Perennial Pasture Systems Research Articles

Nutrient transformations based on sampling scheme and cropping system following subsurface‐banded poultry litter

AbstractPoultry litter (PL) is an excellent source of micro‐ and macronutrients. However, surface applications result in greater nutrient runoff and nitrogen loss via ammonia volatilization. Subsurface banding PL is a promising technology for combating these challenges, but scant information exists on proper soil sampling techniques and management recommendations for subsurface‐applied PL. Therefore, objectives were to quantify the nutrient status based on sampling depth (0–15 cm and 15–30 cm) and schema (systematic [0, 3, 7, and 10 cm from PL bands] and composite) to develop subsurface PL recommendations per system (annual cropping and perennial pasture). Soil samples were collected during PL application (subsurface and surface) and 1, 6, 12, 18, and 24 months thereafter. On average, total N, Mehlich‐3 extractable P, and Mehlich‐3 extractable K were 15%, 96%, and 72% greater, respectively, for subsurface compared to surface applications. Further, Mehlich‐3 and water‐soluble P at the 0‐ to 15‐cm depth were 4–5 and 2–3 times greater in soils receiving subsurface PL in perennial pasture and row crop systems, respectively, compared to surface applications, likely owing to lesser nutrient losses to the air, soil, and water under subsurface PL systems. Compared to surface applications, subsurface PL increased (p < 0.05) N, P, and K crop removal by 75%, 70%, and 72%, respectively, and resulted in 80% and 78% yield increases and N‐use efficiency, respectively. Consequently, subsurface PL conserved greater N, P, and K at the 0‐ to 15‐cm depth, thus increasing nutrient‐use efficiency in row crop systems and improving water quality in sensitive watersheds.

Effect of Long-Term Semiarid Pasture Management on Soil Hydraulic and Thermal Properties

Semiarid pasture management strategies can affect soil hydraulic and thermal properties that determine water fluxes and storage, and heat flow in unsaturated soils. We evaluated long-term (>10 years) perennial and annual semiarid pasture system effects on saturated hydraulic conductivity (ks), soil water retention curves (SWRCs), soil water thresholds (i.e., volumetric water content (θv) at saturation, field capacity (FC), and permanent wilting point (PWP); plant available water (PAW)), thermal conductivity (λ), and diffusivity (Dt) within the 0-20 cm soil depth. Forage systems included: Old World bluestem (Bothriochloa bladhii) + legumes (predominantly alfalfa (Medicago sativa)) (OWB-legume), native grass-mix (native), alfalfa + tall wheatgrass (Thinopyrum ponticum) (alfalfa-TW), and annual grass-mix (annual) pastures on a clay loam soil; and native, teff (Eragrostis tef), OWB-grazed, and OWB-ungrazed pastures on a sandy clay loam soil. The perennial OWB-legume and native pastures had increased soil organic matter (SOM) and reduced bulk density (ρb), improving ks, soil water thresholds, λ, and Dt, compared to annual teff and alfalfa-TW (P < 0.05). Soil λ, but not Dt, increased with increasing θv. Grazed pastures decreased ks and water retention compared to other treatments (P < 0.05), yet did not affect λ and Dt (P > 0.05), likely due to higher ρb and contact between particles. Greater λ and Dt at saturation and PWP in perennial versus annual pastures may be attributed to differing SOM and ρb, and some a priori differences in soil texture. Overall, our results suggest that perennial pasture systems are more beneficial than annual systems for soil water storage and heat movement in semiarid regions.

Strawberry clover (Trifolium fragiferum): current status and future role in Australian agriculture

Strawberry clover (Trifolium fragiferum L.) is periodically raised as an alternative perennial pasture legume for temperate regions of Australia. Its tolerance of waterlogging is widely known, yet its ability to persist through periods of soil moisture deficit is often understated. Other desirable characteristics include its stoloniferous growth habit and tolerance of mildly saline conditions. Only four strawberry clover cultivars have been registered in Australia, and the most popular, cv. Palestine, is a direct introduction, released in 1938 and first certified in 1951. Furthermore, strawberry clover’s distribution has largely been confined to niche environments, particularly waterlogged and saline areas. This paper reviews the taxonomy and breeding system, morphology, distribution and ecology, and subsequent transfer of strawberry clover to Australia. It reviews and maps the suitability of strawberry clover for perennial pasture systems in the medium–-high rainfall and irrigated temperate zones of Australia, with reference to future climates. The paper also highlights the breeding focus, commercialisation and marketing required to supersede cv. Palestine and lists the germplasm available in the Australian Pastures Genebank, with origins. We conclude that, although strawberry clover is unlikely to become a dominant perennial pasture legume species in Australia, it could be used in a wider range of environments than just those affected by salinity and/or waterlogging stress.

Compost and legume management differently alter soil microbial abundance and soil carbon in semiarid pastures

AbstractEstablishment of improved perennial pasture systems for livestock production has been demonstrated to improve soil health in the semiarid Texas Southern High Plains (SHP). Use of waste products from other components of the animal production chain, such as applying composted manure from feedlot operations to grazed pastures, may provide an additional means of improving soil health and sustainability of these systems. However, few studies have examined the impact of composted animal manure on the changes in soil microbial communities, although they are important indicators of soil health. We investigated the effects of a one‐time composted cattle manure application at 3.36 Mg ha−1 on soil microbial community size and structure, soil organic C (SOC), total N (TN), and soil organic matter (SOM) up to 1.5 yr after application. We compared pastures consisting of either WW‐B. Dahl Old World bluestem grass [Bothriochloa bladhii (Retz.) S.T. Blake] alone or in mix with alfalfa (Medicago sativa L.). Results showed that compost application significantly increased SOC by about 4.4 g kg−1 soil within 1.5 yr after application. In N‐fertilized grass‐only pastures, compost addition increased microbial phospholipid fatty acid abundance, SOC, TN, and SOM, but no significant differences were observed between compost treatments in unfertilized pastures containing legumes. Our results show that even a one‐time compost addition at a relatively low rate can augment SOC in this semiarid pasture system after 1.5 yr, and that stimulation of soil microbial abundance and soil C and N from compost is more pronounced in fertilized grass‐only pastures compared with those with legume establishment.

Assessing the impacts of biochar and fertilizer management strategies on N and P balances in subtropical pastures

Improper nutrient management strategies often results in soil N and P imbalances, which can lead to unintended environmental consequences. Nutrient budgets can be useful tools to identify nutrient imports and exports and assess the agronomic and environmental performance of different pasture nutrient management options. In this 3-yr study, we used a farm-gate nutrient budgeting approach to determine N and P use efficiency in subtropical perennial pasture systems subjected to different nutrient management strategies. Treatments consisted of repeated application of biosolids and inorganic fertilizer (at an equivalent rate of 160 kg plant available N ha−1 yr−1) either alone or in combination with (20 Mg ha−1 yr−1). Major N and P inputs and outputs were: N and P added via fertilizer and biochar, plant uptake, leaching, and denitrification (N budget only). Nitrogen recovery in forage above-ground biomass accounted for a significant proportion of applied N (~64%) and P (22%). Greater N leaching occurred in inorganic fertilizer (29% of applied N) vs. biosolids treatments (average of 7% of applied N). Negligible P leaching (0.1–0.2% of total P applied) occurred, regardless of the treatment. Biochar did not affect either crop N and P use efficiency or P leaching, but reduced N leaching for treatments receiving inorganic fertilizer. Treatments showed no impact on soil N, but vertical distribution of soil total P changed over 3 yr, suggesting downward movement of P. Despite the high initial soil test P levels, biosolids application at P loads exceeding agronomic recommendations improved agronomic N and P efficiency relative to control treatments with no impact on N or P leaching.

Soil health changes following transition from an annual cropping to perennial management‐intensive grazing agroecosystem

AbstractManagement‐intensive grazing (MiG) on irrigated, perennial pastures has steadily increased in the western United States due to pressure for reducing public lands grazing, overall declining land available for pasture, and decreasing commodity prices. However, there are still many unknowns regarding MiG and its environmental impact, especially with regards to soil health. Over a 2‐yr period, a study evaluating the change in soil health under a full‐scale, 82‐ha pivot‐irrigated perennial pasture system grazed with ∼230 animal units (AUs) using MiG. Soil analysis included 11 soil characteristics aggregated into the Soil Management Assessment Framework (SMAF), which outputs results for soil biological, physical, nutrient, chemical, and overall soil health indices (SHIs). Over time, positive impacts were observed in the chemical and biological SHI due to decreases in salt content and increases in microbial and enzymatic activities. Soil organic C (SOC) remained unchanged, yet positive biological SHI changes are potential precursors to future SOC increases. The chemical and nutrient SHI increased in the soil surface due to reductions in salt content in conjunction with increased plant‐available soil P, as a result of salt leaching via irrigation and pre‐study inorganic P fertilizer application in conjunction with manure deposition due to MiG, respectively. Finally, a negative impact was also observed in the physical SHI, driven primarily by increasing bulk density due to hoof pressure from cattle grazing. If managed correctly, compaction issues can be avoided, with MiG systems having potential success in supporting grazing while promoting soil health for environmental and economic sustainability.

Effects of long-term grazed crop and pasture systems under no-till on organic matter fractions and selected quality parameters of soil in the Overberg, South Africa

There is limited soil research on semi-arid, grazed no-till crop and pasture systems. The long-term (10 years) effect of three grazed no-till dryland crop and pasture rotation systems, and perennial lucerne pasture were assessed on soil carbon (C) and nitrogen (N) stocks, soil organic matter functional pools and selected soil quality parameters in the Overberg, South Africa. The largest soil C and N stocks (0–30 cm) were found in crop–pasture systems containing wheat and medic/clover (70.2–74.9 Mg C ha−1 and 8.3–8.4 Mg N ha−1), compared with perennial lucerne pasture (63.4 Mg C ha−1 and 7.7 Mg N ha−1) or cropping-only systems (54.7–58.9 Mg C ha−1 and 6.3–6.7 Mg N ha−1). Significantly higher labile C and N (free particulate organic matter fraction) contents were observed in crop–pasture systems (1.37–1.74 g C kg−1 and 0.107–0.110 g N kg−1) than in continuous cropping systems (0.9–1.0 g C kg−1 and 0.042–0.045 g N kg−1), attributed to higher annual C and N inputs and lower extent of soil disturbance. Significant positive correlations were found between soil C and N functional pools and soil quality parameters (soil respiration, effective cation exchange capacity and aggregate stability) and wheat yields. The results show the importance of the medic/clover pasture and wheat rotations in enhancing soil quality in the Overberg region.

Use of biological indicators of soil health to estimate reactive nitrogen dynamics in long-term organic vegetable and pasture systems

Diverse crop rotations, cover crops and the possibility of integrating livestock make organic systems potentially more sustainable than other agroecosystems. Lower reactive nitrogen (N) in organic systems minimizes the potential for N losses. However, addition of organic manures and residues containing mineralizable N and carbon (C) have the potential to enhance nitrous oxide (N2O) emissions. We conducted a 39 d laboratory incubation to assess key microbiological drivers controlling nitrification and denitrification in long-term organic agroecosystems during simulated freeze-thaw cycles. Soils were collected from two annual organic vegetable systems receiving 1) mixed-compost, or 2) broiler litter and 3) an organic perennial pasture system cropped to vegetables every third year. Soil microcosms amended with 15N labelled sugar beet residue or unamended were maintained at 40, 60 and 80% of water filled pore space (WFPS). Significant N2O was emitted (4287–6138 μg kg−1soil) via denitrification from amended soil microcosms at 3 °C and 80% WFPS. Archaeal (AOA) and bacterial (AOB) nitrifier amoA gene copies were affected by temperature and reactive N species during freeze-thaws. Long-term organic vegetable cropping systems receiving mixed-compost additions had the potential to accumulate C and immobilize excess reactive soil N (particularly nitrates) thereby improving soil health and reducing N2O emissions.

Soil carbon and inferred net primary production in high- and low-intensity grazing systems on the New England Tableland, eastern Australia

Management of grazing lands for the accumulation of soil carbon stocks (CS) has been proposed as an effective way to reduce net greenhouse gas emissions from agriculture. However, there are conflicting reports on the effects of grazing management on soil carbon. Most comparisons have involved some combination of no grazing, rotational grazing and set stocking. In the present study we compared two adjacent commercial grazing systems, distinguished on the basis of inputs and livestock productivity, located on New England basaltic landscapes experiencing a cool temperate climate. The high-intensity (H) system sustains an average stocking rate of 18 dry sheep equivalents (dse) ha–1, with a turnoff rate of 9dseha–1year–1, with high levels of investment in assets, management and fertiliser. The low-intensity (L) system, with less intensive management and half the fertiliser of the H system, sustains a stocking rate of 9dseha–1, with a turnoff rate of 3dseha–1year–1, which is slightly higher than the regional average. Pasture biomass production was inferred (back-calculated) from stocking rates and animal feed requirements using published data. From the H and L systems, seven paired landscapes from valley floor to upper hillslopes and plateaux were selected. The seventh included a forest reserve. One hundred and eighty-six undisturbed soil cores (0–0.5m depth) were assessed for bulk density, total C and N, particulate C and a range of plant nutrients. There were few differences in CS, soil pH and nutrient levels between H and L grazing systems. Average CS (0–0.3m) in pasture soils was 103Mgha–1, but was higher in the forest soil at 190Mgha–1. Regression of CS versus soil mass was a satisfactory method of dealing with the bias introduced by the higher soil bulk density in perennial pasture systems compared with the forest. The similarity of CS in H and L pasture soils was despite inferred net primary production being 1.9–3.6MgCha–1year–1 greater in H than L systems, implying higher rates of C turnover in the former. The global warming potential of the inferred annual emissions of CH4 and N2O in the H and L systems was equivalent to approximately 19% and 13% of the cycling atmospheric–plant CO2 carbon respectively.

The ability of the DGT soil phosphorus test to predict pasture response in Australian pasture soils – a preliminary assessment

AbstractDiffusive gradients in thin‐films (DGT) technology provides an alternative assessment of available phosphorus (P) for a range of crops, suggesting a preliminary examination of the performance of the new DGT‐P test, compared to existing bicarbonate extractable Olsen and Colwell P tests, for pastures is justified. This study utilized historic data from the Australian National Reactive Phosphate Rock (NRPR) study (1992–1994) that included 25 experimental sites representing a wide range of soil types and climates used for pasture production. Stored (~19 yr) soil samples were analysed for DGT‐P, Olsen P and a single point P buffering index (PBI) and re‐analysed for Colwell P. Results showed the traditional bicarbonate extractable Colwell (r2 = 0.45, P &lt; 0.001) and Olsen P (r2 = 0.27, P &lt; 0.001) methods predicted relative pasture P response more accurately, compared to the novel DGT‐P test (r2 = 0.09, P = 0.03) when all 3 yr of data were examined. We hypothesize that the harsher bicarbonate extraction used for the Olsen and Colwell methods more accurately reflects the ability of perennial pasture roots to access less labile forms of P, in contrast to the DGT‐P test, which does not change the soil pH or dilute the soil and appears unable to fully account for a plants ability to solubilize P. Further studies are needed to compare the capacity of DGT‐P to measure P availability in perennial pasture systems and to better understand the soil chemical differences between pasture and cropping systems.

Effect of poultry litter application method on ammonia volatilization from a conservation tillage system

Ammonia (NH₃) volatilization from agricultural fields is important economically as a direct loss of the valuable crop nutrient nitrogen (N), but it can also be a significant environmental concern for soil, air, and water quality of nearby ecosystems. As poultry production has expanded in cropland areas of the southeastern United States, poultry litter has become a major source of crop nutrients for farmers using conservation tillage systems. However, the conventional application method of broadcasting poultry litter on the soil surface can allow as much as 60% of the applied litter N to volatilize as NH₃. To provide management options that can prevent NH₃ losses and help farmers use poultry litter nutrients more efficiently, a research team at USDA9s Agricultural Research Service developed a prototype tractor-drawn implement for subsurface application of dry poultry litter in perennial pasture and conservation tillage systems. When compared to surface broadcasting, previous research showed that subsurface application of poultry litter decreased odor problems, increased crop yields, prevented more than 90% of nutrient losses in runoff, and prevented NH₃ volatilization from perennial pasture systems. The current study was conducted to expand our knowledge regarding the effect of this litter application method on NH₃ volatilization from row-crop conservation tillage systems. For two consecutive summers, field plots with a uniform high-residue surface cover of chopped wheat straw received about 5,000 kg ha⁻¹ (4,500 lb ac⁻¹) of poultry litter applied by surface spreading with no incorporation, surface spreading followed by light disking, or subsurface banding using the prototype USDA ARS applicator. Small mobile wind tunnels monitored NH₃ volatilization for at least five days after each litter treatment. Results for both years showed that NH₃ losses were consistently affected by diurnal variations that were closely related to the vapor pressure deficit. Compared to conventional surface spreading of poultry litter, NH₃ volatilization decreased an average of 67% when the litter application was followed by light disking, and decreased an average of 88% when the litter was applied below the soil surface using the prototype applicator. These data show that subsurface injection of dry poultry litter can preserve adequate surface cover for conservation needs while constraining NH₃ losses to minimal levels, thus conserving N for row crops and reducing potential nitrogen losses to the environment.

Sensitivity of soil carbon to management and environmental factors within Australian perennial pasture systems

Environmental factors such as parent material and climate can have a large effect on total carbon concentration and soil carbon stocks, yet unlike vegetation type, fertiliser use and grazing pressure, these cannot be changed by management. The relative effects of these environmental and land management factors were compared in the Monaro and Boorowa regions of New South Wales (NSW), Australia. Parent material, geographic region, soil depth and soil fertility had a significant influence on soil carbon stocks to 0.70m while pasture type (introduced vs native pastures) did not. Parent material and soil depth significantly (P<0.05) influenced the mean soil carbon stock (Mg C/ha) in the Monaro region; 159 (11 se) in basalt-derived soils, 77 (11 se) in deep granite-derived soils and 43 (3 se) in shallow granite-derived soils. Climate also significantly (P<0.05) influenced the mean carbon stock, with deep granite-derived soils in the Monaro region having 76.5 (11 se) compared with 51.8 (3 se) Mg C/ha in the Boorowa region. A considerable proportion of the total carbon stock to 0.70m for all sites was measured in the subsoil (0.30 to 0.70m). In the Monaro region, basalt-derived soil contained 43% of the total carbon stock in the subsoil, compared with 28% in deep granite and shallow granite-derived soil. In the Boorowa region, deep granite-derived soil contained 33% of the total carbon stock in the subsoil. Restricting soil carbon measurements to the surface 0.30m of soil may result in erroneous conclusions with respect to the influence of land management on the accumulation of carbon in soil. Total carbon concentration was positively correlated with labile carbon, total nitrogen, cation exchange capacity and extractable sulfur, suggesting that for a given parent material and climate, maintaining adequate pasture nutrition may substantially increase soil carbon stocks.

Sub-paddock scale spatial variability between the pasture and cropping phases of mixed farming systems in Australia

Precision farming techniques are now widely applied within Australian cropping systems. However, the use of spatial monitoring technologies to investigate livestock and pasture interactions in mixed farming systems remains largely unexplored. This paper builds on previously reported work that is using remote sensing technologies to investigate livestock and pasture interactions in the pasture phase and to follow the after-effects of different management strategies into a subsequent cropping phase. Experimental data has been gathered from two dryland cropping sites, one in Western Australia (annual pasture system) and one in north-eastern Victoria (perennial pasture system). Smoothed time series of weekly NDVI composites were constructed by means of the adaptive Savitzky-Golay filter. Eight complete phenological cycles (2004–2011) were processed and eleven phenology metrics were calculated for each cycle. The analysis reinforces previous results that indicated spatial variation in biomass between pasture and cropping phases is consistent and correlated over time. In the annual pasture system, two metrics showed strong correlation between cropping and pasture phases – end of season biomass and peak NDVI. In the perennial pasture system, strong correlations were observed for seven metrics – end of season biomass, time of season onset, end of season, season duration, peak NDVI, season amplitude and rate of NDVI decrease.

Vitamin E and fatty acid content of lamb meat from perennial pasture or annual pasture systems with supplements

The present study investigated the effect of a perennial lucerne and phalaris pasture, or annual pasture with lucerne hay and a range of supplements provided as pellets (700 g/day) on Vitamin E and fatty acid content of skeletal muscle and oxidative stability of lamb meat post-farm gate. Treatments were lambs grazing perennial pasture only (PP); lambs grazing annual pasture with lucerne hay and oat grain pellet supplement (AP); AP with cracked flaxseed (AP+FS); and AP with flaxmeal (AP+FM). After 7 weeks of feeding, lambs were slaughtered after an overnight fast. At 24 h post-slaughter, samples of muscle longissimus lumborum (LL) were collected for determination of fatty acid profile and antioxidant status, as measured by Vitamin E content. Samples were also collected for retail colour assessment of fresh meat at 24 h, 48 h, 72 h and 96 h of post-slaughter. Vitamin E content of the LL from lambs grazing PP was higher (5.9 v. 3.4 mg α-tocopherol/kg, P &lt; 0.01) than that of lambs grazing other treatments. Long-chain n-3 and total n-3 fatty acid contents in the muscle were similar among treatment groups and adequate to claim as a source of n-3. Inclusion of oat grain at 245 g (AP) or at 175 g with flaxseed (AP+FS) or 175 g with flaxmeal (AP+FM) per day in the diet of lambs increased the linoleic acid content (P &lt; 0.05) and the ratio of n-6 : n-3 (P &lt; 0.007) in the LL, compared with lambs grazing PP. Oxidative stability of fresh meat evaluated by retail shelf life (retention of redness) and formation of lipid oxidative substance showed no differences among treatment groups and, as indicated by redness (a*-value) over a 96-h display, all values were within the range (&gt;9.5) for quality meat over the time frame used in the present study. The results provided some evidence that inclusion of PP in the diets of lambs during dry seasons (late summer to autumn) is an effective tool of improving the Vitamin E content of muscle tissues at slaughter.

Lamb growth performance and carcass weight from rotationally grazed perennial pasture systems compared with annual pasture systems with supplements

Annual pastures used to finish lambs can decline in herbage nutritive value (NV) from January to April in the temperate zone. If lambs are to be finished to market specifications for carcass weight during this period, the use of summer-active perennial pastures or supplementation of annual pastures, is required. The present study investigated liveweight (LW) gain and carcass characteristics of lambs finished on perennial pastures compared with annual pastures and supplementation. Fifty-four second-cross lambs were allocated to one of the following four treatments in an asymmetric split-plot design: perennial pasture (PP), annual pasture with hay and grain (AP), AP with flaxseed (AP+FS) and AP with flaxmeal (AP+FM). Lambs were fed for 7 weeks and weighed weekly. Blood glucose and total antioxidant status were determined before, during and at the end of the experiment. Carcass weight and GR fat were measured at 24 h post-slaughter. Lambs grazing PP had significantly higher daily LW gain (P &lt; 0.001), slaughter weight (P &lt; 0.001), carcass weight (P &lt; 0.01) and GR fat (total tissue depth at 12 rib, 110 mm from midline) (P &lt; 0.001) than did lambs grazing AP, AP+FS or AP+FM. Lambs receiving AP+FS and AP+FM grew significantly faster (P &lt; 0.001) than lambs receiving AP. It is likely that lambs grazing the perennial pasture were actively selecting the green portion of lucerne that had higher herbage NV than that indicated by the conventional feed analysis. Results show that lambs grazing a lucerne-dominant perennial pasture performed better than did lambs grazing annual pasture with supplements during the finishing period. Further work is required to determine the efficacy of other perennial species to enable economic finishing of lambs during summer and early autumn.

Earthworm abundance and species composition in organic forage production systems of northern Colorado receiving different soil amendments

We evaluated the effects of soil amendments on earthworm communities in organic annual forage and perennial pasture systems in northern Colorado. In the annual forage study (1) an annual warm season grass teff (Eragrostis tef) and (2) bare fallow were main plot treatments and received one of three soil amendments: (1) composted dairy manure (CDM), (2) raw dairy manure (RDM), and (3) no amendment as control. For the perennial pasture study, CDM was topdressed onto a grass mixture consisting of orchardgrass, smooth and meadow bromegrass at rates ranging from 0 to 44.8Mgha−1. At both sites, earthworm and soil samples were collected in July 2009. The earthworms identified from both systems were composed of endogeic species Aporrectodea rosea (Savigny), A. tuberculata (Eisen), and A. turgida (Eisen), the first being found only in the perennial pasture. In the annual forage study, earthworm total abundance did not differ between teff and bare fallow treatments. However, within bare fallow treatment, earthworm total abundance was significantly affected by soil amendment, with CDM averaging approximately 1.4 and 5.4 times greater earthworm total abundance than RDM and the control, respectively. Earthworm total abundance was found to be positively correlated with soil Cu (R=0.51, P=0.03) and K (R=0.58, P=0.01). In the perennial pasture, earthworm total abundance tended to increase with an increase in the CDM rate to 33.6Mgha−1. However, no further increase was observed when the CDM rate was increased to 44.8Mgha−1. At this site, earthworm total abundance was negatively correlated with EC (R=−0.37, P=0.02). Our results suggest that high quality (low C/N ratio) dairy manure is important for maintaining a high earthworm population. Larger CDM application rates appear to discourage earthworm populations probably due to salinity stress. Further study is necessary to elucidate the exact effects of manure quality and quantity on earthworm populations in annual forages and perennial pastures.

Companion cropping chicory with winter forage cereals for grazing and forage conservation. Dry matter yields, nutritive characteristics and mineral content

Limitations to the current perennial ryegrass-based pasture system on dryland dairy farms in southern Australia has led to research into alternatives that can produce either additional DM, out of season feed or can improve nutritive characteristics. The use of winter annual crops followed by a summer crop have the potential to achieve these goals but often result in considerable periods where new crops are establishing and feed is not available for consumption. Companion cropping offers an option to overcome these limitations. The experiment reported in this paper examines the DM yields, nutritive characteristics and mineral content of companion cropping wheat or triticale at different sowing rates into an existing chicory monoculture over a 2-year period. We hypothesised that oversowing cereal crops in autumn into an existing stand of chicory would result in improvements in nutritive characteristics at ensiling, without adversely affecting DM yield or subsequent chicory DM yields following harvesting, thus negating the need to sow a new summer forage crop each year. Total DM yields for the chicory and cereal monocultures were similar over the experimental period, while DM yields for all triticale mixtures were higher than the chicory only treatment. Chicory produced lower DM yields for silage but higher DM yields at most grazing events. The crude protein and estimated metabolisable energy content of the chicory only treatment was higher than the cereal monocultures and all triticale/chicory mixtures at both silage harvests with wheat/chicory mixes being intermediate. The proportion of chicory in the mixed swards declined over the course of the experiment. The use of chicory with cereals resulted in no adverse effects on total DM yields, some improvements in nutritive characteristics and mineral content and a more continuous supply of DM compared with double cropping with annual species in winter and summer. This experiment has highlighted the potential of oversowing cereal forages into an existing chicory sward to contribute to DM production on dairy farms in southern Australia. Such forage mixes can provide flexibility into forage systems through the provision of forage for grazing in early winter, the production of high DM yield silage harvests and then subsequent feed supply over summer and early autumn.

Impact of perennial pasture and tillage systems on carbon input and soil quality indicators

Soil degradation associated with tillage is a major problem in Uruguayan agriculture. Either rotation of crops with pastures (ROT) or no-till (NT) cropping have been proposed as alternatives to minimize the impact of agriculture on soil quality. The combined impact on soil properties of ROT and NT has not been evaluated. In this study, we report results of the first 12 years of a long-term experiment established on a clay loam soil in western Uruguay. The objective was to determine the influence of conventional tillage (CT) and NT on systems under continuous cropping (CC, two crops per year) or ROT (3.5-year annual crops/2.5-year pastures). Soil samples taken at the beginning of the experiment in 1994 and in 2004 were analyzed for organic carbon (SOC), total organic carbon (TSOC) and total nitrogen content (STN), and for water-stable aggregation (WAS). Soil loss and erodibility indicators were studied using microrain simulator. With 12 years, the cumulative carbon (C) inputs of aboveground biomass were similar between tillage, but C input in CC was 50% higher than ROT. This difference was explained because 84% of the pastures dry matter was consumed by animals. Nevertheless we estimated a higher below ground biomass in ROT compared to CC systems (24.9 Mg ha −1 vs. 10.9 Mg ha −1). NT presented 7% higher SOC than CT (0–18 cm) with no differences between rotation systems. While all treatments declined in STN during 12 years, ROT had 11% and 58% higher STN and WAS than CC systems, with a large impact of the pasture under CT. Runoff and erosion were minimized under NT in both rotations systems. Thus, including pastures in the rotation, or switching from CT to NT improved soil quality properties. The expected benefit of combining NT and ROT will likely require more years for the cumulative effect to be detectable in both C input and soil properties.

Choice of forage crops for animal production in temperate perennial pasture-based grazing systems.

Abstract Choosing a forage crop for animal production is a broad topic with many facets. This review has chosen to concentrate on the in situ use of forage crops within temperate-pasture-based grazing systems. However, the principle of understanding the deficiencies of the pasture-based system before choosing a forage crop applies to any geo-climatic zone. The literature of New Zealand and Australia highlights the potential to increase both stocking rate and per animal performance and the risk associated with introducing forage crops into a perennial pasture system. Higher yields and increased efficiency of use of resources such as water and nutrients are offset by the variability of both crop yield and the time out of production that is often dictated by climatic conditions. Increases in both technical knowledge of crop agronomy and grazing and labour requirements when feeding the crop also influence farmers' decisions and crop success. The final decision to choose an appropriate forage species or cultivar is a relatively minor part of the process that is well supported by the seed retail industry in New Zealand and Australia.

Effect of sowing date of triticale on seasonal herbage production in the central Appalachian Highlands of the United States

AbstractTriticale (X Triticosecale Wittmack) was evaluated as a complementary pasture to buffer those periods when herbage production from mixed perennial pasture is marginal in the central Appalachian Highlands of the United States. Triticale was sown every month from May to October for five consecutive years from 1999 to 2003. Plant population structure and herbage production were evaluated at intervals until May of the year following establishment. Triticale established quickly at all times of sowing except late October. Wet summers resulted in foliar disease and a rapid decline in plant density when triticale was sown in May and June. In contrast, during the relatively dry summer of 1999, triticale stands exhibited minimal decline. Triticale sown in August had a herbage yield of 1580 kg DM ha−1 when harvested in October which was over twice the herbage yield of triticale sown in May, June and July. Average herbage yield in the following April of triticale sown in September was higher (1750 kg DM ha−1) and less variable than herbage yields from other sowing dates. Plant and tiller populations declined throughout the following April but herbage yields in May were high due to stem and seed head development associated with reproductive growth. Incorporating areas of triticale into mixed‐species perennial pasture systems could buffer herbage production during hot and dry summer periods as well as during cool periods of late autumn and early spring.