Media evaluated for extended sweetpotato transplant production in heated beds 1

‘Georgia Jet’ sweetpotato [Ipomoea batatas (L.) Lam] transplants were produced in heated beds to compare aged pine sawdust or builders’ sand (traditional media) to fresh pine bark and aged pine bark, or fresh pine sawdust (alternative media), with regard to transplant production and quality over an extended harvest period. At the first harvest, highest transplant numbers (mean 1400 transplants/m²) were obtained with fresh pine sawdust or fresh pine bark. Media effects on transplant numbers at the first harvest agree with the results of an earlier experiment. The greater productivity of fresh pine bark compared to aged pine media and builders’ sand at the early‐harvest (two harvests) in the previous experiment was not confirmed in this experiment. Extended‐harvest (four harvests) transplant production was greater with fresh pine sawdust (2030 transplants/m²) than with aged pine sawdust (1380 transplants/m2), but was not greater than the number of transplants produced with the other media. Transplant production averaged over the five media, decreased from 1060 and 360 transplants/m² at the first and second harvests, respectively, to 130 transplants/m² at each of the last two harvests. Differences in mean transplant weights due to media were found only at the third harvest. At the first harvest, greater mean lengths of transplants grown with the fresh pine media (mean 25.7 cm) than with the aged pine media (mean 21.4 cm). Shortest transplants were produced with builders’ sand at the first harvest (17.8 cm) and throughout the extended season (17.5 cm). Similar effects of media on mean transplant length were observed at the early‐ and extended‐harvest periods. Media had no effect on the percentage of intact roots at the end of the 15‐week season (mean 71%).     

Lime applications to aged pine media increase early‐season sweet potato transplant production in heated beds

Aged pine sawdust and bark are likely to be the most widely used media for sweet potato transplant production in heated beds in north Alabama. Transplant production in these media, however, may be limited by acid conditions. This experiment was conducted to determine the effects of the application of lime (0.0, 2.2, and 4.4 kg/m³) on early‐season production of ‘Georgia Jet’ sweet potato transplants. Differences in transplant yield and quality due to media were not obtained at the first harvest, but heavier total early‐season transplants were obtained with aged pine bark than with aged pine sawdust. At the first harvest, the highest transplant number (936 transplants/m²) and weight (1.685 kg/m²), and the greatest mean transplant length (23.4 cm) were obtained with 2.2 kg/m³ of lime, but the total early‐season transplant numbers increased linearly from 1025 to 1154 transplants/m² with the addition of lime. Total early‐season transplant quality parameters, however, did not respond to the addition of lime in the same manner. Mean transplant weight decreased from 2.31 to 2.17 g with the addition of lime, and greatest mean transplant length was obtained with 2.2 kg/m³ of lime. High media pH and petiole Ca and Mg concentrations were also obtained as a result of the lime applications.     

Effects of media on early‐season sweet potato transplant production in heated beds

‘Georgia Jet’ sweet potato transplants were produced in heated beds to determine the effects of aged pine sawdust and builders’ sand (traditional media) and fresh and aged pine bark, and fresh pine sawdust (alternative media), on early‐season transplant production and media characteristics. At the first harvest, higher transplant numbers were obtained with the fresh pine sawdust or pine bark (mean 1,053 transplants/m²) than with the other media (mean 619 transplants/m²). Transplant fresh weights at the first harvest responded in a similar manner. The total early‐season number of transplants obtained with fresh pine bark (1,455 transplants/m²) was also greater than the total number of transplants obtained with the traditional media and aged pine bark (mean 951 transplants/m²), but not greater than the total number of transplants obtained with fresh pine sawdust. Mean lengths and weights of transplants obtained with the alternative media were at least as great as the values obtained with transplants grown in the traditional media. Highest media pH values were obtained with builders’ sand; the pH values of the fresh pine media were less acidic than the pH values of the aged pine media. Lower volumetric water contents and greater fluctuations in temperature were obtained with builders’ sand than with the pine media. Media had no effect on the percentage of intact roots at the end of the experiment.     

Leaf mineral nutrient concentrations or media pH affect Georgia Jet sweetpotato transplant number,length, and weight 1

The results of four experiments were combined to determine the relationships between leaf mineral nutrients or media pH and sweetpotato transplant production. The relative number of transplants and the relative mean transplant lengths or weights were determined by comparing the values obtained with unamended aged pine sawdust, a traditional medium. These values were regressed against leaf mineral concentrations and media pH. There was no relationship between relative transplant production and leaf nitrogen (N), potassium (K), or manganese (Mn) concentrations. Compared to sufficiency ranges for nearly mature sweetpotatoes, concentrations of N and K were low and Mn was sufficient. An upper value of 1210 mg/L leaf iron (Fe) was obtained for relative mean transplant weight, but concentrations of this mineral were not associated with relative transplant numbers or relative mean transplant lengths. Leaf calcium (Ca) and magnesium (Mg) concentrations were related to all three transplant characteristics directly, or indirectly through possible effects on leaf phosphorus (P) concentration or media pH. Compared to the established sufficiency ranges for nearly mature sweetpotato plants, Ca and Mg concentrations were low, P and Fe concentrations were sufficient, and zinc (Zn) concentrations were high.     

Composts as Media Constituents for Vegetable Transplant Production

The use of compost with high salt concentration was evaluated, under commercial conditions, as a potential growing media constituent for vegetable transplant production. Two composts were prepared from sweet sorghum bagasse, pine bark, and either urea (compost A) or brewery sludge (compost B) as N source. Three vegetable species — broccoli (Brassica oleracea), tomato (Lycopersicum esculentum), and onion (Allium cepa) with different tolerance to salinity were used. Eleven substrates were formulated and tested: a control consisting of a moss peat-based commercial substrate; compost A; compost B; and, eight mixtures containing 33 or 67% by volume of each compost with either raw peat moss or commercial substrate as diluent. All the substrates prepared had suitable physical, physicochemical and chemical properties for use as growing media, except for the electrical conductivity (ranging from 3.20 to 13.21 dS m^?1) which was above the reference levels for soilless cultivation. Broccoli was the least affected by substrate salinity whilst tomato was the most. Onion transplants had an intermediate response to saline conditions. Tomato seed germination was markedly reduced when compost A, with a higher salt concentration, was used at a rate higher than 67%. Media prepared with either of the composts, and mixed with either a commercial substrate or peat in a rate up to 67%, did not cause any detrimental effect on the growth and nutritional status of broccoli, tomato and onion transplants, despite the high initial salinity of the substrates. These composts appear to be acceptable substitutes for Sphagnum peat in seed sowing mixtures.     

Yard Trimming-Biosolids Compost: Possible Alternative to Sphagnum Peat Moss in Tomato Transplant Production

Large volumes of yard trimmings (YT) and biosolids (BS) co-compost have recently become available to the Florida vegetable industry. Compost used as vegetable transplant medium may be less expensive than traditional Sphagnum peat moss, since it can be locally produced. ‘Agriset 761’ tomato (Lycopersicon esculentum Mill.) seed were sown in five combinations of compost, peat, and vermiculite amended media: 0:70:30 (control), 18:52:30, 35:35:30, 52:18:30, and 70:0:30 % by weight, respectively. The experiment was repeated 3 times over a one-year period to accommodate the Florida transplant production season. YT-BS compost were sieved to a particle size less than 2.4 mm (33 % by weight) to be utilized as a transplant media.

The YT-BS compost had a high initial EC that restricted plant growth in one of the three batches used. By mixing YT-BS compost with peat and vermiculite the EC was reduced to an optimal 0 to 2 dS·m^?1 in the Fall 1997 and Spring 1998a experiments, but not for Spring 1998b.

Transplant media with YT-BS compost increased tomato seedling leaf area and shoot dry weight 21, 28, and 35 DAS (days after seeding) compared with the control. Additionally, YT-BS compost increased root dry weight 28 DAS and final stem diameter 35 DAS compared to the untreated control. Leaf area and shoot dry weight 21 DAS and shoot and root dry weight 28 DAS decreased linearly as compost rate increased. Although root dry weight differences among YT-BS compost rates 21 and 28 DAS were evident, these differences disappeared 35 DAS indicating no effect of compost rate on transplant characteristics. Number of leaves 21, 28 and 35 DAS were similar among all treatments. Utilization of YT-BS compost in the Spring 1998a experiment at any rate provided a slow-release source of nutrients that produced a tomato transplant with higher quality characteristics compared with the traditional peat:vermiculite medium and mineral fertilizer application. Once transplanted to the field, the differences that existed in the transplants grown in compost amended soilless medium disappeared. Fruit yields and size (i.e., large, extra-large, average fruit weight) between the control and compost treatments or among the compost rates were similar, except for the third harvest where the control had more tomato size medium than YT-BS compost treatments.

The results suggest that YT-BS compost can be used as an alternative to peat media for tomato transplant production, and that the percentage of substitution for peat is not critical. However, a lack of product physical and chemical consistency would compromise vegetable transplant and bedding plant production. Our results indicate more quality control is required with this YT-BS compost before it can be used wholesale in these markets.     

Lime Rate Affects Substrate pH and Container-grown Birch Trees

Nursery production of birch (Betula nigra L.) trees commonly occurs in containers using a soilless substrate such as pine bark or peat moss. Birch trees have been reported to suffer from pH-induced micronutrient deficiencies in landscapes; thus, they are recommended to be planted in low-pH soils (<6.5). Little research has addressed the influence of substrate pH on birch trees during container production. Therefore, the objective of this research was to determine if substrate pH influences birch tree growth and development. Birch (Betula nigra ‘NBMTF’) liners were transplanted into 11.4 L plastic nursery containers filled with an 80 pine bark: 20 sphagnum peat moss (v:v) amended with either 0.6 kg.m^?3 of elemental sulfur (S) or 0, 1.8, 3.5, or 7.1 kg.m^?3 dolomitic lime. Substrate pH ranged from 4.8 to 7.3. There were only a few and minor differences in leaf chlorophyll content and no differences in plant growth. Differences in leachate and plant tissue nutrient concentration occurred for some elements, although these differences were not enough to affect plant growth. Container-grown birch trees can be grown over a wide range of substrate pH (4.8 to 7.3) with little or no effect on their growth.     

Cation exchange capacity of two‐component container media predicted from laboratory analysis of components

Abstract

A mathematical equation predicting cation exchange capacity (CEC) of pine bark‐sand container media from CEC of the individual components was formulated. The equation is the weighted sum of milliequivalents contributed by each component and is corrected for shrinkage due to mixing of components. Both measured and predicted CEC increased linearly with increasing percent volumetric bark in pine bark‐sand media. Regression equations describing measured and predicted CEC were not statistically different. The predictive equation was also tested on 6 non‐synthesized 2‐component media prepared from peat moss, perlite, pine bark, vermiculite, and sand. No statistical differences between measured and predicted CEC were obtained.     

Phosphorus immobilization in wood waste‐based potting media

Abstract

Microbially induced nitrogen (N) immobilisation in potting media is accompanied by immobilisation of soluble phosphorus (P), with the P/N ratio of the immobilised elements being about 0.15. Fertiliser N applied to counter N immobilisation should be accompanied by this amount of soluble P if plants are not to suffer from P deficiency. Essentially none of the immobilised P in potting media that contained aged pine bark or eucalypt sawdust was available for short‐term growth of ‘Giant Butterfly’ pansies or Hakea francisiana subsequently grown in them. One implication of these results is that the N drawdown test for potting media will underestimate N requirements if P is not included in the charging solution.     

Domestication of Alpine blue-sow-thistle (<Emphasis Type="Italic">Cicerbita alpina</Emphasis> (L.) Wallr.): six year trial results

Alpine blue-sow-thistle (Cicerbita alpina (L.) Wallr.) is a perennial herb distributed all along the entire Alpine Arc, the shoots of which are still collected in the wild in several areas of Northern-Eastern Italy for food purposes. Our paper deals with experiments of domestication of this species carried out in the surroundings of Trento and lasted from 2004 to 2010. The cultivation was carried out transplanting seedlings, obtained by wild seed of a unique accession. One experimental trial (2004/2008) was carried in the location Frisanchi, located at 1,078 m a.s.l. In this trial the theses compared 4 harvests, 1 week spaced, carried out respectively in the 2nd, 3rd and 4th year after the transplant. Of the total quantity harvested after 4 years, the most shoots (60) and the highest dried weight per m² (14 g) were obtained from shoots collected 2 or 3 years after being transplanted. However, comparing the shoots yielded in the last year of the trial only (2008), the best results were obtained from 3 or 4-year-old transplants (42 shoots/m²; 8.2 g dry weight). Nevertheless there four times harvesting of shoots weakened the plants’ development and a high failure rates was recorded. In addition to the real experimental trial another small cultivation was carried out in an higher location, Monte Bondone at 1,500 m a.s.l., in which 5 years after the transplant (2010) only 2 harvests were carried out. In this experiment the yield recorded was very encouraging (10.5 g m²) and also the quality of the shoots collected was good.     

Prediction of water‐retention of milled pine bark‐sand potting media from laboratory analyses of individual components

Abstract

A mathematical equation which estimates water‐retention of synthesized milled pine bark‐sand pottinq media from laboratory analyses of each medium component was formulated and tested. The equation is the weighted sum of water retained by each component at a specified tension level. Media samples were sequentially subjected to 0‐, 10‐, 50‐, and 100‐cm water tension for 72 hours. Regression equations describing measured and estimated water retention at each pressure level increased linearly with increasing volumetric percent bark. The two regression equations corresponding to each tension level were not statistically different indicating that the equation for estimating water retention is reliable with synthesized pine bark‐sand media.     

Effects of salinity and alkalinity on pansy and impatiens in three different growing media

The quality of irrigation water used for greenhouse crop production can strongly influence plant growth. However, the effect on plant growth is probably a combination of water quality and the type of growing media used. To determine the effect of saline and alkaline irrigation water on plant growth and nutrition, pansy and impatiens were grown in peat, peat:pine bark, and pine bark media under standard greenhouse conditions. Salinity treatments of 0, 100 and OmgL^‐1 NaCl: CaCl₂ and alkalinity treatments of 0, 100, 200, 300, and 400 mg L^‐1 NaHCO₃ were applied at every irrigation. Salinity levels at 100 mg L^‐1 and greater caused necrosis of leaf edges, upward curling of leaves, and reduced flower number for pansy. Treatment symptoms for impatiens were reduced growth, general chlorosis, and reduced flower number. These treatment symptoms increased in severity for plants grown in pine bark. Alkalinity levels at 200 mg L^‐1 and greater caused decreased flower number, necrosis of leaf edges, and downward cupping of leaves of pansy. Treatments symptoms of impatiens were general chlorosis, water‐soaked appearance of leaves and leaf abscission. Elemental concentrations of sodium (Na⁺), chloride (Cl), calcium (Ca⁺⁺), magnesium (Mg⁺⁺), and potassium (K⁺) varied in media solution and tissue with symptom and treatment.     

Physical and Chemical Changes in Container Media in Response to Bark Substitution for Peat

Physical and chemical properties of container media are important factors in controlling the supply and movement of water and nutrients for nursery plant growth. The objectives of this study were to evaluate the physical and chemical properties and quality of media formulated with systematic substitution of composted pine bark (bark) for sphagnum peat (peat) in the presence of sand. Ten formulations were prepared that contained 40-90% bark, 0-50% peat, and 10 or 20% sand by volume. Increasing the percentage of bark increased the percentage of coarse particles, and linearly decreased the medium-sized particles in media in either 10% or 20% sand. Increasing the percentage of bark in the media significantly decreased water holding capacity, whereas bulk and particle densities and total porosity were influenced by the interaction of bark x peat x sand. Increasing the percentage of bark increased electrical conductivity and total C, P, K, Ca, Fe, Cu and Zn. Availability of nutrients were also increased by increasing percentages of bark. Substitution of bark for peat did not influence the pH of the formulated media. Our results suggest that formulated media with 70 to 80% composted pine bark and 10 to 20% peat (V/V) exhibited physical and chemical properties considered optimum for the growth of container nursery plant crops.     

Organic mulch biowall for PAH contaminated groundwater remediation

Organic mulch was used as an alternative supporting material in permeable, biological, barrier walls to prevent migration of PAHs. Three types of organic mulch, cypress bark (C), hardwood bark (H) and pine bark nuggets (P) were selected as potential media to capture pollutants or to support PAH-degrading microorganisms. Among the media, the hardwood mulch was selected for biowall testing. To simulate the fate and transport of PAHs in the subsurface biowall under aerobic conditions, two lab scale mulch-biofilm column reactors were operated. Naphthalene was chosen as the model PAH in these studies and was supplied at a loading rate of 50.9 g m⁻² day⁻¹. During the initial operation period of up to 372 pore volumes, the PAH removal efficiency remained stable at over 99%, due to sorption and biodegradation. After that, the mulch-biowall system showed variable removal efficiencies, in the range of 77–99.99%.     

Effects of amending Container growing media with Dolomitic limestone on the growth of Photlnia ‘Fraseri’

Abstract

The results of three years of experimentation on the effect of the addition of dolomitic lime to pine bark‐sand media shows that Photinia ‘Fraseri’ responds positively to lime additions. This response was not due to pH changes, since for two of the three years only a small change was observed in pH and lime requirement values. It is more likely that the increased growth is due to an improved magnesium environment. Not only was the magnesium content of the foliage increased with lime addition, but the K:Mg ratio was decreased to a level where potassium‐magnesium antagonism was not important.     

Physico-Chemical Evaluation of Organic Wastes Compost-Based Substrates for Eucalyptus Seedlings Growth

Eucalyptus growth was evaluated in five compost-based substrates formulated with different proportions of sewage sludge, coffee husk, peat, chicken manure, cattle manure, pine bark, sawdust, and coconut fiber, compared to two commercial substrates (CS). Organic wastes compost-based substrates (OWS) and CS were characterized regarding the available contents of macro and micronutrients, sodium (Na⁺), pH, electrical conductivity (EC), and bulk density (BD). Substrate attributes and eucalyptus biomass production were submitted to principal component analysis (PCA) to detect patterns of clustering. The different proportions of organic wastes influenced the physico-chemical characteristics of OWS and, consequently, the eucalyptus biomass production. The highest biomass was observed in one of the CS that is rich in available boron (B) and calcium (Ca), less concentrated in most of the nutrients and with low EC and Na⁺ contents. The PCA allowed the verification that B availability was the attribute that explained most of the variation in eucalyptus biomass production.     

Response of Four Container Grown Woody Ornamentals to Immature Composted Media Derived from Waxed Corrugated Cardboard

Four containerized deciduous ornamental shrubs [deutzia (Deutzia gracilis L.), silverleaf dogwood (Cornus alba ‘Elegantissima’), red-osier dogwood (Cornus sericea L.), and ninebark (Physocarpus opulifolius L.)] were grown during each of two separate growing seasons using 12 different immature (nonaged) composts as media (year one, 12 weeks from start of windrowing; year two, 16-weeks) and also two control nursery mixes (100 percent ground pine bark; and 80:15:5 by volume of pine bark:sphagnum peat:top soil). The compost formulations (volume basis) consisted of spent mushroom substrate (50 percent), waxed corrugated cardboard, 0 percent, 25 percent, or 50 percent), and/or pulverized wood wastes (50 percent, 25 percent, and 0 percent). Supplemental N was added to some composts as poultry manure (18 kg·m^?3), soybean wastes (24·kg·m^?3), or both at the same application rates. Despite the immaturity of the compost media and the presence of high initial contents of soluble salts primarily from the spent mushroom substrate (EC ≤6.4 dS·m?1, 1:1 v/v medium:water extracts), the top dry weight (averaged over two seasons) of each of the four species grown in compost media, regardless of waxed corrugated cardboard (WCC) level, exceeded that obtained in 100 percent pine bark. Compared with the 0 percent WCC compost, plants of all four species grew better in 25 percent and/or 50 percent WCC compost media and growth in these treatments was more (silverleaf dogwood), similar (deutzia and red-osier dogwood), or less than (ninebark) that in the 80:15:5 nursery mix. Rapid leaching of the potentially toxic soluble salts from the containerized compost media within days after planting minimized any adverse effects on the plants. There was no difference in foliar concentrations of N, P, K, Ca, Mg, Fe, Mn, and Zn due to WCC level, or to the N supplements which had little or no effect on growth. The foliar contents of heavy metals (Cu, Ni, Cr, Cd, Co, and Pb) were low and/or below detection limits.     

Prediction of H‐ion activity of two‐component potting media from analysis of components

Abstract

A mathematical equation which predicts H‐ion activity (HA) of container media from laboratory analysis of components was devised and tested. The equation is based on the weighted sum of HA contributed by each component. Both measured and predicted HA increased linearly with increasing volume percent bark in milled pine bark‐sand media. Regression equations describing measured and predicted HA were not statistically different. The predictive equation was also tested on other 2‐component potting mixtures with no statistical differences occurring between measured and predicted HA. Measured pH and pH values derived from the HA predictive equation were in close agreement.     

Forms and extractability of manganese in potting media

Abstract

Sequential extraction of pine bark medium alone and after amendment with either manganese sulfate (MnSO₄), composted rice hulls, or soil showed that at pH 5.5–7.0 most of the manganese (Mn) exists in a form that is extracted by acidic hydroxylamine hydrochloride, and which could therefore be in oxide or strongly‐bound forms. Acidification to pH 4.5–5.0 transferred large amounts of this ‘oxide’ Mn into ‘readily available’ and ‘weakly adsorbed’ fractions. Similar extractions of Sitka spruce bark showed that most of its Mn was extracted by weak cationic reagents ('readily available’ and ‘weakly adsorbed’ fractions). Growth of oats in pine bark, peat, and eucalypt sawdust media, with and without MnSO₄ amendment, lowered the amounts of Mn in ‘readily soluble’ and ‘weakly adsorbed’ fractions and caused some loss of ‘oxide’ Mn. Comparison of data for Mn extracted by 2 mM DTPA (1:1.5 v/v) with Mn in sequential fractions showed that DTPA dissolves some ‘oxide’ Mn. The data further suggest that up to about 36 mg/L DTPA‐extractable Mn would not be toxic to most plants growing in media of pH 6.0, but 60 mg/L DTPA‐extractable Mn may be if the medium pH falls below 5.5.     

Soil testing of horticultural substrates for cyclamen and poinsettia

Abstract

The 1: 1.5 water, Spurway and saturated media extract procedures were evaluated for cyclamen and 1: 1.5 water extract for poinsettia growing in bark, peat and peat + soil using nutrient uptake as the criterion. In addition, the N, P, and K desirable values (DV) to give maxi Timm dry wt in two harvests and to give maximum growth rate for various growing periods, in samples taken at the start of the trial and midway through the trial, were determined using a quadratic function for both crops. The relationships between N, P and K uptake and the soil test values were generally very good, although the methods overestimated N uptake and underestimated P uptake in bark‐relative to peat. Underestimation of P uptake in peat + soil was even greater. The initial desirable N soil test value in relation to midterm harvest (IDVM) for cyclamen in peat varied from 100–104 ppm for water, 303–312 ppm for saturated media and 44–46 for Spurway extraction. The midterm soil test value in relation to final harvest (MDVF) values varied from 125–136 ppm for water, 471–502 for saturated media and 44–53 ppm for Spurway extraction. Corresponding values in bark were generally higher. The IDVM and MDVF values using the water extract for poinsettia were 180–225 ppm and 155–215 ppm in peat and bark respectively. It was not possible to determine phosphorus IDVM values for cyclamen due to the poor fit of the response curve. The phosphorus MDVF values in peat for cyclamen were 8.1–8.8 ppm for water, 24.5–26.7 ppm for saturated media and 3.2–3.5 ppm for Spurway extraction. The corresponding values in bark were about half of those values and even lower in peat + soil. The phosphorus MDVF values in peat for poinsettia were 14–19 ppm and in bark 4–4.5 ppm for the water extraction. It was not possible to determine K desirable values for cyclamen because of lack of adequate plant response from K application. Potassium IDVF and MDVF values for poinsettia in peat were 100–136 and 80–126 ppm respectively. The DV obtained using growth data were broadly similar to those using plant dry wt. The desirable plant nutrient levels for maximum dry wt of cyclamen at final harvest varied from 1.9–2.4% for N, 0.10–0.17% for P and 1.0–1.7% for K. The DV values for poinsettia at mid harvest were 3.6–4.6% N, and at final harvest 2.7–3.6% N and 0.18–0.37% P.