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Average monthly temperature and cumulative rainfall during both experimental runs (Nov. 2019 to July 2020). Experiment run 1 was initiated on 20 Nov. 2019, and experimental run 2 was initiated on 2 Feb. 2020, with both experiments being harvested at 24 weeks after planting. 1 inch = 2.54 cm, ( F 2 32) 4 1.8 = C.
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Substrate stratification is a method of filling nursery containers with “layers” of different substrates, or different textures of the same substrate. Recently, it has been proposed as a means to improve drainage, substrate moisture dynamics, and optimize nutrient use efficiency. Substrates layered with larger particle bark as the top portion and s...
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... the study were not assessed. However, because the initial root ball depth of liners was only 2 inches at planting, plant roots in stratified treatments were likely under at least minor drought stress initially because the entire root ball was planted in a top substrate with lower than recommended water-holding capacity. Paired with low rainfall (Fig. 1), this water stress likely contributed to reduced growth indices early in the experiment for both species, along with potentially lower access to nutrients in comparison with incorporated substrates. As plant roots reached the 0.38-inch bottom substrate, growth decreases were no longer evident, and all plants reached a marketable size ...
Citations
... Accordingly, P that is released from the fertilizer and leaches past the root zone may be adsorbed to the FSB before draining from the container. Growing containerized nursery and greenhouse crops in strategic layers of substrate, sometimes referred to as substrate stratification, has recently been proposed to decrease fertilizer requirements [30], reduce weed growth and weed seed germination [31,32], mitigate crop water stress during drought [33], and reduce peat use [34]. However, stratifying a substrate to include a P-sorbing base layer has not yet been explored. ...
Phosphorus (P) fertilizers applied to container-grown nursery crops readily leach through pine bark-based substrates and can subsequently runoff and contribute to surface water contamination. The objectives of this research were to determine the effect of adding a layer of FeSO4·7H2O-amended pine bark (FSB) to the bottoms of nursery containers on P leaching characteristics. Phosphorus and iron (Fe) leaching in response to FSB layer height (4 or 7.5 cm), FeSO4·7H2O rate (0.3, 0.6, or 1.2 kg·m⁻³ Fe), and form (i.e., granular versus liquid) used to formulate the FSB layer, and the inclusion of dolomite in the FSB layer were also investigated. Greenhouse studies lasting 15 and 19 weeks were conducted, in which 2.5 L nursery containers containing the FSB layer treatments below non-amended pine bark substrate were fertilized with 199 or 117 mg P from a soluble or controlled-release fertilizer, respectively. Leachate resulting from daily irrigation was collected and analyzed for P and Fe weekly. All FSB treatments leached less P than the control (non-amended pine bark only), with P reductions ranging from 22% (4 cm FSB with 0.3 kg·m⁻³ Fe) to 73% (7.5 cm FSB with 1.2 kg·m⁻³ Fe). Phosphorus leaching decreased linearly with an increase in Fe rate or layer height. The amount of Fe that leached from containers with FSB was <5% of that applied, regardless of the Fe rate. Granular- and liquid-applied FeSO4·7H2O with or without dolomite were equally effective at reducing P leaching. Adding 0.6 kg·m⁻³ Fe to the bottom 500 cm³ of pine bark increased P adsorption by 0.053 mg·cm⁻³ P, which equates to 17.9 mg P adsorbed per gram of FeSO4·7H2O added. Results from this research suggest that including an FSB layer in the bottom of nursery containers is an effective strategy for reducing P runoff from container-based nursery production sites.
... It has been recently suggested that using this technique will improve drainage, control substrate moisture levels, and increase nutrient use effectiveness. In theory, a layer substrate made up of larger particle bark on top and smaller particle bark at the bottom of the container would allow for rapid drying of the surface, which would inhibit weed germination while also retaining adequate moisture for crop development [43]. A recent study conducted by Khamare et al. [43] showed that coarse bark (<1.27 cm or 1.9 cm particle size) when used as the top substrate and finer bark (<0.96 cm particle size) when used as the bottom substrate in the container can reduce the growth of the weed species bittercress (Cardamine flexuosa With.) by 80% to 97%, and the liverwort (Marchantia polymorpha L.) coverage decreased by 95% to 99%. ...
... In theory, a layer substrate made up of larger particle bark on top and smaller particle bark at the bottom of the container would allow for rapid drying of the surface, which would inhibit weed germination while also retaining adequate moisture for crop development [43]. A recent study conducted by Khamare et al. [43] showed that coarse bark (<1.27 cm or 1.9 cm particle size) when used as the top substrate and finer bark (<0.96 cm particle size) when used as the bottom substrate in the container can reduce the growth of the weed species bittercress (Cardamine flexuosa With.) by 80% to 97%, and the liverwort (Marchantia polymorpha L.) coverage decreased by 95% to 99%. ...
... Furthermore, this approach may have an edge over standard mulch materials such as pine bark nuggets or rice hulls, which are typically applied to the top layer of nursery containers. Growers have suggested that this method can be implemented using their existing equipment, but a cost-benefit analysis is necessary to ascertain if the benefits of substrate stratification surpass the rise in labor costs [43]. ...
Weeds are undesirable plants that can interfere with human activities and can hamper crop production and practices. The competition among ornamentals and weeds for space, nutrition, light, and moisture within a restricted area, such as in container production, can be intense and destructive. In response to increasing concerns regarding herbicide injuries and the effects of pesticide use on the environment, many growers are extremely interested in non-chemical pest-management approaches. There are various non-chemical strategies to control weeds in containers, which include scouting, sanitation practices, hand weeding, mulching, irrigation management, substrate stratification, mulch discs or geo discs, lid bags, and fertilizer placement. In a restricted growth environment, weeds have been shown to reduce crop growth significantly. Limited information is available on the effects of weed densities and container sizes on ornament–weed competition within containerized production and how the concepts of fertilizer placement can be used efficiently to control weeds in containers without using any herbicides on the ornamentals. There is an immediate need to evaluate the interference and competitive effects of pernicious weed species in container-grown ornamentals in the North Central United States and to develop effective non-chemical weed control strategies by altering fertilizer placement in container production.
... Research has also focused on innovative ways of applying mulch in containers to reduce weed growth and improve crop growth. One such area of research is in the form of substrate stratification and strategic fertilizer placement (Fields et al., 2021;Khamare et al., 2022b). Substrate stratification involves different textures of the same substrate or different substrates applied in layers in a container. ...
... The upper layer of the substrate lacks nutrients and sufficient moisture for weed seeds to establish, while the lower layer contains nutrients and greater water retention capacity beneficial for the intended crop. Substrate stratification has shown to reduce the growth of bittercress by 80% to 97%, spotted spurge by 14% to 55%, and liverwort 97% to 100% (Khamare et al., 2022b;Khamare et al., 2022c). Additionally, the stratified substrates had no impact on the growth or quality of two commonly produced nursery crops. ...
... This practice further minimizes any potential toxic impact of mulch materials on the intended crop. Research involving different types of bark and wood chips as components of substrates in numerous greenhouse and nursery experiments have indicated that crops can be grown with comparable quality to those grown in peat moss Fain et al., 2008;Jackson and Wright, 2009;Boyer et al., 2009;Khamare et al., 2022b;Khamare et al., 2022c). ...
Weed management in container plant production is a serious problem and remains one of the most expensive and time-consuming aspects of the industry. Weeds cause severe reductions in crop growth due to the limited growing environment characteristic of container plant production. The container nursery industry relies heavily on a limited number of preemergence herbicide options. The use of herbicides as the primary means to manage weeds has resulted in some negative consequences such as high chemical costs, leaching, runoff, and concerns with recycling irrigation water. Additionally, nursery growers are shifting their focus toward different nonchemical weed management strategies because many ornamental plants are very sensitive to preemergence herbicides. One such method is using organic mulch to control weeds in container plant production. Mulching is the foundation of a nonchemical weed management protocol and acts as the first line of defense against weeds. Organic mulches used in container plant production include rice hulls, pine bark, wood chips, wood shavings, coconut coir, nut (peanut, pecan) shells, oyster shells, cacao bean hulls, pelletized newspaper, recycled newspaper, pine straw, and other materials; material selection often depends on the availability of the product. The objective of this manuscript is to provide a comprehensive review of existing research on the utilization of various mulch materials as a weed management tool in container plant production. Additionally, it aims to highlight any critical knowledge gaps and provide suggestions for possible future research.
... Substrate stratification, a new substrate management approach, has been shown to be a tool for weed management [10,11]. Substrate stratification involves creating layers of diverse substrates or textures of the same substrate within a container [12]. ...
... Substrate stratification involves creating layers of diverse substrates or textures of the same substrate within a container [12]. Substrate stratification was initially designed to improve water and fertilizer efficiency [13][14][15], and then in other work, the original principle was modified to evaluate its use to control weeds [10,11]. The method of substrate stratification for weed management involves using larger, coarse, and easily draining particles as the top strata without any fertilizer and a substrate that is highly capable of retaining moisture, finely textured, with fertilizer incorporated as the bottom strata [10]. ...
... Substrate stratification was initially designed to improve water and fertilizer efficiency [13][14][15], and then in other work, the original principle was modified to evaluate its use to control weeds [10,11]. The method of substrate stratification for weed management involves using larger, coarse, and easily draining particles as the top strata without any fertilizer and a substrate that is highly capable of retaining moisture, finely textured, with fertilizer incorporated as the bottom strata [10]. As a result, the top stratum of the substrate lacks nutrients or moisture for weed seeds to establish. ...
The objective of this study was to determine how topdressing or incorporating fertilizer with stratified or mulched substrates could affect the growth of Hibiscus rosa-sinensis ‘Snow Queen’, a popular ornamental plant, and the growth of liverwort (Marchantia polymorpha) and bittercress (Cardamine flexuosa), two common nursery weed species. Five different substrate treatments were evaluated, which included three stratified substrates composed of pine bark screened to a small (0.63–1.27 cm), medium (≤1.90 cm), and large (0.96–1.90 cm) particle size and two industry-standard substrates that were either mulched with rice hulls or remained unmulched. All treatments were then fertilized via either topdressing or incorporating a controlled-release fertilizer (CRF). Bittercress control was highest in mulched containers, followed by those stratified using the medium pine bark, and its growth increased overall in topdressed vs. incorporated containers regardless of substrate or mulch treatment. All the stratification treatments resulted in a decrease in liverwort coverage compared to the industry standard treatment, but topdressing generally increased liverwort coverage compared with incorporating fertilizer. In conclusion, both topdressing and incorporation appear to be compatible with fertilizer placement methods with substrate stratification from a crop production standpoint; however, weed growth may increase if fertilizer is topdressed.
... An additional cultural or nonchemical method that could have potential as a weed management tool is "layering" or stratified substrates (Khamare et al., 2022). This is a new area of research in which multiple substrates, or the same substrate with differing physical properties, are layered within a container to accomplish a production goal, such as decreasing water use or nutrient leaching, or potentially reducing weed growth (Criscione et al., 2022;Fields et al., 2021;Khamare et al., 2022). ...
... An additional cultural or nonchemical method that could have potential as a weed management tool is "layering" or stratified substrates (Khamare et al., 2022). This is a new area of research in which multiple substrates, or the same substrate with differing physical properties, are layered within a container to accomplish a production goal, such as decreasing water use or nutrient leaching, or potentially reducing weed growth (Criscione et al., 2022;Fields et al., 2021;Khamare et al., 2022). Because of the inherent moisture gradient in a container filled uniformly with the same substrate, the upper portion dries quickly, which requires more frequent irrigation to provide enough moisture for recently potted plants to establish, especially soon after transplanting and before roots are fully developed (Fields et al., 2020(Fields et al., , 2021Owen and Altland, 2008). ...
... In another study, stratified substrates improved the growth and quality of 'Ruby' loropetalum (Loropetalum chinense) compared with a traditional homogenous substrate system in which the entire container was filled uniformly with a single substrate throughout the container (Criscione et al., 2022). In a previous study, we applied the stratification strategy described by Fields et al. (2021) inversely to evaluate weed control benefits (Khamare et al., 2022). The larger coarse particles were used as top strata containing no fertilizer, and a fine-textured, highly moisture-retentive substrate comprised the bottom strata. ...
Substrate stratification is a new research area in which multiple substrates, or the same substrate with differing physical properties, are layered within a container to accomplish a production goal, such as decreasing water use, nutrient leaching, or potentially reducing weed growth. Previous research using stratification with pine ( Pinus sp.) bark screened to ≤1/2 or 3/4 inch reduced the growth of bittercress ( Cardamine flexuosa ) by 80% to 97%, whereas liverwort ( Marchantia polymorpha ) coverage was reduced by 95% to 99%. The objective of this study was to evaluate substrate stratification with pine bark screened to remove all fine particles as the top strata of the substrate and determine its effect on common nursery weeds and ornamental plants. Stratified treatments consisted of pine bark screened to either 1/8 to 1/4 inch, 1/4 to 1/2 inch, or 3/8 to 3/4 inch, applied at depths of either 1 or 2 inches on top of a standard ≤1/2-inch pine bark substrate. An industry-standard treatment was also included in which the substrate was not stratified but consisted of only ≤1/2-inch pine bark throughout the container. A controlled-release fertilizer was incorporated at the bottom strata in all stratified treatments (no fertilizer in the top 1 or 2 inches of the container media), whereas the industry standard treatment had fertilizer incorporated throughout. Compared with the nonstratified industry standard, substrate stratification decreased spotted spurge ( Euphorbia maculata ) counts by 30% to 84% and bittercress counts by 57% to 94% after seeding containers. The shoot dry weight of spotted spurge was reduced by 14% to 55%, and bittercress shoot dry weight was reduced by 71% to 93% in stratified treatments. Liverwort coverage was reduced by nearly 100% in all the stratified substrate treatments. Compared with the industry standard substrate, stratified treatments reduced shoot dry weight of ligustrum ( Ligustrum japonicum ) by up to 20%, but no differences were observed in growth index, nor were any growth differences observed in blue plumbago ( Plumbago auriculata ).
... As measured by quality ratings and overall growth (i.e., physiological measurements), the equal or greater performance of crops produced in the stratified substrate systems have been reported [6,[9][10][11]. In the stratified systems, improved crop growth and quality were the most notable within the first year, especially during crop establishment [6]. Furthermore, water and fertilizer inputs can be significantly reduced while producing containerized crops of equal or greater size in the stratified systems [9]. ...
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, this research aimed 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 compared to non-stratified systems (uniformly filled nursery containers). Cyclic irrigation significantly increased the 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 ty reach effective container capacity conditions (p < 0.0001n compared to non-stratified systems. The stratified systems took longer to leach all gravitational pores (p = 0.0266). In dry moisture conditions, non-stratified substrates were more hydrated when cyclic irrigation applications were applied compared to single applications (p = 0.0492). 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.
... In a survey of a palm nursery in Bursa, Türkiye, Cyperus rotundus and Portulaca oleraceae during summerautumn, and Urtica dioica and U. urens during winter-spring were identified as the most dense and difficult to control weeds (Inci and Uludag, 2017). Beyond the lack of postemergence herbicides registered for container-grown ornamental plants, any potential non-selective herbicide drift can cause an injury and reduce the prices due to the high-demands of ornamental market (Case et al., 2005;Khamare et al., 2022;Inci and Uludag, 2017). Similarly, the preemergence herbicides can significantly increase the growth length by months even with minor injuries (Khamare et al., 2022). ...
... Beyond the lack of postemergence herbicides registered for container-grown ornamental plants, any potential non-selective herbicide drift can cause an injury and reduce the prices due to the high-demands of ornamental market (Case et al., 2005;Khamare et al., 2022;Inci and Uludag, 2017). Similarly, the preemergence herbicides can significantly increase the growth length by months even with minor injuries (Khamare et al., 2022). ...
Approximately 500 growers from the Bayındır District of Izmir Province, Türkiye share one quarter of outdoor ornamental plant production in Türkiye. Weeds at pots can significantly affect growth of ornamental plants and results with income loss. A face-to-face grower survey was carried out with 46 growers from Bayındır to find out weed problems and management practices of pot production of outdoor ornamentals. Furthermore, two nurseries were observed for their management practices in 2020 and 2021. Growers are mostly 30-50 years old range and 65% of enterprises are family farms approximately one hectare premises. More than half of the growers has over 10 years of experience in outdoor plants production. The highest produced species are Cupressus macrocarpa, Cupressocyparis leylandii, and Viburnum tinus out of ~30 species. Weed management and irrigation were considered as the fourth foremost problem following to production costs, selling prices, and marketing. Sprinkler irrigation is followed by drip irrigation and flood irrigation. One third of growers stated that weed control is a must while half of the growers it should be done if needed. Herbicide applications can be delivered two to 12 times in a season, but mostly five to seven times. Due to loss of herbicide efficiency, hand weeding and hoeing are followed by herbicide applications. Tarping on soil is done by ~20% of producers which helps the weed control. Tarping is considered mostly as an expensive method by farmers who do not apply. Glyphosate is the most common herbicide followed by pendimethalin. Experienced farmers thought weed control is done in all stages of production and showed tendency of using overdoses of herbicides comparing to less experienced ones. On the contrary, more less experienced farmers thought herbicides has lost their efficiency. Different weed species were recorded from observed enterprises and observations supported survey results. It is concluded that continues irrigation increases weeds that lead herbicide use often which ends up herbicide efficiency lost or herbicide resistance in weeds (that is not verified in this study) that causes use of overdoses and environmental pollution, increases costs and labors.
ADDITIONAL INDEX WORDS. air-filled porosity, crepe myrtle, Lagerstroemia indica, pine bark, root architecture, soilless, water-holding capacity SUMMARY. Substrate stratification is an emerging substrate management strategy involving layering multiple substrate materials within a single container to modify physiochemical characteristics of the substrate system. Specifically, stratifying allows growers and researchers to rearrange the air-water balance within a container to modify hydraulic characteristics. Moreover, fertilizer can be incorporated into just the upper strata to reduce leaching. Research to date has shown benefits associated with resource efficiency, production timing, and weed control. With the associated benefits for substrate stratification, interested growers will need pragmatic solutions for onsite trials. Therefore, the objective of this study was to identify a cost-effective solution for growers interested in exploring stratification options. As such, this research was designed to identify a single-screen bark separation to generate fine and coarse bark textures suitable for use as the top and bottom substrate strata. Loblolly pine bark (Pinus taeda) was screened with either a 4.0-mm, 1/4-inch, or 3/8-inch screen, with the particles passing through the screen (unders) separated from retained particles (overs). Stratified substrate systems were engineered with an individual screen wherein the fines were layered atop the coarse particles from the same screen. 'Natchez' crepe myrtle (Lagerstroemia indica) liners were planted in either of the three stratified substrate treatments or a nonstratified control. Substrate physical characteristics were assessed for each strata by pre-and postproduction properties to identify changes of substrate. The final growth index of the crop was unaffected by the substrate treatment (P = 0.90); however, stratified substrates did increase dry root weight (P = 0.02), with the smallest screen (4.0 mm) resulting in the greatest root weight. Separation of roots between the two strata indicated the presence of more roots in the upper strata in all substrates. However, the stratified substrates resulted in a greater shift in root location, encouraging increased rooting in the upper strata with fine particles, with the largest screen (3/8 inch) resulting in the greatest differentiation between upper and lower rooting. Each stratified treatment had increase in water-holding capacity in the lower (coarser) strata without changes in the upper strata. Thus, we conclude that single screens can be used to build stratified substrate systems. Moreover, screen aperture size may be used to achieve different outcomes with regard to root growth and development as well as water-air balance. Further research may indicate that screen selection may be used to target specific crop needs.
