Root exploration, initial moisture conditions, and irrigation scheduling influence hydration of stratified and non-stratified substrates

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

Submitted to: Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2022
Publication Date: 9/8/2022
Citation: Criscione, K.S., Fields, J.S., Owen Jr, J.S. 2022. Root exploration, initial moisture conditions, and irrigation scheduling influence hydration of stratified and non-stratified substrates. Horticulturae. 8(9). Article #826. https://doi.org/10.3390/horticulturae8090826.
DOI: https://doi.org/10.3390/horticulturae8090826

Interpretive Summary: Soilless substrate (i.e. growing media) stratification, layering unique substrates within a single container, is an emerging substrate management strategy that may provide opportunities to reduce water use in controlled environment agriculture (e.g. nursery and greenhouse). Our research analyzed water movement during and shortly after an irrigation, applied as single application or in three pulses, to conventional and stratified substrates that were initially wet or fully hydrated, partially wet or in need of irrigation, or dry – reflecting a substrate in which a crop was wilting. Pulse or cyclic irrigation significantly increased the water retention in a partially wet or dry stratified substrate and decreased the total volume leached from the bottom of the container. Using cyclic irrigation, or pulses of water, in concert with stratified substrates resulted in the container reaching its maximum water retention unlike conventional, non-stratified substrates. This study demonstrated that cyclic irrigation scheduling enhanced water retention in both non-stratified and stratified profiles under different initial moisture conditions and can be used as an irrigation strategy when dry substrate conditions prevail. Additionally, pairing cyclic irrigation with stratified substrate systems supports better water efficiency when compared to single irrigation applications.

Technical Abstract: Soilless substrate stratification (i.e., layering unique substrates within a single container) is an emerging substrate management strategy that may provide opportunities to augment nursery resource use. As such, the objective of this research was to analyze water movement through containers during hydration events under different initial moisture conditions. The results indicated substrate stratification had minimal influence on water movement when compared to non-stratified systems (uniformly filled nursery containers). Cyclic irrigation significantly increased stratified substrates ability to retain water when irrigated at 20% volumetric water content ( p < 0.0001) and significantly decreased the total volume leached (p < 0.0001). Moreover, irrigating the substrate profile with shallow and more frequent irrigations facilitated stratified substrates to closely reach effective container capacity conditions (p < 0.0001) when compared to non-stratified systems. Stratified systems took longer to leach all gravitational pores (p = 0.0070). In dry moisture conditions, non-stratified substrates hydrated more when cyclic irrigation applications were applied when compared to single applications (p = 0.0492). In all, this study demonstrated that cyclic irrigation scheduling enhanced water retention in both non-stratified and stratified profiles under different initial moisture conditions and can be used as an irrigation strategy when dry substrate conditions prevail.