A field study was conducted in a nutrient-impacted marsh in Water Conservation Area 2A (WCA-2A) of the Everglades in southern Florida, USA, to evaluate early stages of plant litter (detritus) decomposition along a well-documented trophic gradient, and to determine the relative importance of environmental factors and substrate composition in governing decomposition rate. Vertically stratified de...

Having been introduced to the northern edge of Asian tropics, the rubber tree (Hevea brasiliensis) has become deciduous in this climate with seasonal drought and cold stresses. To determine its internal nutrient strategy during leaf senescence and deciduous periods, we investigated mature leaf and senescent leaf nutrients, water-soluble soil nutrients and characteristics of soil microbiota in n...

The hydraulic properties, such as hydraulic conductivity and water retention, of aged diesel-contaminated and bioremediated soils were examined and implications of the hydraulic properties for assessing bioremediation performance of soils were proposed. Bioremediation of diesel-contaminated soil was performed over 80 d using three treatments; (I) no nutrient added, column-packed soil, (II) nutr...

Soil nutrient availability, invasive plants, and insect presence can directly alter ecosystem structure and function, but less is known about how these factors may interact. In this 6-year study in an old-field ecosystem, we manipulated insect abundance (reduced and control), the propagule pressure of an invasive nitrogen-fixing plant (propagules added and control), and soil nutrient availabili...

Plant roots exude numerous metabolites into the soil that influence nutrient availability. Although root exudate composition is hypothesized to be under selection in low fertility soils, few studies have tested this hypothesis in a phylogenetic framework. In this study, we examined root exudates of three pairs of Helianthus species chosen as phylogenetically-independent contrasts with respect t...

Water use by willow (Salix viminalis L.) was studied in lysimeters containing clay landfill cap and sandy loam soils under different watering and amendment regimes. With plentiful water and amendments, seasonal ET increased annually and was highest in the sandy loam, increasing from 360 l plant(-1) in the establishment year to almost 1200 l plant(-1) in the third year. Seasonal ET was highly co...

Legume cover crops have various important effects on nutrient cycling in tropical fruit tree production: they (i) fix atmospheric N2 and may amend the soil and trees with N, (ii) recycle nutrients, and (iii) affect soil nutrient availability. Aboveground N accumulation usually is very large in legume cover crops as seen from Pueraria phaseoloides being 8 to 14 times higher than in intercropped ...

................................................................................................................................................... ii Preface...................................................................................................................................................... 1 Background ..............................................................................

The effects of two plant species—soybean (Glycine max), and sunflower (Helianthus annuus) on nutrient availability in two soils (an organically farmed soil, OF, and a native grassland soil, GS, both Alfisols)—were measured with anion exchange membranes (Plant Root Simulator, PRS probes) in a greenhouse study. Vegetation (especially sunflower) in the OF soil caused significant reductions in soil...

Mining of nutrients from soil is a major problem causing soil degradation and threatening long-term food production in developing countries. In present research, an attempt was made for carrying out nutrient budgeting, which includes the calculation of nutrient balance at micro (plot / field) and meso (farm) level and evaluation of trends in nutrient mining / enrichment. A nutrient budget is an...