface drained ‘tile’ fields as a function of climate and management practices can help develop strategies for its mitigation. A field study was conducted from 1999 through 2003 to investigate effects of the most vulnerable application of pig manure (fall application and chisel plow), safe application of pig manure (spring application and no-tillage) and common application of artificial nitrogen (UAN spring application and chisel plow) on NO₃-N leaching losses to subsurface drainage water beneath corn (Zea mays L.)–soybean (Glycine max L.) rotation systems as a randomized complete block design. The N application rates averaged over five years ranged from 166 kg-N ha^?1 for spring applied manure to 170 kg-N ha^?1 for UAN and 172 kg-N ha^?1 for fall applied manure. Tillage and nitrogen source effects on tile flow and NO₃-N leaching losses were not significant (P?<?0.05). Fall applied manure with CP resulted in significantly greater corn grain yield (10.8 vs 10.4 Mg ha^?1) compared with the spring manure-NT system. Corn plots with the spring applied manure-NT system gave relatively lower flow weighted NO₃-N concentration of 13.2 mg l^?1 in comparison to corn plots with fall manure-CP (21.6 mg l^?1) and UAN-CP systems (15.9 mg l^?1). Averaged across five years, about 60% of tile flow and NO₃-N leaching losses exited the fields during March through May. Growing season precipitation and cycles of wet and dry years primarily controlled NO₃-N leaching losses from tile drained fields. These results suggest that spring applied manure has potential to reduce NO₃-N concentrations in subsurface drainage water and also strategies need to be developed to reduce early spring NO₃-N leaching losses.     

Biochar and Sewage Sludge Application Increases Yield and Micronutrient Uptake in Rice (Oryza sativa L.)

A greenhouse experiment was conducted in the Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.), India, during kharif 2013 to find out the effect of biochar and sewage sludge (SS) on growth, yield, and micronutrient uptake in rice crop. Nine treatments were employed using six different doses of biochar (2.5, 5.0, 7.5 10, 15, and 20 t ha^?1) amended with a fixed dose of SS (30 t ha^?1) and 50% recommended dose of nitrogen (50% RDN), i.e., 60 kg ha^?1. Other three treatments were absolute control (no fertilizers), 100% recommended dose of fertilizers (100% RDF) which was 120:60:60 kg ha^?1 as nitrogen (N): phosphorus pentoxide (P₂O₅):dipotassium oxide (K₂O), and 30 t ha^?1SS + 50% RDN. Experimental results showed a significant increase in yield of rice crop with increasing levels of biochar along with SS. Application of biochar at 20 t ha^?1 along with 30 t ha^?1SS increased grain yield to the extent of 2.5 times over absolute control (no fertilizers) and 8.5% over control (100% RDF). The uptake of iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn) (micronutrients) increased significantly with graded doses of biochar application from 2.5 to 20 t ha^?1 in the soil. The maximum micronutrient uptake and grain yield of rice were found in T₉ where 30 t ha^?1SS along with 20 t ha^?1 biochar was applied with only 50% RDN. The maximum availability of micronutrients in soil was found with 30 t ha^?1 of SS + 50% RDN (T₃) followed by conjoint application of 20 t ha^?1 of biochar and 30 t ha^?1 SS + 50% RDN (T₉).     

15N-labelled fertiliser recovery by maize (Zea mays L.) and leaching of nutrients as influenced by oil palm empty fruit bunch biochar in a mini-lysimeter under controlled tropical environment

Converting oil palm empty fruit bunches into biochar is an alternative waste management method and has strong potential to improve N fertiliser use efficiency in agriculture. The aim of this study was to determine the effectiveness of oil palm empty fruit bunch biochar (EFBB) in improving recovery of ¹⁵N-labelled nitrogen fertiliser by maize (Zea mays L.) and leaching of mineral N and K. An experiment was conducted in a mini-lysimeter system with randomised complete block design layout and six replications under controlled environment in a rain shelter. Each mini-lysimeter was filled with 20 kg of sandy loam soil before adding EFBB (0, 5, 10 and 20 Mg ha^?1). The N source used was (¹⁵NH₄)₂SO₄ at 80 kg N ha^?1 (2 at% ¹⁵N excess). Maize was irrigated to induce leaching every 4 days. Maize plant and soils were sampled 58 days after sowing (tasselling stage). Application of EFBB significantly reduced cumulative leachate volume and mineral N leaching. Soils applied with EFBB significantly improved ¹⁵N fertiliser recovery in maize and dry matter weight. This study shows that EFBB has the potential to be applied on highly weathered acidic soil as an amendment to improve fertiliser efficiency and crop growth.     

Effects of biochar application on greenhouse gas emissions,carbon sequestration and crop growth in coastal saline soil

To evaluate the benefits of application of biochar to coastal saline soil for climate change mitigation, the effects on soil organic carbon (SOC), greenhouse gases (GHGs) and crop yields were investigated. Biochar was applied at 16 t ha^?1 to study its effects on crop growth (Experiment I). The effects of biochar (0, 3.2, 16 and 32 t ha^?1) and corn stalk (7.8 t ha^?1) on SOC and GHGs were studied using ¹³C stable isotope technology and a static chamber method, respectively (Experiment II). Biochar increased grain mass per plant of the wheat by 27.7% and increased SOC without influencing non‐biochar SOC. On average, 92.3% of the biochar carbon and 16.8% of corn‐stalk carbon were sequestered into the soil within 1 year. The cumulative emissions of CO₂, CH₄ and N₂O were not affected significantly by biochar but cornstalk application increased N₂O emissions by 17.5%. The global warming mitigation potential of the biochar treatments (?3.84 to ?3.17 t CO₂‐eq. ha^?1 t^?1 C) was greater than that of the corn stalk treatment (?0.11 t CO₂‐eq ha^?1 t^?1 C). These results suggest that biochar application improves saline soil productivity and soil carbon sequestration without increasing GHG emissions.