Herbert H. Bryan

Distribution and fractionation of phosphorus, cadmium, nickel, and lead in calcareous soils amended with composts.

Abstract Composts improve organic carbon content and nutrients of calcareous soils but the accumulation and distribution of phosphorus and heavy metals among various fractions in soil may vary under the south Florida conditions. The accumulation of P, Cd, Ni, and Pb with depth and the distribution of water soluble, exchangeable, carbonate, Fe–Mn oxides, organic and residual forms of each element were investigated in soils amended with municipal solid waste (MSW) compost, co-compost and biosolids compost and inorganic fertilizer (as control). Total concentrations of P, Cd, Ni, and Pb were higher in the 0–22 cm soil layers and decreased considerably in the rock layers. These elements were in the decreasing order of P ≫ Pb > Ni > Cd. Amounts of water soluble and exchangeable forms of P, Cd, Ni and Pb were negligible at 0–22 cm soil depths except for Cd in the 10–22 cm depth. Amending calcareous soil with either organic or inorganic amendments rendered phosphorus, nickle and lead in the residual form followed by Fe–Mn oxides form in the 0–10 and 10–22 cm soil layers. Cadmium was predominantly in the Fe–Mn oxides fraction followed by the residual and carbonate forms in both soil layers. A significant positive correlation was found between various organic carbon fractions and organic forms of P, Cd and Pb in the surface soil layer. Soil amended with MSW compost had higher concentration of Cd in the organic fraction whereas, co-compost and MSW compost amended soil had higher concentrations of organic Ni fraction in the 0–10 cm soil layer.

Utilization of Compost Increases Organic Carbon And Its Humin, Humic and Fulvic Acid Fractions In Calcareous Soil

Organic carbon sustainability in a gravelly calcareous soil is a great challenge under the humid conditions of south Florida. The beneficial effects of compost utilization on soil fertility prompted an investigation on (i) accumulation of total organic carbon and (ii) the soil organic carbon (SOC) in humin, humic acid (HA) and fulvic acid (FA) fractions in a gravelly calcareous soil amended with composts or inorganic fertilizer. In 1996 and 1998, compost from municipal solid waste (MSW) (100% MSW), Bedminster cocompost (75% MSW and 25% biosolids) and biosolids compost (100% biosolids) at 72, 82.7 and 15.5 Mg ha−1, respectively, were each incorporated in soil beds and inorganic fertilizer (6-2.6-10) NPK at 2.8 Mg ha−1. A control (no amendment) treatment was also included. Total organic carbon and various fractions of soil organic carbon were determined in two depths (0-10 and 10-22 cm) for both soil particles (< 2mm) and pebbles (> 2mm). Inorganic and organic soil amendments had decreased soil pH and increased soil electrical conductivity (EC) 19 months from initial application. Total organic carbon contents in soil particle were 4-, 3-, and 2-fold higher in MSW compost, Bedminster cocompost and biosolids compost treatments, respectively, than those in fertilizer treated or non-treated soils. MSW compost increased total organic carbon in pebbles by 4- and 3-fold in the 0-10 and 10-22 cm deep layers, respectively, more than other treatments. The soil organic carbon accumulation decreased with depth in all treatments in soil particles, but did not in pebbles. Amending soils with MSW compost significantly increased the organic carbon in humin, HA and FA fractions more than those treated with inorganic fertilizer or non-amended. MSW compost has a potential to be used as a soil amendment to increase and sustain the organic carbon in calcareous soils of south Florida.

ACCUMULATION AND FRACTIONATION OF COPPER, IRON, MANGANESE, AND ZINC IN CALCAREOUS SOILS AMENDED WITH COMPOSTS†

Amending soils with compost may lead to accumulation of metals and their fractions at various concentrations in the soil profile. The objectives of this study were to determine 1) the accumulation of Cu, Fe, Mn, and Zn with depth and 2) the distribution of water soluble, exchangeable, carbonate, Fe-Mn oxides, organic and residual forms of each metal in soils amended with MSW compost, co-compost, biosolids compost and inorganic fertilizer (as control). Total concentrations of Cu, Fe, Mn and Zn were concentrated in the 0–22 cm soil layer and scant in the rock layer. These metals were in the decreasing order of Fe ≫ Mn > Zn ≥ Cu. Copper, Fe, and Zn were predominantly in the residual form followed by fractions associated with Fe-Mn oxides, carbonate, organic, exchangeable and water soluble in all treatments except MSW compost amended soil where the organic fraction was higher than the carbonate fraction. In fertilizer, co-compost and biosolids compost treated soils Mn concentrated mainly in the Fe-Mn oxides form followed by residual, carbonate, and organic forms whereas, in MSW compost treated soil the same pattern occurred except that Mn organic fraction was higher than that in the carbonate form. The MSW compost has a greater potential to be used as a soil amendment to supply plants with Cu, Mn and Zn than other treatments in calcareous soils of south Florida. † Florida Agricultural Experiment Station Journal Series R-07656

Cultivation of Phyllanthus amarus and evaluation of variables potentially affecting yield and the inhibition of viral DNA polymerase.

Phyllanthus amarus (Euphorbiaceae) possesses activity against hepatitis B virus and related hepadnaviruses. One such activity, the inhibition of endogenous hepadnavirus DNA polymerase, differed little between cultivatedP. amarus and plants collected from the wild. Inhibitory activity equivalent to that in wild plants was obtained from both shoots and roots sown at different times of the year in a subtropical region (Dade County, Florida, U.S.A.). Plant size and two levels of fertilization did not significantly affect activity. Plots were planted using a cellulose gel to evenly disperse the small seeds. Gel amendments used at sowing had no significant effect on the antiviral activity of harvested plants. Drip irrigation permitted successful cultivation during the dry season. Plastic mulch was used to control weeds.Phyllanthus amarus grows slowly, and reaches a maximum size and vigor at about 5–7 months after sowing. Under south Florida conditions, the greatest biomass ofP. amarus was produced when seeds were sown in mid-winter for a summer harvest. With weed control by the mulch, water and fertilization via the drip irrigation, six and a half month old plants (from sowing) reached an average dry weight of approximately 40 glplant when harvested in July or August.ResumenPhyllanthus amarus (Euphorbiaceae) posee actividades contra el virus hepatitis B y otros hepadnavirus relacionados. Una actividad específica, la inhibición de la polimerasa DNA endógena de los hepadnavirus, no varió entre las plantas cultivadas y colecciones de plantas silvestres. Un nivel de actividad inhibitoria equivalente a plantas silvestres se obtuvo de vástagos y raices de plantas sembradas en diferentes epocas del ano en una región subtropical (Dade County, Florida, EE UU). El tamaño de la planta y dos niveles de abonamiento no tuvo efecto significativo sobre la actividad. Las parcelas fueron sembrados usando un gel de celulosa para dispersar homogéneamente las pequeñas semillas. Diferentes enmiendas de gel al sembrar no tuvieron efecto sobre la actividad antiviral de las plantas cosechadas. El uso de riego por goteo permitio el cultivo exitoso durante la temporada seca. Se usó plástico para controlar las malezas. El crecimiento deP. amarus es lento, y llega asu máximo tamaño y vigor entre los 5 y 7 meses después de la siembra. Bajo las condiciones del sur de la Florida, se produjo la máxima bíomasa cuando se sembró en medio del invierno para cosechar en el verano. Por medio del uso de plástico para controlar malezas, riego por goteo y la fertilizatión a través del riego, el promedio de peso seco por planta de seis meses y medio de edad fue de 40 g al cosecharlas en julio o agosto.

Factors affecting germination and stand establishment ofphyllanthus Amarus (Euphorbiaceae)

Interest inPhyllanthus amarus (Euphorbiaceae) has been generated by reports of antiviral activity and wide usage in traditional medicine. Attempts at cultivation resulted in poor stands. The objectives of these studies were to determine the effects of light, storage temperature, age of seeds, time ofdehiscence, and a scarification procedure on the germination ofP. amarus. Seeds ofP. amarus require light to germinate, and thus should not be covered at sowing. Freezing did not significantly affect the germination of dry seeds compared to seeds stored at ambient room temperature or higher, but storage at 10°C was deleterious. Percent germination was typically less than 50% and significantly decreased with time. Germination of freshly harvested seeds was slower than older seeds. Seeds from the first capsules to dehisce had a higher percent germination. A scarification procedure rendered seeds inviable. These results helped explain poor stands seen infield plots. In a previously planted plot, the re-established stand by natural reseeding was equivalent to that following intentional reseeding procedures.RésuméSegún se ha informado el interés en cuanto a Phyllanthus amarus (Euphorbiaceae) es debido a su actividad antiviral y su uso en la medicina tradicional. Al intentar su cultivo, la post-germinación fue menos de lo esperado. Los objetivos de estos estudios fueron probar los efectos de la luz, la temperatura de almacenamiento, la edad de las semillas, el periodo de la apertura de las cápsulas conteniendo las semillas y un procedimiento de escarificación en la germinación deP. amarus. Las semillas deP. amarus necesitan luz para germinar; es por eso que no se las debe cubrir al sembrar. Temperaturas de congelamiento no afectaron significativamente la germinación de las semillas secas al compararlas con las semillas mantenidas bajo temperatura ambiental o más aha, pero sin embargo el almacenamiento a 10°C sí afectó severamente la viabilidad. El porcentaje de viabilidad por lo general fue bajo, generalmente menos de 50%, y disminuyó con el tiempo. Las semillas nuevas germinaron más lentas que las semillas más viejas. Las primeras semillas que salieron de las cápsulas mostraron un mayor porcentaje de germinación. El procedimiento de escarificación que seprobó dio semillas inviables. Estos resultados ayudan a explicar la baja post-germinación observada en el campo. En terrenos anteriormente sembrados, la post-germinación de siembra natural fue equivalente a los procedimientos intencionales de siembra.

Biomass Yield and Flower Production in Sunn Hemp: Effect of Cutting the Main Stem

ABSTRACT A field experiment was conducted at the Tropical Research and Education Center, University of Florida, Homestead, to determine the effects on plant morphology, biomass yield, and flower production. of cutting the main stem of sunn hemp (Crotalaria juncea L.) plants at different heights. Seeds treated with cowpea (Vigua unguicalata)-type rhizobium were sown on 15 April 1999. The main stems were cut at 30, 60, and 90 cm above soil surface 100 days after seeding when the plants were about 1.5 m tall. Control plants were left uncut. Biomass that had been cut from plants was included in the total biomass yield. Seventy days following stem cutting, individual plants were evaluated for: plant height; main stem diameter; fresh and dry weights of roots, main stems, primary branches, secondary branches, leaves, open flowers, and unopened flowers. Leaf area and nutritional analyses of the plant parts were determined. Cutting the main stem at 30 and 60 cm above soil surface reduced total plant biomass, whereas cutting at 90 cm height increased biomass yield. Cutting at 30 cm produced the highest quality of biomass by increasing the leaf yield and reducing the weights of root and main stem both of which are low in N and high in C/N. Cutting the main stem at 90 cm produced the highest biomass yield, increased the number and weight of primary and secondary branches and, consequently, increased the number of flowers per plant. Nitrogen was highest in flowers and lowest in roots and main stems. Flowers were highest in K, P, Zn and Cu, whereas roots were highest in Fe content. We conclude that cutting the main stem at 30 cm height and allowing the plants to grow for an additional 70 d result in the highest quality biomass for use as green manure, windbreaks, and mulch. Cutting at 90 cm produced the largest biomass yield and increased flower production.

Ammonium bicarbonate‐DTPA extraction of elements from waste‐amended calcareous soil

Abstract Use of soil testing for both nutrient and heavy metal interpretations could prove to be a readily available tool for management of calcareous soils amended with solid waste products. The ammonium bicarbonate‐DTPA (di‐ethylenetriaminepentaacetic acid) [AB‐DTPA] extradant was used in this study, based on its successful use in other calcareous regions, and existence of interpretations for both nutrients and selected heavy metals. In southern Florida, addition of large volumes of composted waste products to shallow agricultural soils formed from crushed Oolitic limestone appears to be a viable disposal alternative to rapidly expanding lanfills or incineration. For two years, the effects of processed wastes (PW) on selected, AB‐DTPA‐extractable soil mineral element concentrations were determined for tomato (Lycospresicon esculentum Mill.) and squash (Cucurbita maxima Duch. Ex Lam.) grown with three different irrigation rates (3.78, 2.53, or 1.25 L/min). The PW composts were added at supplier‐recommend...

Influence of Coal Ash/Organic Waste Application on Distribution of Trace Metals in Soil, Plant, and Water

This study was conducted to evaluate effects of coal ash mixture (coal ash, biosolids and yard waste compost ratio of 1:1:1 v/v) on accumulation of trace metals in soil and their distribution in crop leaves and fruits, and its leaching potential into groundwater. Coal ash mixture was applied at rates of 0, 25, 75 Mg ha−1. Samples of soil and tomato (Lycopersicon esculentum Mill. cv. ‘Sanibel’) tissue (leaves and fruits) were collected and analyzed for trace metals (Zn, Cu, Mn, Fe, Cd, Pb, Ni, and Mo). Zero-tension pan lysimeters were installed to monitor water quality. Application of the coal ash mixture significantly increased AB-DTPA extractable Fe, Ni and Mo in treated soils and concentrations of Mn and Mo in tomato leaves. Only concentrations of Fe and Mo in tomato fruits from plots treated with this coal ash mixture were greater than those from control plots. Application of 75 Mg ha−1 coal ash mixture significantly increased total amounts of Zn, Pb and Mo collected in lysimeter water during 12 months following application. Concentrations of trace metals analyzed in this study were very low. The maximum concentrations of Mn, Pb and Cd in lysimeter water samples from both treated and control plots were only occasionally greater than MCL (Manxmen Contaminant Level for drinking water). Therefore, appropriate application of coal ash mixture should not lead to any significant detriment to soil, food, and groundwater.