Pasture Phase Research Articles

Enhancing composition and persistence of mixed pasture swards in southern New South Wales through alternative spatial configurations and improved legume performance

This study examined whether the productivity and persistence of mixed pastures that included subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.), and/or phalaris (Phalaris aquatica L.) were improved if species were spatially separated rather than being sown together in each drill row. The study also compared the productivity and persistence of subterranean clover with alternative annual legume species biserrula (Biserrula pelecinus L.) and strand medic (Medicago littoralis Rhode ex Loisel). Twelve pasture treatments were sown in replicated field experiments at five locations across the medium-rainfall region of south-western New South Wales in 2012 and monitored for 3 years. Pastures that included lucerne, phalaris and subterranean clover were generally more productive than pastures with only one or two of those species, regardless of sowing configuration. Averaged across sites, subterranean clover regeneration in year 3 was 29% higher and total cumulative biomass 13% higher where subterranean clover was sown in a 1 : 1 configuration with lucerne than where the species were mixed together in every drill row. There were fewer consistent benefits of alternative spatial configurations on swards containing phalaris with subterranean clover or with lucerne. Results of the present study appeared to be highly site-specific, or season-dependent, and therefore alternative spatial configurations cannot be recommended as a universal strategy at this time. More research is required to understand the factors driving the responses to alternative spatial configurations observed in the present study. Neither biserrula nor strand medic was superior to subterranean clover in a 3-year pasture phase with lucerne, despite abundant rhizobia compatible with all species at all sites. The density of subterranean clover in year 3 was 29% and 41% higher than of biserrula and strand medic, respectively. A narrow choice of adapted cultivars as well as excessive levels of hard seed for the legumes used in phased pastures with lucerne are suggested as contributing to the inferior performance of the alternative legumes species tested in the study.

Modelling the comparative growth, water use and productivity of the perennial legumes, tedera (Bituminaria bituminosa var. albomarginata) and lucerne (Medicago sativa) in dryland mixed farming systems

Tedera (Bituminaria bituminosa var. albomarginata) has been proposed as an alternative perennial forage legume to lucerne in the mixed farming zone of Australia. Simulation of growth and production of tedera would be a useful tool for assessing its integration into Australian farming systems and agronomic and management options. This paper describes the development and testing of a model of the growth and development of tedera in Agricultural Production Systems Simulator (APSIM). The existing APSIM-Lucerne was modified to develop APSIM-Tedera. The key physiological parameters for tedera were obtained from the literature or by measuring and comparing the phenology and growth characteristics of tedera and lucerne in glasshouse experiments and partially from field experiments. The model was tested using data from a diverse range of soil and climatic conditions. Using the modelling approach, the production of tedera and lucerne was also assessed with long-term (1951–2015) weather data at Arthur River, Western Australia. Biomass simulations of tedera (n = 26, observed mean = 510 kg dry mass ha–1) explained 66% of the observed variation in field experiments (root mean square deviation = 212 kg dry mass ha–1). Long-term simulations of a 4-year pasture phase showed that more total annual biomass (5600 kg ha–1) would be obtained from lucerne than tedera if the pasture forage was harvested four times a year. Less biomass (400 kg ha–1) was also simulated for tedera in summer under this management. When the pasture forage was harvested when biomass was more than 2000 kg ha–1, tedera and lucerne produced similar accumulated biomass in the second (8000 kg ha–1), third (12 000 kg ha–1) and fourth (15 000 kg ha–1) years, but much less in the first 2 years for tedera. The model can be used for assessing tedera production, agronomic and management options in the Mediterranean climate of Australia. The present preliminary study indicates that tedera is not as effective as lucerne for total biomass production, but it may provide useful feed in situations where the summer-autumn feed gap is a major constraint to production. Further research is also necessary to determine the potential role of tedera in areas where lucerne is not well adapted.

Effects of Feeding Field Pea Diets on Fresh Beef Quality

ObjectivesThe objective of this study was to evaluate the effects of feeding field peas during 2 phases of production (grazing and finishing) on beef tenderness, lipid oxidation, color, and fatty acid profiles of beef.Materials and MethodsA total of 232 crossbred steers and heifers were randomly assigned to 1 of 6 dietary treatments in a 3 × 2 factorial consisting of 3 pasture and 2 finishing supplementations. The pasture phase consisted of 1) no supplement, 2) field peas at 0.5% BW, or 3) dry-rolled corn supplement at 0.5% of BW. The finishing phase consisted of 1) field peas at 20% DM or 2) no field peas. The study was conducted over a 2-yr period (with steers for year 1 and heifers for year 2) and at harvest strip loin samples were obtained and aged for 14 d. After aging, steaks were subject to retail display for a total of 7 d. Analyses included tenderness (WBSF and SSF), objective (L*, a*, b*) and subjective color, lipid oxidation (TBARS) and fatty acid composition.ResultsThere were minimal effects due to diet. Dietary treatment had no effect on tenderness (WBSF or SSF) or content of saturated fatty acids, unsaturated fatty acids, monounsaturated fatty acids, or polyunsaturated fatty acids (p > 0.05). However, cattle backgrounded with no supplementation had greater content of C18:1v in comparison to cattle backgrounded on peas or corn (151.19 vs. 95.34 and 69.66 mg/100 g, respectively; P = 0.0285). There was an interaction between grazing and finishing diets (P < 0.0001) for total content of fatty acids. For cattle backgrounded without supplementation, those finished with field peas had greater total fatty acid content in comparison those finished with corn. Whereas, for cattle backgrounded with field peas, those finished on corn had greater total fatty acid content in comparison to those finished on field peas. Meat from cattle finished with field peas had slightly greater lipid oxidation than samples from cattle not receiving field peas during finishing (1.56 vs. 1.44 mg malonaldehyde/kg tissue, respectively; p = 0.0541). Thiobarbituric acid reactive substances had a significant retail display effect, increasing over time (0d = 0.94, 4d = 1.46 and 7d = 2.11 mg malonaldehyde/kg tissue; p < 0.0001). Discoloration, L* and a* statistically displayed triple interactions for retail display, pasture and finishing diets (p < 0.0001, p = 0.0524 and p = 0.024, respectively). Although these interactions were statistically significant, no consistent patterns due to treatments could be identified.ConclusionThese data indicate field peas may be used as an alternative diet for growing and finishing cattle with minimal to no negative impact on fresh meat quality.

Does establishing lucerne under a cover crop increase farm financial risk?

Rainfed farms in south-eastern Australia often combine annual cropping and perennial pasture phases with grazing sheep enterprises. Such diversity serves in managing diseases, pests and plant nutrition while stabilising income in the face of wide, uncorrelated variations in international commodity prices and local weather over time. We use an actuarial accounting approach to capture the above contexts to render financial risk profiles in the form of distributions of decadal cash balances for a representative 1000-ha farm at Coolamon (34°50ʹS, 147°12ʹE) in New South Wales, Australia. For the soil and weather conditions at this location we pose the question of which approach is better when establishing the perennial pasture lucerne (Medicago sativa L.): sowing with the final crop of the cropping phase, or sowing alone following the final crop? It is less expensive to sow lucerne with the final crop, which can provide useful income from the sale of grain, but this practice can reduce pasture quantity and quality in poorer years. Although many years of field research have confirmed that sowing lucerne alone is the most reliable way to establish a pasture in this area, and years of extension messages to this effect have gone out to farmers, they often persist in sowing lucerne with their final cereal crops. For this region, counting all costs, we show that sowing lucerne alone can reduce farm financial risk (i.e. probability of negative decadal cash balances) at stocking rates &gt;10 dry sheep equivalents (DSE)/ha, compared with the practice of sowing lucerne with a cover crop. Establishing lucerne alone allows the farmer the option to profitably run higher stocking rates for higher median decadal cash margins without additional financial risk. At low stocking rates (i.e. 5 DSE/ha), there appears to be no financial advantage of either establishment approach. We consider the level of equity, background farm debt and overhead costs to demonstrate how these also affect risk-profile positions of the two sowing options. For a farm that is deeply in debt, we cannot suggest either approach to establishing lucerne will lead to substantially better financial outcomes.

Complementary use of neotropical savanna and grass-legume pastures for early weaning and effects on growth and metabolic status of weaners and inter-calving intervals of dams

Extensive, rangeland-based beef production systems that predominate in the neotropical savannas of northern South America are low input-low output beef breeding systems, and their intensification faces major hurdles due to their location, soil, water and topographic constraints. Intensification requires the introduction of improved pastures strategically managed to complement the native savannas, to improve production and to allow opportunities for a wider range of associated ecosystem services. This study assessed the feasibility of early weaning of beef calves onto small areas of sown pastures to aid system intensification. Weaning calves at 90 days of age and grazing on Andropgon gayanus, A. gayanus-Pueraria phaseoloides, A. gayanus-Centrosema acutifolium and Brachiaria humidicola-Arachis pintoi sown tropical pastures stocked at 6 animals/ha was compared with conventional weaning on native savanna over 4 consecutive years. The reproductive performance of their Brahman ( Bos indicus ) and crossbred [Brahman x San Martinero (native; B. taurus )] dams grazing savanna (0.2 cows/ha) was monitored in comparison with control cow-calf systems, where calves were weaned onto savanna between 240 and 270 days of age. Post-weaning weight gains of early weaned calves on sown pasture (0.1‒0.2 kg/d) were much lower than those of unweaned animals on savanna (0.31‒0.35 kg/d), but compensatory gains realized after the end of the weaning experiments allowed early weaned calves to reach weights similar to those of control animals 400 days after the end of the pasture phase. As expected, early weaned cows achieved higher live weights and had shorter inter-calving intervals than their counterparts. Trade-offs between performance of calves and of cows are discussed, but it is suggested that the strategic use of small areas of sown pastures for early weaned calves may productively complement large areas of native savannas. It is hypothesized that the improved quality, frequency and intensity of management required by these intensified systems may place a burden on these low-input primary enterprises, which may also challenge the productive and environmental adaptive capacity of primary resource users. Keywords : Cattle , extensive systems, intensification, rangelands, sustainability, tropical pastures.

Spatially governed climate factors dominate management in determining the quantity and distribution of soil organic carbon in dryland agricultural systems.

Few studies describe the primary drivers influencing soil organic carbon (SOC) stocks and the distribution of carbon (C) fractions in agricultural systems from semi-arid regions; yet these soils comprise one fifth of the global land area. Here we identified the primary drivers for changes in total SOC and associated particulate (POC), humus (HOC) and resistant (ROC) organic C fractions for 1347 sample points in the semi-arid agricultural region of Western Australia. Total SOC stock (0–0.3 m) varied from 4 to 209 t C ha−1 with 79% of variation explained by measured variables. The proportion of C in POC, HOC and ROC fractions averaged 28%, 45% and 27% respectively. Climate (43%) and land management practices (32%) had the largest relative influence on variation in total SOC. Carbon accumulation was constrained where average daily temperature was above 17.2 °C and annual rainfall below 450 mm, representing approximately 42% of the 197,300 km2 agricultural region. As such large proportions of this region are not suited to C sequestration strategies. For the remainder of the region a strong influence of management practices on SOC indicate opportunities for C sequestration strategies associated with incorporation of longer pasture phases and adequate fertilisation.

Light grazing of crop residues by sheep in a Mediterranean-type environment has little impact on following no-tillage crops

Abstract Crop residue is often grazed by sheep after harvest, over the dry summer period from December to March in Mediterranean environments. However, soil cover provided by crop residues is a key component of conservation agriculture for maintaining favourable soil structure and high yields. A series of 31 site × year experiments was conducted to assess the effect of summer stubble grazing on residue levels and following crop yields. Relatively light grazing, with stocking rates below 10 dry sheep equivalent (DSE) and between 90 and 471 DSE days ha −1 , had no significant effect on the amount of residue, soil properties, soil water, weeds or yield in the following crop. The main effect of grazing was to knock down and scatter the standing crop residues. However, longer term grazing at relatively high intensity (956 DSE days ha −1 ) on heavy soil, over both summer and winter, as in a pasture phase, did significantly reduce residue levels, infiltration and yield (by 59%). The effect of summer grazing on soil mineral N was small and inconsistent, with increased mineral N, by about 3–7 kg N ha −1 , following grazing at two of the 13 sites. By contrast, higher mineral N, by 2–15 kg N ha −1 , was measured in the un-grazed plots at three of the 13 sites. This was due to increased growth of legume pastures in the absence of grazing. More research is needed to confirm the yield effects when cropping after an annual pasture/fallow that is grazed over summer and winter, particularly on different soil types.

Soil Use Intensity Effects on Soil Organic Carbon in No-till Crop-pasture Rotations Systems

Soil organic carbon (SOC) is a key soil quality indicator for cropping systems sustainability. We evaluated 20 yrs. soil use intensity effects on SOC (0-5 cm and 5-15 cm depth) in a 72 ha no-till crop-pasture rotation experiment (33°:15’36S, 54°:29’26W, 60-m elevation) in Treinta y Tres, Uruguay (Abruptic Argiaquolls and Oxiaquic Vertic Argiudolls). Treatments between 1995-2005 were: Continuous cropping (CC) of ryegrass ( Lolium multiflorum Lam. or oat Avena sp . in winter and sorghum ( Sorghum bicolor L.) or foxtail millet ( Setaria italica ) in summer; 2) Short Rotation (SR): two years idem CC and two years pasture of red clover ( Trifolium pretense L.) and Holcus lanatus L.; 3) Long Rotation (LR) two years idem CC and four years pasture of tall fescue ( Festuca arundinacea L.), white clover ( Trifolium repens L.) and birdsfoot trefoil ( Lotus corniculatus L.); 4) Permanent Pasture (PP): natural pasture overseeded with legumes used in RL. Since 2005 until now, grain crops substituted forage crops in the «cropping phase» of all rotations (CC, SR, LR), maintaining without modifications the pasture phase of them. Grain cropping sequence was: Oat ( Avena sativa L.), Sorghum bicolor (L.), black oat (Avena sp., as a winter cover crop) , soybean (Glycine max L.) and wheat (Triticum aestivum). After 20 years, significant SOC differences (0-5 cm) were found between rotations. Continuous cropping decreased SOC by 16%, 18%, 31% compared to SR (25.55 g kg-1), LR (26.17 g kg-1) and PP (31.32 g kg-1), respectively. Although no SOC differences were found between rotations that include perennial pastures (SR and LR), both had 18% lower SOC than PP. A trend of SOC decrease (12%) was observed also in PP compared to the original situation that existed at the beginning of the experiment (natural pasture 35.25 g kg-1). No SOC differences were found in the 5-15 cm depth between treatments that included pastures. However, there was an average SOC increase of 14% in these treatments (13.34 g kg-1) compared to CC. The aggregate of data suggest that, even under no-till, continuous cropping reduced SOC compared with cropping systems that include some proportion of pastures in the rotation. For undisturbed fragile soils incorporated to grain production, like those prevalent in 1 million ha in Eastern Uruguay, the inclusion of perennial pastures in the rotations is critical for soil conservation and mitigation of SOC losses in cropping systems.

Soil Use Intensity Effects on Soil Organic Carbon in No-till Crop-pasture Rotations Systems

Soil organic carbon (SOC) is a key soil quality indicator for cropping systems sustainability. We evaluated 20 yrs. soil use intensity effects on SOC (0-5 cm and 5-15 cm depth) in a 72 ha no-till crop-pasture rotation experiment (33°:15’36"S, 54°:29’26"W, 60-m elevation) in Treinta y Tres, Uruguay (Abruptic Argiaquolls and Oxiaquic Vertic Argiudolls). Treatments between 1995-2005 were: Continuous cropping (CC) of ryegrass (Lolium multiflorum Lam. or oat Avena sp. in winter and sorghum (Sorghum bicolor L.) or foxtail millet (Setaria italica) in summer; 2) Short Rotation (SR): two years idem CC and two years pasture of red clover (Trifolium pretense L.) and Holcus lanatus L.; 3) Long Rotation (LR) two years idem CC and four years pasture of tall fescue (Festuca arundinacea L.), white clover (Trifolium repens L.) and birdsfoot trefoil (Lotus corniculatus L.); 4) Permanent Pasture (PP): natural pasture overseeded with legumes used in RL. Since 2005 until now, grain crops substituted forage crops in the «cropping phase» of all rotations (CC, SR, LR), maintaining without modifications the pasture phase of them. Grain cropping sequence was: Oat (Avena sativa L.), Sorghum bicolor (L.), black oat (Avena sp., as a winter cover crop), soybean (Glycine max L.) and wheat (Triticum aestivum). After 20 years, significant SOC differences (0-5 cm) were found between rotations. Continuous cropping decreased SOC by 16%, 18%, 31% compared to SR (25.55 g kg-1), LR (26.17 g kg-1) and PP (31.32 g kg-1), respectively. Although no SOC differences were found between rotations that include perennial pastures (SR and LR), both had 18% lower SOC than PP. A trend of SOC decrease (12%) was observed also in PP compared to the original situation that existed at the beginning of the experiment (natural pasture 35.25 g kg-1). No SOC differences were found in the 5-15 cm depth between treatments that included pastures. However, there was an average SOC increase of 14% in these treatments (13.34 g kg-1) compared to CC. The aggregate of data suggest that, even under no-till, continuous cropping reduced SOC compared with cropping systems that include some proportion of pastures in the rotation. For undisturbed fragile soils incorporated to grain production, like those prevalent in 1 million ha in Eastern Uruguay, the inclusion of perennial pastures in the rotations is critical for soil conservation and mitigation of SOC losses in cropping systems.

A comparison of a pasture ley with a maize monoculture on the soil fertility and nutrient release in the succeeding crop

ABSTRACTSpecialization within agriculture has been a key factor in increasing farm income. The production systems have become increasingly simple, since farmers only grow a small number of crops which have a favourable market price. However, monocultural systems require increasing use of agrochemicals leading to unsustainable environmental costs. In this work, the soil fertility of two plots in a crop rotation previously grown for 5 years as pasture or maize monoculture was evaluated. In the pasture, the upper 0–20 cm soil layer sequestered 17.4 Mg organic C ha−1 and accumulated 403 kg N ha−1 more than under maize monoculture. Analytical data from pot experiments showed that soil samples from the pasture plot released significantly more mineral N than soil samples from the maize monoculture. Maize dry matter (DM) yields in 2012 and 2013 were 15.3 and 10.0 Mg ha−1 in the pasture plot and 8.8 and 8.4 Mg ha−1 in the maize monoculture plot. Nitrogen recoveries by maize were 175.4 and 68.0 kg ha−1 in the pasture and 78.3 and 50.3 kg ha−1 in the maize monoculture plot. The pool of organic matter accumulated during the pasture phase immobilized important nutrients which benefited the succeeding crop as the organic substrate was mineralized.

Effect of cropping practices on soil organic carbon: evidence from long-term field experiments in Victoria, Australia

Despite considerable research, predicting how soil organic carbon (SOC) in grain production systems will respond to conservation management practices, such as reduced tillage, residue retention and alternative rotations, remains difficult because of the slowness of change and apparent site specificity of the effects. We compared SOC stocks (equivalent soil mass to ~0–0.3 m depth) under various tillage, residue management and rotation treatments in three long-term (12-, 28- and 94-year-old) field experiments in two contrasting environments (Mallee and Wimmera regions). Our hypotheses were that SOC stocks are increased by: (1) minimum tillage rather than traditional tillage; (2) continuous cropping, rather than crop–fallow rotations; and (3) phases of crop or pasture legumes in rotations, relative to continuous cropping with cereals. We found that zero tillage and stubble retention increased SOC in some circumstances (by up to 1.5 Mg C ha–1, or 8%) but not in others. Inclusion of bare fallow in rotations reduced SOC (by 1.4–2.4 Mg C ha–1, or 8–12%) compared with continuous cropping. Including a pulse crop (field pea, where the grain was harvested) in rotations also increased SOC in some instances (by ~6–8 Mg C ha–1, or 29–35%) but not in others. Similarly, leguminous pasture (medic or lucerne) phases in rotations either increased SOC (by 3.5 Mg C ha–1, or 21%) or had no significant effect compared with continuous wheat. Inclusion of a vetch green manure or unfertilised oat pasture in the rotation did not significantly increase SOC compared with continuous wheat. The responses in SOC to these management treatments were likely to be due, in part, to differences in nitrogen and water availability (and their effects on carbon inputs and decomposition) and, in part, to other, unidentified, interactions. We conclude that the management practices examined in the present study may not reliably increase SOC on their own, but that significant increases in SOC are possible under some circumstances through the long-term use of multiple practices, such as stubble retention + zero tillage + legume N input + elimination of fallow. The circumstances under which increases in SOC can be achieved require further investigation.

Effects of beef production system on animal performance and carcass characteristics.

The objective of this study was to evaluate conventional (CONV) and natural (NAT) beef production systems from annual pasture through finishing through grazing. Beef steers (n=180, initial BW=250±19 kg) were assigned randomly to 2 treatments in the pasture phase. Steers were implanted with 40 mg of trenbolone acetate (TBA), 8 mg estradiol, and 29 mg tylosin tartrate (CONV), or received no implant (NAT). Steers on the 2 treatments grazed wheat or cereal rye for 109 d. Conventional steers had an 18.5% improvement in ADG (1.22 vs. 1.03 kg/d, P<0.01) and a heavier final BW (385 vs. 366 kg, P<0.01) compared with NAT steers. Following the pasture phase, steers (n=160 steers, 5 steers/pen, 8 pens/treatment) were assigned to a 2×2 factorial in the feedlot phase. Production system (NAT vs. CONV) was maintained from the pasture phase, and the second factor was 7 vs. 12% low-quality roughage (DM basis, LOW vs. HIGH). During finishing, CONV steers were given 120 mg of TBA and 24 mg estradiol at processing, fed monensin and tylosin, and fed zilpaterol hydrochloride for the last 20 d of the experiment. There were no program×roughage level interactions (P>0.07). The CONV steers ate 6.9% more feed (11.8 vs. 11.0 kg/d, P<0.01), gained 28.4% faster (1.90 vs. 1.48 kg/d, P<0.01), and were 24.2% more efficient (0.164 vs. 0.132, P<0.01) compared with NAT steers. The LOW steers had greater G:F (0.153 vs. 0.144, P<0.01) compared with HIGH steers. There was a 28.3% improvement in estimated carcass weight gain (1.36 vs. 1.06 kg/d), 18.6% improvement in carcass efficiency (0.115 vs. 0.097, P<0.01), and 21.6% improvement (1.52 vs. 1.25 Mcal/kg, P<0.01) in calculated dietary NEg for CONV compared with NAT steers. Hot carcass weight was increased by 62 kg (424 vs. 362 kg, P<0.01) and LM area was increased by 16.9 cm2 (100.9 vs. 84.0 cm2, P<0.01), decreasing USDA yield grade (YG, 3.09 vs. 3.54, P<0.01) for CONV steers compared with NAT steers. Natural steers had a greater percentage of carcasses in the upper 2/3 of USDA Choice grade (48.7 vs. 18.7%, P<0.01), a greater percentage of YG 4 and 5 carcasses (25.4 vs. 9.3%, P<0.01), and a greater percentage of abscessed livers (39.6 vs. 10.5%, P<0.01) compared with CONV steers. The results show that CONV production results in more rapid and efficient production that resulted in heavier carcasses with superior YG and desirable quality grades with both roughage levels.

A review of organic carbon accumulation in soils within the agricultural context of southern New South Wales, Australia

The accumulation of carbon (C) in soil as organic matter (SOM) is considered to be a win–win situation for agriculture and the environment. Retention of crop and pasture residues should contribute to this accumulation of organic C in soil. However the retention of crop stubble has not necessarily resulted in increases in soil organic matter in long term field trials in southern New South Wales (NSW), Australia. Even under permanent pasture, annual or perennial, the rates of accumulation of soil organic matter are only about 500kg C/ha/year at best in the environment of southern NSW. Hence the C accumulation rates in soil are not likely to generate a significant income stream from C trading. Further, in the mixed farming systems of the inland areas, the traditional rotation has relied upon the build up of organic matter during the pasture phase and the mineralisation of nitrogen (N) (and hence C) during the cropping phase. A change from this system requires increased reliance on the use of N fertiliser. Either way, an additional problem is that the accumulation of organic matter during a pasture phase, or the use of N fertiliser, is commonly associated with soil acidification, requiring the application of limestone and the release of CO2 in order to maintain agricultural productivity. In addition to these soil based processes, the climatic variability that is commonly experienced in the semi-arid environment of southern NSW means that year to year variability in dry matter return to soil and in decomposition rates of residues will be relatively large. The net result is that the signal to noise ratio of any trend in SOM accumulation is low.

The influence of land use and management on soil carbon levels for crop-pasture systems in Central New South Wales, Australia

Changes in land use and management have been proposed as a way to increase soil organic carbon (SOC) in crop and pasture systems. Some of the proposed activities to improve SOC are the introduction of pasture phases in cropping systems, stubble retention, no-till cropping, improved fertilisation, introduction of more productive pasture species and grazing management. There is also growing interest in novel farming systems, such as pasture cropping (intercropping cereal crops with established perennial pastures), which may improve SOC. However, there have been few broad scale surveys to determine whether these land management changes have an impact on commercial farms. In this study, comparisons of land use were established for mixed farming and pasture cropping systems in the slopes region (average annual rainfall: 500–650mm) and for cropping and pasture in the plains region (average annual rainfall: 300–500mm) of Central West NSW, Australia. The survey aimed to determine the difference in SOC stocks (Mg C ha−1) and the composition of three soil organic carbon fractions (particulate – POC, humus – HUM and resistant – ROC). The influences of management actions and pasture composition were also assessed across pasture and cropping land uses. Cropping systems had lower SOC stocks in the soil than pasture systems in each region, but pasture cropping was not different from perennial pasture. Generally, there were larger differences in the POC due to land use and management than the other SOC fractions. Management practices in cropping systems explained greater variability in SOC than in pastures. For cropping systems, higher amounts of P fertiliser were associated with higher SOC, POC and ROC while higher amounts of N fertiliser were associated with lower SOC, POC and ROC. For pastures, the proportion of bare ground was associated with lower SOC and POC. These associations indicate there is an opportunity to increase SOC by converting cropping land to permanent pasture, increasing the frequency of pasture phases, changing crop fertiliser regimes and reducing bare ground in pastures, but further work is needed to verify the causality behind these associations.

Pasture grazing intensity and presence or absence of cattle dung input and its relationships to soybean nutrition and yield in integrated crop–livestock systems under no-till

In integrated soybean–beef cattle systems, the pasture grazing intensity affects the grain crop performance in succession. In addition, the dung cattle input influences the soil nutrients distribution in the field affecting the grain crop yield. This experiment aims to evaluate the effects of winter pasture heights and cattle dung input in soybean crop performance in succession. Main soil macronutrient content, soybean plant population, dry shoot biomass, plant height, plant nutrient content, soybean yield and yield components were assessed in the 10th experimental year. The experiment was conducted in the state of Rio Grande do Sul, Southern Brazil, in a long-term integrated crop–livestock systems implemented in 2001. Treatments were arranged in a split plot design with four pasture heights (0.10, 0.20, 0.30, and 0.40m) and two levels of dung input (with or without). For all the variables analyzed, there was no interaction between pasture heights and cattle dung input (P>0.05). The pasture height management had only effect in soil P content, soybean dry biomass production, plant height and number of grains per pod. The increase in grazing intensity was associated to the rise in soybean plant height and dry mass production but was without effect on grain yield. The presence of grazing animals in the integrated soybean–beef cattle systems, and the resultant augmentation of dung input increased by 122% and 38% the availability of soil K and P, respectively in relation to the absence. Thus, the content of such nutrients in the plant were increased in 41% and 7%, respectively. The improvement in soybean nutrition increases the amount of pods per plant by 20%, and resulting in a 23% increase in soybean yield. These results indicate that cattle dung input resulting from grazing animals in the pasture phase increased soybean grain yield due to better plant nutrition. Although, the occurrence of cattle dung was very concentrated in some spots of the field and thus future studies should address strategies to improve spatial distribution of cattle dung input.

The IPCC Tool for predicting soil organic carbon changes evaluated for the Pampas, Argentina

The Intergovernmental Panel on Climate Change (IPCC) has developed a methodology for predicting soil organic carbon (SOC) stocks and changes known as the IPCC Tool. We tested the use of this tool for soils of the Pampas Region of Argentina by comparing its predictions with results from a soil survey performed on 82 farms widely distributed over the region. The sample comprised soils in uncultivated as well as agricultural fields, both under crops or in the pasture phase of a mixed rotation. Using the default parameters, the IPCC Tool could not predict SOC stocks of uncultivated fields with an acceptable performance (R2=0.249; RMSE=27.7tha−1=48.5% of the mean SOC stock). On average, the methodology estimated SOC decreases on cultivation of 21%, but measured SOC changes were 10–14%. We therefore propose that default parameters values should be calibrated using local data. Using measured SOC stocks from uncultivated fields as reference values and locally calibrated parameters, led to an improvement in the estimation of land use change effect on SOC, but the fit to observed results was still poor (R2=0.403; RMSE=14.9tha−1=31% of the mean SOC stock). Possible causes of this failure of the methodology to capture land-use change effects on SOC are discussed, as well as the performance attained by other methodologies for estimating SOC in the Pampas.

Evolution in crop–livestock integration systems that improve farm productivity and environmental performance in Australia

Australian farming systems have an enduring history of crop–livestock integration which emerged in the face of high climate variability, infertile soils and variable landscapes. Ley farming systems with phases of shorter annual legume pasture phases with cereal crops predominate but, emerging sustainability issues and the need to manage risk is driving ongoing innovation in crop–livestock integration. We discuss the recent evolution of selected innovations that integrate crop and livestock production and their impacts on farm productivity, sustainability and business risk. Dual-purpose use of cereals and canola (Brassica napus) for forage during the vegetative stage while still harvesting for grain is now practiced throughout southern Australia's cropping zone. This practice provides risk management benefits, diversifies crop rotations, reduces pressure on other feed resources and can significantly increase both livestock and crop productivity from farms by 25–75% with little increase in inputs. Sacrificially grazing crops when expected grain yield is low and/or livestock prices are attractive relative to grain provides further flexibility in crop–livestock management systems vital for business risk management in a variable climate. Replacing annual pastures with perennial pasture phases in rotation with crops can provide a range of benefits including improved hydrological balance to reduce dryland salinity, subsoil acidification and water-logging, provide a management tool for herbicide-resistant or problem weeds, improved soil nutrient and carbon stocks as well as increased livestock productivity by filling feed gaps. In some environments, integration of perennial forages in mixtures with cropping, such as alley cropping and inter-cropping, also provide options for improving environmental outcomes. These practices are all innovations that provide flexibility and enable tactical decisions about the mix of enterprises and allocation of land and forage resources to be adjusted in response to climate and price. We discuss these innovations in the context of the emerging constraints to crop–livestock integration in Australia including the continuing decline in labour availability on farms and increasing management skill required to optimise enterprise profitability.

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.

Assessing costs of soil carbon sequestration by crop-livestock farmers in Western Australia

Carbon sequestration in agricultural soil has been identified as a potential strategy to offset greenhouse gas emissions. Within the public debate, it has been claimed that provision of positive incentives for farmers to change their land management will result in substantial carbon sequestration in agricultural soils at a low carbon price. However, there is little information about the costs or benefits of carbon sequestration in agricultural soils to test these claims. In this study, the costeffectiveness of alternative land-use and land-management practices that can increase soil carbon sequestration is analysed by integrating biophysical modelling of carbon sequestration with wholefarm economic modelling. Results suggest that, for a case study model of a crop-livestock farm in the Western Australian wheatbelt, sequestering higher levels of soil carbon by changing rotations (to include longer pasture phases) incur considerable opportunity costs. Under current commodity prices, farmers would forego more than $80 in profit for every additional tonne of CO2-e stored in soil, depending on their adoption of crop residue retention practices. This is much higher than the initial carbon price of $23t−1 in Australia’s recently legislated carbon tax. This analysis does not incorporate the possibility that greenhouse gas emissions may increase as a result of including longer pasture phases. Accounting for emissions may substantially reduce the potential for net carbon sequestration at low carbon prices.

Desempenho e características das carcaças de novilhos superprecoces em pastos hibernais submetidos a intensidades de pastejo

O objetivo deste trabalho foi avaliar os efeitos de intensidades de pastejo na terminação de novilhos superprecoces, em pastagens de inverno em sucessão à soja. Foram avaliadas diferentes alturas de pré-pastejo de pastos mistos de azevém e aveia: 10, 20, 30 e 40 cm. Empregou-se o delineamento de blocos ao acaso, com três repetições. Foram utilizados machos mestiços de raças de corte, inteiros, com idade de 10 meses e peso médio inicial de 192±12 kg. As seguintes variáveis foram avaliadas: massa e oferta de forragem, altura do pasto, taxa de acúmulo diário e acúmulo total de forragem, ganho de peso médio diário (GMD), carga animal e ganho de peso vivo por unidade de área (GPA), além de características qualitativas de carcaça. Os novilhos foram abatidos aos 14 meses de idade. O GMD ajustou-se a um modelo de regressão quadrático e teve o ponto de máximo desempenho entre 20 e 25 cm de altura de pré-pastejo, enquanto o GPA ajustou-se a um modelo linear negativo. A qualidade da carcaça dos novilhos foi satisfatória, quando os pastos foram manejados em alturas superiores a 10 cm. É possível produzir carcaças de novilhos superprecoces, na fase de pastagem de sistemas integrados de produção, durante o inverno, em sucessão à soja. O manejo de pastos mistos de azevém e aveia, em alturas entre 20 e 25 cm, otimiza o desempenho animal individual e por área.