Exploring water movement through stratified substrates

Authors: CRISCIONE, KRISTOPHER - Louisiana State University Agcenter; FIELD, JEB - Louisiana State University Agcenter; Owen Jr, James - Jim

Submitted to: International Plant Propagators Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/10/2021
Publication Date: 6/7/2022
Citation: Criscione, K.S., Field, J.S., Owen Jr, J.S. 2022. Exploring water movement through stratified substrates. Combined Proceedings of the International Plant Propagators Society. 71:116-124.

Interpretive Summary: An increase in horticultural production requires a greater demand for more water use. Soilless substrates, particularly bark-based systems used in nursery production, can be inefficient with regards to water utilization. Substrate stratification is an innovative substrate management technique that involves the layering or stacking two substrates of unique hydraulics properties within the container system. The objective of this study was to monitor how stratifying substrates influences water relations between two different irrigation schedules. Stratified substrates allow for added water retention in the upper half of the container, whereas in the lower half, the amount of air was increased. Thus, stratifying the substrate through layering fine bark on top of coarse bark has been shown as a method to effectively reduce daily water fluctuations within the container while maintaining optimal water tensions throughout the container system. Furthermore, pairing stratified substrates with more efficient and targeted irrigation strategies (i.e. cyclic or repeated daily irrigation in smaller individual amounts) can further stabilize substrate moisture tensions during and between irrigation events.

Technical Abstract: An increase in horticultural production requires a greater demand for more water use. Soilless substrates, particularly bark-based systems used in nursery production, can be inefficient with regards to resource utilization. Substrate stratification is an innovative substrate management technique that involves the layering or stacking two substrates of unique hydraulics properties within the container system. The objective of this study was to monitor how stratifying substrates influences substrate water potential between two different irrigation schedules. Stratified substrates allow for added water retention in the upper half of the container, whereas in the lower half, air-filled porosity was increased. Moreover, stratified substrates significantly reduced tension fluctuations that notoriously occur in the upper portion of the substrate profile. Oscillations were even further reduced when a cyclic irrigation schedule was implemented. Thus, stratified substrates have potential for improving water efficiency in nursery crop production.