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Permanent Grassland (permanent + grassland)
Selected AbstractsLandscape composition and vole outbreaks: evidence from an eight year study of Arvicola terrestrisECOGRAPHY, Issue 6 2000E. Fichet-Calvet This study investigates the relationships between landscape composition and the population dynamics of the fossorial water vole Arvicola terrestris. Land use patterns were studied based on agricultural and forestry data from the French Ministry of Agriculture collected in 1955 and 1988. In the Massif Central, France, water vole populations were monitored from 1985 to 1993 by using index methods. Outbreaks of water vole populations occurred in many dispersed epicentres and spread suddenly and widely over > 7500 km2. At a regional scale, the fluctuation lasts six years on average with an outbreak period lasting from two to three years. Density variation patterns are positively correlated with the proportion of permanent grassland to agricultural land. A high risk of outbreak is linked to a high proportion of permanent grassland (over 90%), whereas a low risk of outbreak is linked to a proportion of < 80%, Conversely, density variation patterns are negatively correlated with the proportion of temporary grassland to agricultural land and with the proportion of forest to total land in the western (major) part of the study area. Temporary grassland thus appears to be a marginal habitat for water voles and extensive forests could act as a brake on outbreaks. The increase in the area of permanent grassland from 1955 to 1988 was apparently the major cause of chronic high densities of water voles. Therefore, land use and landscape management could be one way to control water vole outbreaks. [source] Shrinkage of initially very wet soil blocks, cores and clods from a range of European Andosol horizonsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2007F. Bartoli Summary In advanced stages of volcanic ash soil formation, when more clay is formed, soil porosity values and soil water retention capacities are large and the soils show pronounced shrinkage on drying. Soil shrinkage is a key issue in volcanic soil environments because it often occurs irreversibly when topsoils dry out after changes from permanent grassland or forest to agriculture. European Andosols have developed in a wide range of climatic conditions, leading to a wide range in intensity of both weathering and organo-mineral interactions. The question arises as to whether these differences affect their shrinkage properties. We aimed to identify common physically based shrinkage laws which could be derived from soil structure, the analysis of soil constituents, the selected sampling size and the drying procedure. We found that the final volumetric shrinkage of the initially field-wet (56,86% of total porosity) or capillary-wet (87,100% of total porosity) undisturbed soil samples was negatively related to initial bulk density and positively related to initial capillary porosity (volumetric soil water content of soil cores after capillary rise). These relationships were linear for the soil clods of 3,8 cm3, with final shrinkage ranging from 21.2 to 52.2%. For soil blocks of 240 cm3 and soil cores of 28.6 cm3 we found polynomial and exponential relationships, respectively, with thresholds separating shrinkage and nearly non-shrinkage domains, and larger shrinkage values for the soil cores than for the soil blocks. For a given sample size, shrinkage was more pronounced in the most weathered and most porous Andosol horizons, rich in Al-humus, than in the less weathered and less porous Andosol horizons, poor in Al-humus. The Bw horizons, being more weathered and more porous, shrank more than the Ah horizons. We showed that the structural approach combining drying kinetics under vacuum, soil water analysis and mercury porosimetry is useful for relating water loss and shrinkage to soil structure and its dynamics. We also found that the more shrinkage that occurred in the Andosol horizon, the more pronounced was its irreversible mechanical change. [source] Preferential phosphorus leaching from an irrigated grassland soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2005G. S. Toor Summary Intact lysimeters (50 cm diameter, 70 cm deep) of silt loam soil under permanent grassland were used to investigate preferential transport of phosphorus (P) by leaching immediately after application of dairy effluent. Four treatments that received mineral P fertilizer alone (superphosphate at 45 kg P ha,1 year,1) or in combination with effluent (at , 40,80 kg P ha,1 year,1) over 2 years were monitored. Losses of total P from the combined P fertilizer and effluent treatments were 1.6,2.3 kg ha,1 (60% of overall loss) during eight drainage events following effluent application. The rest of the P lost (40% of overall loss) occurred during 43 drainage events following a significant rainfall or irrigation compared with 0.30 kg ha,1 from mineral P fertilizer alone. Reactive forms of P (mainly dissolved reactive P: 38,76%) were the dominant fractions in effluent compared with unreactive P forms (mainly particulate unreactive P: 15,56%). In contrast, in leachate following effluent application, particulate unreactive P was the major fraction (71,79%) compared with dissolved reactive P (1,7%). The results were corroborated by 31P nuclear magnetic resonance analysis, which showed that inorganic orthophosphate was the predominant P fraction present in the effluent (86%), while orthophosphate monoesters and diesters together comprised up to 88% of P in leachate. This shows that unreactive P forms were selectively transported through soil because of their greater mobility as monoesters (labile monoester P and inositol hexakisphosphate) and diesters. The short-term strategies for reducing loss of P after application of dairy effluent application should involve increasing the residence time of applied effluent in the soil profile. This can be achieved by applying effluent frequently in small amounts. [source] Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decadesGLOBAL CHANGE BIOLOGY, Issue 7 2009D. W. HOPKINS Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source] Assessment of the nitrogen status of grasslandGRASS & FORAGE SCIENCE, Issue 2 2004A. Farruggia Abstract Two types of diagnostics are used for N management in grasslands: diagnostics based on N concentration of shoots and diagnostics based on soil mineral N. The Nitrogen Nutrition Index (NNI) is an example of the first type. However, its evaluation requires the determination of shoot dry weight per unit area and, thus, constitutes a practical limit to its utilization in the context of farm studies. In order to simplify its evaluation, a method based on the N concentration of the upper sward layer (Nup) has been proposed. The objectives of this study were to test the relationship between NNI and Nup in the context of permanent grassland and to examine the relationship between Nup and soil mineral status. The study was conducted as two experiments, one on small cut-plots receiving contrasting rates of mineral N fertilization, and a second on plots of an existing field-scale lysimeter experiment. In each plot and at several dates, shoot biomass within quadrats was measured, N concentration was determined on the upper leaves and on the entire shoots, and mineral nitrogen of the soil below the vegetation sampled was determined. N concentration of the upper lamina layer of the canopy was linearly related to the NNI determined on the entire shoots. Therefore, determining N concentration in leaves at the top of canopy appears to be an alternative means to evaluate NNI without having to measure shoot biomass. The absence of an overall significant correlation between soil mineral N content and sward N index, observed over the two studies, indicates that each of these two indicators has to be considered specifically in relation to the objective of the diagnostic procedure. As sward N index may vary independently of soil mineral N content, the sward N indicator does not appear to be a suitable indicator for diagnosis of environmental risks related to nitrate leaching. However, soil mineral N content does not allow the prediction of sward N status and thus is not a suitable indicator of sward growth rate. Although soil mineral N content is an important environmental indicator for nitrate-leaching risks during potential drainage periods, it has a limited diagnosis value with respect to the herbage production function of grasslands. [source] Influence of herbivory, competition and soil fertility on the abundance of Cirsium arvense in acid grasslandJOURNAL OF APPLIED ECOLOGY, Issue 2 2000G.R. Edwards Summary 1. ,The extent to which the weed Cirsium arvense (creeping thistle) may be controlled by manipulating interspecific competition and herbivory was examined in two factorial experiments in order to identify non-chemical herbicide-based control methods for the weed. 2. ,In the first experiment, a single spring cultivation of grassland intensively grazed by rabbits led to a 25-fold increase in C. arvense cover within 3 months, the effects of which were still present the following summer. As well as destroying the competing perennial vegetation, cultivation created and dispersed small root fragments (3,5 cm in length) from which almost all shoot recruitment occurred. 3. ,Fencing the cultivated plots against rabbits decreased the cover of C. arvense because ungrazed regrowth from palatable/grazing intolerant species reduced recruitment of C. arvense seedlings and shoots. Seedling competition, in the form of a wildflower seed mix sown soon after cultivation, reduced C. arvense cover on fenced plots to pre-cultivation levels. 4. ,In the second experiment, conducted in a permanent grassland, C. arvense shoot densities on plots fenced against rabbits and treated as a hay meadow were about one-eighth of those found on rabbit-grazed plots where competing vegetation was kept short. Adventitious shoot recruitment was greater on soil disturbances such as molehills and rabbit scrapes than in intact vegetation. Seedling recruitment occurred only on soil disturbances such as molehills. 5. ,Lime and nitrogen fertilizer application to the fenced grassland increased the standing biomass of competing species, which reduced C. arvense shoot density. Outside the fences, rabbit grazing was so concentrated on the competing species of the nitrogen-fertilized and limed areas that C. arvense benefited from competitive release, exhibiting increased shoot density. Cirsium arvense showed pronounced competitive release from grasses, with greater shoot densities where grasses were removed with selective herbicides than where no plant species were removed. 6. ,Exclusion of insects and molluscs with chemical pesticides had no effect on shoot or seedling recruitment or overall shoot density on cultivated soil or in permanent grassland. 7. ,It is concluded that combinations of management procedures that encourage interspecific competition, such as sowing crops soon after cultivation and delaying grazing of them, and nitrogen fertilizer application and non- or reduced grazing of intact grasslands, will help reduce C. arvense abundance. [source] Effect of phosphate fertilization on crop yield and soil phosphorus status,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2003Anne Gallet Abstract To evaluate the effect of three phosphorus (P) fertilization regimes (no P, P input equivalent to P off-take by crops, P input higher than P off-take) on crop yield, P uptake, and soil P availability, seven field experiments (six in crop rotations, one under permanent grassland) were conducted in Switzerland during nine years (six trials) or 27 years (one trial). Soil total P (Pt), inorganic P (Pi), organic P (Po), and the amount of isotopically exchangeable soil P were measured in the 0,20,cm and 30,50,cm layers of the arable soils and in the 0,10,cm layer of the permanent grassland soil. Omitting P fertilization resulted in significant yield decreases only in one field crop trial as the amount of P isotopically exchangeable within one minute (E1min) reached values lower than 5 mg P (kg soil),1. In the absence of P fertilization Pi decreased on average from 470 to 410 mg P (kg soil),1 in the upper horizon of 6 sites while Po decreased only at two sites (from 510 to 466 mg P (kg soil),1 on average). In all the treatments of the trials started in 1989 the E1min values of the upper horizon decreased on average from 15.6 to 7.4 mg P (kg soil),1 between 1989 and 1998. These decreases were also observed when P inputs were higher than crops needs, showing that in these soils the highest P inputs were not sufficient to maintain the high initial available P levels. Finally for the six arable trials the values of the isotopic exchange kinetics parameters (R/r1, n, CP) and P exchangeable within 1 minute (E1min) at the end of the experiment could be estimated from the values measured at the beginning of trial and the cumulated P balance. Der Einfluss der Phosphordüngung auf den Pflanzenertrag und den Phosphorstatus des Bodens Die Begrenzung der Düngung mit Phosphat (P) bei Böden, die bereits hohe Gehalte an verfügbarem P aufweisen, kann zur Verringerung der P-Verluste in Oberflächen- und Grundwasser beitragen. Sieben Feldversuche (6 Versuche mit Ackerkulturen, 1 Versuch mit Dauerwiese) wurden während 9 Jahren (6 Versuche) resp. 27 Jahren (1 Versuch) durchgeführt mit dem Ziel, den Einfluss von drei Düngungsraten (keine P-Gabe, P-Gabe entsprechend dem P-Entzug durch die Pflanzen und P-Gabe höher als der P-Entzug durch die Pflanzen) auf Pflanzenertrag, P-Aufnahme und P-Verfügbarkeit zu studieren. Die Gehalte an anorganischem P (Pi) und organischem P (Po), sowie deren Summe (Pt) und die Gehalte an isotopisch austauschbarem P wurden in den Bodentiefen von 0,20,cm und 30,50,cm der ackerbaulichen Versuche und in einer Bodentiefe von 0,10,cm in der Dauerwiese gemessen. Der Verzicht auf P-Düngung führte nur in einem der ackerbaulichen Versuche zu einer signifikanten Abnahme des Pflanzenertrags, wobei der Gehalt an isotopisch austauschbarem P (E1min) unter 5 mg P (kg Boden),1 fiel. Pi sank bei Verzicht auf P-Düngung im oberen Horizont von 6 Böden durchschnittlich von 470 auf 410 mg P (kg Boden),1, während Po nur in 2 Böden absank (durchschnittlich von 510 auf 466 mg P (kg Boden),1). Ueber alle Düngungsverfahren jener Versuche, die 1989 begonnen hatten, sank E1min im oberen Horizont von 1989 bis 1998 durchschnittlich von 15.6 auf 7.4 mg P (kg Boden),1. Die Abnahme wurde auch beobachtet, wenn die P-Gabe höher war als der P-Entzug durch die Pflanzen, was zeigt, dass in diesen Böden selbst die höchste P-Gabe nicht genügte, um den ursprünglich hohen Gehalt an verfügbarem P aufrecht zu erhalten. Schließlich wurden in den 6 ackerbaulichen Versuchen die Parameter der Isotopenaustauschkinetik (R/r1, n, CP) und E1min am Ende des Versuches mit den ursprünglichen Werten zu Beginn des Versuchs verglichen. Es ergaben sich signifikante Beziehungen zwischen den Werten am Ende des Versuchs einerseits und den ursprünglichen Werten und der P-Bilanz andererseits. [source] Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decadesGLOBAL CHANGE BIOLOGY, Issue 7 2009D. W. HOPKINS Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source] Re-evaluation of the liming-fertilization interaction in grasslands on poor and acid soilsGRASS & FORAGE SCIENCE, Issue 2 2010V. Poozesh Abstract The effect of surface liming on herbage production in permanent grasslands is rather uncertain. To better understand the effect of liming on the grassland, a study was made with a field experiment and a pot experiment with soil from the same field. In the field, the effects of liming and NPK fertilization on the production and composition of the vegetation were studied. In pots, the effects of liming and phosphate fertilization on different grass species were analysed. The effect of NPK fertilization (+3·96 t ha,1) on the production of the original grassland was greater than that of liming (+0·68 t ha,1), which was only observed (P < 0·05) on the unfertilized plots. Liming increased the total number of species and the proportion of dicotyledons. After replacing the semi-natural community with Dactylis glomerata L., the effects of liming (+2·37 t ha,1) and fertilization (+6·52 t ha,1) were increased. These results, together with those of the pot trial, show the important role of phosphorus in the fertilization effect, and are interpreted as a protective effect of P against aluminium toxicity. [source] | |||||||||||||