macetas plastico – Nature Ecrogrow

The dimension of the channel depends on the type and age of the plant

Split-root systems are widely studied and have been adapted to rhizoboxes as well as to pots and tubes . In the rhizosphere, plants host a wide diversity of bacteria on the surface of the root as well as within roots in the vascular tissue . Due to its abundance and importance, the bacterial community in the rhizosphere is perhaps the most widely studied among other microbial members in the rhizosphere ecosystem. While the study of endophytic bacteria requires inevitable destructive sampling due to its localization, several non-destructive approaches have been developed to study microbes inhabiting the rhizoplane. One of the most widely studied plant-microbe interactions in the rhizosphere is that of the symbiotic relationship between legumes and rhizobia . Once a potential nodule forming bacteria is isolated, it is often required to authenticate its nodule forming phenotype by inoculating on host plants. However, conventional methods such as the use of soil pouches do not allow long term incubation, while “Leonard jars,” consisting of two stacked glass jars forming the top soil layer and the bottom nutrient solution layer, can be expensive and time consuming . A recent study challenges this by describing the use of clear plastic CD cases as minirhizotrons with potential for use in phenotyping root traits such as legume formation, and demonstrated innovation that democratizes research opportunities in rhizosphere research . Other microbial interactions in the rhizosphere, however, may not result in visible changes to the root system and often rely on next-generation omics technologies. As such,macetas plastico physical separation of the rhizosphere from the bulk soil becomes paramount in elucidating changes to microbial community and interactions.

One approach to this end is the use of nylon bags with differing pore sizes . The nylon bag restricts the movement of roots and the soil inside the bag is then regarded as the rhizosphere soil to compare against the surrounding root free bulk soil . Developing further on this concept, Wei et al. designed a specialized rhizobox that allowed repeated non-destructive sampling by adding individual nylon bags of root-free soil surrounding the root compartment which are then used as a proxy for the rhizosphere . These methods allowed easy distinction of the rhizosphere and the bulk soil but, we now know that the rhizosphere community is not only distinct from the bulk soil but also varies with type, part and age of the root, largely as a consequence of varying root exudation patterns . Studying this phenomenon in situ in the soil requires separation of desired roots from others without disturbance to plant growth or soil. To address this, researchers have used a modified rhizobox design with a side compartment to regulate root growth and quarantine specific roots from the main plant chamber . This additionally creates easy distinction between old and new roots and allows testing on specific quarantined roots despite plant age. A study using this set up showed specific microbial chemotaxis toward different exudates on an individual root whereas another showed spatial and temporal regulation of niche differentiation in microbial rhizosphere guilds . Similar physical perturbations to regulate root growth in response to microbial stimuli have also been applied in the micro-scale and are explored in the next section. Our assessment of the major growth chambers showed that most of the systems applied share similarities in basic structural components such as in the use of two parallel sheets in rhizoboxbased devices. While these growth chambers brought many of the rhizosphere processes to light, limitations do exist. One limitation is with the scale of applicability.

Most of these growth systems are mesoscale and can easily reproduce pot scale studies but may not be easily translatable to interactions occurring at the micro-scale nor recapitulate processes occurring at field-relevant scale. The next section describes advances in technology resulting in a new wave of unique devices making use of microfluidic processes and fabricated ecosystems which are specifically made to investigate specific rhizosphere processes. A complex web of biochemical processes and interactions occur in micro-scale dimensions in the rhizosphere. Having the ability to interrogate and manipulate these micro-scale processes and environmental conditions with high spatiotemporal resolution will elucidate mechanistic understanding of the processes. Microfluidics has proven to be a powerful approach to minimize reagent usage and to automate the often-repetitive steps. The micro-scale of the channels also allows precise control of reproducible conditions utilizing the laminar flow and automated fluidic operations . In addition, the microfluidic devices are well integrated with conventional imaging techniques by using a glass slide or coverslip as a substrate bonded with polydimethylsiloxane . These characteristics, as well as the ability to rapidly prototype and reproducibly manufacture using soft lithography technique, have enabled new ways of interrogating and studying the rhizosphere environment in a reproducible manner. Many of the microfluidic devices used for studying the rhizosphere share a similar design concept . They have an opening port, sometimes with pipette tips inserted into the PDMS body where the seed of the seedling rests and a micro-channel where the primary root grows into.

For example, an Arabidopsis thaliana’s seedling is typically grown in a microfluidic device up to 10 days, with chamber dimension around 150 to 200 µm in height, whereas the Brachypodium distachyon seedling chamber is 1 mm in height due to its thicker roots . Media and/or inoculation of the microbiome is achieved through additional channels to the main chamber. The PDMS body with the channels is typically bonded on a 50 mm by 75 mm microscope slide, and is made to accommodate multiple plants to increase throughput. Automated control offers the ability for continuous imaging and manipulation of media conditions with high temporal resolution. One notable example of a microfluidic device for rhizosphere studies is the RootChip, which uses the micro-valves in a PDMS device to control the fluidics . The first study using the RootChip grew 8 Arabidopsis plants on a single device with micro-valves but by the second iteration, the throughput has been doubled indicating rapid technological advances in the field. In addition, all these studies demonstrated spatiotemporal imaging at single-cell resolution and dynamic control of the abiotic environments in the rhizosphere. Another microfluidics-specific application to rhizosphere study is to use the laminar flow to generate the spatially precise and distinct micro-environment to a section of the root as demonstrated by Meier et al. . A young Arabidopsis’ seedling was sandwiched and clamped between two layers of PDMS slabs with microchannel features to tightly control synthetic plant hormone flow with 10 to 800 µm resolution to the root tip area,cultivar arandanos enabling observations of root tissues’ response to the hormones. As many root bacteria produce auxin to stimulate the interactions with the root, this study showed the possible mechanism of microbiome inducing the interaction by stimulating root hair growth. Another application of laminar flow utilized the RootChip architecture by adding the two flanking input channels to generate two co-laminar flows in the root chamber, subjecting a root to two different environmental conditions along the axial direction to study root cells adaptation to the micro-environment at a local level . These studies revealed locally asymmetrical growth and gene pattern regulations in Arabidopsis root in response to different environmental stimuli. Microfluidic platforms have also been successfully employed to study the interactions between the root, microbiome and nematodes in real time . In the systems, additional vertical side channels are connected perpendicularly to the main microchannel to enable introduction of microorganisms and solutes to the roots in a spatially and temporally defined manner . A recent micro-fluidic design incorporated a nano-porous interface which confines the root in place while enabling metabolite sampling from different parts of the root . These studies demonstrated the potential of microfluidics in achieving spatiotemporal insights into the complex interaction networks in the rhizosphere. Despite several advantages of microfluidics in rhizosphere research as described above, some challenges remain. All the microfluidic applications grow plants in hydroponic systems where clear media is necessary for the imaging applications and packing solid substrates in the micro-channels is not trivial.

The micro-scale of the channels limits the applications of these devices to young seedlings. Thus, interrogating the micro-scale interactions in bigger, more developed plants is not possible with current microfluidic channel configurations. In addition, technical challenges such as operating the micro-valves and microfabrication present a barrier to device design and construction for non-specialists. Fabricated ecosystems aim to capture critical aspects of ecosystem dynamics within highly controlled laboratory environments . They hold promise in accelerating the translation of lab-based studies to field applications and advance science from correlative and observational insights to mechanistic understanding. Pilot scale enclosed ecosystem chambers such as EcoPODs, EcoTrons and EcoCELLs have been developed for such a purpose . These state-of-the-art systems offer the ability to manipulate many parameters such as temperature, humidity, gas composition, etc., to mimic field conditions and are equipped with multiple analytical instruments to link below ground rhizosphere processes to above ground observations and vice versa . Currently, however, accessibility to such systems is low as there are only several places in the world which can host such multifaceted facilities due to the requirement of significant financial investments. Switching back to lab-scale systems, a recent perspective paper calls for the need to standardize devices, microbiomes and laboratory techniques to create model ecosystems to enable elucidation of molecular mechanisms mediating observed plant-microbe interactions e.g., exudate driven bacterial recruitment . Toward this goal, open source 3D printable chambers, termed Ecosystem Fabrication devices, have been released with detailed protocols to provide controlled laboratory habitats aimed at promoting mechanistic studies of plant-microbe interactions . Similar to a rhizotron setup, these flow through systems are designed to provide clear visual access to the rhizosphere with filexibility of use with either soil or liquid substrates . Certainly, there are many limitations to these devices in that they are limited to relatively small plants and limit the 3D architecture of the root system. Still, an advantage with the EcoFAB is that its 3D printable nature allows for adaptations and modifications to be made and shared on public data plat forms such as Github for ease of standardization across different labs and experiments . In fact, a recent multilab effort showed high reproducibility of root physiological and morphological traits in EcoFAB-grown Brachypodium distachyon plants . The development of comparable datasets through the use of standardized systems is crucial to advancing our understanding of complex rhizosphere interactions. Open science programs such as the EcoFAB foster a transparent and collaborative network in an increasingly multidisciplinary scientific community. Specialized plant chamber systems are necessary for nondestructive visualization of rhizosphere processes and interactions as all destructive sampling approaches tend to overestimate the rhizosphere extent by 3–5 times compared to those based on visualization techniques . Nonetheless, plants in such chambers are still grown in defined boundaries and suffer from inherent container impacts. For instance, studies have pointed out that container design significantly influences root growth during early developmental stages and leaves lasting impacts on plant health and phenotype . The majority of the lab-based chambers are also centimeter scale and are unlikely to replicate exact field conditions in terms of soil structure, water distribution, redox potential or root zone temperatures . While comparisons between chamber-grown and pot-grown plants show similar outputs , studies comparing plants grown in confined spaces to those directly grown in the field are missing. A recent review mapped the gradient boundaries for different rhizosphere aspects and found that despite the dynamic nature of each trait, the rhizosphere size and shape exist in a quasi-stationary state due to the opposing directions of their formation processes . The generalized rhizosphere boundaries were deducted to be within 0.5–4 mm for most rhizosphere processes except for gases which exceeds > 4 mm and interestingly, they are independent of plant type, root type, age or soil . Bearing this in mind, our assessment of the different growth chambers revealed possible overestimation of rhizosphere ranges in some chamber set ups. For instance, the use of root-free soil pouches representing rhizosphere soil despite being cm-distance away from the rhizoplane. This prompts the need for careful evaluation of new growth chamber designs to ensure accurate simulation of natural rhizosphere conditions.

Growers in the Napa Valley considered the use of Christmas trees as a barrier crop

The new modeling suggests that incentives or zoning may be introduced to induce industries to modify their behavior. Furthermore, in some cases optimal resource allocation, which takes into account both pollution and transportation costs, may lead to establishment of green zones separating animal production from urban areas. The disposal of animal manure in the Chino area has historically caused severe groundwater contamination problems. Dairies in this region designated certain lands as disposal areas where all liquid and solid animal wastes are disposed. In many cases, one acre of land is needed for disposing of the wastes from more than 30 or 40 cows, and most of the salt content in this waste percolates into the groundwater. The Clean Water Act was introduced in the early 1970s. One of its most important purposes was to reduce groundwater contamination and especially salinization by animal waste. The standard regulation proposed by the State Water Quality Control Board restricted the ratio of cows’ disposal acres—the tons of manure disposal compared to the animal waste produced by one cow—to be no greater than 1.5. Studies performed at the time to assess the economic impacts of this standard suggested that it would reduce the dairy cow population drastically and reduce the economic surplus that this industry generates by about 80 percent . Not surprisingly, the proposal encountered strong objections by dairy farmers and resulted in heavy litigation. An alternative proposal was to treat solid and liquid wastes separately; the solid waste was to be hauled to safe disposal areas outside the Valley,macetas plastico and restrictions were to be imposed on the disposal of liquid waste so that the original target of salt reduction could be met. On analysis this policy proposal was found to meet regional water quality targets at less than 50 percent of the cost of the original proposal.

This policy was adopted, and enabled the industry to survive for another two decades. The use of disposal areas for animal waste is not optimal and is not sustainable in the long run, however. A major challenge for the California dairy industry is to find better solutions for disposal of animal wastes. Accommodating the animal waste regulation requires investment in waste disposal facilities. Some farmers may have significant credit constraints and not be able to obtain the resources from private lenders to invest in the waste disposal facilities. Government credit provision may alleviate this problem and reduce the difficulty of adjusting to the waste disposal regulation. Macdougall et al. show that credit support policies can significantly reduce the cost of adjustment to water quality regulation in the Chino area. They also show that the ability of the dairy industry to withstand animal waste regulation is much higher in periods of low interest rate and economic prosperity and thus that regulation should be introduced in such periods. The concern with the environmental side effects has resulted in a wide variety of constraints and regulation that resulted in outcomes that are consistent with the theory presented above. Many dairies have moved from the Chino area to the San Joaquin Valley, where growers could find both larger disposal areas and better opportunities to market their manure as fertilizer. Four of the five leading dairy counties in California are now in the San Joaquin Valley: Tulare, Merced, Stanislaus, and Kings . Part of this move is certainly a shift away from the high land values brought by residential development, but much of it is also due to decreasing the environmental costs. California has not yet found the balance between transportation costs and environmental concern in locating its animal facility and managing its land resources. The design of optimal policies to control the side effects of animal agriculture will be one of the major challenges to policymakers and agricultural economists in the coming years.The Mediterranean fruit fly, Ceratitis capitata , or the Medfly, is an imported pest, infestations of which have serious consequences for California agriculture.

The 1980-81 infestation was ultimately eliminated at a great expense—reported at over$100 million—to the State of California and the federal government. A significant amount of public funds has been spent on eradication efforts for subsequent infestations. In 1989-90 there was another Medfly infestation , and findings of the Medfly have continued since. Because of aggressive eradication efforts, the impact on the California agricultural industry has been minimal compared to potential damage. However, the eradication efforts have not been without controversy. In addition, infestations to date have been in urban areas. The protocol for eradication involves a system of traps, aerial application of Malathion-treated bait, and the use of sterile male Medflies. The most controversial part of the protocol has been the aerial application of bait. This technique has raised fears and concerns among urban residents, and, coupled with diminished availability of public funds, has caused local officials, public interest groups, environmental groups, and health and safety groups to raise questions about the necessity of eradicating the Medfly. The outbreak of the Medfly in 1993-94 raised the specter of a possible embargo of California products by Japan, and probably Korea, Taiwan, and Hong Kong . This concern increased with the discovery that the Medfly had spread eastward into Riverside County near commercial citrus orchards. Japan has indicated that if a fertile female Medfly is found in a commercial orchard, it will consider placing an embargo on shipments of fresh fruit and vegetables from California. The list of crops that serve as hosts to the Medfly is quite extensive. In a 1991 production-cost study, 22 different commodities were included: apples, apricots, avocados, bell peppers, cherries, dates, figs, grapes, grapefruit, kiwis, limes, mandarin oranges, nectarines, olives, peaches, pears, persimmons, plums, prunes, and tomatoes . In 1992, these commodities represented nearly 1.6 million acres of irrigated cropland and over $4.2 billion in value of farm production. The farm value of exports amounted to $559 million, with a substantial amount shipped to Japan and other Asian countries. The assumption made in the production-cost study was that through periodic and regular applications of Malathion-treated bait, a marketable product would be produced.Increased costs would come from the application of bait and, for those crops shipped from California in a fresh state, there would be a post-harvest treatment using methyl bromide or a cold treatment to meet U.S. Department of Agriculture quarantine restrictions.

The annual increased costs were estimated to range from a low of $349.6 million to a high of $731.9 million. The reason for this range is that the effective application of pesticides is dependent on weather factors and the length of the season. The estimated cost for post-harvest quarantine treatments was $135.3 million, which includes the cost of the treatment and the loss of fruit due to treatment damage. An additional $8.1 million in transportation costs for movement to and from treatment facilities was also estimated. Hence, total annual costs of controlling the Medfly were estimated to range from a low of $493 million to a high of $875.3 million. Compared to the 1992 value of the total value of production for the crops affected, these costs are substantial. The economic impacts from a trade embargo would include effects on fresh shipments of apples, apricots, avocados, bell peppers, sweet cherries, dates, figs, table grapes, grapefruit, kiwis, lemons, limes, tangerines, oranges, nectarines, peaches, pears, persimmons, plums, and tomatoes. These commodities do not necessarily match those of the production study, because an embargo would likely include all exported commodities to the countries in question. For example, in the production-cost study, lemons were excluded; however, in the embargo study, they are considered. Also,cultivar arandanos the embargo would likely take place even though the commodities could be treated for shipment. The 1992 farm value of these products was $2.1 billion, and the farm value of total exports was $354.8 million. These crops were grown on 655,000 acres . The 1992 total f.o.b. value of shipments of these products, including both domestic and export , was $2.9 billion. The total f.o.b. export value was $605.5 million, and the f.o.b. value of shipments to Japan, Korea, Taiwan, and Hong Kong was $376.3 million, amounting to 62.1 percent of total exports for this product. Estimates of the changes in revenue from 1992 due to an export embargo vary by crop as to their significance.In most cases, the estimated change in price was small and not very significant as reflected in the lost revenue figure. However, for the citrus crops—grapefruit, lemons, navel oranges, and Valencia oranges—which were the most impacted, the estimated revenue loss was highly significant. For grapefruit, the loss in revenue is estimated to be 51 percent of the 1992 levels; for lemons, 38 percent; for navel oranges, 15 percent; and for Valencia oranges, 55 percent. The loss in revenue for all of the commodities considered was $564.2 million or 20 percent of the 1992 value of shipments. This loss represents a decrease in income to growers, packers, and shippers of the commodities involved. At the levels indicated, it is highly unlikely that any profits would result to those commodities most heavily impacted. The costs of growing, packing, and shipping the commodities would still occur.

The question that remains is how long the industries involved would continue to produce at the levels that existed before an embargo. The total impact of a Medfly infestation on the industries involved should also take into account the costs of controlling the pest. When these costs are added to the embargo estimates, they indicate even higher losses to the industry. The total impact on the commodities would range from a low of $1.057 billion to a high of $1.44 billion. These figures represent losses to all segments of the industries involved—from pesticide applications to control the Medfly, to losses in revenues due to losses in export markets and price decreases in domestic markets. In the short run, the domestic consumer would benefit from an embargo, particularly from citrus.Estimated price decreases range from no change in the case of apricots, to over 60 percent for grapefruit. How long the consumer would benefit from these price decreases would depend on how long it took for the industry to readjust its production or to find new markets. Price decreases of the magnitude estimated for the citrus industry would be expected to last no longer than two years before production adjustments would be made. In the long run, the consumer might be worse off. Producers would eventually decrease production in order to raise prices enough to regain lost revenues and adequately cover capital investments. In addition to a loss in income to the commodities affected, the California state economy would also be impacted. It is estimated that there would be a $1.2 billion decrease in gross state product and a loss of 14,200 jobs. Hence policies to eliminate pest invasions have a significant impact on both the industries affected and the general economy.The sharpshooter transfers the bacteria from an infected host plant to other plants. Once infected, yield decreases, and often the vine will die. The leaf hoppers breed over winter in riparian vegetation, ornamentals, and/or pastures, picking up the Xylella bacteria from host plants. The insects then migrate in the spring to feed on succulent vegetation, such as grape vines, infecting the vines as they spread. An infectious blue green sharpshooter has more than a 90 percent chance of transmitting the bacteria. Recent PD outbreaks in California’s Napa Valley wine grapes, one of the premier wine-producing regions of the United States, are estimated to have cost vineyard owners $46 million in 1999 . Insecticides have limited effectiveness on PD in vineyards where the sharpshooters enter each spring from riverbank vegetation. Applying insecticide to the riparian area where the insects are concentrated might control the spread of PD, but applications are constrained due to wildlife and water quality concerns. Removal of the bacterial and sharpshooter host plants at their riparian sources might reduce incidences of the disease, but the riparian vegetation may be protected by legislation. Brown et al. considered the economic impact of planting crops between the source area and the grape vines. These crops act as a barrier to transmission in order to slow or prevent the sharpshooter migration, but this strategy requires taking land out of grape production. The optimal barrier crop strategy depends on the profitability of the barrier crop relative to wine grapes and the effectiveness of the barrier crop, measured by percentage reduction in pest penetration per unit of barrier length.

Regulations may also limit the ability of specialty crop operations to store water

Microirrigation allows for precise delivery of water to the container-plant system and provides the potential to implement fertigation if controlled release fertilizers are not used or are depleted before the end of the growing season.Freshwater is a finite resource. Yet, demand for water has increased due to population growth and increasing water use by agricultural systems needed to support larger populations . Although most nursery and greenhouse crops do not feed people directly, these plants can enhance human well-being and expand our connection to the natural environment . Globally, agriculture is estimated to use 69% of freshwater supplies, while industry and energy use is 23% and household consumption is 8% . Concerns regarding water scarcity, particularly in arid or semi-arid regions such as the western USA and Australia, intensify during times of drought, but long-term water use continues to be a major problem. The majority of the specialty crops, grains, fruits, vegetables, and nuts consumed within USA and exported around the world are produced in the western USA . During times of drought, allocation and conservation of a limited water supply among agriculture, industry, and household use receive increased attention. During 2015–2016, much of California was in either extreme or exceptional drought,cultivar arandanos the two highest categories, impacting over 36 million people in the state . Growers were forced to fallow land and remove established agricultural specialty crops because of limited water availability. Changing weather patterns can significantly impact both crop yield in non-irrigated land and the volume of water required to supplement rainfall in irrigated lands .

Agricultural systems, in general, will likely need to produce more plants with less water, use lower-quality water, or both . Crop water use efficiency, defined as the water volume required to produce a given dry mass of yield, and water use reduction can be accomplished in part by breeding for drought tolerance , but growers must also conserve water through irrigation and other management practices . Increased crop water use efficiency can be achieved via precise water quantity delivery to the container based on crop-based demand to limit leaching from over-irrigation. Additionally, irrigation type , timing , and use of new technology have been reported to increase irrigation efficiency. Regardless of method, improved water application and scheduling precision reduces the presence of agrichemicals and other contaminants in production runoff .Transport of contaminants from irrigation runoff into the neighboring ecosystem is a concern for all agricultural production, but particularly in specialty crop production . Contaminants of concern in specialty crop operations can either be removed, recycled on-site, volatilized, or transported off-site, depending upon production practices at the operation and prevailing environmental conditions. Contaminant presence, along with increased economic and regulatory pressure to develop alternative irrigation water sources, results in a challenge for many growers. Recycling runoff water for irrigation is an ideal solution from a water quantity standpoint, in that the water is already available on-site, reducing volume of water needed from other sources. This recycled water also contains contaminants that could be detrimental to the environment; recycling water would help to limit agrichemical escape into the environment . Growers are typically concerned about negative impacts of bioactive concentrations of pesticides or phytopathogens which may diminish crop health if they are present in recycled runoff water.

Perception of risk associated with these contaminants represents a significant barrier to grower adoption and use of this readily available water source . Fertilizers deliver plant essential mineral nutrients to ensure optimal growth, but application of fertilizers in excess of plant requirements can result in nutrient leaching; of particular environmental concern are nitrogen and phosphorus . Fertilizer runoff from agriculture, including specialty crop production, is a major problem in a number of impaired waterways and can lead to environmental problems such as algal blooms . The ability to recycle mineral nutrients is perceived as a benefit for some growers, and these recycled fertilizer salts are sometimes accounted for in their nutrition programs, particularly in greenhouse production . Agrichemical residues in water can be detrimental if not mitigated, as both surface water and groundwater can become contaminated . The fate and transport of agrichemicals depends on a number of factors, including location applied, soil characteristics, slope, and timing of rain/irrigation events . Chemicals vary in their modes of action and half-lives in the environment ; thus, managing agrichemical contaminants in recycled runoff can be challenging. However, prevention of contamination and remediation of contaminants to minimize reapplication injury to the crop and environmental/biotic damage is feasible using best management practices . Phytopathogen contamination can create economic and ecosystem stressors, causing disease within both the operation and the surrounding ecosystem via runoff . Economic analysis of production losses attributed to phytopathogens in container-grown specialty crops is not widely available, making it difficult to calculate the impact on grower profits and the surrounding environment. Specialty crop production losses to pathogen infection have been estimated to range from 5 to 30% for some crop taxa, but losses are likely to be crop specific and fluctuate annually based on environmental and production conditions.

Ecosystems may be negatively impacted by the discharge of pathogens from crop production facilities via plant transport from nurseries and eventual pathogen escape into the environment as illustrated by the pathogen causing sudden oak death, Phytophthora ramorum . While fungicide applications can suppress pathogen growth, in general they are not curative. As a result, many growers prefer to minimize potential for crop infection by either sanitizing water before it is used or not reusing runoff. Management of pump intake depth and location within a reservoir were identified by Ghimire et al. as key mechanisms for limiting introduction of pathogen propagules via irrigation water. Additional insights into propagule movement,survival, persistence, and/or pathogenicity in production runoff and their economic and environmental impacts are potential areas of future study In 1972, the USA passed the Clean Water Act, which created an impaired waters list [also known as the 303 list], which identifies bodies of water that do not meet water quality standards, including chemical contaminants, dissolved oxygen, excess algal growth, or other factors that may reduce the ecological health of a waterway . The goal of this list is to remediate impaired waters and remove them from this list. Many areas of the USA contain impaired waterways. In 2016, the US Environmental Protection Agency listed 42,509 impaired waterways on the 303 list due to aforementioned impairment. Cumulatively since 1995, 69,486 TMDLs have been assigned to water bodies, of which 13,313 are for high pathogen loads, 6235 for excessive nutrient loads, 3950 for excessive sediment loads, and 1351 for pesticides . Although agriculture is not the sole contributor to impairment in these impaired waterways, reducing the environmental impact of agriculture via non-point source contaminant reduction should be a conservation goal.Runoff from specialty crop container operations is from two sources: uncontaminated water and operational water. In this context, uncontaminated water is water from rainfall events that has not come into contact with production areas, crops, agrichemicals, retention basins, or runoff collection reservoirs that collect and retain production runoff, nor should it contain contaminants above background levels . Runoff from a greenhouse roof is an example, as this water should not require treatment prior to leaving an operation or mixing with operational water to supplement the irrigation water supply. Operational water is any water flowing from, in, through, or around production areas. As a result of contact with soils, agrichemicals, and phytopathogens, this water may have elevated concentrations of contaminants, which may require treatment before reuse or release, depending on operational needs and local regulations.Ideally, both operational water and uncontaminated water would be captured, treated, and released from or reused by container operations. This is not always possible for nursery or greenhouse operations for a number of reasons. Often, operations have geographic limitations that constrain their capacity to capture runoff. Rainfall events in some regions of the USA are intense over short durations, resulting in runoff volumes that exceed the capacity of existing containment infrastructure. In some parts of the country, a high water table can limit feasibility to capture or treat runoff water. Saltwater intrusion and storm surges are also major concerns, particularly in coastal areas . Some operations, especially smaller or more urban operations, may be land limited, so there may not be sufficient land area to store water for treatment or reuse. Other areas may not be able to store water due to topography or soils . These limitations must be considered when developing regulations and implementing BMPs for a particular area or operation.As populations increase,macetas plastico particularly in the western USA where water is more limited, state and local regulations may limit the amount of water that can be captured or stored at an operation. For example, Oregon requires all users, including nursery and greenhouse operations, to obtain water rights permits to store rainfall in a containment reservoir since it is considered a state resource .

Similar regulations may become more common across the country as water becomes more limited and may be a short-term advantage to producers not under those restrictions.The following information about layout and site design is meant to represent the ideal production scenario; however, site constraints and owner priorities will dictate what is possible. A new operation should be designed to balance water collection, water storage, and production to ensure ample amounts of quality water. Containment reservoirs should be situated at the lowest part of the nursery,allowing water to flow freely towards the containment reservoir while minimizing contact with production areas . Chen reported remediation benefits associated with a multi-reservoir design, where water flows through multiple reservoirs before it is recycled. Pathogens are relatively short-lived without a host; therefore, if multiple ponds are used to increase water retention time, fewer pathogens survive to reinfest plants . If multiple reservoirs are not available, locating the irrigation pump intake as far from the entrance of operational water as possible in order to increase hydraulic retention time and 1 m above the bottom of the reservoir can help reduce pathogen loads applied to crops . In greenhouse operations, one or more cisterns may be used to store irrigation runoff , particularly for ebb and flood systems. Return water must be treated prior to storage or reuse to reduce or remove pathogens, particulates, and other potentially harmful constituents that can impact the irrigation system and plants. One of the most important steps to ensuring efficient capture of runoff water is proper grading and utilization of well-drained bed base such as coarse gravel. These measures can reduce disease incidence by minimizing standing water under containers and convey water to containment reservoirs for reuse or remediation . Grading may be minor or extensive, depending on the layout of the property and the site design. More detailed information regarding infrastructure and surface water recycling is available in Bilderback et al. ; Merhaut ; Yeager .Remediation can be defined as the process of removing chemicals, pathogens, and other constituents of concern to reduce loads of harmful substances to a water system . Contaminant type, required load reduction, and the economics and efficacy of treatment technologies depend on a number of factors at each operation. Below, we highlight research that evaluates various treatment technologies and assess where technologies may be of most effective use in production systems. A summary of each technology, scalability, relative cost , contaminants managed, and relative efficacy for each technology are presented in Table 1.Filtration is accomplished via several mechanisms including adhesion , flocculation , impaction , interception , and straining . Contaminant removal efficacy is in part determined by particle size, contaminant loading rate, and flow rate; these should be considered when selecting treatment technologies. Important considerations for filtration include both the flow rate and the loading rates of contaminants that must be removed, as well as the cost of installation and upkeep .Rapid sand and glass filters consist of tanks that hold sand or glass of a specific particle size . As water moves through the sand or glass, particulates are removed. These filters are able to process large volumes of water quickly . As sand or glass particle size decreases , filters are able to remove smaller particles, but require more force to move the same volume of water per unit time.