Use Of Controlled-release Fertilizers Research Articles

THE INFLUENCE OF FERTILIZER TYPE AND Trichoderma harzianum INOCULATION ON THE GROWTH AND PHYSIOLOGY OF YOUNG PLANTS OF Cordia americana

In this study, we sought to determine the influence of combined treatments with different types of fertilizer and inoculation of the fungus Trichoderma harzianum on the growth and physiological characteristics of young plants of Cordia americana. To this end, we adopted a completely randomized experimental design, comprising six replications in a 5 × 2 factorial scheme, to assess the effects of five different types of fertilizer applied with or without T. harzianum inoculation. At 180 days post-planting, we performed measurements of plant height, stem diameter, leaf dry mass, root dry mass, stem dry mass, total dry mass, leaf area, Falker’s chlorophyll index, and chlorophyll fluorescence. It was found that the combined application of T. harzianum and a controlled-release fertilizer or manure-based organominerals was effective in enhancing the growth of C. americana plants under conditions similar to those in the field. The use of controlled-release fertilizer as a base fertilization was found to have a positive influence on all evaluated variables and was effective in maximizing the initial development of C. americana plants. Granulated fertilizers derived from swine manure were established to promote plant growth and photosynthetic efficiency, thereby confirming their efficacy as a fertilizer for the cultivation of C. americana.

Advances in Controlled Release Fertilizers: Cost‐Effective Coating Techniques and Smart Stimuli‐Responsive Hydrogels

AbstractTo meet the needs of a rapidly expanding global population, farmers will need more fertilizers than ever before to maintain a steady supply of affordable, nutritious food. The formulation of controlled release fertilizers (CRF) to synchronize nutrient release according to the demand of plants has emerged as a viable solution to the current problems associated with the poor nutrient usage efficiency of fertilizers. Yet, the greatest obstacle that still stands in the way of broad use of CRF in agriculture is their expensive manufacturing costs. The first section of this analysis focuses on broad topics related to CRF. Afterward, the differences between several cost‐effective raw materials and some of the production techniques used to make CRF are examined. Furthermore, the emerging field of “smart” coating materials, such as stimuli‐responsive coatings, which can accurately tailor nutrients delivery to the demands of the vegetation, is discussed, and the most important research work that could lead to their extensive use in agriculture is pointed out. The purpose of this review is to provide a strong assessment of CRF's development over the past several years by highlighting innovations and providing in‐depth analysis of prevailing patterns to better understand the future of agriculture.

Ammonia loss potential and mitigation options in a wheat-maize rotation system in the North China Plain: A data synthesis and field evaluation

The North China Plain (NCP) is an intensive agricultural area and ammonia (NH3) emission hotspot in China. Urgent mitigation actions are needed to reduce its environmental impact. A field trial was conducted, and results combined with a synthesis of existing data to assess the NH3 loss and mitigation potentials in a wheat-maize double-crop rotation, a dominant crop production system in the NCP. Ammonia volatilization losses from N fertilizer applied to summer maize and winter wheat were 9.1% and 5.0%, respectively, based on the data synthesis, and were significantly affected by fertilizer application method and N fertilizer type. From the field trial, optimized reduction in N application rate, compared with conventional practice, had great efficiency for NH3 mitigation. Despite their high NH3 reduction potential, the higher input costs associated with the use of controlled-release fertilizers, replacement of urea with calcium ammonium nitrate or inclusion of double inhibitors (urease and nitrification inhibitors) with urea limited their applicability from an economic perspective. The inclusion of a urease inhibitor with urea achieved over 70% reduction in NH3 emission and also gave a significant improvement in grain yield, net income and N use efficiency. Future adoption of NH3 mitigation options in the NCP should focus on establishing a reduction target and consider the cost-benefits of simultaneous implementation of multiple mitigation techniques.

Controlled-release nitrogen fertilizers for improving yield and fruit quality of young apricot trees

• The effect of N fertilizers releasing speed and rate on apricot morpho-physiology, yield and fruit quality was assessed. • The 6-month controlled-released fertilizer had higher yield than conventional in the second growing season. • The 150 kg ha −1 N rate increased fruit yield (compared to 75 kg-N ha −1 ) but reduced sucrose and a* (redness) color coordinate, the visual guide for consumers to choose ripe fruits. • The long-term use of controlled-release fertilizers hold promise for increasing apricot production and reducing environmental contamination. The objective of this two-year field study was to assess the effects of controlled-nitrogen (N) fertilizers releasing speed and rates on tree morphology, physiology, yield and fruit quality of apricot ( Prunus armeniaca cv. Mogador). In this study, four different releasing speed (conventional: < 1 month, controlled-release: 3, 6 and 9 months) and three N rates (56, 75, and 150 kg ha −1 which is equivalent to 75%, 100% and 200% of recommended rates, respectively) were used. Parameters evaluated included: gas exchange (photosynthesis, transpiration, and stomatal conductance), chlorophyll content index, leaf and soil N concentration, fruit yield and quality component [total soluble solids, sugar content, fruit color coordinates (L*, a*, b*), firmness, and radical scavenging activity]. The physiology and fruit quality of apricot trees responses to 6-month controlled-release fertilizer was comparable to the conventional. In both growing seasons (2019–2020), gas exchange, soil and leaf N concentration and fruit quality components from the 6-month controlled-release fertilizer were similar or higher (never lower) than conventional. Interestingly, the 6-month controlled-release fertilizer had higher yield than conventional in 2020. This study revealed that the response of apricot trees to controlled-release N fertilizers was significant after two years of application. Higher N rate (150 kg ha −1 ) significantly increased fruit yield and reduced sucrose content compared to 75 kg N ha −1 in both years. In 2019, high N rate (150 kg ha −1 ) reduced fruit redness coordinate (a*) which is considered a visual guide for consumers to select ripen fruits. Overall, this study highlighted the usefulness of using controlled-release fertilizer as an alternative “less waste” N source. The long-term use of controlled-release fertilizers hold promise for increasing apricot production and reducing environmental contamination.

Toward Identifying Alternatives to Fencing for Forest Restoration: Tube Shelters Outperform Mesh Shelters for Deer Browse Protection of Live Oak, Quercus virginiana

Herbivory is a common forest regeneration challenge across ecosystems. While fencing effectively reduces animal browse damage, it can be impractical. Tree shelters are an alternative forest restoration tool to protect seedlings from herbivory that may also provide a favorable microclimate. Yet, regeneration responses to tree shelters often vary among tree species, environmental conditions, and shelter specifications. To restore the once dominant Quercus virginiana (live oak) and its associated conservation values to subtropical U.S. maritime forests, control of animal browsing is critical. We evaluated the effects of tube and mesh tree shelters to exclude animal browse, combined with the use of controlled-release fertilizer to promote Q. virginiana seedling growth. After two growing seasons, mean seedling survival was 83% for protected seedlings, either from tube or mesh shelters, compared to 68% with non-sheltered seedlings. Seedlings in solid-wall tube shelters had significantly less browse incidence compared to both seedlings in mesh shelters and non-sheltered seedlings. Seedlings in tube shelters had greater height and diameter, followed by mesh shelters, and lastly, the no shelter treatment. Fertilizer resulted in higher browsing incidence and greater seedling height and diameter after the first growing season only, with no shelter treatment interactions. Our findings illustrate the efficacy of tree shelters to improve early regeneration success of Q. virginiana and may have application to the restoration of other forest ecosystems.

Growth and Quality of Yerba Mate Seedlings Affected by Fertilizer Doses in South Brazil

Given the lack of information on the use of controlled-release fertilizers in yerba mate seedlings production, this study aimed to evaluate growth and morphological characteristics of seedlings produced with two controlled-release fertilizers applied at different doses. We used seeds from a clonal seed orchard, which were sown in a commercial substrate based on peat and vermiculite, with Osmocote® MiniPrill 3M (CRF 3M) and Basacote® Plus 9M (CRF 9M) fertilizers, both in doses of 0, 2, 4, 6, 8, 10, and 12 kg m-3. Seedling height and stem diameter were measured at 60, 90, 120, and 180 days after sowing and, at 180 days, shoot, root, and total biomass, tube withdrawal ease, and root aggregation. From these data, we calculated Dickson's quality index, technical efficiency, Height/Stem diameter ratio, and maximum technical efficiency dose. We verified values statistically superior to control treatment (0 kg m-3) in all variables in response to controlled-release fertilizer 3M and 9M, demonstrating the viability of yerba mate seedling production using controlled-release fertilizers. This is also evidenced through results obtained for growth in height and stem diameter. Although CRF 3M favored seedling growth, CRF 9M showed similar efficiency. The Osmocote® MiniPrill 3M is more efficient than Basacote® Plus 9M in most of the variables analyzed and has a lower input required to obtain quality seedlings. For these reasons, Osmocote® MiniPrill 3M is indicated to produce yerba mate seedlings in the dose 8.50 kg m-3.

Tea-planted soils as global hotspots for N2O emissions from croplands

Tea-planted soils generally receiving high nitrogen (N) fertilizer doses are more vulnerable to acidification, and turn into significant sources of the potent greenhouse gas nitrous oxide (N2O). However, little is known about the magnitude of soil N2O emissions from global tea plantations. Based on a global meta-analysis of field experimental data collected from major tea growing countries, we quantify annual N2O emissions, calculate direct emission factors (EFd) and identify key environmental controls of emissions from tea plantations. However, most data are from China and Japan, which is to be expected given that tea plantations in these countries represent >60% of the global area and the vital environmental research community in both countries. Results suggest that annual N2O emissions from soils of global tea plantations are on average 17.1 kg N ha−1 (or 8008 kg CO2-eq ha−1), being substantially greater than those reported for cereal croplands (662–3757 kg CO2-eq ha−1). The global mean EFd for N applications to tea plantations equals 2.31% (with a 95% confidence interval of 1.91%–2.71%), being two times higher than the Intergovernmental Panel on Climate Change default value of 1%. Across tea plantations worldwide, total N2O emissions are estimated to be 57–84 Gg N yr−1, or 1.5%–12.7% of total direct cropland N2O emissions. Given that tea plantations account for only 0.3% of total cropland area, our finding highlights that tea-planted soils are global hotspots for N2O emissions and that these systems might be prime targets for climate change mitigation in the agricultural sector. Considering that tea is a high price commodity for which consumers may be willing to apply pressure for more climate-smart production, possible mitigation efforts include use of controlled-release fertilizers or nitrification inhibitors, and application of biochar and/or lime for increasing soil pH; i.e. measures that increase N use efficiency while reducing the climate footprint of tea production.

‘Ray Ruby’ Grapefruit Affected by Huanglongbing II. Planting Density, Soil, and Foliar Nutrient Management

Since the arrival of Huanglongbing (HLB) disease in Florida, several management approaches, including modification of orchard architecture design and nutritional therapy, have been explored. High-density plantings anticipate early economic returns from HLB-affected orchards. With no cure available for HLB, balanced nutrient application through soil and foliar spraying can mitigate the disease. A 2-year study was conducted to investigate the effects of three grapefruit (Citrus paradisi) planting densities [single-row (300 and 440 trees per ha), and double-row high-density (975 trees per ha)], two controlled-release fertilizer (CRF) blends, and foliar-applied micronutrients (FAM) (a blend of B, Mn, and Zn at 0, 1.5, 3, and 6 times the recommended rates) on grapefruit growth and fruit yield, physiological parameters, and foliar nutrient concentrations in an HLB-affected orchard. All the trees tested positive for HLB based on real-time quantitative polymerase chain reaction (qPCR) test. The highest planting density resulted in the lowest trunk diameter and canopy volume. Despite lower yield per tree in 2019–20, 975 trees per ha planting induced the greatest fruit and solid yields per ha. Also, the fruit produced from 975 trees per ha planting tended to be acidic with the deposition of more soluble solids. Use of CRF with higher micronutrients increased canopy volume with the expense of reduced fruit number in 2019–20. FAM did not affect cycle threshold (Ct) value and tree growth parameters. Fruit yield, photosynthesis rate, and stomatal conductance (gS) decreased, and all leaf nutrient concentrations except B increased in 2019–20 with all FAM rates tested. In conclusion, our study showed that high-density planting optimizes yield under HLB-endemic conditions. In addition, supplemental soil and foliar micronutrient application do not enhance yield of HLB-affected trees over a 2-year timeframe, warranting further research for confirmation of results.

Nitrogen Pollution Impact and Remediation through Low Cost Starch Based Biodegradable polymers

The world does not have too much time to ensure that the fast-growing population has enough land, food, water and energy. The rising food demand has brought a positive surge in fertilizers’ demand and agriculture-based economy. The world is using 170 million tons of fertilizer every year for food, fuel, fiber, and feed. The nitrogenous fertilizers are being used to meet 48% of the total food demand of the world. High fertilizer inputs augment the reactive nitrogen levels in soil, air, and water. The unassimilated reactive nitrogen changes into a pollutant and harms the natural resources. The use of controlled-release fertilizers for slowing down the nutrients’ leaching has recently been practiced by farmers. However, to date, monitoring of the complete discharge time and discharge rate of controlled released fertilizers is not completely understood by the researchers. In this work, corn starch was thermally processed into a week gel-like coating material by reacting with urea and borate. The granular urea was coated with native and processed starch in a fluidized bed reactor having bottom-up fluid delivery system. The processed starch exhibited better thermal and mechanical stability as compared to the native starch. Unlike the pure starch, the storage modulus of the processed starch dominated the loss modulus. The release time of urea, coated with processed starch, remained remarkably larger than the uncoated urea.

Controlled-Release Fertilizer in the Production of Seedlings of Anonna cacans Warm

The use of controlled-release fertilizers is a promising alternative for supplying nutrients during the initial growth of nursery seedlings. The aim of this study was to verify the effects of different doses of controlled-release fertilizer (CRF) on initial growth and nutritional status in seedlings of Anonna cacans Warm. The seeds were originally sown in a seedbed and then, after initial seedling development, were transplanted into polyethylene bags containing a substrate of washed medium sand, to which different doses of CRF had been added before transplanting. The experimental design was completely randomised, with four treatments, five doses of Osmocote® NPK 19-06-10 formulation (0, 1, 2, 4 and 8 g L-1 of substrate), with four replications, each replication comprising three seedlings (one in each container). Increases in root-collar diameter and plant height were determined throughout the experimental period (6 months) from data collected every 30 days after transplanting. At the end of the experiment the following were evaluated: height, root-collar diameter, N concentration, chlorophyll index, chlorophyll concentration (a, b and total) and leaf area. Root-collar diameter and height showed a positive linear response to increases in the fertilizer dose. From a 4 g L-1 dose of CRF, the nutrient supply added to the substrate of medium sand optimises the initial phase of plant growth and guarantees the adequate nutritional status of Anonna cacans, and can be suggested as a viable technique for use in forest nurseries, and one which results in efficient use of the input material and avoids fertilizer wastage.

Assessment of Pruning and Controlled-release Fertilizer to Rejuvenate Huanglongbing-affected Sweet Orange

Previous research has shown that Huanglongbing {HLB [causal agent Candidatus Liberibacter asiaticus (CLas)]}-affected sweet orange (Citrus sinensis) trees have a reduced root-to-shoot ratio, potentially due to the high rate of root death. The diminished root system cannot support the existing aboveground canopy and a cycle of imbalance begins. As a result, the tree enters into a continuous carbohydrate stress cycle and, eventually, the tree declines. Therefore, the goal of this study was to evaluate pruning as a strategy to adjust the root-to-shoot ratio to improve growth and productivity of HLB-affected trees. In Jan. 2015, a 3-year trial was initiated on a 14-year-old grove of ‘Hamlin’ sweet orange on Swingle citrumelo (Citrus paradisi × Poncirus trifoliate) rootstock that was symptomatic of HLB and produced less than 180 lb of fruit per tree. The four pruning treatments were as follows: 1) 0% pruning (no canopy removal), 2) 25% pruning (canopy removed), 3) 50% pruning (canopy removed), and 4) 80% pruning (canopy removed). In a split-plot design, two sources of fertilizer were evaluated in combination with the pruning: 1) conventional fertilizer [CNV (dry granular)] applied at 200 lb/acre nitrogen (N) in five split applications per year, and 2) controlled-release fertilizer (CRF) applied at 150 lb/acre N, split in three applications per year. Within each pruning treatment, half of the trees received CNV and the other half received CRF. The fertilizer treatments were applied in each of the 3 years; however, pruning was performed only once in the beginning of the experiment. The trees that were pruned produced new vegetative growth that looked healthy with no visual HLB symptoms (initially); however, the trees remained positive for CLas throughout the study as determined by quantitative real-time polymerase chain reaction. The 80% pruned trees grew vigorously over the course of 3 years but remained significantly smaller in canopy than control trees (0% pruning) for both CRF and CNV treatments. The 25% and 50% pruned tree canopies grew back and were similar in canopy size as 0% pruning (control) treatment by the end of year 2. At the end of the study, the use of CRF on 25% pruned trees resulted in a significantly higher leaf area index as compared with trees receiving CNV. A significant positive linear correlation was observed between canopy volume and root density; the root density decreased with intensive pruning. A significant positive correlation was also observed between canopy volume and yield, and a negative correlation between canopy volume and fruit drop. There were no significant increases in yield resulting from any pruning or fertilization treatments compared with controls (0% pruning). However, with the use of CRF, the amount of N and frequency of application were reduced. Overall, our results indicate that pruning did not improve the productivity of HLB-affected trees over the course of 3 years. Therefore, severe pruning is not a viable option to rejuvenate the HLB-affected trees.

Maize yield and economic return with controlled-release urea

Balancing fertilization of nitrogen, phosphorus, potassium and the use of controlled-release fertilizers are valuable practices for increasing yield and nutrient use efficiency. This 8-year field study was conducted using a mixture of controlled-release urea and soluble urea to evaluate maize yields, net returns and nutrient interactions in the North China Plain. The treatments included nitrogen application rates at 0, 150, 300 and 450 kg ha−1 using mixture; phosphorus application rates at 0, 16, 32 and 48 kg ha−1; and potassium application rates at 0, 125, 250 and 375 kg ha−1. The treatment using only soluble urea as the nitrogen source represented the standard farming practice in the region, with nitrogen, phosphorus and potassium being applied at 300, 16 and 250 kg ha−1, respectively. The results showed that the net return of the treatment with nitrogen, phosphorus and potassium being applied at 300, 16 and 250 kg ha−1, was increased by 14.8% over that of the farming practice treatment. Notably, controlled-release urea reduced the risks of decreased yields associated with price fluctuations. Multiple regression analysis results (R2 = 0.9726, P = 0.009) suggested that the coefficients of nitrogen × phosphorus, nitrogen × potassium were synergistic, while that of phosphorus × potassium was antagonistic. The interaction effects of the two factors decreased in the order nitrogen × potassium > nitrogen × phosphorus > phosphorus × potassium. The optimal maize yield was 9.2–9.3 t ha−1 at nitrogen, phosphorus and potassium application rates of 276–290, 27–29 and 210–226 kg ha−1, respectively. This study demonstrates that balanced fertilization based on controlled-release urea and soluble urea blend can improve maize yields and net returns.

Controlled-release Fertilizer in the Production and Quality of Acacia mangium Seedlings

ABSTRACT In order to evaluate the use of controlled-release fertilizer in the production and quality of Acacia mangium seedlings, this experiment was conducted in randomized blocks, and treatments consisted of five levels (0, 2.5, 5.0, 7.5 and 10.0 kg m–3 of substrate) of Osmocote Plus® in six replicates. After 130 days of sowing, the production and quality variables of Acacia seedlings were analyzed. All production and quality variables, height/shoot ratio (HSH) and Dickson quality index (DQI) were influenced by the fertilizer doses. The greatest mean values of stem diameter, total height, shoot dry mass, root dry mass, the best HSH and the highest DQI, were obtained for doses ranging from 7.1 to 7.8 kg m–3 of substrate. The largest leaf area was obtained using a dose of 9.3 kg m–3 of substrate.

Description of Enhanced-Efficiency Fertilizers for Use in Vegetable Production

In response to the Federal Clean Water Act of 1972 and the Florida Restoration Act of 1999, a series of best management practices (BMPs) was implemented to improve surface and ground water quality. BMPs are cultural practices that, when implemented as a plan, help reduce the environmental impact of production while maintaining yield and quality. One of these BMPs includes the use of controlled-release fertilizer, which is an enhanced-efficiency fertilizer. This publication describes the common enhanced-efficiency fertilizers and the factors affecting their use in Florida vegetable production. This 9-page fact sheet was written by Luther Carson and Monica Ozores-Hampton, and published by the UF Department of Horticultural Sciences, October 2014.

Effect of Controlled-release and Soluble Fertilizer on Tomato Production and Postharvest Quality in Seepage Irrigation

Florida best management practices include the use of controlled-release fertilizers (CRFs), which are soluble nutrients coated with a resin, polymer, sulfur, or a polymer covering a sulfur-coated urea. The purpose of this study was to compare the effects of three CRFs (coated, homogenized NH4NO3 and urea, and coated KNO3) rates in a hybrid CRF/soluble nitrogen fertilizer (SNF) system and two SNF rates [University of Florida/Institute of Food and Agricultural Science (UF/IFAS) and grower standard] on seepage-irrigated fall tomato (Solanum lycopersicum L.) yields, leaf-tissue nitrogen (LTN) concentration, postseason soil nitrogen (N) content, and postharvest fruit quality. Treatments of 112, 168, and 224 kg·ha−1 CRF N plus 56 kg·ha−1 SNF for total N of 168 (CRF112/SNF56), 224, and 280 kg·ha−1 were compared with IFAS (224 kg·ha−1) and grower standard (280 kg·ha−1) of pre-plant SNF. Tomatoes were planted on 29 Aug. 2011 and 3 Sept. 2012 on polyethylene mulch. Air temperature averaged 23.0 and 22.6 °C for the 2011 and 2012 fall seasons with 33.4 and 37.4 cm of rainfall, respectively. Soil temperatures ranged from 15.2 to 40.1 °C in 2011 and 13.6 to 36.6 °C in 2012. Leaf tissue N concentration exceeded the UF/IFAS-recommended sufficiency range for all treatments and sample dates, except CRF112/SNF56 at the last sample date of 2012. There were no differences in extra-large and total marketable yield at first harvest nor in total extra-large yield (three harvests combined) among treatments in 2011; however, total marketable yield for UF/IFAS, CRF112/SNF56, 168/SNF56, and 224/SNF56 was greater than that of the grower standard. In 2012, CRF112/SNF56 and CRF168/SNF56 had the greatest first harvest extra-large and total yield, but there were no differences between season total marketable yields. No differences between treatments were found for total N remaining in the soil postseason in 2011 or 2012. The grower standard, UF/IFAS, and CRF112/SNF56 were firmer at red ripe (less fruit deformation) in 2011, but there were no differences in 2012. In 2011, CRF112/SNF56 and CRF224/SNF56 were rated highest in red color among the treatments, and in 2012 there were no differences. A hybrid system containing lower and equal N rates (112 to 168 kg·ha−1 CRF N and 56 kg·ha−1 SNF56) compared with UF/IFAS-recommended rates produced comparable marketable yield and fruit quality.

Longevity of Controlled-release Fertilizer Influences the Growth of Bedding Impatiens

Controlled-release fertilizers (CRFs) have not been extensively used in floricultural production, perhaps due to lack of grower experience and research-based information with their use in herbaceous plant production. Any information about the correct use of CRF should increase growers’ confidence in using this type of fertilizer. The objective of this research was to compare the growth and quality of bedding impatiens (Impatiens wallerana XTREME™ ‘Scarlet’) when grown with typical water-soluble fertilizer (WSF) and with different combinations of longevity and rates of a single formulation of CRF. The CRF 16N–3.9P–10K consisted of different longevities (3–4, 5–6, 8–9, or 12–14 months) and application rates (1.4, 3.4, 6.8, 10.2, or 13.6 kg·m−3). Plants were grown in the greenhouse, and consumer evaluations were performed at market maturity. Plant canopy cover, flower cover (FC), and shoot dry weight (DW) were also determined. Commercially acceptable plant quality was achieved with CRF application rates between 3.4 and 6.8 kg·m−3. At low CRF application rates, the faster release rate (shorter longevities) CRFs produced larger plants [DW and leaf canopy cover (LCC)] with greater flowering potential (FC) than slower release rate CRFs. At higher application rates, slower release rates (longer longevities) outperformed the faster release CRFs for the same parameters. CRF-grown plants were smaller than WSF plants when CRFs were applied at the lowest rates. No differences in any of the three variables measured were found when plants were grown at a rate of 6.8 kg·m−3 CRF of any longevity or with WSF. Growers should adjust CRF application rates according to CRF longevity.

Reduction of fertilizer amount by use of controlled-release fertilizers to Parsley

Reduction of fertilizer amount by use of controlled-release fertilizers to Parsley

Controlled-release Fertilizer Type and Rate Affect Landscape Establishment of Seven Herbaceous Perennials

Use of controlled-release fertilizers (CRF) has been recommended to the landscape service industry as a best management practice for establishing landscape plants. However, application practices vary considerably among professionals and recommendations are lacking for the appropriate type (tablet vs. granular), application rate, and timing of CRF to establish herbaceous perennials. In this study, cigar plant (Cuphea ignea), daylily (Hemerocallis ‘Stella de Oro’), gaura (Gaura lindheimeri ‘Siskiyou Pink’), lantana (Lantana camara ‘New Gold’), mexican heather (Cuphea hyssopifolia), purple coneflower (Echinacea purpurea), and rudbeckia (Rudbeckia fulgida ‘Goldsturm’) were fertilized with granular CRF (GF) 15N–3.9P–10K (8 to 9 month) at 0, 1, 2, or 4 lb/1000 ft2 nitrogen (N) at transplant (no fertilization, GF1, GF2, and GF4, respectively), a split application of GF with 1 lb/1000 ft2 N applied at transplant and 1 lb/1000 ft2 N applied 5-months later (GF2-split), or tablet CRF 16N–3.5P–10K (8 to 9 months) at two tablets per plant (7.5 g) at transplant (TF2). Plant size and visual quality (VQ) at 5 months after transplant (MAT) were improved by fertilization for all perennials except ‘Stella de Oro’ daylily. Compared to GF2, GF4 improved the growth of perennials of larger size and greater biomass production (i.e., cigar plant), but did not further improve their VQ. All perennials grown with TF2 had similar size and quality as those grown with GF2 at 5 MAT. At 15 MAT, no difference was found among fertilizer treatments for surviving perennials except cigar plant. Split application (GF2-split) did not improve overwinter survival or second-year plant growth and quality for most species when compared with GF2. On the basis of these results, we recommend applying two tablets (7.5 g) of 16N–3.5P–10K per plant at transplant to establish the perennials tested in this study.

The use of controlled-release fertilizer in nursery pots for transplanting onion

The use of controlled-release fertilizer in nursery pots for transplanting onion

Controlled-release Fertilizer for Vegetable Production: The California Experience

Research on controlled-release fertilizers (CRF) in vegetable production has been conducted in California for several decades, and commercial CRF products have been marketed throughout most of that time. CRF remain niche products used on only a small percentage of vegetable fields. The potential advantage of CRF is maximized in production systems in which in-season nitrogen (N) leaching is significant but beyond the control of the grower, and where there are cultural constraints on in-season fertilizer application. Neither of those conditions is typical of the California industry. Annual rainfall in the major vegetable-producing regions averages less than 400 mm, with the majority of that received during winter months when vegetable production is limited; in-season leaching occurs almost exclusively from irrigation. The alluvial soils favored for vegetable production tend to be relatively fine-textured, with high water holding capacity that reduces N leaching potential. The widespread adoption of drip irrigation allows for efficient irrigation and for multiple applications of less expensive N fertilizers in synchrony with crop demand. Under representative California field conditions it has been difficult to show a horticultural benefit from the use of CRF, and the higher cost of these products has therefore limited their use. Future government regulation for water quality protection may require more efficient N fertilization practices, but significant expansion of CRF use is unlikely even under that scenario.