please help - show me the best auto water!!! Do you know a better way, Do they work well ? Capillary Mat Systems

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FEED GUIDE FOR 60/40	FEED GUIDE FOR PEBBLES
Start	2 x 15 minute feeds per day	2 x 15 minute feeds per day
Veg	3 x 15 minute feeds per day	3-4 x 15 minute feeds per day
Flowering	4-5 x 15 minute feeds per day	4-6 x 15 minute feeds per day

INNER POT:	Aqua Pot, Culture Pot, Punched Pot
SIZE:	6 Pot System (100L Tank), 12 Pot System (225L Tank), 18 Pot System (225L Tank), 24 Pot System (225L Tank), 36 Pot System (400L Tank), 48 Pot System (400L Tank)

Do like the passive systems no power needed

 

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[Ca++]

My local store, which became a national hub, had full time staff knocking these out the door. Until I got one, and realised it didn't work properly. Sent word back after modding it, and now the stands exist. Though I don't set them at an angle. Which is why mine is kinda sip, and could use a float to maintain it as such. I have other mods to maintain the level, stop root blockages, and quieten it down. The basic idea is great though.

I think they misunderstood why the stands are needed. As with the sip drawings, you need an air gap between the water, and the inner pot. Or the roots go to mush. There is no need to tip the bit out though. Or indeed, have them quite so high above the brain bucket. The pipe they use into the outer, is just a couple of inches, so tipping the roots to it, is illogical. The pipe needs to reach the center, so circling or dropping roots, don't go straight for it. After which, it's very reliable, but noisy. Mine... you hear the relays click. Only as it's the standard box still, not one of my own. Which are 12vdc, because it's a grow room.

Pebbles don't really hold enough water for a few hours between cycles. They have pots packed closely, indicating smaller plants, and no access routes. Most people are using 4 pots per meter, maybe less. They need a bit of water in the bottom. These are all things to think about, when running these systems. I can help anyone running into difficulties though. That noisy air hole that eventually blocks and floods the place, for example.

 

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GROW TREES
Yeild more with less reduce plant counts more production per plant

Wasted floor space results in less root and yield? Round buckets ok? Square buckets better ?
You already know where im going with this ?

As with the sip drawings, you need an air gap between the water, and the inner pot. Or the roots go to mush.

Aeration is a issue if there is a power outage

Expandable Sip design. Passive.

Thats what makes a system like this so attractive

That noisy air hole that eventually blocks and floods the place, for example.

The overflow valve, must have a safe overflow plan if flood is a danger


The above system is only 35 gallon ?

• Current Culture Under Current Solo COMM 35 Gallon (6 Site x 5.5" Net Pot Lid)

 

[Ca++]

The hole is an anti-siphon arrangement. The pump in the tank, will send water to the brain, setting up a siphon if not dealt with. This system has a hole drilled in that delivery tube, just before it leaves the tank. This squirts water back into the tank while the fill pump runs, then lets in air to break the siphon, once the pump stops.
This tends to salt up shut, especially when people cover it. Which they do because it's remarkably noisy. Like a kid with a straw, trying to get the last drop from a plastic cup.
The answer is simple enough. The delivery pump only has a 1.5m head. The short answer is you don't have a hole, you have an air admittance pipe, reach up past 1.5m. Where the pump can't get water out of it.

Personally, I use solenoids now. This means non of my pipes are blowing bubbles, or pouring water out their ends into freefall. Each pipe terminates under water. For everyone else, it's an air admittance pipe. With it's termination sized to effect flow, and noise.

 

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RO water input...
recirculating and aeration running on solar RDWC

The hole is an anti-siphon arrangement.
The pump in the tank, will send water to the brain, setting up a siphon if not dealt with.

 

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Fusarium and Pythium species infecting roots of hydroponically grown marijuana (Cannabis sativa L.) plants​

Zamir K. Punja
&
Gina Rodriguez
Pages 498-513 | Accepted 19 Sep 2018, Published online: 16 Nov 2018

• https://doi.org/10.1080/07060661.2018.1535466

magnification 45x

Fusarium - Wikipedia

en.wikipedia.org

Pythium - Wikipedia

en.wikipedia.org

 

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Front. Plant Sci., 18 September 2023
Sec. Plant Metabolism and Chemodiversity
Volume 14 - 2023 | https://doi.org/10.3389/fpls.2023.1233232

Figure 7 Least square means (±standard error) for the content of (A, B) nitrogen, (C, D) phosphorus, and (E, F) potassium in leaves (left) and inflorescences (right) for the fertilizer concentrations (80, 160 and 240 mg N L−1) at different harvest dates (days after planting, DAP). For each harvest date within each single figure, means with different letters were significantly different from each other according to Fisher’s LSD test with α=0.05.

Cannabis Hunger Games: nutrient stress induction in flowering stage – impact of organic and mineral fertilizer levels on biomass, cannabidiol (CBD) yield and nutrient use efficiency​

 

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4 Discussion​

This is the first study showing the potential to reduce fertilizer input while maintaining CBD yield of medicinal cannabis. Even though inflorescence yield was lower at the final harvest, this was compensated by a higher CBD concentration, a trend found across fertilizer types. Furthermore, we found that the higher nutrient use efficiency of N, P, and K was achieved by a larger mobilization and translocation of nutrients, increasing the utilization efficiency of acquired nutrients. Differences in CBD yield between fertilizer types occurred only at the final harvest, where the higher CBD concentration could not compensate for the lower inflorescence dry matter. Our results showed a lower acquisition and utilization efficiency for the organic fertilizer. There were no significant interactions between fertilizer type and concentration for the analyzed variables: yield, nutrient concentration, content and efficiency indices. This study contributes to the growing body of scientific evidence that fertilizer use efficiency can be improved in the cultivation of medicinal cannabis with the aim to reduce negative environmental impacts related to the excessive use of fertilizers.

4.1 Does fertilizer type matter?​

Several mineral and organic liquid fertilizer solutions are commercially available. Previous studies showed differences in inflorescence biomass, CBD yield and nutrient use efficiency for organic and mineral fertilizers. Our results partly confirm the need for higher concentrations of organic fertilizers to reach the productivity of mineral fertilizers, as indicated by optimum nutrient concentrations for organic of 212–261 mg N L−1 (Caplan et al., 2017a) in comparison to 160 mg N L−1 for mineral fertilizers (Saloner and Bernstein, 2021) due to the lower nutrient uptake efficiency.

Our study revealed, in addition, that the difference in final yield was mainly attributed to the last two weeks before harvest, when the mineral fertilization had significantly higher inflorescence dry matter than organic treatments (Figure 3). This was supported by the higher nutrient use efficiencies of mineral nutrients. However, differences in CBD yield between fertilizer types were lower due to lower CBD concentration with mineral fertilization (Figure 3), indicating a possible dilution effect (Shiponi and Bernstein, 2021b; Bruce et al., 2022). Vegetative plant growth was not affected by the type of fertilizer as indicated by similar values of leaf area and specific leaf area (Figure 2). During the last two weeks before harvest, inflorescence dry matter strongly increased and cannabinoids were accumulated, presenting a large sink with high assimilate and nutrient demand (Figure 3). During this phase, plants receiving mineral fertilizer maintained a faster growth indicating that the mineral form of nutrients was more readily available for uptake compared with the organic nutrients.

The allocation of mineral nutrients between plant organs (Figure 6) showed the translocation of individual macro elements in relation to plant organs and age as also reported in other studies for medicinal cannabis (Bernstein et al., 2019; Malík et al., 2021). Nutrient stress levels were comparable in both fertilizer types as indicated by similar SPAD values (Figure 8). The highest translocation rate of nitrogen (i.e., reduction of SPAD value) occurred also during the last two weeks before harvest – especially for mineral fertilizers – indicating that plants could not provide nutrients for inflorescence growth mainly by root uptake, being the re-mobilization of nutrients necessary at that point. For organic fertilizers, the re-mobilization occurred before that, as the nutrient uptake efficiency (NUpE) was lower, and thus the acquisition of nutrients throughout the flowering period.

The lower NUpE of organic fertilizers is in general related to the complexity of biological interactions that are necessary to convert and make nutrients available. Several microorganisms like fungi and bacteria are responsible to mineralize organic nutrients and improve their availability to plants (Lowenfels and Lewis, 2010; Lowenfels, 2013). One main difference among nitrogen forms in fertilizer types is that organic fertilizers contain higher ratios of NH4+ to NO3− than mineral fertilizers.

The impact of N form on cannabis plant function and production was also demonstrated by a 46% decrease in inflorescence yield with the increase in the share of N supplied as NH4+ from 0 to 50% (Saloner and Bernstein, 2022). Yet, moderate levels of 10–30% of NH4+ showed only minor adverse effects on plant function and secondary metabolism but produced lower inflorescence yields compared with pure NO3− nutrition. Under a level of 50% NH4+, the plants demonstrated toxicity symptoms, which impaired plant growth. In our study, NH4+ toxicity symptoms were also observed in plants of the highest organic fertilizer treatment (240), which showed burned tips of leaves (Figure 1). In an outdoor experiment by Bruce et al. (2022), commercial organic solid fertilizer increased inflorescence biomass compared to mineral fertilizer treatments, while the concentration of cannabinoids was not altered. The highest CBD concentrations were found for manure-based compost treatments, which produced the lowest inflorescence yield in the first year, but the highest in the second year. This indicates a time interaction between nutrient availability and the ratios of NH4+ to NO3− (Bergstrand et al., 2019).

Besides yield metrics, organic fertilizers could enhance quality traits, e.g. a higher lycopene concentration in tomatoes compared to mineral fertilizers was reported (Bilalis et al., 2018). Authors reported a non-significant difference in lycopene yield between organic and conventional tomatoes, suggesting organic production as a suitable alternative for lycopene production. Long-term studies demonstrated that NUE increased when multi-nutrient and organic fertilizers were used in field conditions (Zhu et al., 2023), suggesting a limited interpretation of comparative results between higher efficiencies of mineral to organic fertilization strategies. This can be true for single-use substrates but seems not to be the case in other cultivation systems. It can be observed that organic medicinal cannabis cultivation facilities are adopting raised beds and living soil systems that are used for several cultivation batches.

Micronutrients (Cu, Fe, Mn, and Zn) are important co-factors of the group of enzymes superoxide dismutases that detoxifies reactive oxygen species, which normally accumulate more under both biotic and abiotic stress conditions than under ambient conditions. B is important in cell wall formation and flowering. Apart from Zn, these micronutrients were present in higher concentrations in the mineral fertilization regimes than in the organic. This may have influenced the results. However, as pointed out in section 2.2.1, we assume this effect negligible as no deficiency or toxicity symptoms were observed during the experiment.

4.2 Can fertilizer concentration be reduced?​

The reported environmental impact and carbon footprint (Mills, 2012) associated with the fast increase of commercial cannabis cultivation draw attention toward a more efficient use of fertilizers (Wartenberg et al., 2021). The response of plant growth to an increase in fertilizer concentration often follows a convex bell-shaped curve. As demonstrated, cannabis growth responds positively until an optimum amount of N, P and K and then decreases at higher rates (Bevan et al., 2021).

Our results showed that plant growth responded positively from the lowest to the highest fertilizer concentration with an increase in plant and inflorescence dry matter and leaf area (Figures 4 and 5), as confirmed by other studies in literature (Bevan et al., 2021; Malík et al., 2021). The final CBD yield, however, did not show significant differences between 240 and 160 as the lower inflorescence dry matter was at least partly compensated by a higher CBD concentration (Figure 5) resulting in 95% of the CBD yield using one-third less fertilizer. It is unclear whether this effect is due to enhanced cannabinoid accumulation due to nutrient stress or simply a dilution effect, indicating a maximum production capacity of cannabinoids. Nonetheless, plants experiencing nutrient stress were able to use nutrients more efficiently to produce inflorescence biomass (AEinflorescences) and CBD yield (AECBDyield), mainly due to the higher NUtE for N and K, i.e. already acquired nutrients were re-mobilized from other plant organs. This effect was also reported for other plant species (Kant et al., 2011)

A high concentration of N in the plant does not necessarily correlate with stimulation of the secondary metabolism in cannabis (Saloner and Bernstein, 2021). Rather, the authors suggest a specific impact of N in inflorescences creating a negative correlation between inflorescence N concentration and the production of secondary metabolites not containing N, such as cannabinoids and terpenoids. This correlation is also described as the carbon–nutrient balance, which states that under low N concentration, the production of N-rich primary metabolites and hence growth is restricted, and plant metabolism and energy expenditure shift from creating N-containing metabolites to the production of metabolites that do not contain N, as terpenoids and cannabinoids (Lerdau and Coley, 2002; Song et al., 2023).

The values found for AE in inflorescences are in accordance with the literature (presented as NUE values) ranging from 5 to 17 for the range of fertilizer concentrations between 30 and 320 mg N L−1 and a linear decrease of NUE with increasing N concentration was found for liquid mineral fertilizer (Saloner and Bernstein, 2021).

Under mineral fertilization, an optimal N supply range of 160–230 mg N L−1 responded best for maximizing inflorescence yield (Bevan et al., 2021), while P was recommended at a rate of 30 mg P L−1 (Shiponi and Bernstein, 2021a; Shiponi and Bernstein, 2021b). and 60 mg P L−1 (Bevan et al., 2021). For K, the range between 60–175 mg K L−1 did not affect plant development but increased K in the leachate indicating a limited K uptake at higher concentrations (Saloner et al., 2019). Nonetheless, it is difficult to compare results to our study – e.g. for optimum fertilization under 160 mg N L−1 – due to differences in fertilization regimes, as the experiment by Saloner and Bernstein (2021) was performed with continuous mineral fertigation with drainage, whereas the results by Bevan et al. (2021) are based on a soilless system with replacement of nutrient solution weekly. Thus, it is challenging to calculate exact nutrient inputs and nutrient use efficiencies. In another way, our study highlights the controlled application of fertilizer and induction of nutrient stress only during flowering as a more sustainable fertilization technique to avoid nutrient disposal.

Regarding rates of liquid organic fertilizer, Caplan et al., (2017a; 2017b) recommend a fertilizer rate of 389 mg N L−1 (4.0N-1.3P-1.7K) for the vegetative growth stage and 212–261 mg N L−1 (2.0N-0.8P-3.3K) for the flowering stage. A positive correlation between fertilizer rate and inflorescence yield but a negative correlation to THCA concentration and yield was found during flowering. This indicates a dilution of compounds with yield increase and points to a reduction of N and P supply during flowering to promote N and P translocation, which can increase utilization and overall agronomic use efficiency.

In our study, the applied nutrient concentrations triggered a nutrient deficiency response, which resulted in an increased production of secondary metabolites as shown by significantly higher CBD concentrations (Figure 3) and higher CBD yield agronomic efficiencies (AECBDyield). Nutrient deficiency stimulated the translocation of N from older (source) to younger leaves (Supplementary Table 4) and generative organs (sinks) (White, 2012). Higher NUtE can be explained by differences in mobilization and translocation of nutrients, which became larger and started earlier with decreasing nutrient concentration, in particular, for N (Figures 7A, 8). These differences in nutrient content over time were to a large degree mediated by the increase in dry matter, but in addition, by higher concentrations in plant organs especially for N and K (Figures 7A, B, E, F). At 69 DAP, nutrient contents in inflorescences were not significantly different between treatments with nutrient deprivation stress (Figure 7), indicating that nutrient availability was not a limiting factor for the utilization of nutrients during the initial growth of inflorescences. Nevertheless, higher nutrient availability in treatment 240 enhanced biomass production.

Since the inflorescences are commonly the only harvested material in medicinal cannabis cultivation, nutrients accumulated in other plant organs at harvest and in the substrate are unused and discarded. In our study, no significant differences between fertilizer concentrations were found for P concentration in inflorescences at the final harvest, whereas, P concentration in leaves, stem and substrate were significantly higher for treatment 240 (Supplementary Table 4). This indicates an overfertilization with P (240 in comparison to 160) at the flowering stage as P utilization by the plants was not increased.

In the experiment from Westmoreland and Bugbee (2022), there was no significant effect of P concentration in inflorescence yield or cannabinoid concentration, but significant differences in leachate P increasing 12-fold in response to the 3-fold increase in P fertilizer rate (25 to 75 mg P L−1). The authors suggested an optimum P supply of 25 mg P L−1 for continuous mineral fertilization. These values are in line with other studies for CBD- (11 mg P L−1) and THC-cultivars (30 mg P L−1) (Cockson et al., 2019; Shiponi and Bernstein, 2021b). These studies and our results indicate that maintaining high nutrient levels in leaves and substrate is not relevant at the harvest point. Furthermore, promoting nutrient stress during flowering to enhance P re-mobilization and translocation seems to be a suitable strategy to increase P use efficiency and avoid excessive P fertilization. This is currently a relevant issue to decrease the environmental impact of medicinal cannabis cultivation (Westmoreland and Bugbee, 2022).

4.3 Future outlook​

The controlled application of fertilizers is paramount to enhancing nutrient efficiency in medicinal cannabis. Differences in cultivars and fertilization regimes make it challenging to compare study results. Experiments are made with different cultivation systems, e.g. continuous fertigation with leaching (Saloner et al., 2019; Saloner and Bernstein, 2021; Westmoreland and Bugbee, 2022) or the controlled fertilizer application in our study. Fertilizer demand can also be genotype-specific and different ranges of optimum nutrient concentrations have been reported for THC- (Bernstein et al., 2019; Shiponi and Bernstein, 2021b) and CBD-rich (Westmoreland and Bugbee, 2022) genotypes. In addition, few studies report the exact amount of nutrients applied and nutrient use efficiency indices. It is important to note that this study is based on a single CBD-rich cannabis chemotype III genotype and for future research, the effect of controlled nutrient stress should be tested within different chemotypes and strains to observe genotype-specific stress responses and nutrient use efficiencies.

The timing of nutrient application and starvation is another important aspect as different fertilizer types have distinct nutrient forms and thus availability over time differs, which has a direct impact on nutrient uptake and use efficiency. Our results indicate, that organic fertilizer should be applied earlier at a higher rate to be available during the final two weeks of flowering when the sink demand for inflorescences is very high. Besides the timing of application, soil amendments, such as plant growth-promoting microorganisms (PGPMs) (i.e., N2-fixing and phosphate solubilizing bacteria) and arbuscular mycorrhiza (AM) can also increase nutrient availability of organic fertilizers (Ahmed and Hijri, 2021). Furthermore, the potential of utilizing PGPMs and AMs are manifold, e.g. increase in yield, quality and pathogen resistance as a result of nutrient mobilization, hormone production, disease control and improved stress tolerance (Conant et al., 2017; Backer et al., 2019; Lyu et al., 2019). Nonetheless, it is worth indicating that the application of soil amendments and microorganisms for medicinal cannabis is still under investigation, as results are often contradictory and microbial diversity and efficacy, as microbial communities can be genotype-specific (Winston et al., 2014). Future research should explore if the earlier application of organic fertilizer is sufficient to produce comparable results to mineral fertilizers and whether the application of soil amendments and microorganisms can enhance the bio-availability of nutrients, especially by increasing P uptake efficiency and the conversion of NH4+ to NO3−.

The combination of both mineral and organic fertilizers for integrated crop nutrition as performed in our study and also cited in the literature (Bernstein et al., 2019; Da Cunha Leme Filho et al., 2020; Laleh et al., 2021) suggests that the higher availability of mineral fertilizer can be important for plant initial growth, while organic fertilizers can be employed as a more sustainable nutrient complementation during flowering without major yield losses. It is relevant to further investigate the effects of nutrient deprivation in the different stages of flowering, as the major balance between biomass accumulation and the concentration of secondary metabolites can be modulated. Results show that promoting the use of already acquired nutrients in plant increases agronomic use efficiency, but it is still unclear if nutrient deprivation can actually enhance cannabinoid production. Future research should explore the molecular role of nutrient stress in terpenoids and cannabinoids production on trichomes.

Finally, the development of tools for visual assessment of nutrient status in cannabis (e.g., multispectral, hyperspectral) would certainly enable a more flexible adjustment of nutrient inputs according to the actual demand. This would help both producers and as well researchers by facilitating non-destructive analysis with a high temporal resolution.

5 Conclusion​

Our study showed the potential to reduce fertilizer input while maintaining CBD yield of medicinal cannabis. The decrease in inflorescence yield at the final harvest was compensated by a higher CBD concentration, resulting in 95% of CBD yield using one-third less fertilizer. The utilization efficiency at lower fertilizer rates was increased by a larger re-mobilization and translocation of acquired nutrients. Nutrient acquisition was lower for the organic fertilizer during the final two weeks before harvest, resulting in reduced biomass and CBD yield compared to mineral fertilizer treatments. The fertilizer rate of P can be in general reduced during end of flowering to avoid unproductive nutrient accumulation in vegetative plant organs.

 

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Front. Plant Sci., 16 November 2020
Sec. Plant Nutrition
Volume 11 - 2020 | https://doi.org/10.3389/fpls.2020.572293

 

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Shame the above skipped a 200ppm N example. I actually like the 240ppm plant. It's not needed to grow more roots to find food. However I have my reservations. Roots have other functions.
My N is over 200, but not 240. There is a lot missing from that story though. That N is calculated as the tank is made. If I was dtw I could claim to stay at these figures, but I'm recirc. The N is taken out in hours, and then I might have just 60N from top-ups. A situation we have no time-frame for. Thus my top-up are also extra N and K this run. Two things pulled out quickly, that tomato growers double in there top-up solutions. I have gone 50%. I'm happy, yet cautious. I have done my 7 weeks, then a week topping up with just 160ppm not over 300 as my bloom cycle got. Yes.. 300ppm in my top-up solution. Into a tank that might be 60N. Giving maybe 120ppm N once a day.
It's all about frequency of addition, so a study showing 160 and 240 doesn't really say how often. I find it hard to digest. It's a good size meal though. How many are we having per day? I think it's dwc in the pics, and they like to do these test runs as a weekly or fortnightly fill. So most of the time, it was nowhere near those numbers. You couldn't actually measure for N use and put it back to keep at those numbers. There has to be time between such doses.


I feel an on topic picture drop coming. I need to steady myself.

They were late in, so I removed half the height of some. Aiming around 4 branches each.
Some time later, they got a bit too big again

A useful number of branches though, so I flattened them

And just 48h later, the money shot

That was near 240N but a week or so back. The EC has been maintained, but you can see the plant took the N into storage, giving dark leaves. These supported growth by starting to give it up after a few days, then the last 48h we can see the N is actually low. It's purely talk, but it's felt stored N can't be as useful as supplied N. Energy and time are involved in releasing N from the stores. So I think we see here, it can't quite keep up, but the stores are not yet deficient. I must load up again now. I actually just did it. A top-up not using 240N, but more like 350ppm N. To get the tank around 160N, as I'm just too unsure about this new path I'm walking, be be trying to get the tank back to 240N again. It's just a lot of guesswork really.
There is just one seed plant, that's actually in a 3" pot of soil, in the pebble F&D. So I can't look at it's red stress markers as anything more than my own toxic mess. I had no F&D for it, when it was started.

I think it's looking like a productive self watering system. Nothing ground breaking, but my efforts to hold them back are failing. For 48h, that looks alright to me.