Citrus Drainage (Fake, 2012)
description
Transcript of Citrus Drainage (Fake, 2012)
Citrus Drainage Management
Cindy Fake University of California Cooperative
Extension, Placer & Nevada CountiesApril 2012
Importance of Orchard Floor Management• Citrus have shallow
roots, most in top 30 cm of soil
• Small root zone to exploit
• Manage soil to provide good root/soil environment
• Not just nutrient management, but soil management
• Feed the soil to feed the tree!
3
Agenda• Orchard floor techniques • Mandarin root structure• Improving drainage
Importance of Orchard Floor Management• Citrus have shallow
roots, most in top 30 cm of soil
• Small root zone to exploit
• Manage soil to provide good root/soil environment
• Not just nutrient management, but soil management
• Feed the soil to feed the tree!
Orchard Floor Management Techniques• Mulch• Cover crops• Minimize cultivation - maintain
undisturbed root zone• Divide fertilizer
applications to optimize nutrient use
• Ensure good drainage
Mandarin Root Structure • Typically no tap root• Woody lateral roots radiating
from the trunk• Fibrous feeder roots grow
from woody roots• Feeder roots absorb
nutrients and water• Most roots in top 30 cm,
under tree canopy• 3 root growth flushes: early
spring, early summer and late summer
Mandarin Roots in Saturated Soil• Citrus root growth starts ±12ºC • Roots do not function in saturated (very
wet) soil • Citrus roots need oxygen and water• In wet soil, tree roots cannot “breathe” • Absorbing roots start to die
within 1 to 2 weeks• Major root loss =>
yellowing leaves, then leaf drop• Worse in hot weather
In Chronically Saturated Soils…• Fibrous roots grow on the soil surface • Not enough oxygen is
available in the soil• Roots have plenty of water,
but cannot get nutrients from soil
• These roots should not be removed, they may be the ONLY functioning roots
• Improve drainage!
Improving Drainage• Dig shallow drainage
ditches across the slope for runoff
• 1-2º downward slope• 15 m intervals in heavy
clay soil• 30-60 cm deep, V shaped• Top width 2+ m• Bottom 1-1.5 m
Use A-frame level to determine slope
Improving Drainage• Protect drainage ditches with gravel or
stones to prevent erosion• Allow vegetation to grow in ditches
to slow runoff• Or install drainage pipe
Other problems with Saturated Soil…
• Increases Phytophthora root disease
• Disease damages roots, decreases productivity
• Toxic levels of gases e.g. hydrogen sulfide (H2S) collect in wet soil
• Improving drainage in heavy soils => improve tree health & root mass => increased yields & fruit quality
Goal is healthy roots for a healthy tree!
Citrus Drainage
Thank you!
Cindy Fake University of California Cooperative
Extension, Placer & Nevada CountiesApril 2012