Constant Liquid Fertilization Research Articles

Fertilization and Paclobutrazol Application for Sustainable Production and Post-production Performance of Petunia

This study examined the interaction between constant liquid fertilization (CLF) concentrations and plant growth regulator (PGR) application concentrations on petunia (Petunia ×hybrida) growth and flowering in the production and post-production environments. Paclobutrazol application is a common practice in bedding plant production to achieve a compact plant that increases greenhouse space-use efficiency, shipping density, and tolerance to physical handling stresses in the post-production environment. The objective of this research was to determine the best strategy for balancing CLF and PGR application concentration in the greenhouse environment so that growth and flowering can be maximized in the post-production environment. A two-factorial combination of four CLF concentrations [50, 100, 150, or 200 ppm nitrogen (N)] and four paclobutrazol drench concentrations (0, 5, 10, or 20 ppm) were provided to plants during the production phase, and plant growth and flowering were recorded in the production and post-production environments. From a sustainability perspective, the ideal PGR concentration was 5 ppm paclobutrazol, since this concentration resulted in the best combination of production and post-production characteristics and performance. At this PGR concentration, all plant growth and flowering measures increased as CLF increased from 50 to 200 ppm N; however, all CLF concentrations also produced commercially acceptable plants. Therefore, the ideal CLF concentration depends on the size of plant desired; that is, CLF concentrations as low as 50 to 100 ppm N can be provided depending on the market size requirements of the plants being grown. Based on our results, a combination of 50 ppm N CLF with 0 ppm paclobutrazol or 100 ppm N CLF with 5 ppm paclobutrazol both demonstrated adequate growth control during both production and post-production phases.

Fertilization Strategy Affects Production and Postproduction Performance of Petunia

The amount of fertilizer applied during the commercial production of bedding plants has decreased in recent years because of increasing concerns about environmental impacts and the need to minimize production costs. However, reduced fertilization affects plant growth and flowering during production and in the postproduction environment. Plants grown with lower nutrient levels may perform satisfactorily during greenhouse production, but they may possess insufficient nutrients to sustain further growth in the postproduction environment, where fertilizer application is frequently lacking. This study examined conventional and alternative fertilizer delivery strategies that produce high-quality petunia (Petunia ×hybrida) during greenhouse production and continue to support plant growth and flowering in the postproduction environment. The fertilizer treatments during production consisted of four constant liquid fertilization (CLF) treatments of 0, 50, 100, or 200 ppm nitrogen (N) and three controlled-release fertilization (CRF) treatments (0, 4, or 8 lb/yard3). Three pulse fertilization (PF) treatments (0, 300, or 600 ppm N) were applied immediately before moving the plants to the postproduction environment. During production, petunia growth and development increased as CLF increased from 0 to 200 ppm N, but the addition of CRF resulted in the increase occurring at a declining rate. During postproduction, the interactive effects of CLF and CRF continued in a similar pattern as that seen in the production environment. The additional PF treatments resulted in further increases in plant growth. Across all CLF and CRF treatments, the leaf area increased from 466 to 540 cm2 as PF increased from 0 to 300 ppm N, and the leaf area increased further to 631 cm2 as PF increased from 300 to 600 ppm N. Based on our findings, two alternative strategies are possible. First, 0 to 50 ppm N CLF can be combined with 4 lb/yard3 CRF. The second strategy maintains the standard commercial practice of applying 100 ppm N CLF treatment and then applying a 300- to 600-ppm N PF treatment. These results suggest that a relatively low CLF rate can be used to achieve the desired production characteristics while reducing the cost of plant growth regulation, and that additional plant nutrition can be provided with CRF and/or PF to enhance the postproduction performance.

Enhancing blue hydrangea sepal coloration by applying aluminum sulfate through constant liquid fertilization

Enhancing blue hydrangea sepal coloration by applying aluminum sulfate through constant liquid fertilization

Establishment of Leaf Tissue Nutrient Sufficiency Ranges of Two Perovskia Selections by Chronological Age

The objective of this study was to determine optimum fertilizer concentrations, identify leaf tissue nutrient sufficiency ranges by chronological age, and establish leaf tissue nutrient standards of containerized Russian sage (Perovskia sp.). Common Russian sage (P. atriplicifolia Benth.) and ‘Crazy Blue’ Russian sage were greenhouse-grown in a soilless substrate under one of six constant liquid fertilizer concentrations [50, 75, 100, 200, 300, or 400 mg·L−1 nitrogen (N)] with a constant level of a water-soluble micronutrient blend. Fertilizer concentrations sufficient for optimal plant growth and development were determined by analyzing plant height, diameter, growth index, primary shoot caliper, axillary shoot number, and total dry mass; they were found to be 100 to 200 mg·L−1 N after a 6-week crop cycle. Recently, mature leaf tissue samples were collected from plants fertilized with 100 to 200 mg·L−1 N and analyzed for elemental contents of 11 nutrients at 2, 4, and 6 weeks after transplant (WAT). An overall trend of increasing foliar nutrient concentrations over time was observed for all elemental nutrients. For instance, at 2 WAT, the total N concentrations of common Russian sage and ‘Crazy Blue’ Russian sage ranged between 3.68% and 5.10% and between 3.92% and 5.12%, respectively, and increased to ranges of 5.94% to 5.98% and 5.20% to 5.86% at 6 WAT, respectively. Before this study, no leaf tissue concentration standards have been reported; therefore, this study established leaf tissue concentration sufficiency ranges for the trialed Perovskia selections.

Leaf Tissue Nutrient Sufficiency Ranges of Four Heuchera Cultivars by Chronological Age

Coral bells (Heuchera sp.) are popular herbaceous perennials grown for their colorful foliage and venation and their aesthetic appeal in mixed containers and landscapes. Commercial coral bell production requires greenhouse or nursery growers to optimize production inputs such as managing mineral nutrition, thereby maximizing plant growth potential and foliage color. The objective of this study was to determine the optimum fertilizer concentrations, identify leaf tissue nutrient sufficiency ranges by chronological age, and to expand leaf tissue nutrient standards of coral bells grown in soilless substrates during container production. Coral bells (H. hybrida ‘Black Beauty’, ‘Cherry Cola’, ‘Marmalade’, and ‘Peppermint Spice’), varying in leaf color, were grown under one of six constant liquid fertilizer concentrations [50, 75, 100, 200, 300, or 400 mg·L−1 nitrogen (N)] with a constant level of water-soluble micronutrient blend in a greenhouse. Fertilizer concentrations for optimal plant growth and development were determined by analyzing plant height, diameter, growth index, and total dry mass, and were found to be 50 to 75 mg·L−1 N after a nine-week crop cycle. Recently mature leaf tissue samples were collected and analyzed for elemental content of 11 nutrients at 3, 6, and 9 weeks after transplant (WAT) from plants fertilized with 50 to 75 mg·L−1 N. The black- (‘Black Beauty’) and red- (‘Cherry Cola’) colored-leaved cultivars contained higher total N, phosphorus (P), potassium (K), calcium (Ca), sulfur (S), zinc (Zn), and boron (B) than the orange- (‘Marmalade’) and green- (‘Peppermint Spice’) colored-leaved cultivars. For instance, in mature growth, total N concentration for ‘Black Beauty’ and ‘Cherry Cola’ ranged between 3.45 to 3.63% and 3.92% to 4.18% N, respectively, whereas for ‘Marmalade’ and ‘Peppermint Spice’, ranges were between 2.98% to 3.25% and 2.78% to 3.23% N, respectively. Optimal leaf tissue concentration sufficiency ranges determined in this scientifically based study were narrower and often times higher than previously reported survey values for coral bells.

Hibiscus Leaf Tissue Nutrient Sufficiency Ranges by Chronological Age

Perennial hibiscus (Hibiscus sp.) are popular summer-flowering plants that are grown in greenhouses or nurseries, where growers must optimize production inputs such as fertility to maximize plant growth and produce high-quality flowering crops. The objective of this study was to determine the optimum fertilizer concentrations, identify leaf tissue nutrient sufficiency ranges by chronological age, and to expand leaf tissue nutrient standards of Hibiscus hybrid L. (hibiscus) grown in soilless substrates during container production. Two cultivars of hibiscus (H. hybrid L. ‘Mocha Moon’ and ‘Starry Starry Night’) were grown under one of six constant liquid fertilizer concentrations [50, 75, 100, 200, 300, or 400 mg·L−1 nitrogen (N)] with a constant level of water-soluble micronutrient blend in a greenhouse. The fertilizer concentrations sufficient for optimal plant growth and development were determined by analyzing plant height, diameter, growth index (GI), primary shoot caliper (PSC), and total dry mass, and they were found to be 100–300 mg·L−1 N after an 8-week crop cycle. Recently, mature leaf tissue samples were collected and analyzed for elemental content of 12 nutrients at 2, 4, 6, and 8 weeks after transplant (WAT) from plants fertilized with 100–300 mg·L−1 N. An overall trend of increasing sufficient tissue concentration over time was observed for total N, phosphorus (P), calcium (Ca), sulfur (S), zinc (Zn), copper (Cu), and boron (B), whereas a decreasing trend was observed for potassium (K), iron (Fe), manganese (Mn), and aluminum (Al). For instance, at 2 WAT, total N ranged from 3.1% to 5.1% N and increased to a range of 4.2% to 4.7% N at 8 WAT. At 2 WAT, Fe and Mn ranged from 79.2 to 103.6 mg·L−1 Fe and 66.3–82.8 mg·L−1 Mn and decreased to ranges of 75.6–82.9 mg·L−1 Fe and 18.1–99.7 mg·L−1 Mn at 8 WAT, respectively. Optimal leaf tissue concentration sufficiency ranges determined in this scientifically-based study were narrower than previously reported survey values for the genera Hibiscus.

OSTEOSPERMUM LEAF TISSUE NUTRIENT SUFFICIENCY RANGES BY CHRONOLOGICAL AGE

Four cultivars of Osteospermum were grown under six constant liquid fertilizer regimes, 50, 100, 200, 300, 400, or 500 mg L-1 N. Fertilizer rates sufficient for optimal plant growth were determined by analyzing plant height, diameter and dry weight after a period of 12 weeks. Tissue samples were collected and analyzed for the content of 12 elemental nutrients every two weeks for a period of 12 weeks. Sufficiency ranges were established for each nutrient over time, with upper and lower limits of the range defined as the mean tissue concentration ±1.28 SD. An overall trend of decreasing tissue concentration over time was observed for N, P, Mg and S. An overall increasing trend was observed for Mn, B and Mo. A positive correlation was observed between tissue nutrient concentration and fertilizer rate for N, P, K, Mg, Zn, Cu, and B. Compared to concentrations previously published for Osteospermum, concentration ranges observed in this study were broader. This study accounts for differences in tissue nutrient concentrations over the entire crop cycle and reflects levels associated with current fertilization practices.

GERBERA LEAF TISSUE NUTRIENT SUFFICIENCY RANGES BY CHRONOLOGICAL AGE

Gerbera liners of 'Festival Light Eye Yellow' were transplanted one plant per 5-inch pot. Plants were fertilized with one of six constant liquid fertilizer levels (50, 75, 100, 200, 300 or 400 mg·L -1 N) for 8 weeks. Plants were harvested at week 2, 5 and 8 after transplanting. Recently fully expanded leaves were sampled and analyzed for the concentration of 11 nutrients (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn). Upper and lower optimal nutritional limits were established for each element over time by analyzing the plant growth (plant height, diameter, dry weight and growth index (CI)). The sufficient tissue concentration of N, K, B, and Cu increased over 8 weeks. At 2 weeks, N and K ranged from 2.94 to 3.2% and 2.73 to 3.28% and increased to 3.33 to 4.16% and to 3.22 to 4.55% at 8 weeks, respectively. At 2 weeks, B and Cu ranged from 26.6 to 26.8 mg·kg -1 and 1.4 to 2.4 mg·kg -1 and increased to 32.0 to 35.8 mg·kg -1 and to 4.1 to 7.6 mg·kg -1 at 8 weeks, respectively. The range of other nutrients decreased over the 8 weeks. The optimal concentration ranges observed were narrower than previously published concentrations for gerberas for pot plant production. In addition, this study accounted for differences in concentrations over the entire crop cycle and reflected modern fertilization practices.

Fertilizer Source and Irrigation System Affect Geranium Growth and Nitrogen Retention

Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).

132 Fertilization Methods to Match Nutrient Supply with Demand for Potted Chrysanthemum

A greenhouse study was conducted in Autumn 1998 using standard cultural practices for potted chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura] to determine how fertilization affected plant growth and quality and nutrient leaching. Fertilization treatments included constant liquid fertilization until anthesis (LFA), constant liquid fertilization until disbud (LFD), slow-release resincoated fertilizer (SRF), and no-fertilizer control. Frequency of irrigation was determined gravimetrically, and leaching fractions maintained near 0.2. Plant growth and quality for LFA, LFD, and SRF met commercial crop standards. Nearly 60% of the total nitrogen applied with LFA was applied during the 4 weeks between disbud and anthesis, due to increased water demand. During the same period when liquid fertilization was discontinued for LFD, leachate electrical conductivity (EC) levels dropped from 4 to <1 dS·m-1. Leachate EC levels for LFA at anthesis remained high, but were <1 dS·m-1 for the other treatments. LFD and SRF drastically reduced the total amount of nutrients applied during the course of production compared with LFA. Use of an appropriate slow-release fertilizer or discontinued use of liquid fertilizer at disbud allow soluble salt levels to decrease during the latter weeks of the mum production cycle, when nutrient demand is low and water demand is high.

Cultivar, Fertilizer, and Irrigation Affect Vegetative Growth and Susceptibility of Chrysanthemum to Western Flower Thrips

`Fontana', `Iridon', `Pink Lady', `Splendor', `White Diamond', and `White View Time' chrysanthemum (Dendranthema × grandiflorum Ramat.) were grown for 10 weeks with N rates of 80, 160, or 240 mg·L-1 constant liquid fertilization and irrigated at sufficient (high) or deficient (low) amount. Cultivars differed in growth habit, and treatments significantly affected all variables measured. Plants fertilized with 80 mg·L-1 had lower leaf and stem dry mass, less leaf area, and were deficient in leaf N compared with plants fertilized with twice the amount of N. The highest stem dry mass was produced with 160 mg·L-1. Leaf and stem dry mass were reduced 25% for plants receiving low irrigation compared to those receiving high irrigation. In general, leaf area increased when fertilizer was raised from 80 to 160 mg·L-1 but differed by cultivar and irrigation regime when fertilizer was increased to 240 mg·L-1. Three weeks after the experiment started, electrical conductivity (EC) of runoff collected weekly from `White Diamond' plants fertilized with 240 mg·L-1 exceeded the average EC of the irrigation solution. The 240 mg·L-1 treatment also resulted in excessive EC in the growing substrate at the end of the experiment and reduced stem dry mass by 11% compared with the 160 mg·L-1 fertilizer regime. Substrate EC differed between cultivars in response to fertilizer and irrigation. Significantly more adult western flower thrips [Frankliniella occidentalis (Pergrande)], 55% and 52%, were found on the foliage of `Pink Lady' and `Fontana', respectively, than on `Iridon'. `Pink Lady' and `Fontana' had more immature thrips at the end of the experiment than `Iridon' and `White View Time'. Fewer adults and immatures were found on plants fertilized with 80 mg·L-1 than 240 mg·L-1. Fewer adults were detected in plants under high versus low irrigation, while irrigation had no effect on the number of immatures. The simultaneous use of plant varietal resistance and plant cultural growing techniques has the potential to lower thrips populations on chrysanthemum.

Slow release versus water soluble fertilization affects nutrient leaching and growth of potted chrysanthemum

In two experiments, ‘Charm’ and ‘Delano’ chrysanthemum [Dendranthema x grandiflorum (Ramat.) Kitamura] were grown in a peat‐based root medium using standard greenhouse cultural practices. Fertilization treatments included (1) alternate liquid fertilization (ALF): water‐soluble formulation of 15N‐4.3P‐24.9K (15–10–30) at 536 mgL‐1 N alternated with tap water irrigation; (2) Constant Liquid Fertilization (CLF): 15N‐4.3P‐24.9K(15–10–30)at268 mgL‐1 Napplied at each irrigation; (3) slow release resin‐coated fertilizer (SRR): slow release formulation of 12N‐4.3P‐14.1K(12–10–17); and (4) slow release tablets (SRT): slow release formulation of 14N‐1.7P‐4.9K (14–4–6). Irrigation volume and timing of application were arbitrary for all plants in the first experiment, but they were determined gravimetrically for each treatment in the second experiment. Irrigation volumes exceeded container capacity by 20 to 30% (leaching fractions of 0.2 to 0.3). Leachate had lower electrical conductivity and higher pH with the slow release products than with liquid fertilizer. All treatments except SRT produced plants which met commercial crop standards and had adequate nutrient levels in shoot tissue. However, root dry mass was higher with slow release fertilizer than with liquid fertilizer. Rootrshoot ratios were ranked SRT>SRR>ALF=CLF. Root data suggest that an advantage of SR fertilization over LF fertilization is that greater root mass will develop. Estimations of nitrogen (N) recovery in Experiment 2 suggest that chrysanthemums grown with SRR resulted in most efficient uptake of fertilizer with 64 to 68% of applied N recovered in plant tissue (compared to 41 to 46% from LF treatments) and 18 to 21 % recovered in container leachate (compared to 32 to 41% from LF treatments).

PLANT GROWTH AND LEACHATE AS AFFECTED BY CONTROLLED-RELEASE AND LIQUID FERTILIZER

Poinsettia (Euphorbia pulcherrima `Gutbier V-14 Glory') were grown using commercially available poinsettia fertilizer of various combinations of controlled-release (CRF) and constant liquid fertilizer (LF). At the end of the production period, plants treated with 83, 165 or 250 mg/l LF only were 10% taller than plants treated with the same concentrations of CRF. The total number of cyathia and the number of open cyathia at harvest was 18% and 50% higher for plants treated with LF only compared to plants treated with CRF only. Plants treated with 165 CRF/ 83 LF or 83 CRF/250 LF were not different compared to 250 CRF/0 LF or 0 CRF/ 250 LF in height, number of cyathia at anthesis, and total number of cyathia at the end of the production period. When LF was changed to clear water 5 weeks before the end of production, nitrate runoff from 83 CRF/250 LF treatment was reduced 30% for the last two weeks, and from the 165 CRF/83 LF treatment nitrate leachate was reduced gradually from 33 to 66% over the 5-week period.

THE FATE OF N FROM COMPOSTED POULTRY MANURE WHEN APPLIED TO FORSYTHIA AND CHRYSANTHEMUM

`Lynwood Gold' forsythia and `Jessica' chrysanthemum were grown for 12 weeks in a nursery mix consisting of 5 parts composted pine bark, 1 part composted hardwood bark and 1 part sand. Fertilization was by topdress applications of composted poultry manure at rates of 1, 2 and 3 g N per container, resin coated slow release fertilizer at 3 g N per container, or with constant liquid fertilization at 200 mg N per liter. Leachate samples were collected weekly and nitrate, nitrite, ammonium and total nitrogen determined. At 12 weeks, plant dry weight and the amount of nitrogen in the plant, media and leachate determined. Total nitrogen loss in the leachate for the compost was rapid during the first three weeks and then fell to low levels. The resin coated fertilizer released a higher and constant nitrogen flux during the study than the composted manure but total nitrogen loss over the 12 week period was lower than for compost. The leachate nitrogen in the constant liquid fertilization treatment increased during the study. The relative proportion of nitrogen in the medium, compost and leachate will be discussed.

DESIGN AND TESTING OF A NURSERY BLOCK FOR WATER RUNOFF RESEARCH

Water quality has become a significant issue in the nursery industry. Local testing of runoff contamination from nursery production is, however, of little value to other growers because of the variation in management practices and nursery layouts. Two nursery blocks have been designed and constructed to test runoff from production with sprinkler and drip irrigation systems in combination with constant liquid fertilization and controlled release fertilizers. Management practices using various combinations of irrigation systems with fertilizer application rates are being tested in a small area with reasonable control of inputs. Preliminary data has shown no difference in plant response to irrigation method, but runoff was significantly reduced with drip irrigation. Plant quality was better with controlled release fertilizer, which generally yielded less N and P contamination in runoff, than constant liquid fertilization except during extremely hot weather.

EFFECT OF CONTROLLED-RELEASE AND CONSTANT LIQUID FERTILIZATION ON LEACHATE AND PLANT QUALITY

Poinsettias (Euphorbia pulcherrima 'Gutbier V-14 Glory'), chrysanthemums (Dendranthema grandiflora 'Tara') and geraniums (Pelargonium xhortorum 'Orbit') were grown using various ratios of controlled release:constant liquid fertilization as a percentage of recommended rates (%CRF:%CLF). While plants grown under the 100:0 CRF:CLF regime produced significantly less nitrates, phosphates and total soluble salts in the leachate than 0:100 or 50:50 CRF:CLF, quality rating, plant diameter, and leaf, bract and flower dry weight of poinsettias and chrysanthemums were reduced. Geraniums grown under 100:0, 50:50 or 0:100 CRF:CLF regimes were similar in quality rating, height, diameter, dry weights and days to anthesis. Poinsettias and chrysanthemums grown under 50:50 CRF:CLF were similar in height, days to anthesis, plant diameter, flower and stem dry weights and quality rating but produced less nitrates, phosphates and total soluble salts in the leachate than plants grown under 0:100 CRF:CLF. However, chrysanthemums grown under 50:50 CRF:CLF had lower leaf and root dry weights and poinsettias had lower leaf and bract dry weights than under 0:100 CRF:CLF regime.

EFFECT OF FERTILITY SOURCE AND LIME ON THE PERFORMANCE OF HYDROPHILIC POLYMERS USED WITH SEVEN FOLIAGE PLANT SPECIES.

Studies were undertaken to compare plant growth and water use in a new commercially produced media that contained a hydrophilic polymer combined with a traditional peat-lite media. Rooted cuttings of nephytis, spathiphyllum, parlor palm, pothos, corn plant, `Dallas' fern, and gold dust dracaena were planted into 15cm plastic pots containing either a peat-lite media or the media with hydrophilic polymer. Both mediums were amended with 2.4 kg/m3 gypsum and then treatments of 0, 1.5, or 3 kg/m3 of dolomitic limestone were added. Plant height, width, growth index, top fresh weight and dry weight were measured. Preliminary tests indicated that the media with the hydrophilic polymer performed better with slow-release fertilizer than a constant liquid fertilization program. Plant growth appeared to be optimum at the 0 or 1.5 kg/m3 rate of dolomite. Plants grown in the media with the hydrophilic polymer produced plants of comparable quality to those in the peat-lite media.

Growing Medium and Fertilization Regime Influence Growth and Essential Oil Content of Rosemary

Plants of rosemary [Rosmarinus officinalis L. (Lamiaceae)] were grown in pots containing a soilless (1 sphagnum peat:1 perlite) or soil-based (1 sphagnum peat: 1 perlite:1 field soil) growing medium and fertilized with either 12N-5.2P-12.5K controlled-release fertilizer (CRF) at 9.0 g/pot; constant liquid fertilization (LF) with 20N4.3P-16.7K at 150 mg N/liter; constant LF at 150 mg N/liter, plus CRF at 4.5 g/pot; weekly LF at 150 mg N/liter; or weekly LF at 150 mg N/liter, plus CRF at 4.5 g/pot. Constant LF plus CRF generally reduced plant height and depressed shoot fresh weight relative to other fertilizer regimes. Essential oil content was highest in plants receiving weekly LF. Plants grown in the soil-based mix were shorter, shoot fresh and dry weight tended to be lower, and essential oil yield was higher when compared to plants grown in the soilless mix. Satisfactory growth was obtained in both media when rosemary plants were fertilized with 12N-5.2P-12.5K CRF at 9.0 g/pot or weekly LF with 20N<.3P-16.7K at 150 mg N/liter.

Utilization of Recycled Irrigation Water on Marigolds Fertilized with Osmocote and Constant Liquid Fertilization

Abstract Nitrate and K ions did not accumulate significantly in the irrigation reservoir when the leachate from Osmocote 14N-6.1P-11.6K or constant liquid fertilization (CLF) was utilized. No accumulation of salts occurred whether ‘Scarlet Sophia’ marigolds (Tagetes patula L.) were irrigated by capillary mat or trickle tube. With one exception, plants fertilized with Osmocote 14N-6.1P-11.6K at the recommended rate (lx) or twice (2x) the recommended rate produced plants equal to or better than CLF at 100 ppm N. Except for recycled CLF, macronutrient content of plant tissues was within acceptable ranges. Fertilizer treatments did not affect the number of days to flower. The combination of Osmocote fertilization and capillary mat irrigation was more effective in producing high-quality plants than Osmocote fertilization and trickle-tube irrigation. Tap-water utilization was reduced substantially by using recycled water.