Comparative role of animal manure and vegetable waste induced compost for polluted soil restoration and maize growth

Soil amendment with two types of composts: animal manure (AC) and vegetable waste (VC) induced composts have potential to alleviate Cd toxicity to maize in contaminated soil. Therefore, Cd mobility in waste water irrigated soil can be addressed through eco-friendly and cost effective organic soil amendments AC and VC that eventually reduces its translocation from polluted soil to maize plant tissues. The comparative effectiveness of AC and VC at 3% rate were evaluated on Cd solubility, its accumulation in maize tissues, translocation from root to shoot, chlorophyll contents, plant biomass, yield and soil properties (pH, NPK, OM). Results revealed that the addition of organic soil amendments significantly minimized Cd mobility and leachability in soil by 58.6% and 47%, respectively in VC-amended soil over control. While, the reduction was observed by 61.7% and 57%, respectively when AC was added at 3% over control. Comparing the control soil, Cd uptake effectively reduced via plants shoots and roots by 50%, 46% respectively when VC was added in polluted soil. However, Cd uptake was decreased in maize shoot and roots by 58% and 52.4% in AC amended soil at 3% rate, respectively. Additionally, NPK contents were significantly improved in polluted soil as well as in plant tissues in both composts amended soil Comparative to control, the addition of composts significantly improved the maize dry biomass and chlorophyll contents at 3% rate. Thus, present study confirmed that the addition of animal manure derived compost (AC) at 3% rate performed well and might be consider the suitable approach relative to vegetable compost for maize growth in polluted soil.     

有机物料还田对双季稻田土壤有机碳及其活性组分的影响

有机物料还田是提升农田土壤有机碳、培肥土壤的重要措施。为探讨不同有机物料的还田效果,采用室外培养方法,研究了在等碳输入条件下,施用水稻秸秆、紫云英、生物有机肥、猪粪和水稻秸秆生物炭对洞庭湖双季稻区潮土有机碳和活性有机碳组分含量的影响。结果表明: 经过180 d的培养试验,与不施用有机物料相比,施用有机物料提高了土壤活性有机碳含量。生物有机肥、猪粪和水稻秸秆生物炭处理分别使土壤有机碳含量显著提升了26.1%、9.7%和30.7%,水稻秸秆和紫云英对土壤有机碳含量的提升效应在试验期间并不显著。水稻秸秆和紫云英还田更有利于土壤可溶性有机碳和微生物生物量碳的积累,猪粪更有利于土壤可溶性有机碳的积累,生物有机肥更有利于土壤微生物生物量碳和易氧化有机碳的积累,水稻秸秆生物炭则更有利于土壤微生物生物量碳和轻组有机碳的积累。与水稻秸秆还田相比,紫云英、生物有机肥、猪粪和水稻秸秆生物炭还田使土壤碳库管理指数分别提高了31.8%、111.6%、62.2%和50.7%。从土壤固碳和土壤碳库管理指数来看,生物有机肥、猪粪和水稻秸秆生物炭的还田效果优于水稻秸秆和紫云英还田。     

The effects of biochars produced in different pyrolsis temperatures from agricultural wastes on cadmium uptake of tobacco plant

Abiotic stresses caused by cadmium (Cd) contamination in soil retard plant growth and decline the quality of food. Amendment of biochar was reported effective in reduction of mobility, plant uptake and toxicity of Cd in plants. The aim of this study was to investigate the effect of biochar applications produced from corn cob and rice husk at three different pyrolysis temperatures (400, 500 and 600 °C) on Cd uptake of tobacco plants. The results showed that the shoot Cd concentration and content of tobacco plants significantly increased with the application of Cd in increasing doses. The results showed that increasing Cd dosescaused significant increase (P < 0.01) in shoot Cd concentration and content of the tobacco plant at three different pyrolysis temperatures of both corn cob and rice husk biochars. The concentration of Cd was 0.48 mg kg^?1 in Cd0 dose of corn cob biochar produced at 500 °C and increased to 61.6 mg kg^?1 at Cd5, while Cd concentration increased to 72.3 mg kg^?1 with rice husk biochar. Despite the increase in Cd concentrations and content, shoot Cd concentrations and contents were significantly (P < 0.01) reduced with the treatments of corn cob and rice husk biochars produced at different pyrolysis temperatures. The Cd concentration at Cd5 dose in the absence of biochar addition was 90.5 mg kg^?1, while Cd concentration at Cd5 dose in 400, 500 and 600 °C treatments of corn cob biochar was reduced to 66.5, 61.6 and 67.3 mg kg^?1 respectively, and to 77.0, 72.3 and 70.2 mg kg^?1 in rice husk biochar. The results also revealed that corn cob biochar treatments were more effective in reducing Cd uptake of tobacco plants compared to rice husk biochar. Higher specific surface area of corncob biochar compared to rice husk biochar caused to the difference between two biochar sources on Cd uptake of tobacco plants.     

Application of Aspergillus niger-treated agrowaste residue and Glomus mosseae for improving growth and nutrition of Trifolium repens in a Cd-contaminated soil

The microbial transformation of sugar beet (SB) agrowaste with or without rock-phosphate (RP) has utility for the improvement of plant growth in a Cd (5 microg g-1) artificially contaminated soil, particularly when the soil is co-inoculated with arbuscular mycorrhizal (AM) fungus Glomus mosseae isolated from a Cd-polluted area. Under such Cd-polluted conditions, the limited growth, mineral nutrition, symbiotic developments (nodulation and AM-colonization) and soil enzymatic activities were stimulated using SB or SB+RP as soil amendments and G. mosseae as inoculant. G. mosseae enhanced plant establishment in a higher extent in amended soil; it is probably due to the interactive effect increasing the potential fertility of such compounds and its ability for decreasing Cd transfer from soil to plant. The amount of Cd transferred from soil solution to biomass of AM-colonized plants ranged from 0.09 microg Cd g-1 (in SB+RP-amended soil) to 0.6 microg Cd g-1 (in non-amended soil). Nodule formation was more sensitive to Cd than AM-colonization, and both symbioses were stimulated in amended soils. Not only AM-colonization but also amendments were critical for plant growth and nutrition in Cd-polluted soil. The high effectiveness of AM inoculum increasing nutrients and decreasing Cd in amended soil indicated the positive interaction of these treatments in increasing plant tolerance to Cd contamination.     

Contrasting effects of maize residue,coal gas residue and their biochars on nutrient mineralization,enzyme activities and CO2 emissions in sandy loess soil

Mismanagement of crop straw and coal gas residue threatens the atmosphere and the economy. Nevertheless, thermal-pyrolysis is an option for management that turns bio-waste into biochar; its viability and adoption by the public as soil amendments is dependent on the agronomic and environmental values compared between biochar and the raw materials. We undertook a 60-day short-term analysis to assess the impact of various wastes and biochars, as well as inorganic nutrients (N), on carbon dioxide (CO₂) fluxes, soil enzyme activities, soil fertility status, and microbial activities. There were eight treatments of soil amendments: without an amendment (CK), Nutrients (N), straw + nutrients (S+N), straw biochar + nutrients (SB+N), coal gas residue + nutrients (C+N), coal gas residue biochar + nutrients (CB+N), straw + straw biochar + nutrients (S+SB+N) and coal gas residue waste + coal gas residue biochar + nutrients (C+ CB +N). The results indicated that soil EC, pH, nitrate N (NO₃^–- N), SOC, TN and available K were significantly (p < 0.05) increased coal gas residue biochar and combined with coal fly ash as compared to maize straw biochar and combined with maize straw and N treatments. The higher concentrations of soil MBC and MBN activities were increased in the maize straw application, while higher soil enzyme activity such as, invertase, urease and catalase were enhanced in the coal fly ash derived biochar treatments. The higher cumulative CO₂ emissions were recorded in the combined applications of maize straw and its biochar as well as coal gas residue and its biochar treatment. Our study concludes, that maize straw and coal fly ash wastes were converted into biochar product could be a feasible substitute way of discarding, since land amendment and decreased CO₂ fluxes and positive changes in soil microbial, and chemical properties, and can be confirmed under long-term conditions for reduction of economical and environment issues.     

Biochar stimulates the decomposition of simple organic matter and suppresses the decomposition of complex organic matter in a sandy loam soil

Incorporating crop residues and biochar has received increasing attention as tools to mitigate atmospheric carbon dioxide (CO₂) emissions and promote soil carbon (C) sequestration. However, direct comparisons between biochar, torrefied biomass, and straw on both labile and recalcitrant soil organic matter (SOM) remain poorly understood. In this study, we explored the impact of biochars produced at different temperatures and torrefied biomass on the simple C substrates (glucose, amino acids), plant residues (Lolium perenne L.), and native SOM breakdown in soil using a ¹⁴C labeling approach. Torrefied biomass and biochars produced from wheat straw at four contrasting pyrolysis temperatures (250, 350, 450, and 550 °C) were incorporated into a sandy loam soil and their impact on C turnover compared to an unamended soil or one amended with unprocessed straw. Biochar, torrefied biomass, and straw application induced a shift in the soil microbial community size, activity, and structure with the greatest effects in the straw‐amended soil. In addition, they also resulted in changes in microbial carbon use efficiency (CUE) leading to more substrate C being partitioned into catabolic processes. While overall the biochar, torrefied biomass, and straw addition increased soil respiration, it reduced the turnover rate of the simple C substrates, plant residues, and native SOM and had no appreciable effect on the turnover rate of the microbial biomass. The negative SOM priming was positively correlated with biochar production temperature. We therefore ascribe the increase in soil CO₂ efflux to biochar‐derived C rather than that originating from SOM. In conclusion, the SOM priming magnitude is strongly influenced by both the soil organic C quality and the biochar properties. In comparison with straw, biochar has the greatest potential to promote soil C storage. However, straw and torrefied biomass may have other cobenefits which may make them more suitable as a CO₂ abatement strategy.     

Effects of Biochar Addition on CO2 and N2O Emissions following Fertilizer Application to a Cultivated Grassland Soil

Carbon (C) sequestration potential of biochar should be considered together with emission of greenhouse gases when applied to soils. In this study, we investigated CO₂ and N₂O emissions following the application of rice husk biochars to cultivated grassland soils and related gas emissions tos oil C and nitrogen (N) dynamics. Treatments included biochar addition (CHAR, NO CHAR) and amendment (COMPOST, UREA, NO FERT). The biochar application rate was 0.3% by weight. The temporal pattern of CO₂ emissions differed according to biochar addition and amendments. CO₂ emissions from the COMPOST soils were significantly higher than those from the UREA and NO FERT soils and less CO₂ emission was observed when biochar and compost were applied together during the summer. Overall N₂O emission was significantly influenced by the interaction between biochar and amendments. In UREA soil, biochar addition increased N₂O emission by 49% compared to the control, while in the COMPOST and NO FERT soils, biochar did not have an effect on N₂O emission. Two possible mechanisms were proposed to explain the higher N₂O emissions upon biochar addition to UREA soil than other soils. Labile C in the biochar may have stimulated microbial N mineralization in the C-limited soil used in our study, resulting in an increase in N₂O emission. Biochar may also have provided the soil with the ability to retain mineral N, leading to increased N₂O emission. The overall results imply that biochar addition can increase C sequestration when applied together with compost, and might stimulate N₂O emission when applied to soil amended with urea.     

Impact of six lignocellulosic biochars on C and N dynamics of two contrasting soils

Both soil and biochar properties are known to influence greenhouse gas emissions from biochar‐amended soils, but poor understanding of underlying mechanisms challenges prediction and modeling. Here, we examine the effect of six lignocellulosic biochars produced from the pyrolysis of corn stover and wood feedstocks on CO₂ and N₂O emissions from soils collected from two bioenergy cropping systems. Effects of biochar on total accumulated CO₂‐C emissions were minimal (<0.45 mg C g^?1 soil; <10% of biochar C), consistent with mineralization and hydrolysis of small labile organic and inorganic C fractions in the studied biochars. Comparisons of soil CO₂ emissions with emissions from microbially inoculated quartz–biochar mixtures (‘quartz controls’) provide evidence of soil and biochar‐specific negative priming. Five of six biochar amendments suppressed N₂O emissions from at least one soil, and the magnitude of N₂O emissions suppression varied with respect to both biochar and soil types. Biochar amendments consistently decreased final soil NO₃^? concentrations, while contrasting effects on pH, NH₄⁺, and DOC highlighted the potential for formation of anaerobic microsites in biochar‐amended soils and consequential shifts in the soil redox environment. Thus, results implicated both reduced substrate availability and redox shifts as potential factors contributing to N₂O emission suppression. More research is needed to confirm these mechanisms, but overall our results suggest that soil biochar amendments commonly reduce N₂O emissions and have little effect on CO₂ emissions beyond the mineralization and/or hydrolysis of labile biochar C fractions. Considering the large C credit for the biochar C, we conclude that biochar amendments can reduce greenhouse gas emissions and enhance the climate change mitigation potential of bioenergy cropping systems.     

Contrasting effects of manure and green waste biochars on the properties of an acidic ferralsol and productivity of a subtropical pasture

Background and Aim

We hypothesised that amending an acidic ferralsol with biochar would improve the productivity of a subtropical dairy pasture via reducing soil acidity related constraints and result in improved nitrogen use efficiency. We examined two contrasting biochars with different carbon, nutrient content and acid neutralising values.

Methods

Field plots were amended with one of three biochar treatments (Nil, feedlot manure biochar [FM], green waste biochar [GW]) in combination with presence or absence of NPK fertiliser and presence or absence of liming. The FM and GW biochars had a carbon content of 44 and 76 %, available phosphorous of 5,960 and 93 mg kg^?1, and liming values of 13 and 5.6 %, respectively. The pasture was managed to supply year round high quality feed for dairy production.

Results

The FM biochar increased total pasture productivity by 11 % and improved the agronomic nitrogen use efficiency by 23 %. It also reduced soil acidity but did not significantly affect the pH dependent soil cation exchange capacity. The GW biochar did not improve pasture productivity. Both biochars resulted in an increase in the soil carbon density.

Conclusions

The high available phosphorous content of FM biochar makes it an effective amendment for acidic ferralsols. Greenwaste biochar did not have sufficient acid neutralising capacity or phosphorous content to reduce soil acidity constraints. Both biochars enhance soil carbon storage in pasture systems on ferralsol.     

Successive straw biochar application as a strategy to sequester carbon and improve fertility: A pot experiment with two rice/wheat rotations in paddy soil

Aims

A pot study spanning four consecutive crop seasons was conducted to compare the effects of successive rice straw biochar/rice straw amendments on C sequestration and soil fertility in rice/wheat rotated paddy soil.

Methods

We adopted 4.5 t ha^?1, 9.0 t ha^?1 biochar and 3.75 t ha^?1 straw for each crop season with an identical dose of NPK fertilizers.

Results

We found no major losses of biochar-C over the 2-year experimental period. Obvious reductions in CH₄ emission were observed from rice seasons under the biochar application, despite the fact that the biochar brought more C into the soil than the straw. N₂O emissions with biochar were similar to the controls without additives over the 2-year experimental period. Biochar application had positive effects on crop growth, along with positive effects on nutrient (N, P, K, Ca and Mg) uptake by crop plants and the availability of soil P, K, Ca and Mg. High levels of biochar application over the course of the crop rotation suppressed NH₃ volatilization in the rice season, but stimulated it in the wheat season.

Conclusions

Converting straw to biochar followed by successive application to soil is viable for soil C sequestration, CH₄ mitigation, improvements of soil and crop productivity. Biochar soil amendment influences NH₃ volatilization differently in the flooded rice and upland wheat seasons, respectively.     

Can Biochar and Phytoextractors Be Jointly Used for Cadmium Remediation?

Phytoremediation of soils contaminated with cadmium was tested after liming (CaO) or biochar addition, using red amaranth (Amaranthus tricolor L.) as test plant species. Two biochars with contrasting characteristics were prepared from two feedstocks and added to the soil at a rate of 3% (w:w): Eucalyptus pyrolysed at 600°C (EB) and poultry litter at 400°C (PLB). Liming was carried out in two treatments (CaO1) and (CaO2) to the same pH as the treatments EB and PLB respectively. Total plant mass increased in soils amended with PLB and with a mixture of PLB and EB; however this was not sufficient to increase the efficiency of phytoextraction. Bioavailable and mobile fractions of Cd diminished after liming or biochar addition. Our study infers that, both the amount of Cd immobilized and the main mechanism responsible for this immobilization varies according to biochar properties.     

Comparative efficiency of wheat straw and sugarcane bagasse biochar reduces the cadmium bioavailability to spinach and enhances the microbial activity in contaminated soil

Abstract

Biochar is considered a novel soil amendment for cadmium (Cd) stabilization in contaminated soils. A pot experiment was conducted to examine the efficiency of wheat straw and sugarcane bagasse induced biochar on Cd mobility in soil and its bioavailability to spinach in contaminated soil. Soil pH, Cd contents in plant tissues and microbial biomass were examined. Results showed that Cd was significantly decreased by 30.95% and 20.83% with wheat straw and sugarcane bagasse biochar at 2% application rate respectively, relative to the control. Similarly, Cd contents were decreased in plants shoots by 15.41 and 14.33%, while in roots by 48.3 and 35.54%, when wheat straw and sugarcane biochar were added at 2% application rate respectively. Moreover, soil microbial biomass was significantly increased with the application of all biochar types and their applications rates. Finally, wheat straw biochar at 2% application rate can be considered as an effective approach for Cd stabilization in contaminated soils.     

不同来源生物炭对砷在土壤中吸附与解吸的影响

采用OECD Guideline 106批平衡方法研究了由凋落松针、玉米秸秆、牛粪制备的3种生物炭对As(Ⅴ)在棕壤中的吸附和解吸特性的影响.结果表明：3种生物炭的添加量为0.5%时,对As(Ⅴ)在土壤中的吸附量大小顺序为牛粪炭处理＞松针炭处理＞玉米秸秆炭处理,这与生物炭的基本性质密切相关;等温吸附曲线能用Langmuir方程进行很好的拟合(R² =0.997);与对照相比,生物炭处理对砷的吸附容量(lgK_f 为1.99～2.10)和吸附强度(1/N 为0413～0.449)降低,生物炭对As(Ⅴ)的主要吸附机制为物理吸附;生物炭处理对As(Ⅴ)解吸率大小顺序为：玉米秸秆炭处理＞松针炭处理＞牛粪炭处理,解吸率在14.5%～18.7%.添加3种来源生物炭降低了棕壤对As(Ⅴ)的吸附,这可能会导致砷的有效性增强,更易被生物吸收,进而增强土壤中砷的毒性.     

Simultaneous Simulations of Uptake in Plants and Leaching to Groundwater of Cadmium and Lead for Arable Land Amended with Compost or Farmyard Manure

The water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year experimental field study, where four organic amendments were applied every second year. Predicted concentrations slightly decreased (Cd) or stagnated (Pb) in control soils, but increased in amended soils by about 10% (Cd) and 6% to 18% (Pb). Estimated plant uptake was lower in amended plots, due to an increase of K_d (dry soil to water partition coefficient). Predicted concentrations in plants were close to measured levels in plant residues (straw), but higher than measured concentrations in grains. Initially, Pb was mainly predicted to deposit from air into plants (82% in 1998); the next years, uptake from soil became dominating (30% from air in 2006), because of decreasing levels in air. For Cd, predicted uptake from air into plants was negligible (1–5%).     

Pyrolysis temperature determines the amendment effects of poplar residue-derived biochars on reducing CO2 emission

Poplars and their hybrids are widely planted in both plantation forestry and agroforestry systems of the world. Along with the utilization and plantation management processes, a large amount of biomass residues are produced, but the relationship between biochar properties and soil CO₂ emissions is largely unknown. Here, a laboratory incubation study was conducted to assess the effects of different biochars and their corresponding biomass residues on soil CO₂ emissions during the 180 days of incubation. Poplar residue-derived biochars were larger in the surface area and total pore volume but lower in nutrients and pH values than the rice straw-derived biochar. Increasing pyrolysis temperature led to a decrease in the total nitrogen (TN) content of poplar leaf- and rice straw-derived biochars, but enhanced the TN in the poplar twig- and poplar bark-derived biochars. After 180-day incubation, the total cumulative CO₂ emission decreased by 33.1%–73.8% in the biochar amendments compared to their corresponding biomass residue addition, whereas the biochars derived from poplar twig and bark residues had more positive effects on reducing soil CO₂ emissions, but depended on the pyrolysis temperature. Correlation analysis showed a significant and positive correlation between the CO₂ emissions and TN content of bio-based materials but the negative relationships to total carbon content and C/N ratio. Meanwhile the positive correlations of CO₂ emissions to the surface area, t-plot micropore area, and volume of the biochars were detected. Our results suggest that application of poplar twig- and poplar bark-derived biochars has a great potential for mitigating global warming.     

生物质炭配施有机物料对贫瘠红壤酶活性和微生物碳源代谢功能的影响

为进一步促进红壤固碳培肥,于2017和2018年通过田间试验研究了两种有机物料(玉米秸秆和羊粪)单施以及与生物质炭配施对贫瘠红壤养分含量、碳转化相关酶活性和微生物底物利用速率的影响。试验设置6个处理,即不施有机物料(对照)、玉米秸秆、羊粪、单施生物质炭、玉米秸秆与生物质炭配施、羊粪与生物质炭配施。结果表明:与对照相比,有机物料施用显著增加了土壤pH值、有机碳、全氮、有效磷和速效钾含量;与单施秸秆和羊粪相比,生物质炭与秸秆或羊粪配施显著增加了土壤有机碳、速效钾和碱解氮含量,但两者无交互效应。与对照相比,有机物料施用显著提高了β-葡萄糖苷酶(BG)、纤维二糖水解酶(CB)、β-木聚糖苷酶(XYL)和过氧化物酶(PERO)活性;与单施秸秆相比,生物质炭与秸秆配施处理酚氧化酶、过氧化物酶活性分别显著降低了28.6%、22.2%;与单施羊粪相比,生物质炭与羊粪配施处理α-葡萄糖苷酶(AG)、BG、XYL和PERO活性分别显著降低了46.1%、50.9%、41.6%和31.3%。与对照相比,有机物料施用显著提高了土壤基础呼吸和微生物对碳水化合物的利用速率,而生物质炭配施处理对碳水化合物、羧酸类底物的利用速率存在显著抑制作用。微生物碳源利用速率与BG和PERO活性呈显著正相关。因此,有机物料与生物质炭配施更有利于提高土壤养分含量,降低有机碳分解酶和微生物碳源代谢活性,从而促进红壤固碳培肥,有利于贫瘠红壤的地力提升。     

Evaluation of Organic and Inorganic Amendments on Maize Growth and Uptake of Cd and Zn from Contaminated Paddy Soils

Pot and field experiments were conducted to investigate the effects of soil amendments (cow manure, rice straw, zeolite, dicalcium phosphate) on the growth and metal uptake (Cd, Zn) of maize (Zea mays) grown in Cd/Zn contaminated soil. The addition of cow manure and rice straw significantly increased the dry biomass, shoot and root length, and grain yield of maize when compared with the control. In pot study, cow manure, rice straw, and dicalcium phosphate all proved effective in reducing Cd and Zn concentrations in shoots and roots. Cd and Zn concentrations in the grains of maize grown in field study plots with cow manure and dicalcium phosphate amendments to highly contaminated soil (Cd 36.5 mg kg^?1 and Zn 1520.8 mg kg^?1) conformed to acceptable standards for animal feed. Additionally both cow manure and dicalcium phosphate amendments resulted in the significant decrease of Cd and Zn concentrations in shoots of maize.     

Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility

The amendment of two agricultural soils with two biochars derived from the slow pyrolysis of papermill waste was assessed in a glasshouse study. Characterisation of both biochars revealed high surface area (115 m² g^?1) and zones of calcium mineral agglomeration. The biochars differed slightly in their liming values (33% and 29%), and carbon content (50% and 52%). Molar H/C ratios of 0.3 in the biochars suggested aromatic stability. At application rates of 10 t ha^?1 in a ferrosol both biochars significantly increased pH, CEC, exchangeable Ca and total C, while in a calcarosol both biochars increased C while biochar 2 also increased exchangeable K. Biochars reduced Al availability (ca. 2 cmol (+) kg^?1 to <0.1 cmol (+) kg^?1) in the ferrosol. The analysis of biomass production revealed a range of responses, due to both biochar characteristics and soil type. Both biochars significantly increased N uptake in wheat grown in fertiliser amended ferrosol. Concomitant increase in biomass production (250% times that of control) therefore suggested improved fertiliser use efficiency. Likewise, biochar amendment significantly increased biomass in soybean and radish in the ferrosol with fertiliser. The calcarosol amended with fertiliser and biochar however gave varied crop responses: Increased soybean biomass, but reduced wheat and radish biomass. No significant effects of biochar were shown in the absence of fertiliser for wheat and soybean, while radish biomass increased significantly. Earthworms showed preference for biochar-amended ferrosol over control soils with no significant difference recorded for the calcarosol. The results from this work demonstrate that the agronomic benefits of papermill biochars have to be verified for different soil types and crops.     

Biochars produced from individual grassland species differ in their effect on plant growth

Biochar, pyrolyzed biomass, has been shown to be a promising way to improve plant productivity and soil quality. Biochar characteristics and its effect on plant performance depend strongly on the type of feedstock from which it is made. However, whether biochars produced from individual grassland species differ in their characteristics and effects on plant growth when applied to soil is poorly understood. The aim of this study was to examine how soil application of pyrolyzed and non-pyrolyzed biomass originating from different grassland species influences plant performance.We measured the growth of the forb Jacobaea vulgaris in soil amended with pyrolyzed or non-pyrolyzed biomass of seven different plant species, and in control soil without amendments.The characteristics (nutrient content, C:N) and effects on plant growth of both pyrolyzed and non-pyrolyzed biomass differed significantly between species from which the biomass originated (‘feedstock species’). For most feedstock species there was no relationship between the effects that the pyrolyzed and the non-pyrolyzed biomass had on plant performance. Our results show that pyrolyzed grassland species differ in their characteristics and their effect on plant growth when amended to soil. This shows that it is important to test what the effect of pyrolysing a chosen feedstock is on a species before applying it on a larger scale and that potentially biochar with predefined effects could be designed for specific purposes.     

Comparison of the effect of market crop wastes and chemical soil fertility amendments on insect pests, natural enemies and yield of Brassica oleracea

Field studies were conducted over three growing seasons during 2 years to assess the relative effect of market crop waste (MCW)‐derived soil fertility amendments and conventional fertiliser (NPK) on tritrophic relations as well as yield performance of white cabbage. A randomised complete block design with four treatments and a control replicated four times was used. Treatments were (a) MCW compost incorporated in the soil, (b) uncomposted MCW incorporated in the soil, (c) uncomposted MCW applied as surface mulch, (d) a conventional chemical fertiliser (NPK) incorporated in the soil and (e) the untreated control. Results indicated that relative to NPK‐amended plants, MCW‐amended cabbage performed better in plant growth parameters as well as yield, despite having sustained aphid and Plutella xylostella infestations that could be as much as double as those in the NPK treatment. Natural enemy occurrence followed the trend of host insect infestations. The average yield performance and net financial benefits from MCW‐compost‐amended plants were three‐fold as that of NPK‐amended plants. Soil analysis results indicated an advantage in soil quality accruing from the MCW amendments. This study, therefore, provides documentation for the utilisation of MCW, previously handled as garbage to be disposed of, as a key component in integrated management of insect pests and depleted soils in crop production in sub‐Saharan Africa and beyond.