BGWA information session - Improving soil health Belinda Rawnsley South Australian Research and Development Institute (SARDI) Tuesday 27 May 2014
Outline What is soil health and importance of soil biology How to sample for soil health Soils in Barossa Valley Improving soil condition
What is soil health? Biological, chemical and physical properties of a soil and its capacity to function and sustain life
Improve soil structure Water holding capacity Water use efficiency Increase soil biology Role of soil health Increase yield Increase reliable production Increase profitability Decrease fertiliser and inputs Increase soil resilience and long term sustainability
Soil biology Require carbon as an energy source to break down organic matter Release nutrients into plant available forms BAM!
Soil biology Require carbon as an energy source to break down organic matter Release nutrients into plant available forms Improve and maintain soil structure
Soil biology Require carbon as an energy source to break down organic matter Release nutrients into plant available forms Improve and maintain soil structure Suppress soil borne disease
Soil biology Require carbon as an energy source to break down organic matter Release nutrients into plant available forms Improve and maintain soil structure Suppress soil borne diseases Degrade chemicals Soil Organic Carbon is slow to change. Soil microbes respond to soil management
Fungi and bacteria Fungi associated with decomposition and soil structure stability High carbon requirement Bacteria regulate nutrient supply Associated with green material Transform nitrogen into a useable form
Nematodes Majority are free-living (saprophytic) nematodes which feed on bacteria and fungi influence decomposition of organic matter and making nutrients available to plants Build soil structure make tunnels, creating aerobic conditions in the soil Parasitic nematodes feed on plant roots
How to sample for soil biological health Majority of organisms live in top 5-10 cm soil Microbes feed on exudates of new feeder roots, so want to sample in the rootzone Coincide soil sampling with periods of peak root growth Root growth commences 3 weeks AFTER budburst 20 cm 40 cm
How to sample for soil biological health Sample 40 cm away from vine trunk, 20 cm out to midrow Depth to 20 cm Random sample of 20 cores bulked to give representative sample Send as soon as possible Midrow cover crops influence soil microbial population
Total microbial biomass 2009/2010 40 HIGH 35 Total microbial biomass (ugc/g) 30 25 20 15 10 2 Nov 2009 1 Feb 2010 25 March 2010 MODERATE 5 0 Cultivated Biodynamic Permanent sward Mulch Grazing land
Microbial activity at depth B -glucosidase enzyme activity (mg p -Nitrophenol/kg soil/h) 140 120 100 80 60 40 20 0 Rhizosphere soil 0-5 5-10 10-20 20-30 30-40 Soil depth (cm) (Rawnsley, 2008)
Just add microbes? 7,000 If current practices have low microbial Nov 2009 populations, 6,000 additions of new microbes Feb 2010 Mar 2010 or organisms are unlikely to thrive and 5,000 persist no. free-living nematodes/200 g soil 4,000 Products stimulate organisms already in soil3,000 Manage 2,000 existing soil biology by feeding the microbes 1,000 0 Conventional cultivation Biodynamic Permanent sward Undervine mulch
GWRDC - Benchmarking soil health Aim to benchmark soil quality Defined set of tests to be used by industry chemical, physical and biological 50 vineyards chosen to represent Barossa soil types Sampled soil undervine, midrow and native vegetation
Greenock Marananga Gomersal Rowland Flat Northern Central Foothills/Vine Vale Lyndoch Eden Valley
Distribution of Soil Organic Carbon in Barossa Valley
Ideal levels of soil carbon dependent on soil type Soil organic carbon (%) in different soil types in SA Sand Sandy/loam Loam Clay loam/clay Low 0.5 0.7 0.9 1.2 Moderate 0.5-1.0 0.7-1.4 0.9-1.8 1.2-2.0 High >1.0 >1.4 >1.8 >2.0 (modified from Baldock and Skjemstad 1999). Benchmark against others in your region
Barossa soil type and organic carbon
Regional differences - Labile organic C
Soil management - Marananga
Soil structure Affects water infiltration, root growth, nutrient use Organic matter holds the soil together Slaking - Soil aggregate falls apart when placed in water Indicates poor structure Prone to crusting, run off and erosion
Soil structure Dispersed soils breakdown separate particles Restricts air movement, root growth, water-logging Permanent Sward - Midrow Bare soil - Undervine
Improved water infiltration = $ savings Season Water Use MegL/Ha Yield Soil management 07/08 0.72 7.74 Clover and medic midrow 08/09 0.64 4.98 Compost applied 2008 09/10 0.5 11.84 10/11 0.16 8.68 11/12 0.23 9.64
Soil water infiltration test it yourself Measure the rate a fixed volume of water soaks into the soil 150 mm diameter PVC pipe cut to 11 cm length and push 2 cm down into the soil Add 500 ml water and record absorption time o Poor >7 mins o Fair 3-7 mins o Good under 3 mins
How can you improve soil condition? Avoid bare soil
Lower structural stability Lower nutrient availability Lower biological activity = Degraded soil
How can you improve soil condition? Avoid bare soil Maintain ground cover Minimise compaction Apply soil organic amendments/compost Control rates of decomposition by continually adding organic material
How can you increase soil biology? Feed the microbes! Organic matter must be continually supplied
Adding organic matter - Long term benefits
Do I till or herbicide the covercrop? Cultivation causes the greatest loss of soil organic carbon Why? Makes organic matter readily available to microbes and increases aeration so breakdown is faster Better to mow to maintain organic matter and slow degradation Regulates soil moisture under cover crops Depending on crop type, herbicide use also minimises soil disruption
Novel methods Dick s crimper
Benefits of Compost Reduces evaporation = improves water use efficiency and water savings Reduces soil temperature Improves soil fertility and structure Adds organic matter and slow release nutrients Weed control, decreases need for herbicides Disease suppression less root disease
What type of compost should I use? Australian Quality Standard AS4454 Fine compost mulch Decays quickly Gives quick improvement to soil structure Can impede water infiltration Coarse textured Large woody particles Allows water penetration Multi-particle Reduces evaporation Slow release nutrients
What is the best way to improve sandy soils if I don t use compost? No tillage is essential little carbon in sandy soil already Maintain covercrop/crop residues Provide adequate nutrients to improve crop growth = organic matter Add a source organic material
Take home message Healthy soils are resilient, more productive and provide consistency Good soil structure improves water infiltration, root growth and plant access to nutrients Build up soil biology to increase nutrient availability > less inputs Monitor soils
More web information Soil Quality soilquality.org.au Soil health factsheets Victorian Resources online > soil health vro.dpi.vic.gov.au Soil biology basics NSW DPI agric.nsw.gov.au