Sown Pastures Research Articles

Fragmentation Status of Tall-Tussock Grassland Relicts in the Flooding Pampa, Argentina

Abstract Since European settlement vast areas of the tall tussock grassland dominated by Paspalum quadrifarium Lam. and Paspalum exaltatum J. Presl (“pajonal” grassland) in the Flooding Pampa of Argentina were converted to croplands and short grasslands. With the use of Landsat satellite images, we analyzed current (1998–2000) cover and spatial integrity of the pajonal community, and compared it with a vegetation map made 50 yr ago (1956–1960). Six categories of land cover were adopted: crops, sown pastures, short grassland, pajonal, wetlands, and anthropogenic areas. With the use of metrics from FRAGSTATS, landscape pattern and composition were analyzed at two scales: 1) regionally, by comparing two edaphic domain areas with relatively low and high restrictions for agriculture (low-restriction domain [LRD] and high-restriction domain [HRD], respectively); and 2) at landscape scale, by comparing ten 22 500-ha randomly selected areas (landscapes) within each edaphic domain. Current relative cover of pajonal grassland (2 173 600 ha) was 32.5%, and similar values were obtained within each edaphic domain. However, the number of pajonal patches was higher and their mean patch size, the Euclidean nearest-neighbor distance among patches (degree of isolation), and their border regularity were lower in the LRD than in the HRD. At landscape scale, the mean size of pajonal patches diminished with the percent of agricultural land within both edaphic domains. The isolation among pajonal patches increased with percent of agricultural land in the HRD, whereas no relationship between the isolation of pajonal patches and percent of agriculture was found in the LRD. As suggested by comparison with past vegetation, current pajonal status mostly results from replacement of pajonal grassland by short grassland types, cultivated pastures, and annual crops (52% and 44% of previously occupied areas in LRD and HRD, respectively), but some expansion of pajonal grassland was also observed (10% and 4% of previously unoccupied areas in LRD and HRD, respectively).

Drying temperature effects on bulk density and carbon density determination in soils of northern New South Wales

There is a widespread and growing need for information relating to soil condition and changes in response to land management pressures. To provide the information needed to quantify land management effects on soil condition, monitoring systems are now being put in place and these programs will generate large numbers of samples. Streamlined procedures for the analysis of large sample numbers are therefore required. Bulk density (BD) is considered to be one of several key indicators for measuring soil physical condition, and is also required to estimate soil carbon density. The standard analytical technique for BD requires drying the soil at 105°C but this procedure creates several logistical and analytical problems. Our initial objective was to derive correction factors between drying temperatures to allow for rapid, low-temperature estimation of BD on large sample numbers. Soil samples were collected from 3 contrasting soil types (basalt, granite, and meta-sediments) in 4 land uses (cultivation, sown pasture, native pasture, woodland) in northern New South Wales to test the effect of soil drying temperature on BD determination. Cores were divided into 4 depths (0–0.05, 0.050–0.10, 0.10–0.20, 0.20–0.30 m), and oven-dried at 40, 70, and 105°C. Drying temperature had no significant effect on BD but the effects of soil type, depth, and land use were significant, varying according to expectations based on previous studies, i.e. higher BD in granite-derived soils and lower in basalt-derived soils, increased BD with depth, and increasing BD with increasing management intensity. These results indicate that lower drying temperatures (40°C) were adequate for the efficient determination of BD especially where analysis of other soil properties from the same sample is required. However, before this approach is applied more widely, further calibration of BD and drying temperature should be undertaken across a wider range of soils, especially on clay-rich soils.

Fertilidade e contaminação por metais pesados e microrganismos fecais de um solo sob pastagem pela aplicação de lama residual urbana

In wide areas of Alentejo, soils under natural pasture have low fertility. Urban biosolids (UB) application introduce organic matter (O.M.) and nutrients in the soil, but it can also add heavy metals and bacteria of faecal origin. Thus, soil monitoring after the application of these residues is required. Organic with UB and mineral fertilisations were compared regarding their effects on some fertility and metallic and faecal pollution indicators of a soil derived from schists and grauwacks, in the 1st year of a field experiment with pastures. The experimental layout was a split-plot design, with six plots of 0.5 ha, referring to three fertilisation treatments (“nil”, mineral, and organic, with UB), in natural and sown pastures. The UB application was about 13 t/ha of a UB mixture from the Alvito and Vila Nova de Baronia plants, rich in O.M., N, and Ca. Mineral fertilisation included N, P, K, Zn, and Mo. Soil samples (fraction <2 mm) collected at the 0-15/20 cm depth, before the fertilisers application and around one year after the establishment of the experiment were analysed for pH (H2O) value and O.M., total N, available P and K, exchangeable cations, and extractable aqua regia Cd, Cr, Cu, Ni, Pb, and Zn. Microbial indicators of faecal contamination (coliform bacteria and enterococci) were also evaluated from topsoil samples (0-5/10 cm), collected immediately after the UB application, and 6 and 13 months afterwards, in the treatments with and without UB application. For both types of pasture, the UB application significantly improved the O.M. content in the soil surface layer, one year after the fertiliser application, and did not change the initial soil levels of heavy metals and bacteria populations of faecal origin.

Which crops should be included in a carbon accounting system for Australian agriculture?

Dryland agriculture is both a potential source and potential sink for CO2 and other greenhouse gases. Many carbon accounting systems apply simple emissions factors to production units to estimate greenhouse gas (GHG) fluxes. However, in Australia, substantial variation in climate, soils, and management across &gt;20 Mha of field crop sowings and &gt;30 Mha of sown pastures in the intensive land use zone, provides substantial challenges for a national carbon accounting system, and simple emission factors are unlikely to apply across the region. In Australia a model framework has been developed that requires estimates of crop dry matter production and harvested yield as the first step to obtain carbon (residue) inputs. We use Australian Bureau of Statistics data to identify which crops would need to be included in such a carbon accounting system. Wheat, barley, lupin, and canola accounted for &gt;80% of field crop sowings in Australia in 2006, and a total of 22 crops account for &gt;99% of the sowing area in all States. In some States, only four or six crops can account for 99% of the cropping area. We provide a ranking of these crops for Australia and for each Australian State as a focus for the establishment of a comprehensive carbon accounting framework. Horticultural crops, although diverse, are less important in terms of total area and thus C balances for generic viticulture, vegetables, and orchard fruit crops should suffice. The dataset of crop areas presented here is the most comprehensive account of crop sowings presented in the literature and provides a useful resource for those interested in Australian agriculture. The field crop rankings presented represent only the area of crop sowings and should not be taken as rankings of importance in terms of the magnitude of all GHG fluxes. This awaits a more detailed analysis of climate, soils, and management practices across each of the regions where the crops are grown and their relationships to CO2, nitrous oxide and methane fluxes. For pastures, there is a need for more detailed, up to date, spatially explicit information on the predominant sown pasture types across the Australian cropping belt before C balances for these can be more reliably modelled at the desired spatial scale.

Pasture - crop rotations for sustainable production in a wheat and sheep-based farming system on a Vertosol in south-west Queensland, Australia

Rainfed grain production, based on winter cereals, is marginal in south-west Queensland, Australia, because of low and variable rainfall and high evapotranspiration. Also, grain yield and grain quality have decreased as soil fertility, particularly soil nitrogen supply, has declined on older cropping lands. An option for improving soil N supply is to include legume-based pastures in rotation with winter cereals. The objective of this study was to determine the effects of short-term (18 months) legume pastures (annual medics and lucerne + annual medics), and longer term (3 years) mixed grass (Bambatsi panic) and legume (lucerne + annual medics) pasture phases on sheep production and on soil water and N supply and production of subsequent wheat crops on a grey Vertosol soil. Two separate phases of annual medics and lucerne + annual medics pastures produced mean total aboveground dry matter yield of 7.10 t/ha of annual medics and 5.80 t/ha of lucerne + annual medics over the 18-month periods. For two phases of the grass + legume pastures, mean total aboveground dry matter yield was 3.95 t/ha for grass and 8.19 t/ha for legume over 3 years. Over an 18-month period, sheep bodyweight gains and fleece weights were similar for the annual medics, lucerne + annual medics and grass + legume pastures and were approximately five times greater than those from native pasture as a result of the greater stocking rate possible on the sown pastures. Greater drying of the soil profile occurred following lucerne + annual medics and grass + legume pasture phases than continuous wheat, resulting in lower soil water content at sowing of wheat crops following these pasture phases on several occasions. Mean soil nitrate-N benefits before wheat sowing in the first year following termination of the 18-month annual medics, lucerne + annual medics, and the 3-year grass + legume pasture phases were 45, 44 and 42 kg N/ha, respectively. Grain N yields and gross margins of the first wheat crops following the 18-month annual medics, lucerne + annual medics, and the 3-year grass + legume pasture phases were similar in value to continuous wheat with ~60, 80, and 40–60 kg N/ha fertiliser applied at sowing, respectively. Improvements in grain N yield and gross margin were still evident in the fifth wheat crop following annual medics and lucerne + annual medics pastures and in the third wheat crop following grass + legume pasture, compared with continuous wheat without N fertiliser addition. Total gross margins from 1996 to 2005 were 1.6–2.5 times greater for the pasture–crop rotations than continuous wheat where no N fertiliser was applied to wheat. However, gross margins were greater in continuous wheat than in pasture–crop rotations where N fertiliser was applied to target prime hard grade grain protein in wheat. The 3-year grass + legume pasture phase showed potential to improve surface soil structure and water infiltration and to reduce decline in soil organic carbon concentration at 0–0.1 m depth, compared with continuous wheat cropping and shorter-term legume pasture phases.

Adaptation of forage legume species and cultivars under grazing in two extensive livestock systems in Italy

Legume-based pastures can increase the forage feeding value, the self-provision of protein sources and the sustainability of grazing systems. This 4-year study provided further knowledge on adaptation of forage legume species and cultivars for pasture sowing in extensive livestock systems of inland Italian areas. Three cultivars of lucerne ( Medicago sativa L.), two of birdsfoot trefoil ( Lotus corniculatus L.) and two of sainfoin ( Onobrychis viciifolia Scop.) were evaluated at Casina (northern Apennines) under cattle grazing and at Torricella Sicura (central Apennines) under sheep grazing in farms using rotational grazing with high stocking rates. Semi-erect lucerne and birdsfoot trefoil morphological types, presumably more grazing-tolerant, were compared with erect types. Species showed contrasting adaptive responses, with lucerne at Casina and birdsfoot trefoil at Torricella Sicura being highest ranking for overall dry-matter yield. Lucerne at the former location, and both lucerne and birdsfoot trefoil at the latter one showed the highest final ground cover. The kind of exploitation at Casina (mob-grazing) may have contributed to lower persistence of birdsfoot trefoil. Sainfoin mostly showed potential as a short-term grazing species. Performance of cultivars within species varied with location. Erect cultivars yielded and persisted as well as, or better than, semi-erect cultivars, possibly because of the adoption of rotational grazing and their Italian origin (implying possible better adaptation to local conditions). Erect cultivars of lucerne were specifically adapted to the geographical area in which they were selected. Specific adaptation and targeted intensity of grazing may be the main determinants in the choice of species and cultivars.

The role of plant leaf attributes in linking land use to ecosystem function in temperate grassy vegetation

We tested predictions of the relative changes in plant leaf traits in response to land uses in Australian eucalypt grassy ecosystems. Predictions were determined from responses observed in European landscapes in relation to disturbances associated with agricultural land uses. We measured specific leaf area (SLA) and leaf dry matter content (LDMC) across five land uses: reference sites (closest to pre-European state), native pastures (unfertilized), fertilized pastures, sown pastures (cultivated and fertilized) and enriched grassland (previously fertilized, no longer grazed). Leaves were expected to have higher SLA and lower LMDC at sites with increasing fertility and/or disturbance. The predictions were confirmed, with SLA increasing progressively in land uses associated with (1) grazing; (2) grazing and fertilization; (3) grazing, fertilization and cultivation. Values for LDMC were closely (but inversely) correlated with those of SLA. For both traits, there were relationships with available soil phosphorus but not with soil total nitrogen. The positive correlation of SLA with phosphorus was not evident above 30 mg kg −1, the recommended level of phosphorus for improved pastures. Results confirm patterns of leaf-trait response to disturbance that reflect fundamental constraints to plant survival in habitats with different levels of resources and disturbances. A conservative strategy for low productivity undisturbed habitats is associated with low SLA and high dry matter content in contrast to fertile disturbed habitats which select for high SLA and low dry matter content. The changes in leaf traits across land uses resulted from species substitution rather than variation within species across sites, and most notably the replacement of native by annual exotic species as land use intensifies. Recommended fertilization rates for pasture production convert the ground layer to plants with soft, digestible leaves, that are responsive to fertilizer and desirable for livestock production. However, fertilization also drastically reduces the diversity of native plants and annual plants tend to dominate. The trade-off associated with high production includes increased vulnerability to soil erosion, due to reduced plant cover and low persistence of cover. If alternative ecosystem values such as erosion control, water quality, salinity control and biodiversity persistence are required, incentives may be needed to offset the loss of production that can be gained from fertilizer application.

Plant responses to agricultural intensification

Summary 1. A large proportion of the world's land surface is extensively managed for livestock production. In areas where livestock systems are becoming more intensive, a major challenge is to predict those plant species likely to decline, persist or increase as a result of agricultural intensification. 2. Most analyses develop inferences for frequent or abundant species, or rely on intensive studies of single species. A promising approach is to identify plant traits related to disturbance to enable inference to be made about changes in plant community composition. We used a Bayesian hierarchical model to analyse the response to agricultural intensification of 494 plant species of pastures and woodlands in southern Australia, and to identify how simple species' traits (life form, growth form and species origin) influence those responses. 3. The probability of occurrence of most species declined along the two intensification gradients, grazing intensity and soil phosphorous concentration, although the occurrence of a greater proportion of species was negatively correlated with soil phosphorous. Responses could be broadly predicted from both plant origin and plant traits, in particular growth form. 4. Native perennial geophytes, ferns and shrubs were most negatively affected by both gradients, while exotic annual grasses and forbs were more tolerant. Along the phosphorous gradient, 24 of the 30 most negatively affected plant species were native geophytes. Mean within-group responses masked considerable within- and between-species variation, particularly for the exotic species group which included species that responded both negatively and positively to intensification. 5. Synthesis and applications. The hierarchical model described here provides a powerful method for estimating individual plant responses and identifying how species' traits influence those responses. Plant species native to southern Australia are sensitive to grazing and phosphorous apparently due to a shared evolutionary history of low grazing intensity and low phosphorous soils. Invading exotic plants have faced strongly contrasting ecological filters, leading to a greater diversity of responses. Where grazing systems have been most intense, a small suite of exotics dominate. Maintaining native and functional plant diversity will necessitate limits being placed on intensive livestock management systems.

Intensive rotational grazing assists control of gastrointestinal nematodosis of sheep in a cool temperate environment with summer-dominant rainfall

While rotational grazing methods have an accepted role in the management of gastrointestinal nematodosis (GIN) of small ruminants in humid tropical regions, their efficacy and application in cool temperate regions is more controversial. This study evaluated GIN over 2 years in three classes of fine wool Merino sheep (lambs, hoggets and ewes) under three different sheep management systems in a cool tableland environment near Armidale NSW Australia (950 m altitude, 30°31′S, 151°39′E). The management systems were High input (HI) with high fertiliser inputs, a target of 100% sown pasture, high stocking rate (13.4 dry sheep equivalents/ha) and relatively long grazing periods; Typical (TYP) New England management system with moderate fertiliser inputs and stocking rate (9.3 DSE/ha) and relatively long grazing periods; and Intensive rotational grazing (IRG) with moderate fertiliser inputs and stocking rate (8.8 DSE/ha) but very short (mean 5 days) grazing periods and long (mean 103 days) rest periods. Twenty sheep of each class in each management treatment were sampled monthly for faecal worm egg counts (WEC, followed by larval differentiation), and body weights with a blood sample taken for haematology every second month. The proportion of sheep with WEC above zero did not differ between management systems but the magnitude of WEC did, with sheep under IRG displaying lower mean WEC than those on the other treatments (IRG: 326, HI: 594, TYP: 536, eggs/g P < 0.0001). This was despite a significantly longer mean interval between anthelmintic treatments (IRG: 144 days, HI: 77 days, TYP: 78 days, P < 0.0001). The IRG management system also influenced the composition of the infections with sheep on this treatment having a significantly lower proportion of Haemonchus contortus in their faecal cultures (IRG: 59.7%, HI: 79.4%, TYP: 80.9%, P < 0.05) and a significantly higher proportion of Trichostrongylus spp. Sheep on the IRG treatment also had a significantly higher haematocrit (HCT) than those on the other management systems. Despite the lower WEC and higher HCT, sheep under IRG also had significantly lower bodyweights and fleece weights overall, although this was only evident in sheep raised to adulthood prior to the experiment, not those raised during the 2-year experimental period. The results demonstrate that IRG systems with short grazing periods and long rest periods between grazing events can assist with control of GIN in cool temperate climates where H. contortus is the dominant parasite.

Soil organic carbon stocks in saline and sodic landscapes

Increasing salinity (high levels of water-soluble salts) and sodicity (high levels of exchangeable sodium) are serious land degradation issues worldwide. In Australia, salinity and sodicity affect a large proportion of the landscape and often coincide with agricultural land. Despite the areal extent of salt-affected soils, both worldwide and in Australia, few data exist on soil organic carbon (SOC) stocks in these areas. For this study, the level of SOC was determined in scalded (bare areas without vegetation), scalded-eroded, vegetated, and revegetated (i.e. sown pasture) soil profiles from 2 sites in the Southern Tablelands region of New South Wales, Australia. SOC concentration was significantly higher in the profiles that were vegetated with native pasture (1.96–2.71% in the 0–0.05 m layer) or revegetated with sown pasture (2.35% in the 0–0.05 m layer), and lower in those profiles that were scalded (1.52% in the 0–0.05 m layer) or scalded-eroded (0.16–0.30% in the 0–0.05 m layer). These lower SOC levels are reflected throughout the profiles of the scalded and scalded-eroded soils. The soil carbon stocks to 0.30 m are also much lower in the scalded and scalded-eroded soils that have been affected by salinity and sodicity. The profiles that were vegetated with native pasture had carbon stocks to 0.30 m of 35.2–53.5 t/ha, while the sown pasture had 42.1 t/ha. This compares with the scalded profiles with 19.8 t/ha and the scalded-eroded profiles with 7.7–11.4 t/ha to 0.30 m. The presence of vegetation ameliorates several soil properties and results in the differences in SOC and other soil properties between scalded and vegetated profiles at the surface and at depth.

Salmonella uptake in sheep exposed to pastures after biosolids application to agricultural land

Young adult sheep grazing pasture on land treated with dewatered biosolids 1–3 weeks before pasture sowing were used to assess the risk of transfer of Salmonella spp. from biosolids to the food chain. Monthly determinations of Salmonella spp. concentrations in the biosolids after land application showed survival for at least 7 months, with concentrations fluctuating between 104/g and below detection limits at various time points. Low concentrations were measured 4–5 months after application, followed by a return to 102–103/g on subsequent samplings. Sheep introduced at 3 or 6 months after biosolids applications of 0, 10, or 15 dry t/ha were assessed monthly for faecal shedding of salmonellae, and at slaughter, 8 months after biosolids application, for intestinal carriage of Salmonella spp. None of 80 sheep grazing the biosolids-treated land were found to excrete salmonellae. A single sheep among those grazing treated land showed Salmonella carriage in slaughter tissues, but the serovar isolated from this animal was different from the 6 serovars of Salmonella detected in the applied biosolids. Use of dewatered biosolids on land later sown for pasture and grazed by sheep thus posed no risk to animal uptake or faecal shedding of Salmonella spp. This in part relates to a low risk of direct pathogen ingestion by grazing sheep and the period of several months necessary for pasture establishment before grazing stock can be introduced.

Avaliação experimental do escoamento e da erosão num Luvissolo Háplico de Mértola: impactos da fertilização em pastagens

In a experimental area located in a hillside of Mertola region, Alentejo, with an Haplic Luvisol (FAO, 2001) and a mean slope of 15%, soil loss by erosion and surface runoff after rainfall occurrence were evaluated in small erosion plots, from October 2001 until June 2004, in 3 field experiments (A, B, and D) with a sown pasture mixture under different fertilization treatments. The experiments A (improved pasture) and B (sown pasture) were established in 1997, but the experiment D (sown pasture) was only installed in 2001. The sown mixture consisted of ryegrass, cocksfoot, some clover species, bisserula, and bird’s foot. In both experiments A and B, the erosion plots (4 × 1 m2) were superimposed on 6 plots. These experiments had three treatments (1 - without fertilization, 5 - inorganic fertilization; 7 - organic fertilization (8 t/ha of urban sewage sludge - SS applied in 1997, plus inorganic fertilizer in the beginning of each growing period) and two replications. In D experiment, the erosion plots were also superimposed on 6 large plots with three SS application rates (L0 = 0, L1 = 12, and L2 = 24 t/ha) and two replications. In each erosion plot, the volume of discharged water was measured and the amount of sediments was estimated when the infiltration capacity was exceeded by the amount of the rainfall occurring for one or several consecutive days of rainfall. The lowest observed runoff coefficient corresponded to the SS treatment, in B experiment. The highest values of that coefficient were reached at the treatment without fertilization in both A and B experiments. In D experiment, all treatments showed low values, between 0.07 and 0.10. The lowest soil loss values in the 3 years occurred in experiments A and B for the treatment with 8 t/ha of SS. In the experiment D, the highest values of soil loss were observed at the plots with L0 treatment.

Camponotus punctulatus ant’s demography: a temporal study across land-use types and spatial scales

Agricultural activities promote the explosion of diverse pest populations. In Argentina, the ant Camponotus punctulatus invades agricultural fields after production ceases. The temporal demography and spatial distribution of colonies of C. punctulatus were studied over a five year period using replicated plots of different land use types representing a gradient of increasing agricultural disturbance. We experimentally tested the hypothesis that the increase in C. punctulatus colony density was related to increasing levels of agricultural disturbance. Abandoned rice fields represented the situation with greatest disturbance. Sown pastures were intermediate. Natural grasslands represented no agricultural disturbance. The predictions were (1) the greater the soil disturbance produced by agriculture, the greater the susceptibility for invasion by C. punctulatus, (2) rice fields offers greater opportunities for establishment of colonizing species than sown pastures, and (3) disturbed land use areas that were more recently colonized as well as land use areas with greater soil disturbance will exhibit patterns of colony aggregation at a small scale but with time the patterns will become uniform. Initially, colonies in the abandoned rice fields had a higher annual mortality and larger turnover than in sown pastures. Over five years, abandoned rice fields sustained higher densities of colonies than sown pastures. The colonies were the largest and had the longest lifespans in abandoned ricefields. Natural grasslands had the lowest colony density, survivorship, and size but had variable levels of colonization. More than one type of spatial distribution was found in field replicates. At small spatial scales across disturbed land use types, replicates exhibited regular distributions. At greater spatial scales, spatial distributions were mostly random in sown pastures, there were many cases of aggregation in rice fields, although some cases of uniform distributions were also found in all disturbed land uses. These results highlight significant intraspecific variation in ant demography across types of land use, space, and time, and show a clear predisposition of C. punctulatus to invade and successfully establish in the most disturbed land use types. Hypotheses that can account for the changes in demography across land use types are discussed.

Responses to the renovation of an irrigated perennial pasture in northern Victoria. 2. Botanical composition, and plant and tiller densities

A field experiment was established in northern Victoria in the autumn of 1999 to quantify the effects of renovating a 15-year-old, irrigated perennial pasture with a high paspalum content. The treatments were: (i) control, the existing pasture; (ii) oversown, the existing pasture grazed, topped and direct drilled; and (iii) resown, the existing pasture sprayed, cultivated and a new pasture sown. The grass species used in both renovation treatments were perennial ryegrass, Italian ryegrass and tall fescue. The treatments were grazed by dairy cows. The botanical composition, tiller density and plant frequency are reported in this paper. Oversowing with either perennial or Italian ryegrass increased the sown grass content by an average of 4–8% DM, and by up to 20% DM during winter and spring, but did not affect the average white clover, volunteer species or dead contents. Oversowing did not affect the sown grass or paspalum tiller densities but annual oversowing with either perennial or Italian ryegrass increased the ryegrass plant frequency and, in 2 of the 4 years, reduced the white clover growing point density. Resowing increased (P &lt; 0.05) the content of sown grasses (by 12% DM for perennial ryegrass and by 20% DM for tall fescue) and white clover (by 8% DM) and decreased (P &lt; 0.05) the content of volunteer species (by 18% DM) and, in years 1 and 2, dead material. The plant frequency of tall fescue increased over time (from 75 to 83% of quadrats), whereas that of perennial ryegrass declined (from 87 to 72% of quadrats). This resulted in the resown tall fescue having a lower (P &lt; 0.05) white clover content and growing point density in years 3 and 4, and a tendency for a lower volunteer species content and tiller density in year 4, than the resown perennial ryegrass. Tall fescue is thus better able to resist the invasion of summer-active species and is less likely to require either oversowing or resowing than perennial ryegrass-based pastures. These results suggest that tall fescue should be considered as an alternative to perennial ryegrass when sowing pastures. The use of nitrogen did not improve the sown grass content, tiller density or plant frequency and will not therefore overcome problems resulting from a low ryegrass content.

Pasture and grazing land: assessment of sustainability using invertebrate bioindicators

Impacts of practices frequently used to manage Australian pastures are reviewed with the aim of determining which groups are responsive to changes in grazing regime, fertiliser use, pasture types, tree clearing, pesticide use, liming and irrigation. Invertebrate groups sensitive to pasture management regimes may be potential candidates for use as bioindicators of ecological sustainability of these pasture types. This review concentrates on the more intensively utilised temperate pastures of southern Australia, as very little work has been done on the impact of the grazing animal and pasture management on invertebrate fauna on the extensive rangelands of the arid and semiarid zones. Background to the relative importance of invertebrates in the functioning of the pasture ecosystem is given. This has culminated in the construction of food webs for two temperate perennial pastures (an unfertilised, native and a fertilised, sown pasture) at Armidale, NSW, for which there is comprehensive data available. Invertebrate bioindicators of pasture sustainability emerged from the consideration of grazing lands and invertebrate responses. Currently, only four groups would seem to be likely candidates as bioindicators of sustainability of pastures. These are soil nematodes, earthworms, protozoa and Collembola. The main difficulty in monitoring these groups is that it requires specialist expertise, and services provided by commercial laboratories for routine biological soil tests are still in their infancy. There are gaps in our knowledge of how invertebrate fauna react to the pressing issues of soil acidity and salinity.

Pasture management in semi-arid tropical woodlands: dynamics of perennial grasses

The effects of a range of pasture management options (introduced legumes and grasses, superphosphate, timber treatment, cultivation before sowing and stocking rate) on the basal cover of perennial grasses were measured from 1982 to 1991 at two sites, ‘Hillgrove’ and ‘Cardigan’, near Charters Towers, in north-east Queensland. Colonisation and survival of eight native and exotic grasses were followed in permanent quadrats in a subset of treatments. Overall, there were significant changes in total basal cover of plots between years and with tree killing, but no significant differences in sown pastures, fertiliser or stocking rate. Basal cover increased when defoliation levels were less than 40% but increases were smaller at higher levels of defoliation and basal cover often declined when defoliation was greater than 60%. Basal cover declined when growing seasons were &lt;10 weeks, remained static with 10–15 weeks growth, and increased when growing seasons were 16 weeks or longer. There was some colonisation in all years but large differences between years. The differences in colonisation between systems were generally small but there was a general trend for higher colonisation at higher stocking rates. Bothriochloa ewartiana (Domin) C.E.Hubb. and Chrysopogon fallax S.T.Blake had low, Heteropogon contortus (L.) P.Beauv. ex Roem.&amp;Schult., Cenchrus ciliaris L. and Aristida spp. had intermediate, and Bothriochloa pertusa (L.) A.Camus and Urochloa mosambicensis (Hack.) Dandy had high colonising ability. Survival of individual species was generally similar at both sites except for Urochloa mosambicensis. Heteropogon contortus and U. mosambicensis at ‘Hillgrove’ were short-lived (&lt;10% survival after 4 years), B. ewartiana, Themeda triandra Forssk. and Aristida spp. had intermediate survival (10–50%), and C. ciliaris, C. fallax, B. pertusa and U. mosambicensis at ‘Cardigan’ were long-lived (&gt;50% survival). Annual survival rates increased with plant age, were higher in good growing seasons than in poor seasons, were higher for large plants than small plants, and were lower at high defoliation levels than where defoliation was less severe. The differences between species in ability to colonise and survive, and the small influence of management compared to seasonal effects on survival, are discussed to explain species performance in pastures.

Ocena plonowania odnowionego użytku zielonego w dolinie Noteci

The aim of this research was to evaluate the yielding of two medow pasture mixtures with varyiny dominants used in the regeneration of a degenerated grassland. The field research was conducted in years 1998–2001 in the Notec Valey in the village Nowe D bie. The experimental field was established on a degenerated pasture on V quality class soil. In the sowing mixtures the dominant species (30 %) were different cultivars of meadow fescue: ’Skra’, ‘Pasja’, ‘Justa’ (model strain), BAH 197 as well as orchard grass cultivars: ‘Amera’ or ‘Astera’. The remaining components of the mixture were the cultivars of the following species: timothy grass – ‘Kaba’ (10 %), perennial ryegrass – ‘Argona’ (10 %), red fescue – “Atra” (15 %), white clover – ‘Rawo’ (20 %), red clover – ‘Karo’ (15 %). The swards were under cutting and grazing utilization. Cultivars of orchard grass were the ones to develop the best from all the sown dominants. The dynamic development suggests high usefulness of orchard grass cultivars in the sowing of meadows and pastures under similar habitat conditions. The cultivars and breading strain of meadow fescue did not develop well. No major influence of the model cultivars and breeding strain of meadow fescue on the assessed parameters was shown. Among other components of the sowing mixtures perennial ryegrass was the most expansive. The yielding of mixtures was strictly connected with the examined factors. With lower frequency of utilization and better development of the sown dominant a much higher yielding was reported.

Selección de especies y efecto del ciervo (Cervus elaphus L.) sobre arbustedos y matorrales de los Montes de Toledo, España central

Los sistemas agroforestales (mosaicos de bosques, arbustedos, matorrales, pastos herbáceos y cultivos) dedicados a la caza del ciervo constituyen una forma rentable y creciente de uso territorial en la España mediterránea desde la década de 1960. Como consecuencia, las cargas cinegéticas han aumentado mucho y sobrepasan con frecuencia los 50 individuos/km2. Ello origina un nuevo problema de sustentabilidad para esos nuevos sistemas agroforestales. Este trabajo analiza la selección de especies leñosas por el ciervo y el efecto de sus poblaciones sobre arbustedos y matorrales de los Montes de Toledo. Se obtuvieron índices de selección para 33 especies leñosas comparando sus porcentajes de utilización (ramoneo) con los de disponibilidad. Phillyrea angustifolia, Arbutus unedo y Quercus faginea presentaron los máximos índices mientras que Thymus mastichina, Daphne gnidium y Pinus pinea exhibieron los más bajos. Las preferencias alimenticias no varíaron significativamente al hacerlo las cargas cinegéticas. El efecto de una carga del orden de 35 ciervos/km2 parece superar el límite de sustentabilidad, incluso teniendo en cuenta que en el área de estudio existen pastos sembrados y cultivos disponibles para los ciervos.

What happens to earthworm casts in the soil? A field study of carbon and nitrogen dynamics in Neotropical savannahs

In the Oxisols of the eastern plains of Colombia, the large native anecic earthworm Martiodrilus sp. is an abundant ecosystem engineer producing long-lasting casts and burrows. Casts deposited in the soil by this species have been estimated at several tonnes per hectare per year. The physical and chemical processes occurring in these casts have never been studied. In this study, we compared the dynamics of water content (WC), total C (C tot), and available N (N avail) contents, and the distribution in size of aggregates in ageing below-ground casts of this species and in the bulk soil. In a native herbaceous savannah and a sown grass/legume pasture ( Brachiaria humidicola, Arachis pintoi, Desmodium ovalifolium and Stylosanthes capitata), fresh surface casts were experimentally injected into artificial burrows of 1 cm Ø and 10 cm depth and sampled at different dates during a total period of 120 days. The injection procedure used resulted in a 34% decrease in WC of the casts from the sown pasture and reduced the mean mass diameter (MMD) of the aggregates of casts from the savannah by 19%. Other properties were not significantly affected by the procedure. For injected casts in both grasslands, MMD and C tot were stable during cast ageing while WC and N avail were initially at levels several times higher than the bulk soil and decreased to similar bulk soil values with ageing. The C tot was twice and one third higher in casts compared with the bulk soil in the pasture and the savannah, respectively. Overall means for cast MMD (8.3 and 7.4 mm) were twice as high as those in the bulk soil (3.8 mm) in the savannah and the pasture, respectively. However, MMD was not significantly different between the casts and the bulk soil in two occasions in the pasture. Available nitrogen (N avail) in injected casts was initially greater than bulk soil levels, reaching maximum levels just after injection (116 and 93 mg kg −1) and remained significantly greater during 1–2 weeks, in the savannah and the pasture, respectively. In conclusion, the tonnes of casts deposited in the soil profile by Martiodrilus sp. each year are likely to contribute greatly to plant nutrition and to the regulation of the soil structure. For each anecic earthworm species, the ecological impact of its below-ground casts is likely to be as important as its surface casts.

Behavioural profile during suckling period in Martina Franca breed jennies reared under semi-extensive conditions

Behavioural profiles of maintenance and social behaviours were studied in Martina Franca breed female donkey (jennies) during the period in which they had suckling foals (1 week to 6 months after foaling). The animals were reared in Southern Italy (40°37′N latitude) and were managed in husbandry conditions, with free access to a natural scrub area and sown pasture all year round. A total of 10 adult, pluriparous jennies, which had a similar foaling date were used. The behavioural observations in the jennies were performed in presence of their foals, for 120 daylight hours. A total of 14 activities were recorded using focal animal sampling (5 min intervals), including maintenance behaviours such as feeding, drinking, walking, resting, and a whole range of less conspicuous activities relative to eliminative and social behaviour such as olfactory communication, grooming, play and vocalisations. Meterological data were also recorded throughout the study. The results indicated that maintenance behaviours differed significantly as a function of the time since foaling (0.05 > P < 0.01). The effect of a.m. or p.m. hours of day were also significant (0.05 > P < 0.01), except for standing. All the activities included in maintenance behaviours were markedly influenced by the individual ( P < 0.01). Among the social ativities considered, the jennies showed a constant proportion of time spent grooming and there was a tendency for an increase in play between dams and their foals by the end of suckling period (4th–5th month). This study offers some information regarding quantitative behavioral profiles of jennies reared under domestic conditions during the suckling period.