Crop Production AGRO321 Past Paper (PDF)

**CROP PRODUCTION -- AGRO321** **AGRO321 Learning Objectives** 1. Describe the constraints to, and potentials of, sustainable crop and horticultural production systems 2. Integrate general principles of soil and plan processes for sustainable ag plan production (dryland and irrigated cr...

**CROP PRODUCTION -- AGRO321** **AGRO321 Learning Objectives** 1. Describe the constraints to, and potentials of, sustainable crop and horticultural production systems 2. Integrate general principles of soil and plan processes for sustainable ag plan production (dryland and irrigated crops and horticultural species) practices 3. Manage crops and horticultural systems for environmental, economic and social outcomes 4. Communicate effectively to others in written and verbal formats on issues relating to sustainability within the Agronomy discipline **Assessment** Assessment Weighting Open Date Close Date ------------------------------ ----------- ----------- ------------ Physiology Quiz **5%** **07/07** **14/07** Crop Water Quiz **5%** **21/07** **28/07** Crop Nutrition and Soil Quiz **5%** **18/08** **25/08** Crop Breeding Quiz **5%** **13/09** **20/09** Prac report A **15%** **23/08** Prac report B **15%** **06/09** Final exam **50%** **Study Schedule** +-----------------+-----------------+-----------------+-----------------+ | WEEK | COMMENCING | TOPIC | ASSESSMENT | +=================+=================+=================+=================+ | 1 | 24-07 | **Industry | | | | | Background and | | | | | Physiology** | | +-----------------+-----------------+-----------------+-----------------+ | 2 | 01-07 | **Physiology | | | | | and Phenology** | | +-----------------+-----------------+-----------------+-----------------+ | 3 | 08-07 | **Physiology: | **Quiz** | | | | PBL and Water** | | +-----------------+-----------------+-----------------+-----------------+ | 4 | 15-07 | **Water** | | +-----------------+-----------------+-----------------+-----------------+ | 5 | 22-07 | **Water: PBL** | **Quiz** | +-----------------+-----------------+-----------------+-----------------+ | 6 | 29-07 | **Stats and | | | | | Nutrition** | | +-----------------+-----------------+-----------------+-----------------+ | 7 | 05-08 | **Mid-tri | | | | | Intensive** | | +-----------------+-----------------+-----------------+-----------------+ | 8 | 12-08 | **Mid-tri | | | | | Intensive** | | +-----------------+-----------------+-----------------+-----------------+ | 9 | 19-08 | **Nutrition and | **Quiz** | | | | Precision Ag** | | | | | | **Report A** | +-----------------+-----------------+-----------------+-----------------+ | 10 | 26-08 | **Precision Ag, | | | | | Protection: | | | | | Diseases and | | | | | Yield | | | | | Protection** | | +-----------------+-----------------+-----------------+-----------------+ | 11 | 02-09 | **Protection: | **Report B** | | | | Weeds, | | | | | Protection: | | | | | Pests and Yield | | | | | Prediction** | | +-----------------+-----------------+-----------------+-----------------+ | 12 | 09-09 | **Protection: | | | | | Pests, | | | | | Protection: PBL | | | | | and Breeding** | | +-----------------+-----------------+-----------------+-----------------+ | 13 | 16-09 | **Revision** | | +-----------------+-----------------+-----------------+-----------------+ | 14 | 23-09 | | **Quiz** | +-----------------+-----------------+-----------------+-----------------+ **WEEK 1** **LECTURE 1:** INDUSTRY BACKGROUND AUSTRALIAN GRAINS INDUSTRY - Around the coast: - Annual rainfall zone - \>250mm (S); \>450mm (N) - 24 million ha (2.6% of land area and 40% of arable land) - \> 40 billion tonnes annually - How nig a deal is this industry? - Valued at \$10 - \$12 billion - About 25 -- 35% of value of ag HOW IMPORTANT IS AG TO AUS? HOW MUCH OF OUR SPACE IS CROPPED? WHAT DO WE DO WITH IT ALL? - Aus is only small growing nation, globally - Typically top 3 international exporter wheat - Who buys it? WHERE HAVE WE COME FROM? - Big gains from: - Breeding - Rotations - Mehanisation - Weed control - Fertilisers - Scale - Key environmental drivers - Water - Nutrition - Pest and disease \*what is driving these improvements -- what is the need to improve? TERMS OF TRADE - 'cost-price squeeze' - Growers as 'price takers' - Pressure from input costs rising, commodity prices dropping - Result: increasing farm sizes, reduced farm numbers, pressure for improved efficiencies  KEY CHANGES THROUGH TIME - Crop diversity - Cultivation practices - Burning, conventional tillage - Stubble retention, minimum tillage and controlled traffic - Residual, selective and knockdown herbicides - Fertiliser usage - Increasing (particularly N) - Replacing pasture long phases (particularly in the South and West) - Increasing topdressing and managements of N nutrition - Increasing legume rotation ONGOING RISKS - Diseases - E.g. crown rot, root lesion nematode, aschchyta, rusts - Breeding is an 'arms race' - Pests - Russian wheat aphid - Herbicide resistance - Increasing list of herbicide resistant species - (\>35 weed sp known to be resistant to at least 1 herbicide) - Environmental sustainability - Environmental resource decline/pollution - Climate variability and changes - Terms of trade, quality and traceability requirements, different crop usage ITS NOT DOOM AND GLOOM! - Cropping is broadly the most efficient means of feeding a expanding global population - Massive market and one that will increasingly need specialist managers and agronomists to ensure quality and productivity into the future SUMMARY - Cropping is relatively 'intensive', often using better land/environments - Aus is not a large producer internationally, but is a large exporter - Significant changes in the industry over time - Practice, productivity and terms of trade - Some ongoing challenges - Very bright and necessary future! **LECTURE 2:** CROP/PLANT PHYSIOLOGY CROP PHYSIOLOGY - Growth stages - How crop growth and the environment interact - Phenology - Thermal time - Photo period - Vernalisation - Growth-leaf area GROWTH STAGES - Different stages for different crops - Why should we care? - Herbicide -- weed control - Herbicide -- desiccation - Fungicidal application - Topdressing fertilisers PLANTS BEHAVE PREDICTABLY BUT NOT THE SAME EVERY YEAR - Interaction with environment - How they avoid bad conditions - Go through a series of phenological (development/maturity stages) - Grow a canopy (catch light) - Store photosynthates - Use water/nutrients - Reallocate resources into grain ZADOCKS OR DECIMAL GROWTH SCALE CEREALS - Way of describing growth stages - Examples for most crops - In general there are 2 dominant stages - Vegetative - Reproductive - It is possible to have multiple Z stages (e.g. tillering and leaf no) - Convention, can average V stages, but not R stages THERMAL TIME - Crops take different times to get from sowing to maturity at different temperatures - Crops grown in cold climates take longer than the same crop in warmer temps - We can calculate the speed they go by seeing how long they take at a given temp to get through a phase - Does it just mean they grow faster? PHENOLOGY - The study of natural cyclic phenomena - Categorising plant development maturity - There is a difference between age and maturity - Key drivers: - Thermal time - Photoperiod - Vernalisation - Summer -- short day plants - Winter -- long day plants WHY SHOULD I CARE? - This is the heart of agronomy - Understanding when our plants are doing what helps us to plan better - Sowing time - Avoidance of frost risk a flowering - Heat/water stress at grain fill PRODUCTION LIMITATION - Why don't all plants grow indefinitely? - The plant systems will always be limited by something SOLAR ENERGY - Leaf area development - Warm temps promote growth rates and accelerate maturity - Warm temps don't necessarily mean a bigger crop - There is a difference between rapid rate of growth and rapid rate of development WHY IS PHENOLOGY IMPORTANT? - Having an understanding of plant growth stages is necessary for appropriate management - Having an understanding of the key drivers for phenology is key for planning better crops. **WEEK 2** **LECTURE 3:** CROP PHYSIOLOGY CONT. RECAP ON PHENOLOGY - Degree days how a plant tells time - Sowing to emergence (115 degree Celsius days) - Emergence to flowering (520 (quick), 600 (long) degree Celsius days) - Vernalisation and photoperiod sensitivity - How a plant tells the seasons - Changes how many degree days it takes to graduate A WALK THROUGH - Plant growth (how do they grow?) - Inputs (light, CO2, water, nutrients) - Gas gets in via stomata - Water leaves when stomata open - Draws up nutrients - Growth and water use are closely related - Rate limited by the most limiting factor - Some parts of the lifecycle have inherent limitations (e.g. leaf area) - Germination and emergence - Potential size of the first 3 leaves is determined by the seed - Imbibition and germination (temp) - Coleoptile (leaf tube) elongates to the surface - Length changes with cultivar and temp - When would it be important? (sowing deep or warm) - Barley leaves are twice the size of wheat from outset, what might that mean? - Early growth rates, light capture and competition and limited in seedlings - How could we fix this? (planting density and variety) - Root growth - 40% of initial growth photosynthates is partitioned towards the root system - Root: shoot is flexible - Slowly decreasing with maturity to anthesis when it stops - 5-7 seminal (primary) roots are produced from seed - Can respond to environment (spatially) - Nodal roots (from nodes in crown/tillers) are secondary and re-explore the surface with rain - Grow on different angles, more densely branching - Tillering - Why? - Plasticity (compensation 60-150pl/m2) - First 3 tillers produced from the base of primary; then those tillers tiller etc - Controlled by the internal N:C ratio of the plant (varietal differences) - Some varieties have lots of tillers (small heads) -- others have few tillers (large heads - Yield would be the same IF everything was non-limiting - Main stem controls development - Tillering stops at elongation (generally) - Tillers have lower yield potential - How could we reduce tillering? -- plant population - Grain potential - Yield = grain \# / area \* grain mass - Variation in yield is usually related to seed set - Plants decide around flowering how many seeds to set - Response based on growth in this period - Embryonic grains that there is not enough 'growth' to fill are aborted - Main stem, mid ear has priority - Hormonally controlled (auxins) - Grain size can be reduced by other stresses - Disease, drought - Seed set is highly sensitive to environment around flowering - So what if we want to get 100% growth potential? - Need unlimited water (soil water in excess of evap) - Rain at tis time is highly beneficial (reduce loss and increases supply) - Need large amounts of sunlight on big leaves - If that comes with temp it reduces the length of flowering window - Low temps are better - Evap and degree days - When do we want flowering? - Biggest yields possible with early flowering but\... frost - The catch - Growing a large crop with big potential yield is no good if it means water and N at flowering is limiting - Need to apply N at the rate corresponding to the water available at flowering - Consider long season varieties - Can produce higher yield potentials\... if you have the resources to fill grain - In water constrained systems short season varieties can yield better - North of Tamworth-Dubbo (short) - South of Dubbo tends to be longer varieties - Why? -- in crop rainfall - Grain fill - Much of the assimilates from boot to 80 degree days after flowering is stored in the stem - During grain development, grain is priority \#1 - Is N demand not met N is removed from leaves - Stored energy everywhere is mobilised to grain - 10% yield variation is from grain weight - 90% yield variation from grain number - Exception: late tillers with inadequate secondary root development - Can contribute to screenings - High plant densities? **LECTURE 4:** CROP PHYSIOLOGY CONT WATER UPTAKE BY PLANTS - The soil holds water - How hard it holds into is the same force it takes the plant to suck water - The supply rate of water to the plant depends on - How hard the plant can suck - How many roots it has and where WATER UPTAKE - Water movement through the plant depends on movement down gradients - Water demand for the plant depends on growth stage and environment - 2 sources - Stored water - In-crop rainfall CROP WATER - Stored soil water - Resistant to evap - Known quality - Fallow rainfall \~30% efficient - Factors affecting? - Can be 50% more effective than the same volume of crop rainfall - In crop rainfall - Unknown quantity or timing at planting - Susceptible to losses (especially early season) - Soil supply is dependent on roots NUTRIENT UPTAKE - Plants absorb nutrients by roots - Actively and passively - Different nutrients have different availabilities and uptake pathways - N mobile, mass flow - P immobile, diffusion limited - Deep placement of P, leaching of N - Despite differing strategies, uptake is dependent on root length and density - Plants have a capacity to adapt - Roots need to be there to collect nutrients - Deep N/water - Subsoil constraints NUTRIENT LIMITATION - Plant growth determines nutrition demand/requirements - How much fert to apply? - How much growth do you expect? - Concentration in tissues is diluted by growth - Nitrogen is one of the most required nutrients in plants - Highly mobile within the plant - Deficiency symptoms in older leaves - At fill-kill older leaves to supply head - Reduced yield and grain protein % HOW DO YOU TELL? - Say we expect a 4t crop and get a 5t year, what happens to: - Yield? - Grain protein %? - How could you tell if you had under-fertilised then? - What if you over-fertilise? - Not quite the same; at high N rates, the translocation efficiency drops so big N applications don't increase protein much APPLICATION - How to choose a variety (management of risk)? - Environment - Frost (potential loss -- 100%) - Water stress (potential loss -- 10-80%) - Heat and evap stress (potential loss 5-20%) - Biotic - Disease, insects, weeds, pests (50%) - Quality (class of products and market fit) - 25% return and 50% on gross margins - Yield benefit - 10% variation **WEEK 3** **LECTURE 6:** CROP WATER MANAGEMENT CUNNING FIENDISH PLAN - Soil physics (designed as Agronomy) - Water is king in Aus ag - Sources: rainfall, stored and irrigation - Difference between 20-80% profile at sowing can mean 8x yield (especially in northern systems \... in WA little stored) - On balance 1/3 of the water used by the crop can come from stored 2/3 from in crop rainfall - Typically fallow efficiencies are low (\< 30%) - Maximising water storage can mean big yield gains WHY IS IT SUCH A BIG DEAL? - Aus evap rates 2.5 -- 3 x rainfall (less in south) - Aus rainfall highly variable and unpredictable in - Intensity, size and timing - Many of our falls are ineffectual - 40% \< 15mm; 50% 15-50mm; 10% \>50mm - In fallow = 70% loss to evap, 10% runoff, 20% fallow moisture - So management is important DEFINITIONS AND PURE STUFF - Plant available water content (PAWC) - How big is the bucket? - Plant available water (PAW) - How full is the bucket? - Pores: Macro \> Meso \> Micro MEASURING PAWC - Why should we care? - Useful to know how big the bucket is - Use it to work out PAW - How do we work it out? - Guess based on soil type (deep clay = big bucket, shallow sand = small bucket) - Can PAWC change? - Changes for each crop and throughout the season - How much the soul can hold that the plant can see (units are in mm/m soil) HOW MUCH IS IN OUR BUCKET? - Why de we care? - Sets varietal choice, fertiliser rates, plant population, benchmarking and yield estimates - Methods: - Push probe - Coring - Capacitance probes - Neutron probes - Model (guesses) HOW DO WE CHANGE IT? - What happens to water in out soils? - Hydrological cycle: - Infiltration - Evap - Runoff - Drainage INFILTRATION - Highway systems (macro pores) - Side streets (meso pores) - Parking bays (micro pores) - Infiltration rate decreases with time (rush hour) - Water movement into wet soil is slower - Aggregate stability - Shrink swell soils - Rain drop impact - What happens when there is a pileup? EVAPORATION - Huge potential losses (60-70% fallow rainfall) - 2 stages (with hectic maths) 1. Take water off surface and more is pulled up to replace it 2. When then films break, water diffuses to the surface as vapor - Top 10-15cm at risk - Need to get water down past that - Ponding on the surface can evaporate rather then infiltrate RUNOFF - When rainfall intensity exceeds infiltration rate - Not affected by slope - Slope changes water speed - Erosion potential DRAINAGE - Once the profile is full (above FC) water can start to move downwards past the root zone - Contribute to salinity, rising water tables - Not a great use of water (mostly) NOW LETS MESS WITH IT - Soil moisture levels affect infiltration rates - Manage crops to dry down the profile and improve infiltration into dry soils - Exception\...sands (especially hydrophobic ones) - Early rain into fallow can be better stored - Trying to store more water above 80% PAWC gets inefficient - Stubble retention improves stored water - Reduced raindrop impact (standing better than flattened) - Slows movement across surface (increasing residence time) - Reduced wind speed (temp and evap short term) - Cereals highest stubble load, cultivation changes - Header tracks, windrows (esp without straw spreaders) - Potential downsides? - Compaction - Blocked pores (traffic jam) - Worse when passing wet, especially with wheel slip - 77% infiltration no-til vs 25% infiltration wheel track - Macro pores and subsoil compaction - Years in rebuilding soil structure can be undone in a single pass **LECTURE 7:** CROP WATER MANAGEMENT CONT. WATER USE EFFICIENCY - Water use efficiency (WUE) -- units: kg/mm/ha - What is it useful for? - It can be used to benchmark crops and management practices - Predict yield - Problem solving poor performance - French and Schultz (1984) -- noticed that the best crops used water more efficiently and yield was closely related to in crop rainfall BASIC FORMULA - Fundamental connection between water use and growth? - Water is used when the plant opens its stomata for CO2 - What does that plane need CO2 for? = carbohydrate synthesis - Basic formual: - Yield = (total water supply -- 200mm) x WUE - WUE = yield / (total water supply -- 100mm) - Total water = fallow water + in-crop rainfall - How de we measure/guess fallow water? - Why would we subtract 100mm (account for evap and biomass) HOW DO WE GET WUE? - Water use for zero yield = WUZY - Evap from soil - Water use before yield - Intercept of the line - Water use efficiency = WUE - Slope of the line - What could give a plant WUE? WHAT CAUSES IT TO VARY? - Short answer: - Anything that uses water that isn't the crop - Anything that causes the crop to underperform - WUE = yield / (total water supply -- 100mm)  USING WUE TO PREDICT YIELD - Formula: yield = (total water supply -- 100mm) x WUE - What do we need to know? WHERE CAN IT GO WRONG? - Do we expect the yield predictions or the measurement of WUE to be exactly right? - Integrative measure, they are kind of a summary stat that helps to know how things went but everything effects it - Most of the values we put in are 'rules of thumb' - 100mm subtracted from the available water (80-170mm) - Assumes that all rainfall (no matter what time) is equal - WUE for yield prediction can vary (5-20kg/mm/ha) - Moisture left at harvest WHAT IS IT GOOF FOR THEN? - Yield protection - Benchmarking (checking how well the crop went) - Or why it went wrong? - How does this paddock compare (can we compare?) - Last year? Next paddock? across district? - What weather conditions has the crop experienced? - Was fallow, weed, sowing management down well? - Crop nutrition correct? Grain protein? P? - Subsoil limitations, water used in profile by harvest? **WEEK 4** **LECTURE 8:** CROP WATER CONT WUE PBL - Long cropping paddock (Dalby, QLD) - Brigalow/ Belah - 400-800mm annual rainfall - Comparison of crop rotations - Wheat -- wheat - Wheat -- chickpea - What do you as the grower next? - What factors could be driving the difference? - 2 lines were evident -- what could cause this? - What would you expect the root system to look like on those plants - Where would you expect the following year to sit on the above line? SOME OF THE OBSERVATIONS - In chickpea -- wheat rotation there was: - 40% increase in yield (825kg/ha) - 1.3% increase in grain protein - Additional 20kgN/ha removed - 35-50 kg N in soil tests at sowing - Similar starting water most years - Rotation increased water removal by 20mm - No secondary root development in '94 and '95 **LECTURE 9:** CROP WATER CONT IRRIGATION - How his an industry is it? - What is it? - Artificially providing additional water to the soil (to the root zone) to improve crop yields and performance - Can anyone irrigate? - Need water - Harvestable rights - State government - Unreg, reg, groundwater (floodplain) - Priority (town, stock and dom \> high sec (reg) \> general sec \> supp) - Trade - What's the best setup? - The best type? - Water security? - Namoi 68% delivery on allocation - Murray 85% delivery on allocation - Upper Namoi 100% deliver on allocation TYPES OF IRRIGATION SYSTEMS - Surface irrigation - Running water across the soil surface to deliver both here and somewhere else - Border check, furrow, bed, contour and bankless - Pressurised irrigation - Where we are spraying water out to deliver it here only (mostly) - Spray lines, travelling, rotary booms, centre pivot and lateral, drip and micro irrigation BORDER CHECK AND CONTOUR IRRIGATION - Border check: - Sloping land - Laser levelled - Check banks - Gates or siphons - Drainage into channel - 300-600m runs - Contour: - Banks of topographic lines - Ponded crops like rice or pastures - Even irrigation - Heavy textures required - Bays may drain into subsequent bays - 50mm intervals (elevation) FURROW OR BED IRRIGATION - Water is delivered down small furrows from head ditch to tail drain - Laser levelling required (not as precise as border check) - Siphons or through bank pipes - 300-1000m runs - Heavy textured soils required - Typically 1-2m apart (can be 4) - 1:500-1:1500 slope BANK-LESS CHANNEL IRRIGATION - No banks - Water controlled by series of check gates - Flows from higher levels to lower ones (terraced) and finds its own way on and off paddocks - Water is generally applies and drained from the bottom of the slope SPRAY LINES (FIXED AND MOVABLE) - Fixed: - Fixed-vegetable and horticultural crops - Permanent mainlines of often permanent sub mains - Water sprayed out of over the crop from risers off a grod of rigid pipes - 5-20mm/hr - 200-450kpa - Moveable - Moveable -- hand shift, end tow, side roll - Pipes that you can shift with sprinklers on top for spraying crop - 150-450kpa - Regular shaped paddocks TRAVELLING BOOMS AND GUNS - Typically come as: - Big gun - Boom - Generally require high pressure - Use water energy to move across paddock - Drag soft hose or can roll up hoses - Booms can use lower pressure emitters - 70-550kpa water pressure - Often pasture (Lucerne) can be used on taller crops CENTRE PIVOT AND LATERAL MOVE - Mobile pipe sprinklers - Pivots-fixed at the centre - Lateral shift march in a line - Large areas at low pressures - Pivots (in particular) can operate over undulating country (ay need flow regulators) - Lateral 800-1000m flexible hose to hydrants - Movement regulated (hydraulic and electric) DRIP IRRIGATION - One of the highest efficiency delivery mechanisms - Deliver water directly to the root zone (safe) - Permanently installed - Reduced labour costs - Clean water required - Flat country required (or pressure compensation) - Not entirely in-vulnerable MICRO IRRIGATION - Often under horticulture (e.g. tee crops) - Fixed spray head below the canopy - 1-12m coverage - 20-600 L/hr - Clean water HOW TO CHOOSE? - Location - Areas, topography, water sources, earthworks - Soil! - Water supply - Quantity (licensing), quality, reliability, storage - Flow rates - Costs involved - Irrigable (yes that's a real word) area - Crops to be grown - Peak water use - Depth per irrigation - Frequency **WEEK 5** **LECTURE 10:** CROP WATER CONT. IRRIGATION - Managed system target -- yield with minimal water use - Water balance - Like a bank acc (only it has more limitations) - Fees, caps, withdrawal rate, deposit rate - All about managing balance - What happens when demand is higher than supply or vice verse? - How can we increase demand? - Cropping intensity or selection - Soil and Rotation management - Pastures/deep rooted - How can we improve supply? - Irrigation scheduling - Rainfall (storage) THE BUCKET IS DYNAMIC - Sustainable management (making sure its balanced) - Filling sporadic (losses are constant) - Make sure the bucket isn't over filled (or doesn't have holes) - Climate - Vegetation and irrigation management - Leaching fraction (\< 3%) MEASURES OF EFFICIENCY - Effective use of water resources - Requires monitoring - Requires management - There are a multitude of measures (we won't go into it) - Benchmarking (enterprise and management) - Efficiencies - Water is efficiency (irrigation, crop) - Production efficiency (economics) - Delivery (irrigation (efficiency) - Metrics often apply at different levels (farm, paddock, crop conduit) EXAMPLE -- WATERPAK WATER BUDGETS - Managing a finite resource when you have unknown amount available - Water budgets are different to irrigation scheduling - Used to determine how much crop should be planted/irrigated before the season - How to best use input as the season develops - Consider: - Seasonal water requirements of the crop - Historical rainfall - Forecasts - Available water supply - Risk strategy - Economics (full vs partial irrigation) - Available decision support tools IRRIGATION SCHEDULING -- WATER USE - The unpredictable nature of our environment requires dynamic scheduling - Good scheduling improves - WUE, reduces water logging, controls canopy development and reduces nutrient/water loss - Terms: evapotranspiration - ET0 -- evapotranspiration of a reference crop (weather stations) - ETc -- evapotranspiration of the crop itself - Kc -- crop coefficient  IS CROP WATER USE CONSTANT? - Environmental factors: - Weather - Soil conditions - Crop health - Systems (windbreaks, cultivation methods, stubble) - Crop stage PEAK DAILT WATER REQUIREMENTS - Need to be able to supply water at rates greater than the peak demand if we are to avoid production losses - Make sure you have the right kit (irrigation method selection) SOIL PHYSICIS STRIKES AGAIN! - Saturation (0kpa) - Field capacity (-10kpa) - Permanent wilting point (-1500kpa) SCHEDULING THEN... - ET based methods (maths) - Uses BOM/SILO data to calculate estimated crop water use - Deficit (today) = deficit (yesterday) -- irrigation -- rain + ETc - IrriSAT now calculated from NDVI - Using crop stress as an indicator - Problem is that its usually too late - Not just water that causes wilting (heat, salinity, nutrients) - Unless you use cool kit - Contact (pressure bomb, sap flow) - Non-contact (IR cameras, remote sensing tech-NDVI) OR YOU MEASURE YOUR BUCKET - Soil sensors - Gravimetric (coring and drying) - Very slow/had/manual but precise - Volumetric - Tells you how much water you have/need - Potential (capacitance matrix, tensiometers) -- tells you what the plant is feeling (not how much you need) - Now we can tell when and how much we need to irrigate! SCHEDULING - We can get profiles = tells us about root activity - Continuous data - ID trends - Water logging - Happy plants - Stressed/dry plants - Summed graph - Sum of water available - Shape tells you how the plant is going - Hard to pick refill point - Stack graph - Each depth represented as different line - Use the 40, 50, 60cm lines to tell you when to irrigate - Values are relative **LECTURE 11:** CROP WATER CONT. WHAT CAN YOU DO ABOUT LIMITED CONDITIONS - Improve water capture of rainfall min tillage, stubble retention, controlled traffic - Change rotations to allow greater storage - Long fallow - Sorghum, chickpea, *long fallow,* cotton, *fallow,* sorghum - Agronomy - Water stress intolerance (e.g. sorghum) - Low water use (winter crops e.g. wheat, barley, chickpea) - Low water use (short season crops e.g. mung beans) - More water use efficient (profitability per mm e.g. maize) - Decide to fully irrigate (small ha) or partially irrigate (larger ha) DRIVERS FOR WATER USE - full irrigation - No water limitation at any point of season - Augmenting water content in the oil to ensure soil water remains above refill point (until maturity) - Absolute max yield under prevailing conditions - Deficit (partial) irrigation - Acknowledge that some parts of the growth will show stress - Minimise water stress at sensitive growth stages - Maximise productivity (returns per mm of applied water) - Split is dependent on economics, risk profile - A lot of decisions support tools to determine this (e.g. CropWaterUse, Irrigation Optimiser IRRIGTION SYSTEM LIMITATIONS - How to manage irrigation systems with inadequate supply rates (low system capacity) - Top up early and allow plants to draw down on stored moisture at peak demand periods - Risk: system may fall below refill point - Staggered plantings - When we don't have much water, we need to deliver it more efficiently (only then?) - Improve how efficiently we deliver water to the root zone - Changes with growth stages - Early crop -- higher flow rates, shorten row lengths (practical?) - Better scheduling - Trade water? IRRIGATED WHEAT - How much water does it take to grow a wheat crop? It depends: 350-550 mm - Crop sensitive stages - Peak water use -- flowering and milk develop (GS60-70) - Fill irrigation - Strive for no limitation - 8t/ha yield - Don't want soil to go drier refill point (50% PAWC) - Can you compensate for water stress with extra water later? - Timing last irrigation -- GS80 (mid dough) if water used 60-90cm depth PARTIALLY IRRIGATED WHEAT - Ideally - Sown into stored moisture, 1-2 irrigations - Single irrigation -\> stem elongation -- flag emergence - Double -\> stem elong., then flag em to flowering - Biomass production to set potential yield - Carryover water to flowering and grain fill - Encourage the development of secondary root development IRRIGATED WHEAT - Lodging can be a major challenge - Nutrition (rapid growth rates, large leaf areas) - Variety choice (lodging risks) - Shallow root systems (high water availability) - Severe weather conditions - Agronomy (canopy management) - Row spacing -- 30cm (wider rows = more crowding in row, less tillering) - Population (higher populations, lower tillering, even more establishment) - Sowing date (selected window for variety -- early in low N, late in high N) - Establishment (stored water \> pre-irrigation \> water up) - Surface soil water 25-30 DAE -- irrigate to initiate secondary root development - Plant growth regulators (for canopy management) - Disease management SORGHUM - Water use typically 400-800mm, yields 9t/ha - Typically, 3-6 irrigations (full) - Generally considered more moisture stress tolerant - Can withhold water early veg growth (6-8 leaf) - Large N, P, K and Zn demand early - (2/3 N at planting, 1/3 at booting) - Varieties - Quick has lower water use (lower yield potential) - Sowing dates - Temps (spring 16 deg rising, summer before cool) - Early -- increased WUE, tillering, yield, midge - Waterlogging (-0.2t/ha/day) **WEEK 6** **LECTURE 13:** STATS LEARNING OBJECTIVES - One wat ANOVA - Sums of squares - The parts of an ANOVA output **LECTURE 14:** CROP NUTRITION AUS GRAIN PRODUCTION - Yield potential - Yield decline - Increases from - Super - Fallowing - Rotations - Nutritionally responsive environment IS PLANT NUTRION IMPORTANT - How big a deal is nutrition? - N is likely to be the largest variable cost - Increased reliance on N with increased cropping intensity - Legume contribution 20-75kg N/ha - Trends in time: - Reduced tillage - Changed application patterns and dependence - Less incorporation, closer to planting - Increased reliability of yield, extraction - Increased the range of deficiencies - Continuous cropping - Crop sequence is important, increasing demand or fert - Natural shift away from monoculture (lower risk, higher return) HOW DO THEY GET A HOLD OF IT? - Plants are accumulators - Uptake - Via root system - Tap/fibrous - Nutrient behaviour - Mass flow - Diffusion - Rhizobium - Arbuscular mycorrhizae - Factors affecting uptake - Water, tempt, pH O2 WHERE ARE WE AT IN THE BIGGER PICTURE? - Fertility decline - Organic carbon - Northern trends - Southern trends - Acification - Causes? - Effects? - Salinity - Sodicity - Physical - Sand -- OM - Silt -- OM/cations - Clay -- cations - Biological - Strong interactions between N+K and disease, P and micro SOIL TESTING - Began in 70s - Allowed site specific recs - Nutrient balances and sustainability - Prediction of likely yield responses - What are soil tests? - Chemical extracts - What bearing does that have on plant performance? - What is the best indicator of plant performance? - Why test? - Aiming for peak productivity, profitability and sustainability SOIL TESTING PROCESS - Sample collection - Representative, Depth, Timing, Collection pattern, shipment - Analysis - Interpretation - Standard values/critical values - Nutrient budgets - Interaction between test values - 40-60% variation - pH, OC, texture, rainfall, yield, quality, agronomy, PBI - recommendation - monitoring PLANT ANALYSIS - what better to tell you what is needed than the plant? - Plant tissue concentrations are more functional but can be too late? - Availability of nutrients - Effected by age, stage, tissue type, position on the plant, other nutrient, disease/pest - Useful for diagnosis and monitoring PLANT SAMPLING - Sample collection - Representative, hygiene, timing, collection pattern, shipment - Analysis - Typically total digests - Interpretation - Standard values - Critical values, deficient, low, optimum, high - Interaction between nutrients - Recommendation - Monitoring **LECTURE 15:** CROP NUTRITION CONT. POTASSUM - High plant requirements - Incidence of K deficiency increasing - Less than 1% of K in soils is available - Exchangeable K, soluble K, remainder (unavailable) in crystal lattice - Availability dependent on CEC - Diffusion and mass flow - Heavy soils (diffusion), light soils (mass flow) - Used in regulation and metabolism - Lodging, winter hardiness, disease resistance, yield and quality - 3-5kg/t cereal grain, 20kg/t soybean, 30kg/t Hay - Major constraint to production appears to be the rate of supply  POTASSIUM FERTILISERS - Deficiency - Scorching in older leaves first - Yellowing inter-venial near margins and tips - Wilted appearance (legumes -- white freckling) - Muriate of potash (KCI) - Sulphate of potash (KSO4) - Potassium nitrate (saltpetre) - 25-100kg/ha (heavy soils up to 400kg/ha) - Split application at large rates improve utilisation - Foliar in some crops at peak requirements (cotton) - Fertiliser burn (side band) BUT WHAT ARE WE RECOMMENDING TO GROWERS? SULFUR - Emerging deficiency (why? -- high analysis fertilisers) - Most of S in organic fractions - Highly mobile (susceptible to leaching) - Mineralised from OM or oxidised from S - Component in proteins - Less mobile in plant than N - Growth and general chlorosis - Grain yield and protein reductions - Reduced tillering - Occurs - Light textured soils - Min till - High yields - Where there is little native gypsum SULFUR FERTILISERS - 2 breeds: elemental forms and sulfate forms - Gypsum (calcium sulfate) - Single superphosphate (11% sulfate) - Elemental S coated products - Goldphos, sulfur fortified - Availability is surface area dependent - Plant uptake is about volume enriched - Application rate: 5-15kg/ha, 20-30kg/ha canola - Critical values - Appropriate sampling depths - The elephant -- declining organic matter reserves NITROGEN - Highly mobile and in flux in the cropping system - Mineralisation, immobilisation, fixation, leaching, volatilisation, denitrification - Influence on soil pH (less effect on heavy textures) - Deficiency symptoms - Older leaves, Stunted growth, Reduced tillering - Pale green/yellow - Low grain protein - Too much - Haying off, Lodging, Reduced yields, - Enviro impacts - Leaf burn - Seedling burn N FERTILISERS - Anhydrous ammonia (82% N) - Conventional and cold flo systems - Urea (46% N) - Ammonium nitrate (34% N) - Nitram (controlled substance) - UAN solution (32-42.5% N) - Ammonium sulfate (20.5% N) - DAP/MAP/KNO3/CaNO3 - Organic sources APPLICATION STRATEGIES - Split application (top dressing) - Soil type - Season dependent (winter dominant) - Pre-plant (upfront) - Soil type - In crop rain difficult to predict - In row application can cause seed burn and poor establishment - Small seeded crops more susceptible - Soil type, moisture, row spacing - 20kg N/ha large seeds (10-30 for sand-clay) - Inter row and side dressing - Mounded systems in side of bed (access and away from furrow) - Careful not to place it too close to the row-pruning - Timing - Early-mid tillering to increase yields, later to increase protein NITROGEN BUDGETS - Why do we need them? - Growth/water use sensitive to N - Hard to measure - Grain N = yield (kg/ha) x protein (t/ha) x protein factor (%) - Crop protein factors (how much N in protein) - Wheat 1.75 - Everything else 1.6 - 3t wheat crop, 13% protein = 68.35 kg N/ha - Tells us how much N was in the grain and not the plant NITROGEN TRANSFER EFFICIENCY - 40-60% of available N ends up in grain -- where is the rest? - At higher protein contents the N transfer efficient gets lower - If we know what yield/quality, we want we can predict N rates - Crop requirement = 68.25 / 0.45 - Crop N requirement = 152kg/ha N HOW MUCH N IS IN OUR SOIL? - Sampling is critical - Rooting depth, bulk density, soil nitrate -- N, soil ammonium -- N - Plant available N = soil NO3-N (mg/kg) x sampling depth increment (depth range/10cm) x bulk density (g/cm3) = 5mg/kg x (0-60cm/10cm) x 1.3 g/cm3 = 5 x 6 x 1.3 = 39 kg N/ha (as NO3) - Soil ammonium -- N is a measure what is likely to be able to be mineralised - Calculate what needs to be added as fertiliser... 152 kg/ha required -- 39 in soil = 113kg/ha as fertiliser **WEEK 9** **LECTURE 16:** CROP NUTRITION CONT. VERTOSOLS IN NORTHERN FARMING SYSTEMS: REFLECTIONS ON FERITLITY AND FECUNDITY - The issues: - Removal is greater than replacement across all vertosols - Removal occurs at depths where it is difficult to replace - Removal occurs in forms we don't usually measure PHOSPHORUS POOLS AND PROCESSES IN VERTOSOLS WHAT ARE WE RECOMMENDING TO GROWERS? - Critical P values used to determine likely response or drivers of P availability in northern Vertosols - Colwell P: - Extraction test method: extracts phosphorus from soil using a solution of sodium bicarbonate (0.5 M HaHCO3) at pH of 8.5 designed to estimated amount of plant available phosphorus - Commonly used in regions where soils have specific characteristics that the method is well suited to - BSES P: - Bureau of Sugar Experiment Stations - Primarily used in QLD - Involves extracting phosphorus from soil using a solution of sodium bicarbonate (0.5 M NaHCO3), extraction and analysis differs slightly in technique or interpretation - Tailored to specific soil types and ag conditions found in QLD, especially for sugar cane crops - Helps in managing P fert to optimize crop yield and soil health EXAMPLES FROM NMI2 - CQ example -- rare - Sorghum trial at Capella - No fert, N only, NP, NPK and NPKS - Not much response to anything unless S limitation was fixed - More typically - Additive effects of S after P limitations are overcome WHAT DOES IT ALL MEAN? - Inputs of P, K and S will increasingly be needed in northern cropping systems - Placement of immobile K (and P) in deeper profile layers essential - Strategic tillage to incorporate K may be required - Mobile N and S can be managed on a seasonal basis - Roots that respond to deep (and shallow) placed nutrients efficiently are critical - Profitability challenges from increasing fertiliser bills require a look at rotation options (legumes) PLACEMENT AT DEPTH HAS CHALLENGES - N and P - Banding of N and P important for max uptake - Roots proliferate (multiple) in bands of N and/or P - Is there genotypic variation in this response? - S and K - Little to no evidence that roots proliferate in response to banded S and K - What is the best strategy for application of S and K to max uptake? HOW DO WE MANAGE DEEP APPLICATIONS - Deep applications when little stubble or moisture to lose (chickpeas/double skip sorghum/cotton) - But moist enough to work -- won't bust up your gear - Allow time for soil to settle after disturbance - Apply enough to match removal in the next 3-5 crops - Maintain the use of starter P, as it fulfils a specific role DEEP P BY STARTER FERT EXPTS - Treat 2 planter widths side-by-side with the same deep P rate - Whole planter runs are either with or without starter - Range of deep P rates such as: - 0, 10, 20, 30, 60kg/ha P - Untreated control 'farmer reference' - Usually use MAP and background out N, S and Zn - 2m buffer untreated between strips CURRENT GRAINS RESEARCH - Strong responses to P banded at \~20cm - Responses very strong in early growth and continue through the season - Crop accumulation P from the bands throughout the growing season STRONG YIELD INCREASES TO P AT DEPTH - P responses at Wondalli highlight the additional P responses above starter P alone - All sites show strong residual effects (6^th^ crop season/5 yrs at Brookstead) - These may be S or K limited also BAND SPACING AND POSITION EFFECTS - Fairly consistent responses to band spacings fro P -- 25cm and 50cm generally more effective than 100cm - Depth effects vary with seasonal conditions but deep or split bands (shallow + deep) more effective than shallow only QUESTIONS - Is there genotypic variation in the ability of wheat to exploit banded P and N? - Yes; different what varieties have varying abilities to utilize banded P and N due to genetic differences that affect root growth and nutrient uptake efficiency - Is the banding of S and K fertiliser an effective strategy for application - Banding S and K fert improves nutrient availability by placing them close to plant roots enhancing uptake efficiency and reducing nutrient loss compared to broadcasting (spreading uniformly over soil surface) UNIFROM LOW P ANC SOIL PROFILE  HIGH P BAND AT 5CM DEPTH SHOOT P UPTAKE SHOOT GROWTH SUMMARY - Vigorous cv Spitfire able to proliferate more roots in banded P compared to slower growing cv Sunvale at the same age - This difference translated into greater P uptake from a band for cv Spitfire - Suggests scope to select genotypes with a better ability to exploit banded P **LECTURE 17:** CROP NUTRITION CONT. SOIL TEST:  - Base cation saturation ration theory - Wrong! (most of the time) - Holds at extremes (based on economics of fertilisation) - Flocculation -- when small particles clump together to form larger aggregates or 'flocs' (Ca\>Mg\>K\>Na) - Ion activities (counter ion competition) - Sufficiency theory SOIL FERTILITY - Physical - Texture - Clay types (mineralogy -- Kaolinite, Illite, smectite) - 1:1 or 2:1 silica: alumina - Structure - Stability and resilience (esp shrink swell) - All about air - Chemical: sufficient nutrition - Biological - 'Biology take care of itself' - Resilient/diverse - Sensitive to changes, long time scales - Scale dependent features SOIL BIOLOGY - Microbes - Bacteria and fungi - Invertebrate animals - Micro-, meso- and macro- fauna - (e.g. Protozoa, nematodes, earthworms) - Influence soil structure?? -- yes at all levels - Aggregation - Soil health - Breakdown disease inoculum MANAGEMENT PRACTICES INFLUENCE SOIL BIOTA - Clearing - Jury is out, earthworm reduction in tropics, increase Euro forests - Cultivation - Fertilisation - Pesticides - Hers- \< insect- \< fungicides - Stubble retention - Crop rotation **LECTURE 18:** PRECISION AGRICULTURE - Use of tools and practices to monitor and manages spatially variable ag - Not just tech in ag - Traditionally we have thought of the paddock as a unit of ag - All know there is variation but dealing with it is often not worth the hassle... any exceptions? - As tech has developed in imaging and application it has become more feasible to start treating small areas differently - Not just sub-paddock but also temporal and increasingly 3D - Incredible development now as its completely tied into tech JUST PRETTY PICTURES OR IS IT USEFUL? - Range of utilities to making it work - Information to aid in decision making and address variability in the production system - Identification of problems (weeds, disease outbreaks) - Useful tool in implementing strategies (VRT) - Steps: 1. Observe and collect data (ground truth) 2. Interpretation and evaluation 3. Implementing management plans IMPORTANT COMPONENETS - Global Nav Satellite System (GNSS) - Uncorrected, differential, RTK - Geographical Information System (GIS) - Guidance & autosteer - Reduced skip and overlap, controlled traffic, inter-row planting - Data! Observation points - Remote sensing - Direct point source measures - Monitor points REMOTE SENSING - Digital imaging (visible light) - Soil mapping, infrastructure, boundaries etc) - Vegetation indices (e.g. NDVI -- not the only one!) - RADAR & LIDAR - Gamma Ray - Limitations - Access -- weather - Integrative indirect measures - Require ground truthing - Alternatives... UAVs? IN FIELD MONITORS - Electromagnetic induction - E.g. M38 - Soil conductivity - EC, water, texture - Ground penetrating radar - Weather stations and soil moisture - Yield monitors - On the go sensors - Protein, moisture, pH - Diesel efficiency maps what could that tell you? - Distance from plane maps? (RTK elevation) IS ALL DATA GOOD? - Think about the quality of the data being generated and whether practice can improve its utility USING THE DATA... - How do we get from points to smoothed surfaces - GIS software (kriging, splines, smoothers, classifiers etc) - What does a yield map tell us? - What would a yield map be used for? - Nutrient removal budgets - N cycling/management - Crop modelling  HOW CLEVER CAN WE GET WITH THIS? - Crop management and monitoring - Build NDVI's into modelling and yield prediction - Use them for observation (irrigation, fert responses) - Pest management - Precision - Variable rate tech - Nutrient replacement - Optical sensors (assumptions...) GOOD FOR MONITORING HANDY FOR OBSERVATION AND CALCULATION OF DAMAGE VARIABLE RATE TECHNOLOGY - Management zones need an agronomic filter - Mechanisms for benefit - Increased efficiency - Reduced rates where there unlikely benefit - Increased rated where greater benefit is possible - Long term data helps but its not a cure-all - Opportunity - Make farmer trials easy - Where its working in the cropping industry - Managing predictable gradients - N - Managing static conditions - pH, texture - aim is to even up production - management unit is still the paddock - key is to understand what's driving the variation MAJOR CHALLENGES - who owns the data? - Will there be a data economy in future? - Frequency and resolution limitations for data - Examples of spatial management limited - Which way should we manage VRT? - Increase the fert rates on high potential soil - Decrease fert rates on low potential soil - Manage for increased uniformity/heterogeneity? - Must use agronomic diagnosis for prescription maps - Can't assume that low NDVI is a nitrogen problem? **WEEK 11** **LECTURE 19:** CROP PROTECTION DISEASE IN CROPS - Potentially major implications - Changed the shape and development of industries (chickpea, wheat) - Epidemics cost \$100's millions - Causes: - Fungi (soil borne and foliar - Major cause of disease in grains industry - Bacteria - Less common (bacertial blights -- *Pseudomonas & Xanthomonas)* - Often entry via wound sites and dependence on wet conditions - Virus - Vector required, symptoms? - Nematodes - Ecto- and endo- paracitic (- sedentary and migratory -- CCN and RLN) SYMPTOMS - Lesions - Chlorosis - Necrosis - Galls - Mosaics - Pustules - Damping off - Vascular wilt DISEASE TRIANGLE (TETRAHEDRON) - While these are conditions required, not having them doesn't mean they aren't there waiting - Enviro conditions drive the appearance and prevalence of diseases - Rusts (stem-warm, stripe cool) - Root Vigor (temp) and pythium/rhizoctonia - Phytophthora wet conditions - Crown rot (some seasons) DISEASE CYCLES  SURVIVAL AND DISPERSAL - Many of our management strategies depend on beating the pathogen in the 'survival' stage - Particularly cultural practices - Stubble management for stubble borne diseases - Yellow leaf spot, crown rot - Some survive as spores (common root rot) - Obligate biotrophs (need a 'green bridge') - Rusts - Wind and water dispersed foliar diseases - Longevity and requirements for wet conditions - Often have secondary cycles -- exponential growth rates - Soil borne diseases - Slow burning, long time scales, patches HOW CAN/DO WE KEEP A TRACK ON IT? - "advice from an old tracker -- if you want to find someone... use your eyes" -- Malcolm Reynolds - Crop monitoring is critical in managing disease - Particularly with foliar diseases -- exponential development! - Methods of measurement - Soil test? PreDicta B - Cereal cysts nematodes - Take all - Rhizoctonia - Crown rot - Root lesion nematode - Stem nematode - Blackspot of Pea - Challenges with PredictaB... it tells you what is there... not what is at a problem level SO HOW TO MANAGE IT? - Ideally -- don't get it in the first place - Exclusion nationally - Locally (any types of pathogens this might not work on?) - Exclusion of - Weeds, diseases and pests - Machinery - Agronomists - Certified seed MANAGEMENT OF EXISTING PROBLEMS - Cultural methods for management in the survival phase - Reducing the quantity of primary inoculum - Burning - Stubble removal - Cultivation (stubble and soil borne pathogens) - *Rhizoctonia* can accumulate in no till systems - Reduce other stresses (N and K nutrition, water management) - Canopy management - Development of BGM in chickpeas - Vector and host management - Stubble retention -- aphids ROTATION - Crop rotation - Particularly effective for soil -- or residue borne pathogens - Reliant on natural (or enhanced) attrition - Weed management is important - Some 'rotations' are better than others - Tolerant populations can still build inoculum - Resistance and tolerance - Tolerance -- yield regardless - Resistance -- suppress pathogen - Horizontal resistance (incomplete resistance broadly applicable) - Vertical resistance (specifically resistance to strains) - Stem rust (stacked vertical resistance) stripe - Adult plant resistance (e.g. stripe rust) FUNGICIDES - Typically, low usage in Aus - Why different in Europe? - Seed treatments more common - Generally used for foliar pathogens - Protectant - Stop/reduce infection - Curative - Kill the pathogen in host tissues - Translocation - Curative are systemic, often protectants are not (various degrees) - Systemic fungicides are prone to resistance development FUNGICIDE APPLICAITION STRATEGIES - Challenges - Applied early in case of foliar - Weather dependent -- risk strategy! - Know crop behaviour -- adult plant resistance - Understood economics - Single spray approach (GS37 -- 39 -- Flag) - Double spray approach (GS33 and GS59) - Resistance?? **LECTURE 20:** CROP PROTECTION CONT. WEEDS - Definition - Plants 'out of place' - Estimated annual costs of control \~ \$1.5b - Estimated lost production \~ \$2.5b - Key costs: - Competition and utilisation of resources - Moisture use - Nutrient - Loss opportunity (N and water) - Alternative hosts for diseases (e.g. *phytophthora* root rot hosted by medics) - Product quality downgrades MODERN GO TO... HERBICIDES - Why? - Pre-emergent - Reduce early season competition - Long acting - Cost effective - When limited in crop options are available - Factors affecting degradation - Stubble tie up (trifluralin \> chlorsulfuron) - Photodegradation (atrazine, simazine, s-metolachlor) - Volatilisation (trifluralin \> chlorsulfuron) - Sorption (trifluralin \> clopyralid) - Solubility (trifluralin \> chlorsulfuron) - Microbial activity (DT50 s-metolachlor 7, trifluralin 170) - Post emergent - Control of germinated weeds in crop - Selectivity (selectivity or knockdown?) - Translocation (contact or systemic) - Double knock -- 2 attacks different MOA - Often systemic followed by contact) - Spray quality important to consider with application - Stress (moisture, frost, heat, pest) - Timing (small weeds, crop effects) - Application (droplet size, adjuvants/oils, water (quality rate), incorporation, interactions) - Rate RESISTANCE - Target site - Specific and high levels of resistance (on/off) - Non-target site (metabolic) - Degradation (partial resistance) - Herbicide will still work if your get enough of it - Resistance development - Selection pressure - Frequency of the gene - What does it look like? - Odd survivors \> patch - Some controlled some not (or other species that are controlled) DEVELOPMENT OF RESISTANCE  ECOLOGY THAT IMPACTS ON MANAGEMENT - Emergence conditions - Dormancy - Temperature - Moisture/rainfall - Persistence - Increases with depth, seed size and hardness - Factors for degradation - Fleabane (5% 1yr surface, 15% 1yr 10cm) - Bladder Ketmia (31% 3yr surface, 52% 3yr 10cm) - Seed production - Range (bindweed \~200 seeds/plant to fleabane \~110k seeds/plant) KEY PRINCIPLES IWM - Depletion of weed seeds - Burning, insect predation, inversion ploughing (20cm), autumn tickle - Kill seedlings in target area - Knockdowns (+double), pre-em, selective, wide row, biological - Stop weed seed set - Spray/crop topping, wiper, desiccation and windrowing - Pasture topping, silage/hay, grazing - Collection of weed seeds - Narrow header trail, chaff cart, seed destructor - Hygiene MANAGEMENT -- ROTATION - Hoe does rotation of crop types help? - Competition - Cost of control - Chemical options - RR\*, TT, IT -- Clearfield (Canola, wheat, barley & maize) - NoGo weeds (e.g. IT -- group B resist Brassicas -- mustard/relish, RR -- resistance ryegrass) GOOD AGRONOMY - Generally reduce seed set - Sowing time - Maturity - Relative competitiveness - Row spacing/sowing depth - Nutrition - Disease - Fallowing - Tram tracking (controlled traffic) - Cultivation - Implement type - Good for yield is often good for competition **LECTURE 21:** CROP PROTECTION CONT. PESTS - Definition - Bad bugs that eat stuff they shouldn't - Estimated annual costs \~\$360 million - Current control methods reduced potential loss by \$1.4 billion - Key costs - Reduced photosynthetic capabilities and productivity - Vectors for pathogens and disease - Product quality downgrades INSECTICIDES - Why? - Since 1950's synthetics pesticides - Cheap and broad -- spectrum - Resistance - Control beneficial species - Secondary outbreaks WHY SUB-LETHAL DOSES ARE BAD FOR RESISTANCE  KEY PRINCIPLES IPM - Enter integrated pest management - Higher time input - Requires understanding of the system and pest biology - Uses a range of control methods -- chemical as a last resort - Aim - Encourage natural predation (beneficial species) - Cultural natural predation (beneficial species) - Selective pesticides where necessary - Use of economic thresholds to trigger applications - Step 1: identify what is likely to be a problem and when - Conditions and crop - Step 2: monitor the crop (pest populations correct ID) - Difficult to understand the dynamics of changes in the pest and friendly population if you don't monitor - Track pests and beneficial species - Beneficial species - Parasitoids (lay eggs in pest species) -- e.g. wasps - Predatory insects -- e.g. lady birds, spiders, predatory mites - Pest pathogens (bacteria viruses and fungi) - Step 3: economic thresholds - Balance between beneficial and pest species is likely to result in greater damage to crop than the cost of control MONITROING INSECTS STEP 4: CONTROL METHODS - Cultural (background stuff) - Shelter belts for refuge of beneficial species - Stubble retention (provide shelter/deterrent) - Rotations - Variery selection - Agronomy for improved crop health - Early sowing of susceptible crops - Weed control/alternative hosts - Grazing - Pupae busting - Uniformity of flowering - Bio-pesticides - Highly selective - No residues - *Bacillus thuringiensis* (BT crops e.g. cotton/maize) - Nuclear polyhedrosis virus (NPV) - Several others in the pipeline (mirids, aphids and silverleaf whitefly) - Nuclear polyhedrosis virus (NPV) -- made IPM possible - Specific to helicoverpa - No impact on beneficials (except *Microplitis*) - Acquisition is rapid (max uptake withing 1 hour) - Optimal coverage critical (ingestion)  - Chemical - Ideally selective (soft) pesticides - Can be spatially or temporally selective -- seed treatments (Gaucho -- imidacloprid) - In-furrow treatments - Perimeter spraying - Decisions by economic thresholds - Management for one species (e.g. Rutherglen bug-Synthetic Pyrethroids) can have implications for resistance accumulation in other species (e.g. *Heliocoverpa*) that may not be the target SUPPORTS TOOLS  BREEDING