Root Residues Research Articles

MATHEMATICAL MODELING OF THE DRYING CURVES OF FOXTAIL MILLET SEEDS IN SPOUTED BED

In order to provide a contribution to future studies of foxtail millet (Setaria italica), the drying kinetics of the seeds was investigated at three different temperatures: 44, 65 and 86°C. The seeds of S. italica with a moisture equal to 30% in dry basis were dried in a conical-cylindrical spouted bed during an interval of 132 min. Some empirical mathematical models were selected to describe the experimental drying kinetics data (Lewis, Henderson and Pabis, Page, Diffusion approach, Midilli and Wang and Singh) and the best models were chosen according to the statistical tests results (coefficient of determination, mean relative percent deviation, mean square root error and residue distribution), using the software Statistica® 7.0 and applying the Quasi-Newton method. Only the decreasing rate period was observed in the drying kinetic curves, indicating that the removal of moisture content was preferably by the diffusion mechanism, which is a characteristic behavior of fibrous products, like the agricultural products. The models of Diffusion Aproach, Page and Midilli were the most suitable to describe the experimental drying curves.

Antioxidant films based on gelatin capsules and minimally processed beet root (Beta vulgaris L. var. Conditiva) residues

ABSTRACTBiocomposite films were prepared by incorporating different concentrations of beet root residue powder (BRP) (2, 4, 8, and 12 g BRP/100 g water) into films based on residues of gelatin capsules (GCR) (40 g GCR/100 g water). Control films had no BRP added. A complete mechanical, physicochemical, barrier, optical, and antioxidant characterization of all films was performed. Among all the films considered, BRP12 was found to present the most adequate properties and was further investigated. SEM micrographs showed that BRP12 presented a less homogeneous surface in comparison with the control film, but they showed similar thermal stability. After 15 days of soil degradation, the films lost over 75% of weight. The films were effective on protecting sunflower oil from primary oxidation process, and BRP12 showed higher protection than control film. Therefore, this study suggests that the formulated films could act as promising antioxidant materials and contribute to environmentally friendly technologies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43094.

Decomposition of Eucalyptus grandis and Acacia mangium leaves and fine roots in tropical conditions did not meet the Home Field Advantage hypothesis

Unlike Eucalyptus monocultures, nitrogen fixing trees are likely to improve the soil nutrient status through the decomposition of N-enriched litter. The Home Field Advantage (HFA) hypothesis states that plants can create conditions that increase the decomposition rates of their own litter. However, there may not be any HFA when most of the decomposers are generalists. A reciprocal transplant decomposition experiment of fine roots and leaves of Acacia mangium and Eucalyptus grandis was undertaken in monocultures of these two species to test the HFA hypothesis using a complete randomized design with three blocks. Three litterbags containing leaf or fine root residues of each species were collected every 3months from each plot over 12months for fine roots and 24months for leaves. The litter mass and C, N and P concentrations were measured at each sampling date. The concentrations of C-compounds were measured 0, 12 and 24months from the start of the experiment. There was no evidence of HFA for either the leaves or the fine roots of either species. The decomposition rates were slower for Acacia litter than for Eucalyptus litter even though initial N concentrations were 1.9–2.9 times higher and P concentrations were 1.5–3.3 times higher in the Acacia residues. N:P ratios were greater than 20–30 for the residues of both species, with the highest values for Acacia. Litter decomposition depended partly on the C quality of the litter, primarily in terms of water soluble compounds and lignin content. As shown recently in tropical rainforests, these results suggest that the activity of decomposers is limited by energy starvation in tropical planted forests. Decomposer activity may also have been limited by P availability which may not have been directly related to the P concentrations or C:P ratios in the residues.

Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria

Manici, L. M., Kelderer, M., Caputo, F., Nicoletti, F., De Luca Picione, F. and Topp A. R. 2015. Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria. Can. J. Plant Sci. 95: 947–958. Replant disease of fruit tree orchards has a multifactorial etiology, mainly due to the decline in soil biodiversity along with an increase in root rot pathogens, which can be principally countered with appropriate cropping practices. Therefore, a study on the impact of cover crops on plant health of young fruit trees in long-term orchards was performed. Bioassays were performed over two consecutive growing cycles using soil from a multigeneration apple orchard affected by replant disease. First, a cycle was performed with three cover crops (alfalfa, barley, marigold) and apple rootstock plantlets; at the end, the above-ground part of the plant was removed and root residues left in the soil. In the second cycle, an apple orchard planting was simulated upon the first experimental design. Changes of diversity and composition of root inhabiting fungi and rhizospheric bacteria were evaluated as well as apple plant growth response to the pre-plant treatments. Results suggest that one cycle with alternate plants was sufficient to induce changes at the rhizosphere level, despite soil microbial resilience caused by the same long-term soil management. Rhizospheric bacteria were generally affected by plant genotype. Findings suggest that all three different cover crops can harbor almost all fungal species that colonize apple in replanted orchards (Fusarium spp., Pythum spp., binucleate Rhizoctonia sp., Cylindrocarpon-like-fungi and a several nonpathogenic saprophytic fungi named “other”), but their infection frequency varied according to the host plant. A single pre-plant break treatment did not overall differ significantly in plant growth of subsequent apple tree; however, break with marigold, which increased abundance of nonpathogenic root inhabiting fungi more than other cover crops, gave significantly higher plant growth than obtained after barley. This study provides evidence about cover-crop potential to increase soil diversity in long-term permanent cropping systems and to manipulate root colonizing fungi involved in crop health.

Effects of water management practices on residue decomposition and degradation of Cry1Ac protein from crop-wild Bt rice hybrids and parental lines during winter fallow season

Rice is the staple diet of over half of the world's population and Bacillus thuringiensis (Bt) rice expressing insecticidal Cry proteins is ready for deployment. An assessment of the potential impact of Bt rice on the soil ecosystem under varied field management practices is urgently required. We used litter bags to assess the residue (leaves, stems and roots) decomposition dynamics of two transgenic rice lines (Kefeng6 and Kefeng8) containing stacked genes from Bt and sck (a modified CpTI gene encoding a cowpea trypsin inhibitor) (Bt/CpTI), a non-transgenic rice near-isoline (Minghui86), wild rice (Oryza rufipogon) and crop-wild Bt rice hybrid under contrasting conditions (drainage or continuous flooding) in the field. No significant difference was detected in the remaining mass, total C and total N among cultivars under aerobic conditions, whereas significant differences in the remaining mass and total C were detected between Kefeng6 and Kefeng8 and Minghui86 under the flooded condition. A higher decomposition rate constant (km) was measured under the flooded condition compared with the aerobic condition for leaf residues, whereas the reverse was observed for root residues. The enzyme-linked immunosorbent assay (ELISA), which was used to monitor the changes in the Cry1Ac protein in Bt rice residues, indicated that (1) the degradation of the Cry1Ac protein under both conditions best fit first-order kinetics, and the predicted DT50 (50% degradation time) of the Cry1Ac protein ranged from 3.6 to 32.5 days; (2) the Cry1Ac protein in the residue degraded relatively faster under aerobic conditions; and (3) by the end of the study (~154 days), the protein was present at a low concentration in the remaining residues under both conditions. The degradation rate constant was negatively correlated with the initial carbon content and positively correlated with the initial Cry1Ac protein concentration, but it was only correlated with the mass decomposition rate constants under the flooded condition. No Cry1Ac protein was detected in the soils surrounding the buried residue. Our results did not reveal any evidence that the stacked genes (Bt/CpTI) or the presence of the Cry1Ac protein influenced the decomposition dynamics of the rice residues. Furthermore, our results suggested that field drainage after residue incorporation would promote Cry1Ac protein degradation.

Biomass Quality of Brassica Oilseed Crops in Response to Sulfur Fertilization

Rapeseed [Brassica napus (L.)], white mustard [Sinapis alba (L.)], and Indian mustard [Brassica juncea (L.) Czern. et Coss] belong to the family Brassicaceae. These crop species synthesize substantial amounts of fat, protein, and glucosinolates (GLS). Brassica species can differ in their concentrations of fat, protein, and GLS in response to S fertilization. Plant material for chemical analyses was harvested from a field experiment conducted in northeastern Poland in 2005 to 2008. The examined species of oilseed crops were fertilized or not fertilized with S applied to soil at optimal rates for each species based on S uptake and forecast seed yield. On average, S fertilization increased seed yield of oilseed crops by 8%, but it did not induce significant differences in the concentrations of fat and protein in seeds. Sulfur fertilization increased total GLS concentrations by 0.22 and 0.27 µmol g−1 dry matter (DM) in the root residues of white mustard and Indian mustard, respectively, and by 0.52 µmol g−1 DM in winter rapeseed. Total GLS concentration in winter rapeseed straw decreased by 0.18 µmol g−1 DM with S application. In white mustard straw, S fertilization increased total GLS concentration by 0.27 µmol g−1 DM. Sulfur fertilization increased total GLS concentrations in the seeds of spring rapeseed, white mustard and Indian mustard by 11.43, 41.75 and 32.05 µmol g−1 DM, respectively. Sulfur fertilization has a significant effect on the seed yield and biomass quality of oilseed crops of the family Brassicaceae.

Effects of liming and mineral N on initial decomposition of soil organic matter and post harvest root residues of poplar

Short-term potential carbon (C) and nitrogen (N) mineralization of soil organic matter and belowground plant litter was determined in the top soil layer of a sandy soil of a short-rotation coppice (SRC) and the effect of addition of lime, mineral nitrogen and poplar roots was determined. Lime addition was equivalent to 1.2mgCaCO3g−1, mineral N and root litter were added corresponding to 6.8μgNg−1 and 13.8mgrootsg−1 soil respectively. Partitioning of carbon dioxide (CO2) derived from lime and soil organic matter (SOM) was calculated by using stable isotope analysis of the CO2. In addition, particulate organic matter (POM) as well as microbial biomass carbon and nitrogen were analyzed after 51days of incubation.Addition of lime decreased CO2 derived from organic matter in all treatments, but the level of decrease varied with N and root litter addition. Microbial biomass C and N increased with N addition in soil without root litter but decreased with root litter, nevertheless an immobilization of mineral N was especially high in soil amended with root litter. Particulate organic matter (POM) decreased by 41% of its dry weight in root litter amended soil. Liming decreased decomposition of POM in these soils, whereas no effect was observed after addition of mineral nitrogen or mineral nitrogen and lime. These results show that liming has the potential to decrease C mineralization of humified organic matter as well as plant residues and that decreased mineralization of organic matter occurred after liming, even if mineral N was added.

The effect of sulfur fertilization on macronutrient concentrations in the post-harvest biomass of rapeseed (Brassica napus L. ssp. oleifera Metzg)

Brassica oilseed crops have very high sulfur requirements. The progressive decrease in the sulfur content of soil, the growing share of cruciferous vegetables in agricultural ecosystems and a significant drop in annual wet and dry deposition of sulfur have prompted a growing body of research into sulfur as a valuable fertilizer ingredient. The aim of this study was to determine the effect of sulfur fertilizers applied to soil on nitrogen, phosphorus, potassium, calcium, magnesium and sulfur concentrations in the root residues, straw and oil cake of winter and spring rapeseed. The experimental material was collected from a field experiment conducted in 2005-2008 at the Agricultural Experiment Station in Balcyny (Poland). The highest concentrations of nitrogen, phosphorus, magnesium and sulfur were noted in the oil cake of both winter and spring rapeseed. Potassium levels were highest in the root residues of winter and spring rapeseed. Winter rapeseed accumulated the highest amounts of calcium in roots, and spring rapeseed – in straw. Sulfur fertilizers applied to soil decreased nitrogen concentrations and increased calcium and sulfur levels in the roots of both spring and winter rapeseed, whereas phosphorus concentrations increased only in the roots of winter rapeseed. Sulfur fertilization led to a drop in the potassium content of winter rapeseed roots (by 0.7 g kg-1 DM) and an increase in potassium levels in spring rapeseed roots (by 1.2 g kg-1 DM). The application of sulfur fertilizers significantly increased potassium and sulfur concentrations in the straw of both spring and winter rapeseed (by 1.3-1.7 and 0.5-0.6 g kg-1 DM, respectively). The application of sulfur fertilizers at optimal dr hab. Krzysztof Jankowski, Chair of Agrotechnology, Agricultural Production Management and Agribusiness, University of Warmia and Mazury in Olsztyn, Oczapowskiego 8/117, 10-719 Olsztyn, Poland, e-mail: krzysztof.jankowski@uwm.edu.pl * Supported by the Polish Ministry of Science and Higher Education, Project No. N310 031 32/167.

Symbiotic fixation of atmospheric nitrogen by different varieties of Lucerne depending on agrotechnological measures in the Southern Steppe

Results of intensive farming and crop rotation violation on decrease in soil fertility are given. Therefore, the issue of preservation and reproduction of soil fertility is one of the most important in the world of agriculture. As a way to suspend the negative processes in the soil and improve its fertility is possible when perennial legumes such as alfalfa are placed in rotations. The objective of the research is the development and scientific substantiation of processing methods increase root mass accumulation in the soil, nitrogen fixation of alfalfa in the year of sowing. The studies were conducted during 2011–2013 years in the experimental field of the Institute of irrigated agriculture NAAS of Ukraine. In regard to soil and climate it is located in the area of South Steppe Inhulets irrigated areas. In our research, we studied the effect of growth conditions on the accumulation of root mass and biological nitrogen varieties of alfalfa Unitro and Zoryana. The root system of alfalfa of the first year of life under different growing conditions was located in a cone with a large accumulation in the 0–10 cm layer, followed by its decrease. In natural conditions, the amount of humidification of dry weight of roots was 1.75 t/ha, whereas it increased drip irrigation to 2.28 t/ha. Fixation of atmospheric nitrogen by plants without irrigation of alfalfa was low and amounted to 72.56 kg/ha. Drip irrigation helped strengthen nitrogen fixation in alfalfa varieties, and was 143.55 kg/ha. Application of growth regulator Plantafol 30 contributed to the increase of these parameters in both varieties of alfalfa. The accumulation of organic matter in the form of root residues and the process of nitrogen fixation occurred most intensively under drip irrigation and the use of growth regulators Plantafol 30.

Response of maize and soil microorganisms to decomposing poplar root residues after shallow or homogenous mixing into soil

AbstractDuring re‐conversion of short‐rotation poplar tree plantations back to arable land use, large amounts of tree residues must be incorporated into soil. A 90‐d pot experiment with and without N addition was carried out after mixing the same amounts of chaffed poplar root residues into the pots at 0–5 cm or at 0–20 cm depth. The objective was to investigate whether shallow mixing has positive effects on maize growth, reduces poplar root residue decomposition, and changes the microbial community structure towards fungi. Aboveground maize yield was strongly reduced after mixing of poplar root residues at 0–20 cm depth without N fertilization, but was not affected if mixed at 0–5 cm depth. Neither the mixing nor N fertilization had significant effects on root residue decomposition, estimated as recovered particulate organic matter. The total increase in microbial biomass C and biomass N was strongest after homogenous mixing of root residues at 0–20 cm, but remained unaffected by N fertilization. In contrast, the total amount of ergosterol remained unaffected by the mixing treatments, but responded positively to N fertilization. Shallow incorporation of poplar root residues did not affect the microbial biomass C/N ratio but disproportionately increased the fungal ergosterol to microbial biomass C ratio. Shallow incorporation of poplar root residues seems to reduce the demand for N fertilization of following crops, which should be further tested in field experiments.

Droplet infiltration and organic matter composition of intact crack and biopore surfaces from clay‐illuvial horizons

AbstractThe organic matter (OM) in biopore walls and aggregate coatings may be important for sorption of reactive solutes and water as well as for solute mass exchange between the soil matrix and the preferential flow (PF) domains in structured soil. Structural surfaces are coated by illuvial clay‐organic material and by OM of different origin, e.g., earthworm casts and root residues. The objectives were to verify the effect of OM on wettability and infiltration of intact structural surfaces in clay‐illuvial horizons (Bt) of Luvisols and to investigate the relevance of the mm‐scale distribution of OM composition on the water and solute transfer. Intact aggregate surfaces and biopore walls were prepared from Bt horizons of Luvisols developed from Loess and glacial till. The mm‐scale spatial distribution of OM composition was scanned using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ratio between alkyl and carboxyl functional groups in OM was used as potential wettability index (PWI) of the OM. The infiltration dynamics of water and ethanol droplets were determined measuring contact angles (CA) and water drop penetration times (WDPT). At intact surfaces of earthworm burrows and coated cracks of the Loess‐Bt, the potential wettability of the OM was significantly reduced compared to the uncoated matrix. These data corresponded to increased WDPT, indicating a mm‐scaled sub‐critical water repellency. The relation was highly linear for earthworm burrows and crack coatings from the Loess‐Bt with WDPT > 2.5 s. Other surfaces of the Loess‐Bt and most surfaces of the till‐derived Bt were not found to be repellent. At these surfaces, no relations between the potential wettability of the OM and the actual wettability of the surface were found. The results suggest that water absorption at intact surface structures, i.e., mass exchange between PF paths and soil matrix, can be locally affected by a mm‐scale OM distribution if OM is of increased content and is enriched in alkyl functional groups. For such surfaces, the relation between potential and actual wettability provides the possibility to evaluate the mm‐scale spatial distribution of wettability and sorption and mass exchange from DRIFT spectroscopic scanning.

Carbon dynamics in a biochar-amended loamy soil under switchgrass

Allaire, S. E., Baril, B., Vanasse, A., Lange, S. F., MacKay, J. and Smith, D. L. 2015. Carbon dynamics in a biochar-amended loamy soil under switchgrass. Can. J. Soil Sci. 95: 1–13. The environmental impacts of switchgrass production for bioenergy could be reduced through the use of biofertilizers rather than mineral fertilizers and through soil amendment with biochar. The objectives of this study were: (1) to assess the impact of biochar and biofertilizer on switchgrass (Panicum virgatum L.) yield and parameters related to carbon dynamics, (2) to correlate carbon parameters with soil physico-chemical properties over the first two growing seasons, and (3) to develop a C budget. A complete randomized block design was installed in a sandy loam with split plot treatment design, the main plots receiving 0 or 10 t ha−1of biochar and the sub − plots receiving no fertilization, mineral N fertilization, or biofertilizers. Biofertilizers had no significant impact on plant and soil. Biochar increased yield relative to the control treatment by about 10% during the first year and root biomass by up to 50% after 2 yr (P>0.1). Mineral N fertilization also increased yield resulting in higher plant C sequestration after 2 yr. Biochar increased CO2soil concentration (CO2-soil) by up to 50% but its impact on CO2emission flux (CO2-flux) changed over time. The impact of mineral fertilization on CO2-fluxalso varied with time. Soil CO2dynamics was mostly influenced by temperature, N and water content. Biochar and fertilization treatments showed interactions on some plant and soil parameters. The highest C sequestration budget was obtained with a combination of biochar and mineral N fertilization. The equivalent of about one-third of the increase in soil C content associated with biochar treatments was respired away by soil microorganisms. Nearly one-fourth of C sequestered by plants remained in or at the soil surface (root and crop residues).

The amounts and dynamics of nitrogen transfer to grasses differ in alfalfa and white clover-based grass-legume mixtures as a result of rooting strategies and rhizodeposit quality

Differences in the ability to fix and transfer N have been shown between perennial legume species. However, the traits responsible for such variations are largely to be identified. This study aimed at comparing the dynamics of N transfer from alfalfa and white clover and test whether their differences resulted from difference in fixation, legume proportion, population dynamics or tissue composition. A three-year field experiment and a greenhouse experiment were carried out. Nitrogen fixation and transfer were assessed trough 15 N dilution and difference methods. Both experiments confirmed significant differences between legumes regarding N transfer capacity. Although alfalfa cumulated twice as much biomass and fixed nitrogen, it transferred smaller amounts of N (59 versus 147 kg N.ha−1 over three years in the field) under a delayed dynamic. The amounts of nitrogen transferred were related to recent decreases in legume population density. Moreover, root tissue composition differed; white clover had a higher proportion of fine roots with a lower C/N and lignin content. This resulted in more rapid N release from the severed roots of clover. The traits controlling plant persistency, root material turnover and residue quality may better explain N transfer dynamics than overall legume production and fixation.

The role of shoot residues vs. crop species for soil arthropod diversity and abundance of arable systems

Removal of crop residues has become common practice in arable systems, however, little is known about how soil arthropod communities change in response to reduced resource availability and habitat complexity associated with residue removal. We added maize residues to wheat and maize fields and investigated soil arthropod diversity and abundance over the period of one year. Residue addition did not affect the diversity and little affected the abundance of soil arthropods in wheat and maize fields with the latter being restricted to few taxonomic groups, suggesting that at least in the short-term soil arthropods benefit little from crop residue-mediated increase in food supply and habitat structure. Contrasting the minor effects of residue addition, densities of soil arthropods were much higher in wheat than in maize fields, presumably due to more dense and more continuous coverage by plants, and higher input of root residues. Furthermore, in wheat fields density of arthropods more strongly varied with season, presumably due to more pronounced pulses of root exudates and root residues entering the soil in wheat as compared to maize fields in summer and winter, respectively. Low density and little variation in densities of soil arthropods in maize fields reflect that environmental conditions and resource supply varied little with crop coverage and season. Overall, the results point to low importance of aboveground crop residues for soil arthropod communities and highlight that belowground plant resources, i.e. root exudates and root residues are the major driver of soil arthropod communities of arable systems. Thus, at least in short term removal of crop residues for e.g., biofuel production is likely to be of minor importance for soil arthropod communities. In contrast, changing crop species from wheat to maize markedly reduces the density of soil animals threatening the ecosystem functions they provide.

Soil properties in the Tol’yatti pine forest after the 2010 catastrophic wildfires

The results of the studies of soil changes after the 2010 fires in the forest outliers of the city of Tolyatti have been reviewed. The morphological analysis of postpyrogenic soils has showed that the fire touched only the upper part of their profiles. It has been revealed that the surface fires favor the more intense loss of organic carbon than the crown fires (2.85 and 2.37%, respectively). However, the crown fires are more destructive for soils, because, first, they are a continuation of the surface fires and, second, sheet and linear water erosion of soils develops because of the complete denudation of the soil cover. It has been found that forest fires result in the dehumification of soils, which is related to the destruction of the organic horizons, the mineralization of root residues, and the almost complete absence of fresh plant waste on the postfire areas. The pyrogenic impact increases the portion of humic acids in the organic matter. Along with the transfer of the clay fraction, the translocation of polycyclic aromatic hydrocarbons resulting from the fires to the accumulative geochemical positions is also possible.

Root and soil carbon distribution at shoulderslope and footslope positions of temperate toposequences cropped to winter wheat

Crop root residues are an important source of soil organic carbon (SOC) in arable systems. However, the spatial distribution of root biomass in arable systems remains largely unknown. In this study, we determined the spatial distribution of macro-root and shoot biomass of winter wheat at shoulderslope and footslope positions from four cultivated slopes within an arable field in western Denmark. In addition, soils from the shoulderslope and footslope positions of four slopes were characterized for physical and chemical properties. Root biomass dry matter (DM) was marginally higher (P=0.06) at footslope (1.2Mg DM ha-1) than at shoulderslope positions (0.9Mg DM ha−1), in particular in the subsoil. Likewise shoot biomass was higher (P=0.03) at footslope (10.3Mg DM ha−1) compared to shoulderslope (7.1Mg DM ha−1) positions. Soil bulk density increased with depth at shoulderslope positions, but was more variable with depth at footslope positions. Root C was significantly correlated with SOC in shoulderslope soils (r=0.98), but not in footslope soils. We conclude that, at shoulderslope positions, SOC originated mainly from root residues whereas at footslope positions, SOC was derived from both root residues and likely soil redistribution processes. Management practices that increase C input at shoulderslope positions potentially enhance soil carbon storage and increase crop productivity, which would probably not be the case for C rich footslope soils. These findings imply that models used to simulate or predict C dynamics and crop productivity should consider topography-controlled variations in root C input and SOC redistribution as well as their effects on soil properties, root growth and crop productivity.

Concentrations of copper, zinc and manganese in the roots, straw and oil cake of white mustard (Sinapis alba L.) and Indian mustard (Brassica juncea (L.) Czern. et Coss.) depending on sulphur fertilization

The purpose of this experiment was to determine the influence of the soil application of sulphur (S) on concentrations of micronutrients in the root residues, straw and oil cake of white and Indian mustard. The plant material for chemical analyses originated from a controlled field experiment conducted in experimental fields at the University of Warmia and Mazury in Olsztyn, Poland (2006–2008). In both white and Indian mustard, the richest source of Cu (7.2; 7.0 mg/kg dry matter (DM)) and Zn (64.6; 55.3 mg/kg DM) was the oil cake from mustard seeds. Regarding Mn, both white and Indian mustard accumulated the highest content of this element in roots (48.2; 50.8 mg/kg DM), less in oil cake (31.9; 35.5 mg/kg DM) and the least Mn was determined in straw of both species (24.0; 17.1 mg/kg DM). The application of sulphur caused a significant increase in the concentration of Zn and Mn in white mustard roots. The content of micronutrients in roots of Indian mustard was not differentiated significantly by S fertilization. The application of sulphur caused a significant decrease in the content of Mn in white mustard straw and Cu in Indian mustard straw. The content of micronutrients in white mustard oil cake and Indian mustard oil cake was not significantly changed by S fertilization.

Alelopatický potenciál durmanu obyčajného (Datura stramonium L.) na skoré štádia rastu kukurice siatej (Zea mays L.) a slnečnice ročnej (Helianthus annuus L.)

Laboratory and glasshouse experiments were carried out to investigate the allelopathic potential of different plant parts of D. stramonium on maize and sunflower on early growth stages. The aqueous leachates of D. stramonium roots and shoot did not produc a significant effect on germination and shoot length of maize, but root length of maize was significantly reduced at the highest (1/1) D. stramonium roots leachate compared to control. From the other side, germination of sunflower was significantly reduced at the highest (1/1) D. stramonium shoot leachate concentration, but lower (1/5 and 1/2) D. stramonium roots leachate concentrations significantly increased root and shoot length of sunflower compared to control. In glasshouse experiment, no one treatment with different D. stramonium plant residues significantly affected density, height and fresh weight of maize plants compared to control. Contrary, D. stramonium mixtures with 1/1 root and shoot residues significantly reduced plants density and fresh weight of sunflower plants compared to control. Lower (1/2 and 1/5) mixtures of D. stramonium roots residues and mixture with 1/5 D. stramonium shoot residues significantly increased the height of the sunflower plants.

Soil organic carbon stocks in a Brazilian Oxisol under different pasture systems

2009). How-ever, productive well-managed pastures can improve degraded soils and increase soil organic carbon (SOC) stocks through humification of grass and root residues. In order to enhance pasture yields and SOC sequestra-tion, nutrient availability in soils must also be improved, especially for N and P. This work aimed to assess how SOC stocks are affected by the combination of grasses and legumes, in comparison with pure grass pastures and other land uses in a clayey Oxisol in southeast Brazil.

Possibility of Introducing Winter Legumes, Hairy Vetch and Faba Bean, as Green Manures to Turmeric Cropping in Temperate Region

A field experiment was conducted to examine the possibility of introducing winter legumes, hairy vetch and faba bean, as green manures to turmeric cropping in a temperate region. Hairy vetch shoots were incorporated to determine the effect of N and P added as green manure. Higher values in plant height and number of leaves of turmeric were observed in the treatment with incorporation of hairy vetch than in that without incorporation (no-incorporation) throughout the growth periods. The differences in total amounts of N and P of turmeric between incorporation and no-incorporation treatments were the highest on 15 October, when the amount was increased by 8.0 g N and 1.1 g P m–2 compared with the no-incorporation treatment. From September to October, curcumin content rapidly increased with rhizome thickening, and gradually increased. We also quantified the N and P contribution from faba bean residues to the succeeding turmeric. The total amounts of N and P in turmeric cultivated after incorporating shoot and root residues into previously cultivated faba bean field were 2.5 g N and 1.0 g P m–2, respectively, larger than incorporating only roots. In previously fallow field, the incorporation of the shoot increased the total amount of N and P in tumeric by 4.5 g and 1.9 g m–2, respectively, compared with that without incorporation. In the second year after incorporation, growth and nutrient uptake of the turmeric crop did not significantly differ from those without incorporation. In the temperate region, these winter legumes would be used as basal organic matters for turmeric production.