Co-composting of sugarbeet vinasse: influence of the organic matter nature of the bulking agents used

Two composts were obtained by co-composting of a concentrated depotassified beet vinasse and two agricultural solid residues with different organic matter nature: grape marc (GM; lignin waste) and cotton gin trash (C; cellulosic waste). Composting was carried out in aerated piles with mechanical turning, in controlled conditions during 4 months. After 71 days of composting, a new addition of vinasse similar to the initial addition was made. Changes in temperature, pH and inorganic nitrogen followed a similar path for both mixtures. However, organic matter fractions showed different behaviour depending on the material co-composted with vinasse. Lower organic matter degradation was observed when GM was used as bulking agent due to its high lignin content. No phytotoxicity was detected in the end products. The chemical and physical properties of both vinasse composts suggest their possible use as fertiliser.     

Co-composting of filter cake and bagasse; by-products from a sugar mill

Thailand has nearly 2 million tonnes of filter cake waste containing 1.8% total N from the sugar cane industry to dispose of annually. Compost studies were conducted to determine how rapidly this material can be converted to a stable product that may be useful in crop production, and to characterize the N transformations. Two kinds of sugar mill by-products were composted, filter cake and filter cake mixed with bagasse, at a 2:1 ratio to reduce the C:N ratio in an attempt to reduce N loss during composting. Materials were mixed manually at 3-5 day intervals during the composting process. Both composts were analyzed at least weekly to measure temperature, pH, NH4+, NO3-, total N content, C loss, and germination index. For both mixtures, the thermophilic stage lasted 15-20 days and was higher than ambient for nearly 80 days. The degradation of organic matter (OM) was rapid in both mixtures to approximately 40 days, after which it began to stabilize. Both mixtures achieved maturity at approximately 90 days as indicated by a stable C/N, low NH4+/NO3-, lack of heat production and a germination index higher than 80%. Mixing filter cake with bagasse helped conserve N during composting. Because N was in excess, approximately 12-15% was lost from the composts. Mixing more bagasse with the filter cake may result in further reduction in N losses. Both composts have potential for use in crop production.     

Effect of the raw materials and mixing ratio of composted wastes on the dynamic of organic matter stabilization and nitrogen availability in composts of Sub-Saharan Africa

The effect of raw materials and their proportions in initial mixtures on organic matter (OM) stabilization and nitrogen (N) availability during pit composting in Sub-Saharan Africa was assessed using biochemical fractionation and laboratory incubations to characterize composts sampled throughout the composting process. Stabilization of OM occurred more rapidly in mixtures with slaughter-house wastes, it was progressive in mixture with household refuses while tree leaves compost remained unstable. Carbon mineralization from compost samples was positively correlated to water soluble and hemicellulose-like organic fractions. Mixtures containing large proportions of household refuses reached the highest stability and total N but available N remained weak. Slaughter-house wastes in the initial mixtures made possible to reach good OM stabilization and the largest N availability. The nature of initial mixing influenced composting parameters, OM stabilization and N availability. It is suggested mixing household refuses and slaughter-house wastes with tree leaves to reach better amending and fertilizer qualities of composts.     

Long-term survival of pathogenic and sanitation indicator bacteria in experimental biowaste composts

For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded Listeria monocytogenes, Salmonella enterica subsp. enterica serotype Enteritidis, and Escherichia coli. Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetables, and green waste, were composted in laboratory reactors with forced aeration. The physicochemical and microbiological parameters were monitored for 12 weeks during composting. The survival of bacteria over a 3-month period at 25 degrees C was assessed with samples collected after different experimental composting times. Strain survival was also monitored in mature sterilized composts. Nonsterile composts did not support pathogen growth, but survival of seeded pathogens was observed. Salmonella serovar Enteritidis survived in all composts, and longer survival (3 months) was observed in mature composts (8 and 12 weeks of composting). Mature biowaste composts may support long-term survival of Salmonella serovar Enteritidis during storage at room temperature. E. coli and L. monocytogenes survival was observed only in 4-week-old composts and never in older composts. Proper composting may prevent long-term survival of E. coli and L. monocytogenes. These results suggest that like composted sewage sludge or manure, domestic waste composts may support pathogen survival. Survival was not related to the physicochemical characteristics of the composts.     

Effects of different methods of acid hydrolysis on the nitrogen distribution in two soils

Summary An inorganic (Bainsville) and an organic (Farnham) soil were hydrolyzed by continuous and stepwise hydrolysis with hot 3N HCl for 1, 2, 3, 4, 11, 15, 18 and 24 h and continuously with hot 6N HCl for 24 h. The following nitrogen forms were determined: total N, hydrolyzable-N, amino acid-N, amino sugar-N and ammonia-N. Proportions of ‘unknown’ N were computed from these data. Continuous hydrolysis with 3N HCl yielded more amino acid-N and less ‘unknown’ N than did stepwise hydrolysis with the same acid strength. But continuous hydrolysis for 24 h with 6N HCl produced more amino acid-N and less ‘unknown’ N than did hydrolysis with 3N HCl by either method. It was estimated that 33 and 54% of the total N in the inorganic and organic soil, respectively, was protein-N. The ‘unknown’ N in the inorganic and organic soil constituted 51 and 37% of the total N, respectively. From our work it appears that the ‘unknown’ N is not proteinaceous. It can be readily degraded chemically and microbiologically to NH₃ and N-gases. More attention needs to be given to identifying the ‘unknown’ N which constitutes a large portion of the total soil-N. A more adequate knowledge of the chemical constitution of the ‘unknown’ soil N may lead to the development of technologies that will make more efficient use of the N in soils.     

Evaluation of maturity and stability parameters of composts prepared from agro-industrial wastes

The objective of this study was to evaluate changes in physical, chemical and biological parameters to assess the maturity and stability of composts prepared from mixture of different farm and agro-industrial wastes over a period of 150 days. All the composts appeared granular, dark grey in color without foul odor and attained an ambient temperature at 120 days of composting indicating the stable nature of composts. Correlation analysis showed that the optimal values of the selected parameters for our experimental conditions are as follows: organic matter loss >42%, C:N ratio <15, water soluble organic carbon (C(w)):organic N (N(org)) ratio <0.55, humic acid (HA):fulvic acid (FA) ratio >1.9, humification index (HI) >30%, cation exchange capacity (CEC):total organic carbon (TOC) ratio >1.7 and germination index (GI) >70%. Compost enriched with sewage sludge, pressmud and poultry waste matured earlier compared to composts either enriched with distillery effluent or un-enriched.     

The role of hemolymph proline as a nitrogen sink during blood meal digestion by the mosquito Aedes aegypti

Mosquitoes utilize the amino acids derived from blood meal protein to produce egg proteins. But the amino acids can also be used to produce egg lipid or can be oxidized for energy production. These latter two processes result in the release of nitrogen as toxic ammonia. Therefore, amino acids must be processed in such a way that amino acid nitrogen can be incorporated into non-toxic waste products. Proline is the predominant amino acid in the hemolymph of the adult female mosquito Aedes aegypti. After feeding on albumin meal, hemolymph proline levels increased five-fold over unfed levels, reached maximal levels in the first hours after feeding and remained high through oviposition. Hemolymph proline levels increased as the concentration of protein in the meal increased. When starved of sugar for 24 h prior to feeding on an albumin meal, hemolymph proline levels increased four-fold over the proline levels of non-starved mosquitoes. Proline levels after feeding on a protein deficient in essential amino acids, pike parvalbumin, increased to twice the levels of albumin fed mosquitoes. Based on these observations, we propose that mosquitoes utilize proline as a temporary nitrogen sink to store ammonia arising from deamination of blood meal amino acid.     

氨基酸肥效作用的研究

本研究证明氨基酸分子可以直接被作物吸收,并有促进作物增产的肥效作用,如与等氮量的无机氮肥相比(如NH_4Cl),混合氨基酸的肥效更高,我们用胱氨酸废液中的游离氨基酸为主要成分制成氨基酸肥料,盆栽和田间试验证明,该肥料具有明显增产作用,这就为毛发水解行业治理环境污染与开辟新的肥料来源结合起来,一举两得。     

Long-Term Survival of Pathogenic and Sanitation Indicator Bacteria in Experimental Biowaste Composts

For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded Listeria monocytogenes, Salmonella enterica subsp. enterica serotype Enteritidis, and Escherichia coli. Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetables, and green waste, were composted in laboratory reactors with forced aeration. The physicochemical and microbiological parameters were monitored for 12 weeks during composting. The survival of bacteria over a 3-month period at 25°C was assessed with samples collected after different experimental composting times. Strain survival was also monitored in mature sterilized composts. Nonsterile composts did not support pathogen growth, but survival of seeded pathogens was observed. Salmonella serovar Enteritidis survived in all composts, and longer survival (3 months) was observed in mature composts (8 and 12 weeks of composting). Mature biowaste composts may support long-term survival of Salmonella serovar Enteritidis during storage at room temperature. E. coli and L. monocytogenes survival was observed only in 4-week-old composts and never in older composts. Proper composting may prevent long-term survival of E. coli and L. monocytogenes. These results suggest that like composted sewage sludge or manure, domestic waste composts may support pathogen survival. Survival was not related to the physicochemical characteristics of the composts.     

Composting of straw in small units

Summary Straw could be composted satisfactorily in 4 to 5 months in small concrete cells holding 30 lb. material (dry basis), providing the straw was thoroughly moistened and sufficient easily available nitrogeneous material added to give an initial carbon/nitrogen ratio of 40. During the composting process about half the dry matter was lost. Results were similar to those obtained using large cells holding 1500 lb. straw. Wire units holding 100 lb. straw were unsatisfactory. Changes in dry matter, carbon/nitrogen ratio, temperature, soluble inorganic nitrogen, and pH of composts prepared with various accelerators are reported.     

Biodegradation of olive husk mixed with other agricultural wastes

In this study, the evolution of the most important parameters (temperature, pH, electrical conductivity, total organic carbon, total nitrogen, and C/N ratio) describing the composting process of olive oil husk with other organic wastes was investigated. Four windrows for obtaining two mixed wastes composts (MWCs) and two green wastes composts (GWCs) were prepared.     

氨基酸肥效研究

本文以植物肥效试验为依据,研究了不同氨基酸在单一和混合状态下的肥效作用,证明混合氨基酸的肥效大于单个氨基酸的作用,也大于等氮量的无机氮肥。还发现某些氨基酸对植物具有独特的生理作用,在植物营养上具有重要的理论和应用价值。     

Aerobic composting of chips from clear-cut trees with various co-materials

Swollen chips made from trees felled during clear-cutting were composted with various organic and inorganic materials in an aerobic composting reactor for 5 months and then piled for 5 months. The organic materials included chicken feces, urea, nitrogenous lime (calcium cyanamide, manure), and material rapidly composted from food garbage in 24-h bacterial fermentation, while the inorganic materials were coal ash and volcanic ash. In this paper, we first attempt to estimate the quality and degree of maturity of each compost from its chemical properties. Furthermore, we try to calculate the maturity of the fermented wood chip composts from their mixture ratio of the initial materials by multiple linear regression analysis. We measured changes in the C/N ratio, nitrate nitrogen (NO3-N) content, percentage of humic acid in the alkali soluble fraction (PQ), cation exchange capacity, pH, and EC during the composting period. The degrees of maturity of the composts were estimated via a plant growth test using Chinese cabbage. We found that the CN ratio, NO3-N concentration, and PQ were suitable for estimating the degree of maturity of wood chip composts. For maturity, the CN ratio should be less than 14, the PQ more than 66.2, and the NO3-N concentration more than 853 mgkg-1. We devised an equation to estimate the degree of maturity after 10 months by a multiple linear regression analysis from the mixing ratio of wood chips and the co-composted materials. From the multiple linear regression analysis, the above three indices of compost maturity could be estimated from the mixing ratio of the initial materials. This equation should enable us to determine the degree of compost maturity after 10 months based on the initial mixing ratio.     

Enhancing the co-composting of olive mill wastes and sewage sludge by the addition of an industrial waste

In this work, the effect of incorporating an acidic ferrous sulphate waste (SF) over co-composting process of sewage sludge and olive mill solid wastes in a 1:2 v/v wet basis was investigated. The SF used was an industrial by-product of titanium oxide synthesis and its addition resulted in a chemical stabilisation of the wastes at low pH. The optimum dose of SF to enhance the composting of the studied biowastes was a 20% v/v (wet basis) and the best moment for the addition turned out to be whenever the composting piles had achieved the thermophilic range. The addition of SF over the composting process made possible a faster stabilisation, increasing the composting rate from 0.033 to 0.13 d(-1), and leading to a Fe and S rich compost. All composts obtained fulfilled the limits determined by current European and Spanish regulations and presented better characteristics for its use as soil amendment and organic fertilizer than the traditional composts without SF. The optimum dose of compost containing SF was determined through agronomic tests being its value about 18 Ton ha(-1).     

长期不同施肥模式对双季稻田土壤酸解有机氮组分的影响

为明确南方双季稻区长期不同施肥模式对稻田不同耕层(0～10和10～20 cm)土壤酸解有机氮组分及其含量的影响,本研究以长期(36年)定位施肥试验田为平台,系统分析了单独施用化肥(CF)、秸秆还田+化肥(RF)、30%有机肥+70%化肥(OM)和不施肥对照(CK)下双季稻田0～10和10～20 cm土壤酸解有机氮及其组分氨基酸氮、氨基糖氮、铵态氮和酸解未知氮含量的变化特征及其与土壤全氮、有机碳含量的关系。结果表明: 与CK相比,OM和RF处理均显著增加了双季稻田0～10和10～20 cm土壤全氮、碱解氮和有机碳含量。OM、RF和CF处理双季稻田0～10和10～20 cm土壤酸解有机氮含量均显著高于CK,分别比CK增加10.7%～42.6%和12.2%～51.5%。与CF和CK相比,OM和RF处理显著提高了双季稻田0～10和10～20 cm土壤氨基酸氮、铵态氮、酸解未知氮和氨基糖氮含量。不同施肥处理稻田0～10和10～20 cm土壤酸解有机氮和非酸解性氮含量大小顺序均表现为OM>RF>CF>CK。各施肥处理稻田0～10 cm土壤氨基酸氮、铵态氮、氨基糖氮和非酸解性氮含量均高于10～20 cm土壤。土壤酸解有机氮含量与土壤全氮、有机碳含量均存在极显著的正相关关系。综上,RF和OM处理有利于增加双季稻田0～10和10～20 cm土壤有机氮含量,增强稻田土壤供氮能力,提高土壤肥力。     

Export of amino acids to the phloem in relation to N supply in wheat

The effect of different N supply on amino acid export to the phloem was studied in young plants of wheat (Triticum aestivum L. cv. Klein Chamaco), using the exudation in EDTA technique. Plants were grown in a growth cabinet in pots with sand, and supplied with nutrient solutions of different NO₃^? concentrations. When plants were grown for 15 days with nutrient solutions containing 1.0, 3.0, 5.0, 10.0, 15.0 or 20.0 mM KNO₃, the exudation rate of sugars from the phloem was unaffected by N supply, but sugars accumulated in the leaf tissue when the N supply was limiting for growth. On the other hand, the rate of exudation of amino acids was proportional to the NO₃^? concentration in the nutrient solution. When the supply of N to plants grown for 15 days with 15.0 mM NO₃^? was interrupted, the exudation of sugars was again unaffected, but there was a fast decrease in the amount of amino acids exudated, and of the concentration of amino acids and nitrogen in the tissues. Also, when 10-day-old plants grown without N were supplied with 15.0 mM NO₃^?, there was a sharp increase in the exudation of amino acids, without changes in the amount of sugar exudated. The rate of exudation of amino acids to the phloem was independent of the concentration of free amino acids in the leaves in all three types of experiment. Asp was the most abundant amino acid in the leaf tissue, while Glu was the one most abundant in the phloem exudate. Asp and Ala were exported to the phloem at a rate lower than expected from their leaf tissue concentrations, indicating some discrimination. On the contrary, Glu showed a preferential export at low N supply. It is concluded that the rate of amino acid export from the leaf to the phloem is dependent on the N available to the plant. This N is used for synthesis of leaf protein when the supply is low, exported to the phloem when supply is adequate, and accumulated in the storage pool when supply is above plant demand.     

Evaluation of three composting systems for the management of spent coffee grounds

This study was conducted to evaluate the optimum composting approach for the management of spent coffee grounds from the restaurant and ready-to-serve coffee industry. Three composting systems were assessed, including in-vessel composting, vermicomposting bins, and aerated static pile bin composting, over study periods ranging from 47 to 98 days. Total carbon content was reduced by 5-7% in the spent coffee ground treatments across the three composting systems. Nitrogen and other mineral nutrient contents were conserved or enhanced from the initial to the final composts in all the composting systems assessed. Earthworm growth and survival (15-80%) was reduced in all the treatments but mortality rates were lower in coffee treatments with cardboard additions. A decline in earthworm mortality with cardboard additions was the result of reduced exposure to organic compounds and chemicals released through the decomposition of spent coffee grounds.     

Adjustment of growth and central metabolism to a mild but sustained nitrogen-limitation in Arabidopsis

We have established a simple soil-based experimental system that allows a small and sustained restriction of growth of Arabidopsis by low nitrogen (N). Plants were grown in a large volume of a peat–vermiculite mix that contained very low levels of inorganic N. As a control, inorganic N was added in solid form to the peat–vermiculite mix, or plants were grown in conventional nutrient-rich solids. The low N growth regime led to a sustained 20% decrease of the relative growth rate over a period of 2 weeks, resulting in a two- to threefold decrease in biomass in 35- to 40-day-old plants. Plants in the low N regime contained lower levels of nitrate, lower nitrate reductase activity, lower levels of malate, fumarate and other organic acids and slightly higher levels of starch, as expected from published studies of N-limited plants. However, their rosette protein content was unaltered, and total and many individual amino acid levels increased compared with N-replete plants. This metabolic phenotype reveals that Arabidopsis responds adaptively to low N by decreasing the rate of growth, while maintaining the overall protein content, and maintaining or even increasing the levels of many amino acids.     

Nitrogen compounds in the apoplastic sap of sugarcane stem: some implications in the association with endophytes

Several nitrogen compounds were identified and quantified in the apoplastic and symplastic sap of sugarcane stems. The sap of stems was composed mainly of soluble sugars, which constituted 95% of the total organic compounds detected. Sap also contained nitrogen compounds, with amino acids (50-70% of N) and proteins (20-30% of N), being the main nitrogenous substances, as well as inorganic forms as ammonium, nitrite and nitrate, in low concentrations (<20% of N). Serine, proline, alanine and aspartic acid together represented around 60% of the amino acids of the sap of both field grown and high nitrogen fertilized plants, and non-nitrogen fertilized plants inoculated with Gluconacetobacter diazotrophicus. The total amino acid content of apoplastic sap was six to nine times lower in non-nitrogen fertilized plants than in fertilized ones. The possible roles of these substances to regulate endophytic associations with sugarcane are also discussed.     

城市污泥与稻草堆肥中邻苯二甲酸酯（PAEs）的研究

将广州城市污泥与稻草进行翻堆、接菌-翻堆、连续通气和间歇通气4种方式的堆肥,应用GC／MS技术对堆肥中6种属于USEPA优控污染物的邻苯二甲酸醇化合物(PAEs)进行分析,探讨堆肥产物中PAEs的含量分布以及不同方式堆肥对PAEs的降解效果,结果表明,4种方式堆肥中PAEs总含量(∑PAEs)在9．815～17．832mg·kg^-1之间,依次为翻堆(17．832mg·kg^-1)>接菌-翻堆(13．927mg·kg^-1)>间隙通气(10．765mg·kg^-1)>连续通气(9．815mg·kg^-1),堆肥中PAEs以邻苯二甲酸正二辛酯(DhOP)为主,占∑PAEs的82．2％～89．696,不同方式堆肥中∑PAEs的降解率为连续通气(45．71％)>间隙通气(40．4696)>接菌-翻堆(22．97％)>翻堆(1．3796)(平均降解率为27．63％),其中邻苯二甲酸二乙醇(DEP)、邻苯二甲酸正二丁酯(DnBP)和邻苯二甲酸丁基苄基酯(BBP)的降解率分别为95．7696～98．6896、79．5696～99．46％和87．42％～98．42％;但邻苯二甲酸二甲酯(DMP)和邻苯二甲酸正二辛酯的含量反而增加,邻苯二甲酸(2-乙基己基)酯(DEHP)在所有堆肥中均未检出。