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Subsoil acidity and aluminum toxicity: Measurement, formation, and management strategies in conservation farming systems
No full textSoil acidity and aluminum (Al) toxicity are significant soil constraints for agricultural production worldwide. Soil acidification, or a decrease in soil pH, is a natural process increased by agriculture due to product removal and nitrate leaching. Its effect on plant production is measured by dividing the soil profile into layers based on nutrient availability. In most regions of Australia, a 0–10cm soil layer is used to define the topsoil, while the subsoil is defined as soil layers below 10cm. The soil acidification process results in an acidic layer typically forming in the 10–30cm soil layer. Hence, subsoil acidity or the occurrence of soil Al is a greater issue than topsoil acidity. Acidity is used to describe the overall problem, but soil Al is the soil factor resulting in reduced root growth and agricultural production. The main toxic species in soils is @equ_0001.eps@, which is abbreviated to Al3+. A soil pH measurement defines the degree of soil acidity, while soil Al3+ content measures the degree of Al toxicity. Both pH and Al3+ are commonly measured using 0.01M CaCl2 at a soil:solution ratio of 1:5 (pHCaCl2 and AlCaCl2). Topsoil with pHCaCl2 less than 5.0 and subsoil with pHCaCl2 less than 4.5 are classified as acidic. At the same time, soils with AlCaCl2 greater than 2.5–4.5mg Al/kg in 0–30cm soil layers restrict wheat (T. aestivum) production.
Lime application to the soil surface effectively treats topsoil acidity/Al3+ toxicity but is ineffective in treating subsoil Al3+ toxicity. The low effectiveness is due to lime’s low solubility combined with soil, environmental, and lime quality restrictions which limit lime dissolution and alkalinity movement from the topsoil to the subsoil. Hence, subsoil Al3+ toxicity management requires combining lime with gypsum applications, using strategic tillage to increase lime dissolution in the topsoil and redistributing lime into the subsoil, and growing Al3+ tolerant crop species. Topsoil alkalinity movement into the subsoil occurs when sufficient lime is applied to maintain the topsoil pHCaCl2 between 5.5 and 7.5. Maintaining pHCaCl2 within this range creates a pool of excess lime alkalinity which is leached into the subsoil to mitigate subsoil Al3+ toxicity. The conservation farming system or the no-tillage seeding system results in the stratification of surface-applied lime in soil layers near the surface. Strategic tillage (surface and deep) is used to increase the effectiveness of surface-applied lime in ameliorating subsoil Al3+ toxicity. Strategic surface tillage increases lime dissolution in the topsoil to achieve the target pHCaCl2 range faster, resulting in greater rates of alkalinity movement. Strategic deep tillage practices redistribute a lime-rich topsoil layer into the subsoil, typically to a depth of 40cm. Gypsum is more soluble than lime, and the applied calcium and sulfate are leached rapidly to treat subsoil Al3+ toxicity. Its application with lime can increase alkalinity movement into the subsoil when measured using a change in AlCaCl2 at pHCaCl2 less than 4.5. Further research is required to understand the soil chemistry process involved and to identify soil types or properties where gypsum and other organic amendments applied with lime can improve alkalinity movement.https://library.dpird.wa.gov.au/books/1045/thumbnail.jp
LANZA® Tedera is strongly suppressed by competition from Lolium multiflorum and is best adapted to light-textured soils
No full textBituminaria bituminosa var. albomarginata, known as Tedera, is a promising forage for Mediterranean climates. An improved variety named LANZA® has been developed. Previous research suggests that soil water saturation in heavy-textured soils might affect its initial development. Competition from grasses could also compromise its successful establishment and persistence. We investigated the effects of soils with contrasting textures (loamy sand vs. clay) with a high soil water content and the competition from Lolium multiflorum on the development of LANZA® in a pot experiment. Dry mass (DM) production of LANZA® was strongly reduced (86%) when grown with L. multiflorum. LANZA® shoot DM was 60% higher than the total shoot DM production of the mixture of LANZA® and L. multiflorum. Soil type did not significantly affect the shoot and total root DM. However, a 44% reduction of the DM of thin roots and slower development was observed in clay soils, which may indicate a preference for light-textured soils. This study provides further information on the factors limiting the establishment and persistence of LANZA®. Future research should confirm these results at field scale and investigate measures aimed at reducing early competition in monocultures and functional complementarity with partner species in mixtures to successfully establish LANZA®
Inland dry season saline intrusion in the Vietnamese Mekong River Delta is driving the identification and implementation of alternative crops to rice
No full textCONTEXT Inland saline intrusion is occurring during the dry season in the Mekong River Delta (MRD), Vietnam. Rising sea levels, tidal fluctuations, drought, and changes to upstream flow contribute to extensive salinisation of rice producing areas of the MRD, leading to substantial rice crop losses.
OBJECTIVE The identification, evaluation and implementation of alternative crop and soil management solutions are required to complement on-going rice production in the region.
METHODS A review of scientific and grey literature was conducted regarding the nature and extent of salinisation in the MRD and the adoption and management of alternative crops to rice.
RESULTS Familiar crops in Vietnam (e.g., maize, soybean), as well as novel crops to the MRD (e.g., quinoa, cowpea) were explored as potential options to replace dry season rice. Management options including surface soil mulches and plastic coverings help maintain soil moisture and reduce salinity damage to plants, and the use of drainage and seed preparation techniques can improve plant establishment and yield. Factors contributing to the success of alternative crops include salt tolerance, timing and efficiency of water use, ability to grow in the dry growing season, tolerance to pests and diseases, labour intensiveness and the crops\u27 marketability.
SIGNIFICANCE The identification of suitable alternative crops to replace dry season rice in saline affected areas of the MRD, combined with management practices like mulching and soil moisture monitoring, could provide farmers with income opportunities to offset rice losses. Documenting the factors contributing to successful crop diversification can assist with decision-making and support initiatives among farmers, agribusiness, and government agencies
Land systems, soils and vegetation of the southern Goldfields and Great Western Woodlands of Western Australia - Volume 1
No full textThis technical bulletin defines and maps the land resources of the southern Goldfields region of Western Australia (WA). The southern Goldfields region, as featured in this bulletin, covers 151,753 km2. The western and eastern borders are variable because they align with various cadastral boundaries. The western survey border, which in part follows the WA State Barrier Fence, demarcates cleared agricultural land from the intact, western extent of the Great Western Woodlands. The eastern border abuts the westernmost Nullarbor pastoral lease boundaries, except for the north-easternmost and south-easternmost edges which continue into Crown land. Major towns are Coolgardie, Kalgoorlie and Boulder in the central north, Kambalda in the centre and Norseman in the central south.
The southern Goldfields survey area is closely aligned with the world’s largest and most intact area of Mediterranean-climate woodland, known as the Great Western Woodlands. These eucalypt-dominated woodlands, which include mosaics of mallee, shrubland and grassland, cover nearly 160,000 km2. This survey and adjacent rangeland surveys in the Sandstone, Yalgoo and Paynes Find, north-eastern Goldfields, and WA Nullarbor regions complete mapping to a scale of 1:250,000, and describe biophysical features over most of the Great Western Woodlands, except for the southernmost extremities.
This survey combines and augments previous studies that mapped vegetation, physiography and soil distribution in a hierarchical framework that adheres to state and national standards. The purpose of this survey was to provide a comprehensive description of the biophysical resources of the southern Goldfields region and an accompanying land system map.
This bulletin provides information on survey methods, climate and landscape evolution. The characteristics and distribution of soils, vegetation and habitat type ecology, and land systems are described. This information will assist individuals, agencies and companies who have interests in land-use planning and development of sustainable systems, monitoring, rehabilitation and conservation of the rangeland habitats and landscapes within the southern Goldfields region. Within the survey area, there are 69 WA soil groups, belonging to 12 soil supergroups; 88 habitat types split between 13 groups; and 101 land systems grouped into 41 broad land types
The phytotoxicity of soil-applied herbicides is enhanced in the first-year post strategic deep tillage
No full textThe sandplain soils of WA are inherently fragile with surface layers that are very low in organic matter and clay content. The advent of minimum- and no-till farming has seen the increase in frequency and intensity of cropping on these soils. However, a combination of soil physio-chemical constraints and agronomic issues remain a challenge to the sustainability of cropping systems on them. These constraints include sub-soil compaction, soil water repellence, sub soil acidity and herbicide resistant weeds. Strategic deep tillage such, as soil inversion and deep soil mixing, have been shown to ameliorate these multiple constraints and dramatically increase crop production. For WA soils, an increase in herbicide usage is correlated with a decrease in regular tillage, and how the two interact is imperfectly understood. As a result, current herbicide strategies and rates are designed to perform optimally in a minimum tillage environment. Two field experiments were established to compare crop damage from a range of commonly used pre-emergent herbicides when grown in soil that remained under minimum tillage, was deep mixed or inverted. These trials demonstrated that both strategic tillage methods significantly changed the soil surface composition that would be expected to directly affect the bioavailability of some herbicides. Two commonly used herbicides, Metribuzin and Diuron, detrimentally impacted crop performance following tillage in both trials. These same treatments reduced yield by a greater extent on both the soil inversion and deep mixing treatments (p \u3c 0.001). No other herbicides, when applied at either label or triple label rates, significantly impacted yield on any of the soil treatments. There was a substantial crop production benefit from strategic deep tillage at Esperance but not at Geraldton. These results reflect that the influence of deep tillage on the toxicity of herbicides is highly dependent upon soil properties and rainfall
PestFacts WA Issue 13 - August 2023
No full textPestFacts WA Issue 13 - August 2023 contents: Diamondback moth numbers are low, but growers are reminded to monitor with warming temperatures Native budworm caterpillars are appearing in the northern region Turnip yellows virus is spreading in canola in Kwinana West and Albany port zones Sclerotinia stem rot updatehttps://library.dpird.wa.gov.au/fc_pestfactswa/1016/thumbnail.jp
Protecting WA Crops Issue 31 - July 2023
No full textProtecting WA Crops Issue 31 - July 2023 contents: New project to reduce Rhizoctonia impact in low and medium rainfall zones Meet Crop Protection team member – Dr Ahmed Saadhttps://library.dpird.wa.gov.au/fc_pwac/1004/thumbnail.jp
Differential impacts of cereal and protein sources fed to pigs after weaning on diarrhoea and faecal shedding of Escherichia coli, production, and total tract apparent digestibility
No full textDifferent cereal types, in combination with different protein sources, are fed to pigs after weaning, but their interactions and possible implications are not well researched. In this study, 84 male weaned piglets were used in a 21-day feeding trial to investigate the effects of feeding either medium-grain or long-grain extruded rice or wheat, in a factorial combination with protein sources of either vegetable or animal origin, on postweaning performance, shedding of β–haemolytic Escherichia coli, and the coefficient of total tract apparent digestibility (CTTAD). Pigs fed either rice type performed the same (p \u3e 0.05) as wheat-fed pigs after weaning. The use of vegetable protein sources reduced growth rate (p \u3c 0.001) and feed intake (p = 0.007) and deteriorated the feed conversion ratio (p = 0.028) in weeks two and three compared to pigs fed animal protein sources. The number of antibiotic treatments given for clinical diarrhoea was similar (p \u3e 0.05). However, the faecal E. coli score showed a trend for the main effect of protein source, with pigs fed animal proteins showing a higher E. coli score than pigs fed vegetable proteins (0.63 vs. 0.43, p = 0.057). There was also a tendency for an interaction (p = 0.069) between cereal type and protein source (p = 0.069), with this difference being associated with a greater faecal score in pigs fed diets with long-grain rice plus animal proteins and wheat plus animal proteins. Significant interactions occurred for the CTTAD when assessed in week three. In general, pigs fed diets with medium-grain rice or long-grain rice with animal proteins had a higher (p \u3c 0.001) CTTAD for dietary components than pigs fed all other diets, and vegetable proteins depressed (p \u3c 0.001) CTTAD compared to animal proteins (main effect of protein: p \u3c 0.001). In summary, pigs tolerated the extruded rice-based diets well and performed equivalently to pigs fed wheat as the sole cereal, and the use of vegetable proteins decreased the E. coli score
Observations of the association by early-juvenile western rock lobster Panulirus cygnus George, 1962 with seagrass assemblages (Decapoda: Achelata: Palinuridae)
No full textThe fishery of the western rock lobster, Panulirus cygnus George, 1962, is Australia’s most valuable wild-caught single-species fishery. Recruitment in some regions of the fishery was observed to be significantly lower than expected after the 2010/2011 West Australian marine heatwave that caused extensive disturbance of dominant coastal habitats. This event generated interest in the study of the factors influencing survival and recruitment of post-larval benthic P. cygnus after settlement. The habitat associations of the highly cryptic post-settlement early-juveniles were previously unknown, with only anecdotal observations of individuals within limestone crevices in nearshore habitats. Our study used early-juveniles derived from ongoing monitoring of puerulus settlement to examine their habitat association mechanism in mesocosm experiments. Comparison of common nearshore habitat assemblages (bare sand, limestone crevices, and seagrasses (Posidonia and Amphibolis) at varying seagrass densities) found that most early-juveniles associated strongly with Amphibolis assemblages at high stem densities (~2,100 stems m–2). A shift in association between Amphibolis fronds and stems at high stem density to Amphibolis-shaded sand and leaf debris at low stem density indicated active habitat selection by early-juveniles. Habitat choices were tested with the scents of prey items and habitat types within Amphibolis assemblages using Y-maze bioassays. No significant olfactory choices were found, suggesting that habitat associations may be driven by multiple cues. Our study provides new laboratory-based insights into the habitat association of early-juvenile P. cygnus and suggests changes in seagrass assemblage identity and density are likely to be important. Further experimentation is needed to define the cues driving these patterns. The impact of habitat change on recruitment in this important fishery remains unknown and should be an objective of future research
Costs of wind erosion in the Northern Agricultural Region
No full textSummary To date, the Department of Primary Industries and Regional Development’s (DPIRD) estimated opportunity cost of wind erosion for Western Australia’s (WA) agricultural region has only included the costs of forgone production income and therefore underestimates the broader costs of wind erosion events. This underestimation of costs was the impetus to create a case study to give an indication of the magnitude of the costs of wind erosion from agricultural land. Farmers in the Northern Agricultural Region (NAR) were contacted to seek information about the on-farm costs of wind erosion events that occurred in 2020. Seventeen farmers responded to the survey and the average on-farm costs of wind erosion per arable hectare were about 100,000. However, the general maintenance programs of the local governments would also include clean-up costs associated with wind erosion. These ‘hidden’ costs were not included in the estimated costs. The estimated health costs for the greater Geraldton area – the only location in the NAR where dust measurements were recorded – were around 80 per person), and one event contributed 80% of these costs. The total health costs for the NAR arising from wind erosion will be higher because the area and consequently the population affected by wind erosion during 2020 is much bigger than the City of Greater Geraldton. Other costs associated with wind erosion were not considered in the case study because of a lack of data. These costs include siltation of waterways, cleaning (businesses and homes), transport disruptions, clogging machinery, sandblasting of infrastructure, potential pollution of food and on-farm water sources, soil movement, weed, seed, chemical and nutrient movement into streams and the broader environment. Given the limitations in data collection and accuracy, this paper is intended to provoke discussion in industry and rural Western Australia about the costs and management of wind erosion. More detailed work is needed to accurately reflect the costs of wind erosion. The costs are illustrative and cannot be generalised because of their limitations. Costs are in Australian dollars