Nuclear and conventional methods for soil determination in sugar cane industry

Scandium and ash methods' performances were compared in terms of soil content assessment in sugar cane loads, emphasizing the common sampling drawbacks. Both methods are adequate for such determination in controlled conditions. The scandium has demonstrated better analytical characteristics, since it is free from interferences of cane matrix, which decreases the accuracy of the ash method in normal mill conditions.     

Predicting Greenhouse Gas Emissions and Soil Carbon from Changing Pasture to an Energy Crop

Bioenergy related land use change would likely alter biogeochemical cycles and global greenhouse gas budgets. Energy cane (Saccharum officinarum L.) is a sugarcane variety and an emerging biofuel feedstock for cellulosic bio-ethanol production. It has potential for high yields and can be grown on marginal land, which minimizes competition with grain and vegetable production. The DayCent biogeochemical model was parameterized to infer potential yields of energy cane and how changing land from grazed pasture to energy cane would affect greenhouse gas (CO₂, CH₄ and N₂O) fluxes and soil C pools. The model was used to simulate energy cane production on two soil types in central Florida, nutrient poor Spodosols and organic Histosols. Energy cane was productive on both soil types (yielding 46–76 Mg dry mass⋅ha⁻¹). Yields were maintained through three annual cropping cycles on Histosols but declined with each harvest on Spodosols. Overall, converting pasture to energy cane created a sink for GHGs on Spodosols and reduced the size of the GHG source on Histosols. This change was driven on both soil types by eliminating CH₄ emissions from cattle and by the large increase in C uptake by greater biomass production in energy cane relative to pasture. However, the change from pasture to energy cane caused Histosols to lose 4493 g CO₂ eq⋅m⁻² over 15 years of energy cane production. Cultivation of energy cane on former pasture on Spodosol soils in the southeast US has the potential for high biomass yield and the mitigation of GHG emissions.     

Biological Nitrogen Fixation in Sugar Cane: A Key to Energetically Viable Biofuel Production

The advantages of producing biofuels to replace fossil energy sources are derived from the fact that the energy accumulated in the biomass is captured directly from photosynthesis and is thus renewable, and that the cycle of carbon dioxide fixation by the crop, followed by burning of the fuel makes no overall contribution to atmospheric CO₂ or, consequently, to global warming. However, these advantages are negated if large quantities of fossil fuels need to be used to grow or process the biofuel crop. In this regard, the Brazilian bioethanol program, based on the fermentation/distillation of sugar cane juice, is particularly favorable, not only because the crop is principally hand harvested, but also because of the low nitrogen fertilizer use on sugar cane in Brazil. Recent ¹⁵N and N balance studies have shown that in some Brazilian cane varieties, high yields are possible without N fertilization because the plants are able to obtain large contributions of nitrogen from plant-associated biological N₂ fixation (BNF). The N₂-fixing acid-tolerant bacterium Acetobacter diazotrophicus was first found to occur within roots, stems, and leaves of sugar cane. Subsequently, two species of Herbaspirillum also have been found to occur within the interior of all sugar cane tissues. The discovery of these, and other N₂-fixing bacteria that survive poorly in soil but thrive within plant tissue (endophytic bacteria), may account for the high BNF contributions observed in sugar cane. Further study of this system should allow the gradual elimination of N fertilizer use on sugar cane, at least in Brazil, and opens up the possibility of the extension of this efficient N₂-fixing system to cereal and other crops with consequent immense potential benefits to tropical agriculture.     

Impact of pre-harvest burning versus trash conservation on soil carbon and nitrogen stocks on a sugarcane plantation in the Brazilian Atlantic forest region

Owing to the increased demand for ethanol biofuel from sugar cane, the area planted to this crop in Brazil has increased from 4.8 to 9.5 Mha since 2000. At the same time there has been pressure from environmental groups and others to cease the pre-harvest burning of cane, and today over 40% of the crop is harvested without burning, thus conserving the trash on the soil surface. While most trash decomposes during the year, it is generally assumed that this transition from burning to trash conservation will have benefits for cane productivity and increase soil carbon stocks. To investigate the possible benefits of this change of practice an experiment was carried out in the state of Espírito Santo, south-eastern Brazil, to investigate the long-term effects of the practice of pre-harvested burning compared to trash conservation on soil fertility and soil C and N stocks. The results showed that over a 14-year period, trash conservation marginally decreased soil acidity and significantly increased soil C and N stocks in 0–10 cm depth interval. Although the trash conservation treatment accumulated 13 Mg C ha^?1 more than the burned treatment, this difference was not statistically different. However, the stocks of N to 100 cm depth were 900 kg ha^?1 higher under the trash conservation treatment and this difference was statistically significant. The ¹³C abundance data suggested that where trash was conserved, more soil C was derived from the sugar cane than from the original native vegetation.     

Life-history ofNeurospora intermedia in a sugar cane field

The life-history ofNeurospora in nature has remained largely unknown. The present study attempts to remedy this. The following conclusions are based on observation ofNeurospora on fire-scorched sugar cane in agricultural fields, and reconstruction experiments using a colour mutant to inoculate sugar cane burned in the laboratory. The fungus persists in soil as heat- resistant dormant ascospores. These are activated by a chemical(s) released into soil from the burnt substrate. The chief diffusible activator of ascospores is furfural and the germinating ascospores infect the scorched substrate. An invasive mycelium grows progressively upwards inside the juicy sugar cane and produces copious macroconidia externally through fire- induced openings formed in the plant tissue, or by the mechanical rupturing of the plant epidermal tissue by the mass of mycelium. The loose conidia are dispersed by wind and/or foraged by microfauna. It is suggested that the constant production of macroconidia, and their ready dispersal, serve a physiological role: to drain the substrate of minerals and soluble sugars, thereby creating nutritional conditions which stimulate sexual reproduction by the fungus. Sexual reproduction in the sugar- depleted cellulosic substrate occurs after macroconidiation has ceased totally and is favoured by the humid conditions prevailing during the monsoon rains. Profuse micro-conidiophores and protoperithecia are produced simultaneously in the pockets below the loosened epidermal tissue. Presumably protoperithecia are fertilized by microconidia which are possibly transmitted by nematodes active in the dead plant tissue. Mature perithecia release ascospores in situ which are passively liberated in the soil by the disintegration of the plant material and are, apparently, distributed by rain or irrigation water.     

Long-term Effects of Pre-harvest Burning and Nitrogen and Vinasse Applications on Yield of Sugar Cane and Soil Carbon and Nitrogen Stocks on a Plantation in Pernambuco, N.E. Brazil

Since the 1970s the area under sugarcane in Brazil has increased from 2 million to over 5 million ha (M ha), and it is expected to pass the 7 M ha mark in 2007. More than half of the cane is harvested to produce bioethanol as a fuel for light vehicles. The distilleries produce approximately 13 L of distillery waste (vinasse) for each litre of ethanol produced. In the 1980s there was considerable concern over the long-term effects of the disposal of this material (containing about 1% carbon and high in K) on cane yields if it was applied to the field. At the same time there was a growing movement to abandon the practice of pre-harvest burning and some research was showing that some Brazilian varieties of sugar cane were able to obtain significant contributions of N from plant-associated biological nitrogen fixation (BNF). For these reasons an experiment was installed on a cane plantation in the state of Pernambuco, NE Brazil to investigate the long-term effects of vinasse and N fertiliser additions and the practice of pre-harvest burning on crop and sugar yield, soil fertility parameters, N balance and soil C stocks. The results showed that over a 16-year period, trash conservation (abandonment of burning) increased cane yields by 25% from a mean of 46 to 58 Mg ha⁻¹. Vinasse applications (80 m³ ha⁻¹ crop⁻¹) increased mean cane and sugar yield by 12 to 13% and the application of 80 kg N ha⁻¹ as urea increased cane yields by 9%, but total sugar yield by less than 6% (from 7.0 to 7.4 Mg ha⁻¹ crop⁻¹). The total N balance for the soil/plant system when only the surface 20 cm of the soil was considered was positive in plots where no N fertiliser was added. However, the data indicated that during the 16 years of the study considerable quantities of soil organic matter were accumulated below 20 cm depth such that the N balance considering the soil to 60 cm depth was strongly positive, except where N fertiliser was added. The data indicated that there were considerable BNF inputs to the system, which was consistent with its low response to N fertiliser and low N fertiliser-use-efficiency. There were no significant effects of vinasse or urea addition, or trash conservation on soil C stocks, although the higher yields proportioned by trash conservation had potentially significant benefits for increased mitigation of CO₂ emissions where the main use of the cane was for bioethanol production.     

Calcium and Magnesium Levels in Agricultural Soil and Sewage Sludge in an Industrial Area from Southeastern Spain: Relationship with Plant (Saccharum officinarum) Disposition

This investigation was initiated to assess the following objectives: (1) to measure the total calcium and magnesium content in agricultural soil and sewage sludge from the Mediterranean coastal area of Motril (southeastern Spain); (2) to determine the pH values of indicated samples in order to evaluate first their influence on calcium and magnesium content, and second on levels of these minerals in the main crop (sugar cane: Saccharum officinarum) grown in the area; (3) to study the influence of industrial activities, first on calcium and magnesium cantents and pH values in agricultural soil, and second on calcium and magnesium concentrations present in sugar cane samples; (4) to check if the calcium and magnesium levels existing in agricultural soil exert any influence on corresponding element uptake by sugar cane plants. Calcium levels found in agricultural soil were significantly higher (p < 0.05) than those found in sewage sludge. Significant linear relationships between calcium and magnesium concentrations in agricultural soil and sewage sludge (p < 0.005) were found. Calcium concentrations found in soil from the industrialized area (39.2 ± 7.2 mg g^?1) were significantly higher than those corresponding to the non-industrialized area (31.0 ± 6.6 mg g^?1). The pH values determined in agricultural soil were significantly influenced by industrial activity (p < 0.05). The industrial activity and pH values measured in agricultural soil did not statistically influence either calcium or magnesium levels in the sugar cane plants. Calcium and magnesium concentrations existing in agricultural soil did not significantly influence the element uptake by sugar cane plants.     

Response of soil microbial biomass and activity in early restored lands in the northeastern Brazilian Atlantic Forest

Intensive land use of the Brazilian Atlantic Forest accelerated with the rise of sugar cane plantations in the northeastern part of Brazil. Consequently, many ecosystems were destroyed, including riparian forests. The number of studies of riparian restoration has increased but comparative studies on the belowground effects of common reforestation strategies are rare. Here, we compared soil microbial properties among four different land use types: native rainforest, sugar cane plantation, single species reforestation, and mixed species reforestation, each replicated at two spatially independent sites. Soil samples were taken in 2013 and 2014, that is 2 and 3 years after reforestation, respectively. In both years, land use types had a significant effect on basal respiration, microbial biomass, and specific respiration (whereas specific respiration was marginally affected in 2014). In 2013, basal respiration in sugar cane plantations was significantly lower (?65%) when compared to native forests. In 2014, basal respiration (+60%) and soil microbial biomass (+90%) were significantly higher in mixed species reforestation compared to sugar cane, whereas single species reforestation had comparable values as in sugar cane plantations. Our results indicate that soil microbial biomass and activity respond rapidly to land use change when mixed species reforestation is used. Thus, using mixed species reforestation may enhance the provisioning of ecosystem services already in the short term.     

Nitrogen-fixing bacteria of the genusBeijerinckia Derx in the rhizosphere of sugar cane

Summary and Conclusions The rhizosphere effect of sugar cane on nitrogen fixing bacteria of the genusBeijerinckia Derx was studied under field conditions, during two growing periods of the cane. Counts ofBeijerinckia in soil samples from the rhizosphere and from the rhizoplan (soil from root surface) showed an increase in this nitrogen fixer of up to 20 times in the rhizosphere and up to 50 times in the rhizoplan. Bacteria, actinomyces, and fungi developing on egg-albumin agar decreased in the rhizosphere of sugar cane.This work was in part, supported by the Conselho Nacional de pesquisas.     

Influence of washing on elemental analysis of leaves of fieldgrown crop plants

Summary Information is limited on soil contamination of leaves from field-grown row crops, especially with respect to aluminum (Al) analyses. The objective of this study was to determine the influence of washing leaf samples with either deionized water or detergent solution on elemental analyses for several agronomic crop plants. The crop plants sampled were corn (Zea mays L.), soybean (Glycine max L. Merr.), grain sorghum (Sorghum bicolor L. Moench), and wheat (Triticum aestivum L.). The crops were grown on a range of soil types, soil pH values, and tillage practices. Samples of upper leaves and lower leaves were collected separately. The samples were either not washed, washed with deionized water, or washed with detergent solution. After drying, grinding, and digesting, the samples were analyzed for Al, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). For all crop plants and conditions studied, there was no effect on measured N, P, K, Ca, Mg, Mn, Zn, or Cu concentrations, but measured Al and Fe concentrations were influenced by washing. In general, washing had a greater effect on Al analyses than on Fe analyses. Soybean samples were most affected by washing, while wheat samples seemed to be least affected. The results reflected greater contamination of lower leaves than upper leaves. Decontamination procedures appear necessary prior to Al and Fe analyses of field-grown crop plants.     

Nitrogenase activity in the rhizosphere of sugar cane and some other tropical grasses

Summary Roots of sugar cane had considerable nitrogenase activity and produced up to 5 n moles ethylene/h/g root by the reduction of acetylene. The rhizosphere soil and soil mid-way between the cane rows also reduced acetylene.Beijerinckia indica was abundant on roots and in the soil. Nitrogenase activity was also associated with roots ofPanicum maximum,Pennisetum purpureum andCymbopogon citratus.     

A method for isolating fungi from soil microhabitats

Summary A technique is described for the separation and washing of soil micro-habitats (the separation being on a size basis). Tests of the efficiency of the washing technique show that, for the soil under experiment, 25 to 30 washings are required to remove most of the fungal spores; the number of washings required will vary from soil to soil. Data is given on the use of this method for fungal isolations from a cultivated soil.     

云南主要蔗龟的生物学研究

蔗龟是云南甘蔗上的1种主要地下害虫。经1987～1991年系统研究,大等鳃金龟、暗褐鳃角金龟、突背蔗金龟是云南危害甘蔗的优势种。前两种主要以幼虫为害根部,造成减产,严重的无收;第三种主要以成虫咬食蔗苗基部,造成枯心死亡。3种均1年发生1代。成虫有趋光性,初孵幼虫喜食已腐烂的有机质。在沙壤土、粘土较重土壤虫口较多;宿根年限越长受害愈重。蔗稻轮作;7～8月雨季用水淹灌蔗地;结合松、培土每亩施用3％甲基异柳磷颗粒剂4～5kg,防治效果达90％左右。     

有机肥对粉垄蔗地土壤养分及甘蔗产量品质的影响

为了研究施用有机肥对粉垄条件下甘蔗产量和品质的影响,该研究以蚯蚓粪、猪粪分别与复合肥配施于粉垄蔗地中,并以单施复合肥作为对照,研究有机肥与复合肥配施对粉垄土壤理化性状及甘蔗养分、产量、蔗茎品质的影响。结果表明:(1)与对照相比,有机肥与复合肥混施可在不同时期分别提高粉垄土壤有机质、全氮、全磷、碱解氮、速效磷、速效钾含量,且对于土壤中速效养分含量的提升主要集中于甘蔗生长前期(6—8月),但在土壤pH值和容重方面影响不显著。(2)蚯蚓粪、猪粪与复合肥混施均能不同程度提高甘蔗生长前期的+1叶和根系中的全氮、全磷、全钾含量,使产量分别比对照提高了28.09%、32.81%。砍收时甘蔗的茎长、茎径、单茎重、有效茎数、蔗汁糖分、甘蔗糖分高于对照但不显著,出苗率、分蘖率、锤度影响不显著。粉垄耕作条件下,选择合适的有机肥与复合肥配施可增加土壤速效养分和有机质、全氮、全磷含量,也能提高甘蔗根叶全氮、全磷、全钾含量,提高甘蔗产量。     

Desorption of Nitroaromatic Compounds From Explosive-contaminated Soil by Washing

The soil contaminated by explosive production wastewater was treated by washing using water as solvent. The effect of contact time and temperature, water/soil ratio and washing steps on desorption efficiency was investigated. Six kinetic models—parabolic diffusion model, zero-order equation, pseudo-first-order equation, pseudo-second-order equation, power function equation and Elovich equation—were used to study the desorption kinetics of nitroaromatic compounds from contaminated soil to water. The eluent of contaminated soil before and after washing was characterized by UV–vis analysis. The results showed that the removal rate was fast at the initial stage and then slowed down after 60 min. The desorption of contaminants from soil to water is endothermic. Washing with small quantities of water in high frequency is preferred when water volume is limited. The pseudo-second-order model can be used to describe the desorption process. Soil washing can remove most of the contaminants from the contaminated soil.     

污染土壤淋洗修复技术研究进展

土壤淋洗修复技术是一种行之有效的污染土壤治理技术,适合于快速修复受高浓度重金属和有机物污染土壤与沉积物。本文综述了土壤淋洗修复技术的特点、技术流程、土壤淋洗剂的研究与应用进展,指出异位土壤淋洗修复技术因修复效果稳定,易于实现系统控制和废弃物减量化等优点而具有更广阔的应用前景,天然螯合剂和生物表面活性剂等环境友好型淋洗剂正逐渐取代人工螯合剂和化学表面活性剂成为土壤淋洗剂研究的主流方向,而现代超分子化学的引入和发展有可能对复合污染土壤的高效淋洗修复研究产生新的影响。     

Effects of a mulch layer on the assemblage and abundance of mesostigmatan mites and other arthropods in the soil of a sugarcane agro-ecosystem in Australia

Sugarcane farmers can utilise a soil conservation technique called green cane trash blanketing, a form of mulching that can increase plant productivity through a number of channels, e.g., via altering soil physical, chemical and biological characteristics, and influence soil arthropod assemblages. Predatory mites (Mesostigmata) are important components of soil communities because they can control populations of other soil-dwelling pest species. Our aim was to characterise mulch-influenced predatory Mesostigmata community assemblages in sugarcane soils in Queensland, Australia. We found that application of a mulch layer significantly increased the abundance of Mesostigmata, and oribatid mites and collembolans, in soils. Furthermore, we observed that the assemblages of Mesostigmata in soil covered by mulch were significantly different to those in bare soil; and the assemblages of Mesostigmata changed over time. The assemblages of Mesostigmata, but not Oribatida or collembolans, were significantly different in soil under mulch depending on whether the mulch was freshly laid, or decomposing. Our results show that the use of mulch, specifically the green cane trash blanket, can increase overall microarthropod abundance including Mesostigmata. This is likely due to increased habitat complexity and changing resource availability.     

Two new species ofNeosartorya from Brazilian soil

Among the isolates from soil of corn and sugar cane plantations in São Paulo State, Brazil, two new species ofNeosartorya, N. botucatensis andN. paulistensis, are described and illustrated.Neosartorya botucatensis differs from the other known species of the genus in having ascospores with long spines on the convex walls.Neosartorya paulistensis is characterized by its ascospore walls with spinose and verruculose ornamentation. The former is compared with the closely related speciesN. spinosa, and the latter is closely related toN. glabra, N. pseudofischeri and N. stramenia.     

Remediation of PCBs in soil by surfactant washing and biodegradation in the wash by Pseudomonas sp. LB400

Solutions from the washing of polychlorinated biphenyl (PCB)-contaminated soil with a variety of commercial nonionic or anionic surfactants were incubated with Pseudomonas sp. LB400 in an attempt to remediate the soil and destroy the PCBs. Nonionic surfactants washed more PCBs from the soil (up to 89%) but inhibited their biodegradation. Anionic surfactants washed less PCBs from the soil but were more effective in biodegradation tests, removing up to 67% of total PCBs.     

Effects of freezing on rhizosphere and root nutrient content using two soil sampling methods

This study investigated how deep freezing affects the mineral nutrient content of roots and rhizosphere soil. Two different methods of separating the rhizosphere from the roots were used: i) a brushing method, where the rhizosphere soil was brushed off and ii) a washing method, where the rhizosphere was extracted together with the roots.When unfrozen material was used, the concentrations of K and Fe were significantly higher in the washing method as compared with the brushing method. When the material had been deep frozen, significantly higher concentrations of K, Fe, Mg, and Al were found in the extract from the washing method, indicating a considerable leakage from the roots. No significant differences were found between frozen and unfrozen material with the brushing method. In bulk soil, freezing resulted in increased concentrations of Mn, Al and Fe, even when no roots were present. The brushing method can be used for both frozen and fresh material, although fresh material is preferable. Extraction of soil plus roots cannot be recommended for deep frozen soil.