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Field preparation, crop r otations , and green manures Mark Pavek - WSU. Pre-cropping practices Crop rotation Green manures Field selection Field preparation. Crop Rotation – What and Why?. Same field – different crop each year Common duration: 3-5 years, then repeat
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Field preparation, crop rotations, and green manuresMark Pavek - WSU Pre-cropping practices • Crop rotation • Green manures • Field selection • Field preparation
Crop Rotation – What and Why? • Same field – different crop each year • Common duration: 3-5 years, then repeat • To build/maintain healthy soils and productive, profitable crops sustainably for the long-term
Crop Rotation Concept • Minimize Pests • Insects, nematodes, weeds, mites • Minimize Disease • Bacteria, viruses, fungi • Optimize Available Nutrients • Nitrogen, phosphorous, potassium, micros • Optimize Soil Health • Aeration, tilth, organic matter • Facilitate Tillage, Planting, Harvest and Post-harvest Activities and Quality
Minimize Insect & Mite Pestswith Crop Rotation • How rotation can help: • Remove host crop of insect • Proximity to other insect hosts • Disrupt insect overwintering in soil via tillage from different cropping practices
Minimize Insect & Mite Pestswith Crop Rotation Insects/mites influenced by rotation & location: Colorado potato beetle (overwinters in soil) Wireworms (flourishes in small grains, clover) Mites (likes corn, alfalfa, mint, dusty roads) Leafhopper (specific weeds, proximity to) Grasshoppers (overwinters in soil) Seedcorn maggot (corn is its favorite) Leather jackets (spring incorporated alfalfa) White grubs
Minimize Nematodes & Diseasewith Crop Rotation Disease and nematode factors: • Non-host alternate crops • Rotation duration • Soil micro-organism dynamics
Nematodesinfluenced by crop rotation Crop rotation can be useful in reducing nematode populations • Root-knot • Alfalfa is not a host • Lesion • Stubby-root Research in the Pacific Northwest has shown that cover crops of rapeseed, mustard, oilseed radish, or sudangrass reduce populations of root knot nematodes when incorporated as green manure.
Diseasesinfluenced by crop rotation • Verticillium wilt • Rhizoctonia • Common scab • Silver scurf • Pink rot • White mold
Minimize Weedswith Crop Rotation • Follow “easy to weed” crops with “hard to weed” and visa versa • Alternating herbicides each year • To prevent herbicide-resistant weeds • Certain weeds not controlled by all herbicides • Consider volunteer-crop-weeds • Consider herbicide carryover
Optimize Available Nutrientswith Crop Rotation • Follow legume forage crops, such as alfalfa, with high nitrogen-demanding crop, like potatoes or corn • Grow less nitrogen-demanding crops following crops like potatoes or corn
Optimize Soil Healthwith Crop Rotation Healthy Soils • Good Soil tilth/condition • Accumulate Organic Matter • Beneficial organisms • Lack of erosion • Nutrient availability • Aeration, lack of compaction • pH balanced, not influenced by additives
Soil Health Managementwith Crop Rotation Soil Tilth, Aeration, Water Availability, Minimal Erosion, Nutrients Important factors: • Accumulation of O.M. • Management of residues • Choice of crops • Tillage traffic
Facilitate Tillage, Planting, Harvest and Post-harvest Activities & Qualitywith Crop Rotation • Consider current crop will influence the next crop Examples • Corn ears in harvested potatoes • Alfalfa roots complicating planting or early season tillage • Residue complicating bed or row formation
A solution might be to chop the stubble into a fine residue prior to tillage
Crop Rotation Typical Rotations: Eastern Idaho Grain Potatoes Grain Grain Potatoes Grain Sugar beets Grain Potatoes Grain Alfalfa (2+ yrs) Grain Potatoes
Crop Rotation Typical Rotations: Central and Western Idaho, Central Washington Combinations of grain, beans, peas, sugar beets, onions, and corn in a 5-6 year cycle with potatoes Beans avoided just prior to potatoes (white mold/sclerotinia)
Green Manures Purposes • Same as rotation: tilth, nutrition, water availability, aeration, pest control • Plus: • Improved erosion control
Radish green manure Grain rotation
Green Manures Types • Rotation crop green manures (full-season) • Interval green manures (between crops)
Green Manures Potential Disadvantages • Reduced income • Additional management costs • Hosting of pests • Additional weed (volunteer) problems
Green Manures Potential Advantages • Improved yield and quality • Reduced fertilizer costs • Reduced soil-borne pest control costs
Green Manures Crops for Green Manures: • Radish and mustard (interval, fall) • Rapeseed (interval, fall) • Legumes (full-season or interval) • Cereals (full-season or interval, regrowth) • Corn (full-season) • Sudangrass (full-season)
Field Selection Important Factors: • Physical properties • Irrigation/water availability • Chemical properties • Topography • Cropping history • Pest history
Field Selection Physical properties • Course to moderate texture • High water infiltration rate • Lack of compaction layers • Adequate organic matter
Field Selection Chemical properties • pH 6.5-7.5 • Adequate CEC • Low salinity (<1.7 ds/m) • Low sodium (sodicity, SAR < 6) • Lack of nutrient toxicity
Field Selection Topography • Slope <5% • Lack of drainage problems
Field Selection Cropping History • Adequate rotation • Avoidance of long grass rotations • Avoidance of heavy-traffic crops
Field Selection Pest History • Avoid fields with known problems: • Nematodes • Wireworms • Verticillium wilt • Volunteer potatoes • Nutsedge
Field Preparation Practices dependent on: • Soil type • Erosion potential • Residue management • Energy costs
Field Preparation Purposes • Incorporate residues • Reduce compaction • Improve permeability • Incorporate fertilizers and pesticides • Prepare bed for planting
Field Preparation • Prior to freezing temps (fall) • Plant green manure, incorp • Cross Rip ~ 18 in deep • Fumigate if necessary • Spring • Soil sample, fertilize, incorp • Plant
Field Preparation Tools • Moldboard plow • Chisel plow • Disk harrow • Roller packer • Bedding tools