Phosphorus and sulphur management for canola production

Non-Peer Reviewe

An n to 2n embedding of incomplete idempotent latin squares for small values of n

AbstractIn 1983, necessary and sufficient conditions were obtained for an incomplete idempotent latin square of order n to be embedded in an idempotent latin square of order 2n, providing n>16. In this paper we consider the case where n⩽16

Effect of tillage and crop rotation on soil quality factors

Non-Peer Reviewe

Nitrogen fertilization management for no-till cereal production in the Canadian great plains

Non-Peer Reviewe

Influence of controlled-release urea (polymer-coated ESN) on seed yield, soil nitrate-N, and nitrous oxide gas emissions in northeastern Saskatchewan

Non-Peer Reviewe

Laser sintering of nano-hydroxyapatite coated polyamide 12 powders

As part of a larger study on the laser sintering (LS) of nano-composite structures for biomedical applications, a wet mixing method was used to coat Polyamide 12 (PA12) particles with nano-hydroxyapatite (nHA). The addition of nHA significantly affected powder processability due to laser absorption and heat transfer effects which led to part warping. This phenomenon has not been reported in other studies investigating LS of polymer/HA and nHA powders. Nano-composites containing 0.5–1.5 wt% nHA were successfully produced and tensile testing showed that 0.5 wt% nHA provided the greatest reinforcement with a 20% and 15% increase in modulus and strength respectively. However, the elongation at break had significantly declined which was likely due to the formation of nHA aggregates at the sintering borders following the processing of the coated powders despite being initially well dispersed on the particle surface

Seed-placed phosphorus and sulphur fertilizers: effect on canola plant stand and yield

Non-Peer ReviewedHybrid canola has a high requirement for phosphorus (P) and sulphur (S). Conventional P and S fertilizers differ in their risk of ammonia and salt toxicity and can significantly reduce canola plant stands if applied in the seed-row above recommended safe rates. Enhanced efficiency fertilizers such as polymer coated monoammonium phosphate (cMAP), Vitasul, or Microessentials S15 (MES15) could be more seed-safe than conventional sources. Field studies were conducted to determine the effect of various sources and rates of seed-placed P and S fertilizers on plant stand and yield of canola. Soil properties may also affect the toxicity of the fertilizer. The risk of ammonia toxicity from ammonium sulphate (AS) may be especially severe on soils with a high calcium carbonate (CaCO3) content, which can frequently occur on eroded knolls in Canadian Prairie landscapes. A growth room experiment was conducted to determine the effect of soils from different landscape positions on the toxicity of seed-placed AS and monoammonium phosphate (MAP) with canola. Under controlled environment conditions, canola emergence was reduced and delayed by conventional sources of seed-placed P and S fertilizers due to salt and ammonia toxicity. Ammonium sulphate, in particular, has a high salt index and risk of ammonia toxicity, especially on calcareous soils; therefore, AS has a greater potential to reduce plant stands than MAP. Under field conditions, the highly available sources of P and S may increase the risk and severity of seedling toxicity, but they also increase the frequency and size of yield response in situations where these nutrients are deficient. Enhanced efficiency fertilizers (cMAP, MES15 and Vitasul) were effective in decreasing seedling damage, but may not be as effective as conventional sources in providing sufficient available nutrients to reach yield potential

Seed-placed P and S fertilizers: effect on canola plant stand and yield

Non-Peer Reviewe

Spatial and temporal variability of soil fertility in relation to crop yield zones on hummocky terrain

Non-Peer ReviewedA field study was conducted on hummocky terrain at the Manitoba Zero Tillage Association Research Farm to determine the variability of crop yield as related to landscape position, soil properties, weed populations and plant disease. This information was also used to evaluate technology required for delineation of management units related to precision farming. Variable rate fertiliser management systems can improve efficiency of fertilizer use and environmental sustainability. Adoption of this technology has been hampered due to the difficulty of classifying fields into management units, the high cost of sampling soils on a grid basis, and the variability of soil and plant properties in the landscape. Technology for variable rate fertilizer systems is available, but there is little information available related to yield response in clay soils on hummocky terrain, and the relationship of plant tissue test levels in relation to soil fertility as measured by soil test nitrate nitrogen. Current soil test recommendations for nitrogen are based on soil test nitrate nitrogen from samples bulked from samples in several locations in the field preferably grouped according to topography. Yield data for 1997-2001 were classified into groups with the fuzzy k means, normal mixtures and self-organizing map variants of cluster analysis. Although fuzzy k means commonly used for classification of crop yield and soil properties, a method based on self-organizing maps provided consistent classes when compared across years. Soil nitrate nitrogen varied considerably across the landscape at the site, but was not significantly different (P<0.05) between classes based on crop yield. Yield data can be used to delineate zones for variable management, although fertilizer inputs may be a function of spring soil moisture, runoff and growing season precipitation as they affect seeding, crop emergence and establishment