Emission factors for open and domestic biomass burning for use in atmospheric models

Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing. All EFs are converted to one standard form (g compound emitted per kg dry biomass burned) using the carbon mass balance method and they are categorized into 14 fuel or vegetation types. Biomass burning terminology is defined to promote consistency. We compile a large number of measurements of biomass consumption per unit area for important fire types and summarize several recent estimates of global biomass consumption by the major types of biomass burning. Post emission processes are discussed to provide a context for the emission factor concept within overall atmospheric chemistry and also highlight the potential for rapid changes relative to the scale of some models or remote sensing products. Recent work shows that individual biomass fires emit significantly more gas-phase NMOC than previously thought and that including additional NMOC can improve photochemical model performance. A detailed global estimate suggests that BB emits at least 400 Tg yr^(−1) of gas-phase NMOC, which is almost 3 times larger than most previous estimates. Selected recent results (e.g. measurements of HONO and the BB tracers HCN and CH_3CN) are highlighted and key areas requiring future research are briefly discussed

Threats to soil quality in Denmark - A review of existing knowledge in the context of the EU Soil Thematic Strategy

The EU Commission is preparing a proposal for a Soil Framework Directive with the purpose of protecting the soil resources in Europe. The proposal identifies six major threats to the sustained quality of soils in Europe. This report addresses the threats that are considered most important under the prevailing soil and climatic conditions in Denmark: compaction, soil organic matter decline, and erosion by water and tillage. For each of these threats, the relevance and damage to soil functions as well as the geographic distribution in Denmark are outlined. We suggest a procedure for identifying areas at risk. This exercise involves an explicit identification of: i) the disturbing agent (climate / management) exerting the pressures on soil, and ii) the vulnerability of the soil to those stresses. Risk reduction targets, measures required to reach these targets, and the knowledge gaps and research needs to effectively cope with each threat are discussed. Our evaluation of the threats is based on soil resilience to the imposed stresses. Subsoil compaction is considered a severe threat to Danish soils due to frequent traffic with heavy machinery in modern agriculture and forestry. The soil content of organic matter is critically low for a range of Danish soils, which should be counteracted by appropriate management options. Soil erosion by tillage, and to a lesser degree by water, adversely affects soil quality on much of the farmland because degradation rates are much higher than generation of soil

Mitigating Greenhouse Gases in Agriculture

Climate change has severe adverse effects on the livelihood of millions of the world’s poorest people. Increasing temperatures, water scarcity and droughts, flooding and storms affect food security. Thus, mitigation actions are needed to pave the way for a sustainable future for all. Currently, agriculture directly contributes about 10-15 percent to global greenhouse gas (GHG) emissions. Adding emissions from deforestation and land use change for animal feed production, this rises to about 30 percent. Scenarios predict a significant rise in agricultural emissions without effective mitigation actions. Given all the efforts undertaken in other sectors, agriculture would then become the single largest emitter within some decades, and without mitigation in agriculture, ambitious goals, such as keeping global warming below two degrees may become impossible to reach. The main agricultural emission sources are nitrous oxide from soils and methane from enteric fermentation in ruminants. In addition, conversion of native vegetation and grasslands to arable agriculture releases large amounts of CO2 from the vegetation and from soil organic matter. The main mitigation potential lies in soil carbon sequestration and preserving the existing soil carbon in arable soils. Nitrous oxide emissions can be reduced by reduced nitrogen application, but much still remains unclear about the effect different fertilizer types and management practices have on these emissions. Methane emissions from ruminants can only be reduced significantly by a reduction in animal numbers. Sequestration, finally, can be enhanced by conservative management practices, crop rotation with legumes (grass-clover) leys and application of organic fertilizers. An additional issue of importance are storage losses of food in developing and food wastage in developed countries (each about 30-40 percent of end products). Thus, there are basically five broad categories of mitigation actions in agriculture and its broader context: zz reducing direct and indirect emissions from agriculture; zz increasing carbon sequestration in agricultural soils; zz changing human dietary patterns towards more climate friendly food consumption, in particular less animal products; zz reducing storage losses and food wastage; zz the option of bioenergy needs to be mentioned, but depending on the type of bioenergy several negative side-effects may occur, including effects on food security, biodiversity and net GHG emissions. Although there are many difficulties in the details of mitigation actions in agriculture, a paradigm of climate friendly agriculture based on five principles can be derived from the knowledge about agricultural emissions and carbon sequestration: zz Climate friendly agriculture has to account for tradeoffs and choose system boundaries adequately; zz it has to account for synergies and adopt a systemic approach; zz aspects besides mitigation such as adaptation and food security are of crucial importance; zz it has to account for uncertainties and knowledge gaps, and zz the context beyond the agricultural sector has to be taken into account, in particular food consumption and waste patterns. Regarding policies to implement such a climate friendly agriculture, not much is yet around. In climate policy, agriculture only plays a minor role and negotiations proceed only very slowly on this topic. In agricultural policy climate change mitigation currently plays an insignificant role. In both contexts, some changes towards combined approaches can be expected over the next decade. Its 13 is essential that climate policy adequately captures the special characteristics of the agricultural sector. Policies with outcomes that endanger other aspects of agriculture such as food security or ecology have to be avoided. Agriculture delivers much more than options for mitigating greenhouse gas emissions and serving as a CO2 sink. We close this report with recommendations for the five most important goals to be realized in the context of mitigation and agriculture and proposals for concrete actions. First, soil organic carbon levels have to be preserved and, if possible, increased. Governments should include soil carbon sequestration in their mitigation and adaptation strategies and the climate funds should take a strong position on supporting such practices. Second, the implementation of closed nutrient cycles and optimal use of biomass has to be supported. Again, governments and funds should act on this. Policy instruments for nitrate regulation are a good starting point for this. As a third and most effective goal, we propose changes in food consumption and waste patterns. Without a switch to attitudes characterized by sufficiency, there is a danger that all attempts for mitigation remain futile. Finally, there are two goals for research, namely to develop improved knowledge on nitrous oxide dynamics, and on methods for assessment of multi-functional farming systems. Without this, adequate policy instruments for climate friendly agriculture and an optimal further development of it are not possible

Prescribed Fire

As the culmination of my nonfiction seminar (ENGL 470C) with Professor Colin Rafferty, I chose to explore three disparate, but interwoven, narratives: the death of and delayed grief over my high school mentor; my struggle with Obsessive Compulsive Disorder; and, the 2011 wildfire that destroyed much of the Great Dismal Swamp. Through a use of segmentation, lyric language, and a manipulation of tense, I explore the tensions underlying these narratives, namely the idea of futility of preparation and the insistence on destructive cycles which sustain themselves. Ultimately, the essay serves on a rumination not on mortality, but on our cultural perception of it as something to be dealt with in the aftermath and the difficulty that subsequently arises from when that perception is flipped and, instead, an end is something to be eternally anticipated and negotiated within that anticipation

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Fresh and atmospherically aged biomass-burning (BB) aerosol mass is mostly comprised of strongly light-absorbing black carbon (BC) and of organic carbon (OC) with its light-absorbing fraction – brown carbon (BrC). There is a lack of data on the physical and chemical properties of atmospheric BB aerosols, leading to high uncertainties in estimates of the BB impact on air quality and climate, especially for BrC. The polarity of chemical compounds influences their fate in the atmosphere including wet/dry deposition and chemical and physical processing. So far, most of the attention has been given to the water-soluble (polar) fraction of BrC, while the non-polar BrC fraction has been largely ignored. In the present study, the light absorption properties of polar and non-polar fractions of fresh and aged BB emissions were examined to estimate the contribution of different-polarity organic compounds to the light absorption properties of BB aerosols. In our experiments, four globally and regionally important fuels were burned under flaming and smoldering conditions in the Desert Research Institute (DRI) combustion chamber. To mimic atmospheric oxidation processes (5–7 days), BB emissions were aged using an oxidation flow reactor (OFR). Fresh and OFR-aged BB aerosols were collected on filters and extracted with water and hexane to study absorption properties of polar and non-polar organic species. Results of spectrophotometric measurements (absorption weighted by the solar spectrum and normalized to mass of fuel consumed) over the 190 to 900nm wavelength range showed that the non-polar (hexane-soluble) fraction is 2–3 times more absorbing than the polar (water-soluble) fraction. However, for emissions from fuels that undergo flaming combustion, an increased absorbance was observed for the water extracts of oxidized/aged emissions while the absorption of the hexane extracts was lower for the aged emissions for the same type of fuels. Absorption Ångström exponent (AAE) values, computed based on absorbance values from spectrophotometer measurements, were changed with aging and the nature of this change was fuel dependent. The light absorption by humic-like substances (HULIS) was found to be higher in fuels characteristic of the southwestern USA. The absorption of the HULIS fraction was lower for OFR-aged BB emissions. Comparison of the light absorption properties of different-polarity extracts (water, hexane, HULIS) provides insight into the chemical nature of BB BrC and its transformation during oxidation processes

The potential of geospatial technology for monitoring peatland environments

There have been significant advances in the spectral and spatial resolution of data collected from spaceborne, airborne and terrestrial based geospatial technologies over the past 20 years. In sensitive peatland ecosystems, the non-intrusive application of these technologies offers great potential to improve vegetation monitoring and topographical mapping. This paper discusses the potential of geospatial technologies for monitoring vegetation, mapping natural erosion features and assessing artificial drainage with reference to two peatland sites in England. Earth Observation (EO) data can now provide colour imagery with spatial resolution comparable to conventional aerial photography. Enhanced spectral resolution of spaceborne sensors has also increased the accuracy of automated image classification for bog vegetation and EO data may challenge the relevance of conventional aerial photography in landscape-scale assessment. Ultra-high resolution data achievable from Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanner (TLS) technologies are providing unprecedented levels of detail from remote sensing. UAV imagery now provides the possibility of identifying individual plants which greatly increases a researcher’s ability to map vegetation from aerial imagery. UAV derived elevation data, combined with the capability of TLS, provide enhanced resolution of gully and artificial drain morphology compared to airborne LiDAR and allow a new approach for quantifying erosion. These technologies provide opportunities to extend traditional surveys over far larger areas than was previously possible and can assist both in targeting areas for future restoration and in monitoring of subsequent change. Traditional survey methods will however maintain an important role in assessing many aspects of peatlands, as they not only provide information to verify remotely sensed data, but are currently the only method that can ‘see’ underneath peatland vegetation

Ecohydrological characterisation of Whangamarino wetland

The Whangamarino wetland is internationally recognised and one of the most important lowland wetland ecosystems in the Waikato Region. The wetland’s hydrology has been altered by reduced river base levels, the installation of a weir to raise minimum water levels and the Lower Waikato Waipa Flood Control Scheme, which is linked via the (hypertrophic) Lake Waikare and affected by varying catchment land use practices. When water levels exceed capacity, the overflow is released into the Whangamarino wetland, which also receives flood waters from Whangamarino River. Water levels in the wetland are also affected at high stage, by a control structure near Meremere at the confluence of Waikato and Whangamarino Rivers, and at low stage by a weir a short distance upstream. The ecohydrology of a representative part of the wetland was studied to assess the linkage between wetland ecology and the natural and anthropogenic modification of the flood regime and land use. The primary goal of this research was to characterise the present state of the wetland, which will aid in developing future goals and approaches for restoration. The study focused on a 2.3 km transect extending from the Whangamarino River, through the wetland to adjacent farmed hillsides. Hydrological and meteorological data were retrieved and analysed from an automated weather station and seven water level sites along the transect. Historical water level records (over 46 years) were used to determine changes in the hydrological regime and the impact of the flood control scheme, through a flood inundation and frequency analysis. During a winter flood event, river water quality was assessed. Peat surface oscillation in the restiad bog was examined. Vegetation patterns were assessed and classified through ordination and statistical techniques. Peat, soil and foliage physical and chemical quality were measured. Atmospheric ammonia (NH3) deposition rates of N into the wetland were measured. Water levels in the inland 0–1.1 km of the transect line (restiad bog) were relatively stable and consistent, rising and falling through winter and summer. This area had rainfall as the primary water input and was independent from the Whangamarino River, except during large flood events where the fringe of the restiad bog was inundated. Closer to the Whangamarino River water levels were more variable and strongly responsive to the river’s hydrological regime. A flood inundation event in September 2010 impacted on wetland water level regimes up to 1.4 km from the river and had a return period of 3.3 years. Frequency analysis showed sites up to 500 m from the river will likely be inundated by floods every year. A 100 year flood was estimated to inundate 1.75 km from the river, but would not cover the entire wetland. River water samples collected during a flood event showed total suspended solids within the Whangamarino River peaking at 260 mg L-1, double the concentration from Pungarehu Canal (86 mg L-1). Nutrient concentrations (such as dissolved reactive phosphorus) followed a similar pattern to the flood hydrograph. Minimum water levels have increased since the development of the artificial weir, but before this occurred water table lowering may have encouraged manuka invasion towards the restiad bog. Increased flood inundation is now the most likely threat to continued wetland degradation and manuka invasion into the restiad bog, due to the change in water levels and the deposition of sediment and nutrients. Nutrients, heavy metals, isotopes (δ15N) and physical soil characteristics (such as bulk density) increased from the start of the manuka belt (1100 m) and were greatest near the Whangamarino River (2300 m). A gradient was observed in peat and soil chemistry patterns, with increasing fertility and a change from bog to swamp-type environments along the transect line towards the river. A mineralised swamp fringe belt was present next to the farmland (0–50 m). From 50–1100 m a restiad bog (dominated by Empodisma minus) was present and changed to a manuka transition zone from 1100–1500 m. From 1500–1900 m, a swamp environment was present with a dominant canopy of manuka changing to Coprosma tenuicaulis closer to the river. C. tenuicaulis appears to be acting as a buffer zone over 150 m, removing a large amount of nutrients and sediment from flood waters. The remaining 400 m (1900–2300 m) of the transect line was a marshland, with the highest nutrient and sediment abundances and the most variable water level patterns. This area was colonised primarily by Polygonum persicaria (willow weed). The major risk to the wetland is from continued flood inundation with nutrient and sediment rich waters. Recommendations for future management include restoring catchment water quality and better management of the flood control regime

History of fires and vegetation since the Neolithic in the Cantabrian Mountains (Spain)

Fire has been one of the main causes of disturbance of vegetation over time, and since the Neolithic has become an irreplaceable tool for the opening of forest spaces and maintenance of pastures. Previous studies showed that the intensity and effects of wildfires are related to the biomass and controlled by climate factors. However, in regions such as Cantabria, where agriculture and livestock have spread throughout the territory since prehistory, fires should also be closely related to human land uses. The aim of this paper was to investigate the history of fires and vegetation since the Neolithic in the Cantabrian Mountains, using sedimentary charcoal and pollen data to study the role of human activities in the processes that have shaped ecosystems throughout the Holocene. The asynchrony and quantitative differences in the results obtained at different sites indicate significant variations in fire patterns at regional scale since the Neolithic, although the type and size of each basin also had a strong influence on charcoal accumulation. Maximum values for charcoal accumulation rate at La Molina were observed between the Neolithic and the Bronze Age but occurred after about 3500 cal years BP at El Cueto de la Avellanosa. At El Sertal, low charcoal accumulation rate values were observed, probably because the sequence begins in a space that already had been cleared; the maximum values occurred during the most recent millennium. These data provide evidence that fire has been a key factor in forest retreat and in maintaining open landscapes since the Neolithic.This article was made possible by two Coordinated Project grants from Spain's Ministry of Economics and Competitiveness (MEC), “El uso del fuego y la conformación de los paisajes en la Montaña cantábrica y el Pirineo oriental: estudio comparado de su evolución histórica y tendencias actuales” (CSO2012-39680-C02-01) awarded to the Department of Geography, Urban studies and Land Planning, Universidad de Cantabria and “Geohistoria ambiental del fuego en el Holoceno. Patrones culturales y gestión territorial desde el inicio de la ganadería y la agricultura en la montaña Cantábrica y Pirineo “awarded to the Department of Geography, Universitat Autónoma de Barcelona (CSO2012-39680-C02-02). In addition, the project was funded by the Catalan government's Applied Geography program, “Grup de Geografia Aplicada” (AGAUR, Generalitat de Catalunya, 2014 SGR 1090)

The vegetational and archaeological history of Rombalds Moor West Yorkshire.

The archaeology of Rombalds Moor, West Yorkshire, is reviewed and discussed. Vegetational information is provided by thirteen pollen diagrams (nine percentage diagrams and four influx diagrams) for seven sites on the moor. At the end of the Late-Devensian period Rombalds Moor was aspecies-rich grassland. Following the Post-glacial warming of the climate-there was a succession of trees arriving in the area, but true woodland was not established until c.8800 years BP. Dates are proposed for two early Mesolithic forest burnings, and late Mesolithic disturbance has been noted, particularly at the Alnus rise. The morphology of the Alnus rise differs in diagrams from different parts of the moor. Differences in diagrams from the same site, together with radiocarbon dating evidence, points to the presence of one or more hiatuses in the late Boreal/early Atlantic. At this site there is evidence that Pinus persisted long after the Alnus rise. There was a small amount of clearance, but no agriculture, in the Neolithic period. In the Bronze Age there was more extensive clearance, some pastoralism, and a limited amount of cereal cultivation in the east of the moor. Pollen analysis of a buried soil provides evidence that a supposed 'Bronze Age' cairn represents a burial, but the radiocarbon date is Iron Age. Major deforestation took place in the Iron Age when the population moved from the higher land into the valleys and there were significant increases in both pastoral and arable farming. Cultivation stopped and woodland regrew in some areas towards the end of the Roman period. There is evidence that removal of the woodland cover led to soil degeneration on the higher parts of the moor which prevented later regrowth of woodland. In the late 13th and early 14th centuries remaining woodland was cleared and agriculture increased, particularly pastoralism. Recent changes involve the decline of heather as a result of overgrazing

Suomen viljelysmaiden rikkitila

A method for determining total sulphur in plant material and soil samples using the induction furnace technique and subsequent turbidimetric determination of sulphate sulphur was discussed. A procedure for extracting sulphur from soil samples with ammonium acetate (pH 4.65), the interference of the organic matter being reduced by oxidation of the extract with H2O2, was proposed. Sulphur balance in Finnish cultivated soils was estimated by taking into account the average amounts of emitted (8 kg S/ha/yr.), precipitated (8 kg S/ha/yr.) and leached (8 kg S/ha/yr.) sulphur. The actual situation in the cultivated soils seems thus to be depending, on an average, on the uptake by plants and the sulphur applied (12 kg S/ha/yr. in the early 1970s). In 104 samples of cultivated soil, the content of total sulphur showed a slight correlation with the content of organic carbon. The amounts of sulphur extracted in various ways were not predictable by means of the soil characteristics used (pHCaCl2, org. C and texture). Extracted sulphur did not correlate sufficiently with the development and sulphur uptake of plants. Under field conditions in northern Finland, sulphur application produced a relatively distinct result in respect both to the ley yields on Carex peat, and their sulphur content. On mineral soils in southern Finland the yields were unaffected by supplementary fertilization with sulphur. In the pot experiments performed a fairly close relationship between sulphur and nitrogen was demonstrated.Tässä tutkimuksessa jouduttiin aluksi rikin määritystapojen joukosta valitsemaan laboratorion varustuksen ja maanäytteiden laadun mukaiset menetelmät. Kokonaisrikin määrittämiseen kehitettiin menetelmä, joka perustuu näytteen polttamiseen induktiouunissa ja sulfaattiakin turbidimetriseen mittaukseen vetyperoksidiin imeytetystä polttokaasusta. Maauutteiden analysoinnissa esille tulevat vaikeudet voitiin selvästi osoittaa. Analyysitulosten arvo näytti yleisesti käytetyn bariumkromaattimenetelmän kohdalla jopa kyseenalaiselta. Rikin määrittämiseksi ammoniumasetaattiuutteesta (pH 4.65) on esitetty uusi menetelmä, jossa eloperäisen aineksen määritystä häiritsevää vaikutusta on vähennetty käsittelemällä uutteita vetyperoksidilla. Suomen viljelysmaitten rikkitase arvioitiin ottamalla huomioon maahan ilmakehästä ja viljelytoimenpiteiden seurauksena tuleva rikki sekä huuhtoutumisesta ja kasvien otosta aiheutuva rikin kulutus. Sateen mukana tulevan ja vesistöihin huuhtoutuvan rikin määrät näyttivät olevan samaa suuruusluokkaa eli noin 8 kg/ha vuodessa. Lannoitusvuonna 1970—71 levitettiin rikkiä lannoitteissa noin 12 kg viljeltyä hehtaaria kohti. Tämä viljasadolle riittävä määrä on ilmeisesti liian niukka paljon rikkiä vaativille kasveille. Alustava tutkimus Suomen viljelysmaiden rikkivaroista ja niiden käyttökelpoisuudesta kasveille suoritettiin analysoimalla joukko maanäytteitä ja järjestämällä näissä maissa astia- ja kenttäkokeita. Näytteet olivat 62 kohteesta linjan Oulu-Kuusamo eteläpuolella. Näytteiden kokonaismäärä oli 104, joista 62 pinta- ja 42 jankkonäytettä. Näytesarjan multa- ja turvemaat (21 kpl) sisälsivät keskimäärin 118±220 mg rikkiä ilmakuivaa maakiloa kohti, savimaat (22 kpl, koska eräs sulfaattimaan näyte jätettiin tarkastelun ulkopuolelle) 450±94, hiesu- ja hiuemaat (18 kpl) 410±100 ja hieta- ja hiekkamaat (42 kpl) 310±43 mg/kg (vaihtelurajat ilmoitettu 95 % luotettavuudella). Kivennäismaiden jankko sisälsi keskimäärin 30 % vähemmän rikki kuin pintamaa. Maanäytteiden kokonaisrikin pitoisuus oli melko hyvin korreloitunut eloperäisen aineksen pitoisuuden kanssa (r = 0.83***). Tutkittuihin reagensseihin (1 % NaCl, 0.03 M NaH2P04-2N CH3COOH ja CH3COONH4-CH3COOH, pH 4.65) uuttuva rikki sen sijaan ei juuri riippunut määritetyistä maan yleisistä ominaisuuksista (pHCaCl2, org.C ja tekstuuri). Tutkituista uuttoliuoksista hapan ammoniumasetaatti uutti vähiten rikkiä myös kun tilavuuspaino otettiin huomioon. Muut kaksi menetelmää antoivat keskenään samaa suuruusluokkaa olevia tuloksia. Mikään uuttomenetelmistä ei pystynyt antamaan selvää kuvaa siitä, miten lannoiterikki vaikuttaa kasvien kehitykseen. Ammoniumasetaattiin uuttuvan rikin määrä kuvasi kuitenkin jotenkin maan rikkitilaa. Tämän menetelmän tärkeä etu näytti olevan tilavuusyksikköön perustuva uuttosuhde, joka antoi vertailukelpoisia tuloksia niin kivennäis- kuin multa- ja turvemaistakin. Timoteivaltaisen nurmen rikkilannoitus saraturvemailla Kuusamossa lisäsi suhteellisen selvästi nurmisatoa ja sen rikinottoa kesällä 1969. 10 kg rikkiä hehtaarille oli tarpeeksi nurmisadon kohottamiseksi tyydyttävälle tasolle. Vielä runsaampi rikkilannoitus aiheutti melkein yksinomaan sadon rikin pitoisuuden lisääntymisen. Etelä-Suomessa vuonna 1970 järjestetyissä kenttäkokeissa rikkilannoitus ei vaikuttanut kevätviljojen satoihin. Lähinnä lannoitteiden koostumuksen suunnittelua ajatellen tutkittiin astiakokein toisaalta rikin toisaalta typen, fosforin ja molybdeenin vuorosuhteita. Tuntui ilmeiseltä, että määrältään ja laadultaan optimaalisen sadon saavuttamiseksi rikkiä ja typpeä täytyy olla kasvien käytettävissä tietyssä suhteessa, joka todennäköisesti on rajojen N/S = 5-20 puitteissa. Kun rapsi kärsi samanaikaisesti näiden kahden ravinteen puutetta, typpi rajoitti ensisijaisesti kasvin vegetatiivista kehitystä ja rikki siementen muodostusta. Rikki ja fosfori tuntuivat vaikuttavan kasvissa toisistaan riippumatta, kun taas molybdeenilannoitus rikin niukkuuden vallitessa kohotti voimakkaasti kasviaineksen molybdeeninpitoisuutta