Joe Grant UC Cooperative Extension

San Joaquin County

Janine HaseyUC Cooperative Extension

Sutter, Yuba & Colusa Counties

Young Almond & Walnut Orchards Workshop, January 14, 2016

And …. LOCAL SEED DEALERS!

http://anrcatalog.ucanr.edu

Winter “green manures”

Annual reseeding

Perennials

Warm season annuals

↑Winter / spring access

↑Water penetration Root channels, Less surface crusting

Remove excess soil moisture in early spring Nitrogen addition or conservation

↓Runoff, erosion, off-site pesticide movement

Weed suppression

↓ Dust Beneficial insects, nematode suppression ?

May use water that trees needWinter: ≅ 2.7 acre-inches per ton of dry matter Reduces salt leaching

Spring/Summer: direct competition / increased orchard water demand

↑ Frost risk May interfere with NOW sanitation

and pruning Nematode & rodent considerations

Mixtures: Large seeded cereal grains (oat, barley) and N-fixing legumes (vetch, pea, bell bean) seeded each fall, cultivated or mowed in

spring.

Single species cover crops

‘Tyndel’ Triticale

‘Lana’ Woolypod

Vetch

Complete pruning operations first

Or seed alternate middles? Prep and plant after harvest

before leaf fall. Good seedbed is essential!

Width per: equipment, avoid root damage, invasion of strips by cover crop

Broadcast or drill Irrigate up if necessary

Maximize biomass without compromising other goals

Remove at early flowering for maximum N content

Allow removal of excess soil moisture without depleting stored reserves

Biomass and N concentration 80-90% of N is in above-ground parts; 10-20% in rootsMax. N contribution is at flowering (2-5%)

Whether the legume species is combined with a grass species

Different legume cover crop species contribute different amounts of fixed N

Whether it is mowed or tilled (incorporated) Mowing: assume a 50% N recoveryIncorporated: assume a 70% N recovery

Used published estimates

OR

Cut and weigh a representative sample, then:

If incorporated, multiply by N conversion factor

OR If mowed (or N conversion unknown), send to lab for N analysis

Legumes Clovers: Subterranean Persian Rose Crimson clover

Bur medics

Grasses: ‘Zorro’ fescue

‘Blando’ brome (soft chess)

Mid-March, Davis, CA

Reseeding annual mixtures

‘Blando’ brome / clover mix

Planted initially in fall

Managed during spring/early summer to allow plants to mature used in no-till orchards

Mowed late May to mid-June Clippings decompose on soil surface

Naturally reseed the following fall

Can reseed (persist) many years

Better fall and winter orchard access Suited to areas with more rainfall

No extra summer irrigation

Legumes fix nitrogen

Grasses – better water penetration Less runoff

Weed suppression

May need fall or winter irrigation to ensure good germination and growth if rains inadequate Need full coverage system for this

Mow (~1 inch) in late February/early March Reduce winter weed competition Also reduces risk of frost injury

Mow to remove in late May – mid-June after seed has matured

Difficult to grow with our weather patterns last 4 years

Need light irrigation in fall after planting if no rain

Need winter irrigation if no rainfall to continue growth

Don’t plant if no ability to irrigate in winter

Not recommended in drought with limited water

Maximize N by maximizing biomass

Range 31 - 250 lbs N/ac Average ~90 lbs N/ac

Mowing 50-75% N recovery ANR pub assumes 50%N

subclover

Increased gopher activity reported not observed in our trials

See publications in binder Species information (soils, nutrition, etc) Seeding rates, equipment, costs Land (seedbed) preparation

Supplemental N Band next to tree rows or through low volume

system Don’t broadcast to maximize N fixation

Thank you!