Adding Clays to Pine bark Potting Substrates Jim Owen, Stu Warren & Ted Bilderback Department of Horticulture Science North Carolina State University

FERTILIZER SUBSTRATE IRRIGATION Container Managing the Container System

Narrow border/filter strips are helpful, but not letting nutrients out of the pot saves money and protects watersheds

Amending Container Substrate With Clay

24/48 4/20

EXPERIMENTAL SUBSTRAES TreatmentSubstrate 8PB:1SANDIndustry Standard OD 5/20 LVMPine Bark + 8% 5-20 mesh LVM OD 4/20 RVMPine Bark + 8% 4-20 mesh RVM OD 24/48 LVMPine Bark + 8% mesh LVM OD 24/48 RVMPine Bark + 8% mesh RVM

Root and Shoot Dry Weights

Irrigation Partition Irrigation water applied, plant use, water leached (L) over 112 days to maintain a 0.20 leaching fraction for Cotoneaster in pine bark substrates amended with 8% clay Water Applied Plant Use (Evapotranspiration) Leached

Cumulative Irrigation Applied Cumulative amount of water (L) applied to maintain a 0.2 leaching fraction on Cotoneaster grown in pine bark substrates amended with clay.

Cumulative Phosphorus Loss Cumulative amount of phosphorus lost over 112 days from 3.7 gal containers pine bark substrates amended with clay to grow Cotoneaster while maintaining a 0.2 leaching fraction.

Total phosphorous leached (mg) per container over 112 days to maintain a 0.20 leaching fraction while growing Cotoneaster spp. In pine bark substrates amended with 8% clay. Cumulative Phosphorus Loss

Cumulative Ammonium Loss Cumulative amount of ammonium lost over 112 days from 3.7 gal containers pine bark substrates amended with clay to grow Cotoneaster while maintaining a 0.2 leaching fraction.

Significance to the Industry 100, ,000 gallons of WATER / A bed space –Significant Drought & Water Conservation Impacts 67% less Phosphate leached from containers –Watershed protection Equivalent Growth to Pine bark:Sand

Adding Clay to pine bark potting mixes may help keep the Monsters out of irrigation supplies and watershed protection.