Table 2.4.1 Resource status and trend summary for soil organic carbon (SOC) Ag Soil Ag Soil Zone Summary Abundance Confidence in Confidence in Zone condition trend number 1 Mid West Low Unclear Limited evidence Evidence and SOC levels vary with rainfall gradient. or limited consensus too low High temperature and soil constraints consensus to make an limit biomass production and SOC. assessment 2 Mullewa to Morawa Low Unclear Limited evidence Evidence and High temperature and low rainfall limit or limited consensus too low biomass production and SOC. consensus to make an assessment 3 West Midlands SOC levels vary with rainfall gradient. Low Unclear Limited evidence Evidence and Lighter textured soils are lower in or limited consensus too low SOC. Soil constraints limit biomass consensus to make an production. assessment 4 Central Northern Low/ Moderate Unclear Limited evidence Evidence and Greater variability in SOC levels Wheatbelt or limited consensus too low associated with rainfall gradient and consensus to make an high temperatures. assessment 5 Swan to Scott SOC levels related to wide rainfall High/very high Unclear Limited evidence Evidence and Coastal Plains range. Very high levels often or limited consensus too low associated with irrigated, fertilised consensus to make an pastures. Decline in SOC under assessment intensively cultivated horticultural systems. 6 Darling Range to SOC levels vary with rainfall gradient. Moderate/ Unclear Limited evidence Evidence and South Coast SOC maintained in conservation areas high or limited consensus too low and areas of reliable rainfall. Risk of consensus to make an SOC decline with increased cropping. assessment 7 Zone of SOC levels vary with rainfall gradient. Moderate Unclear Limited evidence Evidence and Rejuvenated Possible decline where cropping is or limited consensus too low Drainage increasing and pasture declining. Soil consensus to make an constraints can limit biomass assessment production.
Table 2.4.1 Resource status and trend summary for soil organic carbon (SOC) Ag Soil Zone number Ag Soil Zone Summary Abundance Confidence in condition Confidence in trend 1 Mid West SOC levels vary with rainfall gradient. High temperature and soil constraints limit biomass production and SOC. Low Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 2 Mullewa to Morawa High temperature and low rainfall limit biomass production and SOC. Low Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 3 West Midlands SOC levels vary with rainfall gradient. Lighter textured soils are lower in SOC. Soil constraints limit biomass production. Low Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 4 Central Northern Wheatbelt Greater variability in SOC levels associated with rainfall gradient and high temperatures. Low/ Moderate Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 5 Swan to Scott Coastal Plains SOC levels related to wide rainfall range. Very high levels often associated with irrigated, fertilised pastures. Decline in SOC under intensively cultivated horticultural systems. High/very high Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 6 Darling Range to South Coast SOC levels vary with rainfall gradient. SOC maintained in conservation areas and areas of reliable rainfall. Risk of SOC decline with increased cropping. Moderate/ high Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment 7 Zone of Rejuvenated Drainage SOC levels vary with rainfall gradient. Possible decline where cropping is increasing and pasture declining. Soil constraints can limit biomass production. Moderate Unclear Limited evidence or limited consensus Evidence and consensus too low to make an assessment