* It is commonly hypothesized that stand-level fine root biomass increases as soil fertility decreases both within and among tropical forests, but few data exist to test this prediction across broad geographic scales. This study investigated the relationships among fine roots, arbuscular mycorrhizal (AM) fungi and soil nutrients in four lowland, neotropical rainforests. * Within each forest, sa...

Transfer of the 2,4-dichlorophenoxyacetic acid (2,4-D) degradation plasmids pEMT1 and pJP4 from an introduced donor strain, Pseudomonas putida UWC3, to the indigenous bacteria of two different horizons (A horizon, depth of 0 to 30 cm; B horizon, depth of 30 to 60 cm) of a 2,4-D-contaminated soil was investigated as a means of bioaugmentation. When the soil was amended with nutrients, plasmid tr...

Accurate, routine testing of nutrients in soil samples is critical to understanding its potential fertility. Many of the nutrients that are vital to plants are exchangeable cations. These are ions loosely attached to and/or adsorbed onto clay particles and organic matter in soil that may become available to plants. Determination of these cations is of great interest for agronomic diagnostic and...

There is a gradual decline in soil fertility due to its continue use in farming. This necessitates developing new strategies of management programs to recharge soil with nutrients. From review it has been found that reuse of industrial effluents (wastewater) in agriculture can be a good mode to conserve soil nutrients. It may offer a way to fulfill irrigation water demands also. The major chall...

This paper reviews nutrient deficiencies in agricultural crops of PNG using the literature of agronomic trials and field observations made throughout the country. Nutrient deficiencies have been investigated systematically since the mid-1950s, but research has mainly focused on export tree crops and relatively little information is available on food crops. Literature analysis and field observat...

Earthworms mix soil layers and incorporate organic matter into the soil. This mixing allows the dispersion of the organic matter through the soil and makes the nutrients held in it available to plants and improves the fertility of the soil. Earthworms when present improve the soil physical, chemical and biological properties and acts as soil conditioner. They do so by fragmentation, aeration, b...

Surface mining in Appalachia disrupts large areas of forested land. Federal and state laws require disturbed lands be reclaimed by re-constructing the landscape and replacing soil materials to provide a rooting medium. If insufficient quantities of native topsoil are available, substitute materials derived from the overburden may be used as soil media. This study examined soil and foliar nutrie...

Since the 1980s, alpine grasslands have been seriously degraded on the Tibetan Plateau. Grazing exclusion by fencing has been widely adopted to restore degraded grasslands. To clarify the effect of grazing exclusion on soil quality, we investigated soil properties and nutrients by comparing free-grazing (FG) and grazing exclusion (GE) grasslands in Tibet. Soil properties – including soil bulk d...

There are human and animal health concerns related to drainage systems because nutrients, especially nitrogen and phosphorus, can contaminate water supplies. A field study was conducted on consolidated paddy fields of Sari Agricultural Sciences and Natural Resources University, Northern Iran (36.3°N, 53.04°E), to determine the effect of subsurface drain depth and spacing on nitrogen (N) and pho...