Zinc application and its availability to plants

摘要: Globally, low zinc (Zn) soils are widespread, but one of the largest expanses such is in south west Australia (WA). Early Zn research region determined how much fertiliser was required for profitable production spring wheat (Triticium aestivum L.) and subterranean clover (Trifolium subterraneanum L), major crop pasture species at time. The showed that sulfate ZnO were equally effective fertilisers, cheaper so widely used. indicated year application, depending on soil type, between 0.5-1.5 kg Zn/ha provided adequate clover. length time a single application remains fully maintaining crops future years (residual value; (RV)) had not been determined. This knowledge RV fertilisers WA. experiments measured form bulk this thesis. The also initially acutely phosphorus (P) deficient requiring P production. Single superphosphate It manufactured locally using phosphate rock imported from Nauru Christmas Islands. contained Zn, it 400-600 mg Zn/kg. At amounts needed to provide P, Zn-contaminated supplied about 90 g Zn/ha. Therefore, early field applied when annually >150 kg/ha. In these experiments, different nitrogen (N) applied. because has recently very apply N crops, which greatly increased grain yields may have demand thereby probably decreasing original application. there many nil-Zn plots. subsequent years, freshly-applied measure treatments relative fresh treatment. No deficiency detected up 23 after applying while kg/ha per all applied. Subsequently cheap DAP used instead produced urea. 50 Zn/kg (1/12 superphosphate). new strategy induced crops. led further studies determine included 2 treatments. one, no applied, match amount as other treatment same, except 1.5 first only. Relative each year, decreased contact with increased. However, rate decline found differ affected by pH, clay organic carbon content soil, alkaline calcium carbonate soil. Parallel glasshouse sulfate, clover, WA Australian States. varied markedly type strongly influenced soils, soil. In above studies, yield plants (shoots wheat, shoots clover), grain, test ammonium oxalate DTPA procedures. addition, concentration young tissue rest (glasshouse studies) whole (field measured, related % maximum (critical plant parts) procedure, together matter an accurate prognostic indicating likely next or crop. study confirmed (youngest expanded leaves) critical values diagnosing plants. tests now commercial testing laboratories. When diagnosed grown sprays can be foliage prevent minimise decreases end growing season. chelate most compounds. thesis reports results compare effectiveness two compounds spray growth stages (Gs14; seedling Gs24; tillering). seed sowing included. Zinc more than earlier stage, cheaper, both later stage. Recently region, durum (T. L.), narrow-leafed lupin (Lupinus angustifolius yellow (L. luteus white albus canola (Brassica napus chickpea (Cicer arietinum faba bean (Vicia lentil (Lens culinaris Medik) increasingly rotation wheat. Consequently, requirement compared requirements Species less produce same bean, chickpea, canola; Spreadsheet models developed re-application high systems. previous since properties (soil clay, carbon, free carbonate), species, removed harvested hay. The culminated better understanding agricultural systems distribution correction predictable types cropping Accurate identification range analyses, typically youngest mature leaf, possible local conditions. With calibration WA, particularly prognosis potential predicted before appearance loss