Traditional models of chemostat systems looking at interactions between predator, prey and nutrients have used only a single currency, such as energy or nitrogen. In reality, growth of autotrophs and heterotrophs may be limited by various elements, e.g. carbon, nitrogen, phosphorous or iron. In this study we develop a dynamic energy budget model chemostat which has both carbon and nitrogen as c...

†Background Plants require at least 14 mineral elements for their nutrition. These include the macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S) and the micronutrients chlorine (Cl), boron (B), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni) and molybdenum (Mo). These are generally obtained from the soil. Crop production is o...

Physiological investigations of nitrogen content and relation between nitrogen and chlorophyll content at some wheat cultivars were carried out at the outset of the flowering phase. Dependence of nitrogen content from mineral elements in the soil was established at the same time. Investigations were guided on unfertilized soil and four fertilization variants (N, NPK, NP and NK). The results ind...

The avocado grower is usually familiar with deficiency symptoms such as those caused by lack of sufficient iron (3), zinc (11), and nitrogen (4). Also excesses of certain elements produce characteristic symptoms which may be readily identified, e. g. chloride and sodium (2, 9). However, little information is available concerning the remaining elements absorbed by the tree, their symptoms along ...

The expanded growth model is developed to describe accumulation of plant biomass (Mg ha(-1)) and mineral elements (kg ha(-1)) in with calendar time (wk). Accumulation of plant biomass with calendar time occurs as a result of photosynthesis for green land-based plants. A corresponding accumulation of mineral elements such as nitrogen, phosphorus, and potassium occurs from the soil through plant ...