To address knowledge gaps around enhanced efficiency urea fertilizer efficacy for nitrogen (N) management, a study was designed to improve integrated nutrient management systems for western Canadian winter wheat producers. Three factors were included in Experiment 1: (i) urea type [urea, urea + urease inhibitor—Agrotain®; urea + urease and nitrification inhibitor—SuperU®, polymer-coated urea—Environmentally Smart Nitrogen®(ESN®), and urea ammonium nitrate (UAN)], (ii) application method (side-band vs. spring-broadcast vs. 50% side-band: 50% spring-broadcast), and (iii) cultivar (AC Radiant hard red winter wheat vs. CDC Ptarmigan soft white winter wheat). The Agrotain®and CDC Ptarmigan treatments were removed in Experiment 2 to allow for additional application methods: (i) fall side-band, (ii) 50% side-band — 50% late fall broadcast, (iii) 50% side-band — 50% early spring broadcast, (iv) 50% side-band — 50% mid-spring broadcast, and (v) 50% side-band — 50% late spring broadcast. CDC Ptarmigan produced superior grain yield and N utilization over AC Radiant. Grain yield and protein content were influenced by N form and application method. Split applications of N usually provided the maximum yield and protein, particularly with Agrotain®or SuperU®. An exception to the poor fall-application results was the SuperU®treatments, which produced similar yield to the highest-yielding treatments. The results suggest that split applications of N might be most efficient for yield and protein optimization when combined with an enhanced efficiency urea product, particularly with urease or urease + nitrification inhibitors, and if the majority of N is applied in spring.

A field experiment was conducted from 1994 to 2013 at Scott, SK, to assess the effects of cropping diversity and inputs on spring wheat, canola, and barley yield in the context of growing season precipitation (GSP), growing degree days (GDD), and terrain attributes. Main-plot treatments consisted of three levels of agricultural inputs [organic (ORG), reduced (RED), and high (HI)] and sub-plot treatments consisted of three levels of cropping diversity [low (LOW), diversified annual grains (DAG), and diversified annual perennial]. Yield was highest for the HI and RED inputs, and lower for the ORG system. The HI-DAG, HI-LOW, RED-DAG, and RED-LOW rotations produced the highest yields. April precipitation was identified as a primary yield-driving factor in this study. April precipitation and fixed effects accounted for up to 22% and 10% of yield variation, respectively, in analyses by 6-yr periods. Terrain attributes explained up to 4.5% of variation in annual yield. The effects of inputs and diversity on crop yield were influenced by GSP, GDD, and terrain attributes and show the importance of crop management in the context of environmental variability.

Profitable malting barley (Hordeum vulgare L.) production systems are required to reverse the decline in area seeded to malting barley in western Canada. Systems that could increase the profitability of growing malting barley considered the previous crop, nitrogen (N) rate, and fungicide application. The net return (NR) and risk for these systems were computed from western Canada field data. Analysis of variance was used to evaluate the impact of systems on NR over 21 site-years of field data. Risk was evaluated with a stochastic simulation model. NR was higher and risk lower for malting barley when the preceding crop was field pea (Pisum sativum L.), when fungicide was applied at the flag leaf stage for leaf disease control, and when N was 50% of the recommended N rate. Therefore, malting barley should be grown on field pea stubble at a lower N rate, with fungicide applied when there are leaf diseases.

Cutforth, H. W., Angadi, S. V., McConkey, B. G., Miller, P. R., Ulrich, D., Gulden, R., Volkmar, K. M., Entz, M. H. and Brandt, S. A. 2013. Comparing rooting characteristics and soil water withdrawal patterns of wheat with alternative oilseed and pulse crops grown in the semiarid Canadian prairie. Can. J. Soil Sci. 93: 147–160. To improve sustainability and increase economic returns, producers in the semiarid Canadian prairie are diversifying their cropping systems to include alternative crops such as pulses and oilseeds in rotation with wheat. Producers must adopt crops and cropping systems that use water most efficiently. We compared the root systems and water withdrawal patterns for three pulse crops (leguminous grain crops) [chickpea (Cicer arietinum L.), pea (Pisum sativum L.) and lentil (Lens culinaris Medik. L.)] and three oilseed crops [canola (Brassica napus L. and Brassica rapa L.) and mustard (Brassica juncea L.)] with one cereal crop [wheat (Triticum aestivum L.)] under well-watered, rain-fed, imposed drought water regimes during 1996–1998. Wheat withdrew the most water, whereas pulses withdrew the least amount of water from the soil profile. Pulses withdrew substantially less water than oilseeds and wheat below about the 80-cm depth, whereas oilseeds withdrew less water than wheat from the upper regions of the soil profile, thus increasing soil water available to the following crops. Therefore, producers can increase the overall efficiency of a crop rotation by growing deeper rooting crops, such as wheat and canola, following pulses, and by growing crops, such as wheat, that will use the increased soil water reserves following canola.

In western Canada, canola is traditionally grown in rotation once every 4 years to restrict losses due to pests. Recently, growers have begun to produce canola more intensively due to market opportunities and cultivar improvements. This study was initiated to investigate the consequences of more intensive production of canola in rotations, integrated with currently available disease management practices, including blackleg resistant cultivars and fungicides. A 4 replicate split-plot experiment was established at Scott and Melfort, Saskatchewan with canola rotation treatments ranging from yearly to every second, third or fourth season in combination with pea, wheat and flax using a blackleg resistant and a blackleg susceptible cultivar. Sub-plots were fungicide treatments for blackleg and sclerotinia stem rot diseases. Blackleg incidence and severity was increased in rotations comprising more than one canola crop every four years, regardless of cultivar, although the blackleg resistant cultivar was much less affected than the blackleg susceptible cultivar. The yield of the blackleg resistant canola cultivar was similar among rotations that included canola every 2, 3 and 4 years. Fungicide application was of limited value to maintain canola yield. The results suggest that canola cultivars with strong blackleg resistance can be grown more intensively than once every 4 years with limited yield reduction. However, the increased severity of infection and amount of infested residue produced as canola rotations are intensified, which occurs even with resistant cultivars, increases the risk of inoculum carry-over, resistance breakdown and yield loss. Therefore, it would be prudent for western Canadian canola growers to adhere to less intensive inclusion of canola in rotations, such as one canola crop in 4 years, as an effective blackleg management strategy.

The proper use of organic and inorganic nutrient sources is important to sustain high levels of crop production, while maintaining or enhancing soil and environmental quality. A 4-year (2009 to 2012) field experiment was established in spring 2009 on a Gray Luvisol (Typic Haplocryalf) loam soil at Star City, Saskatchewan, Canada, to determine the effectiveness of organic/biological (compost, wood ash [fine and granular], alfalfa pellets, distiller grain, thin stillage, glycerol, fish food additive, Penicillium bilaiae), inorganic/mineral (granular-gypsum, rapid release elemental S [RRES], rock phosphate [granular and fine]) and chemical/synthetic (granular-ammonium nitrate, triple super phosphate and potassium sulphate) nutrient sources (amendments/chemicals) in improving seed yield, straw yield, seed quality and nutrient uptake (N, P, K and S) in seed + straw of canola. Combined application of N, P and S chemical fertilizers (NPS) produced considerably greater seed yield, straw yield and nutrient uptake of canola compared to the unamended control in all four years. In treatments receiving only organic amendments, thin stillage produced the greatest seed yield, straw yield and nutrient uptake in all years, and it was similar to the NPS balanced fertilizer treatment, while fish food additive and distiller grain dry of wheat in 2009, 2011 and 2012, distiller grain dry of corn in 2009 and 2012, and compost and alfalfa pellets in 2011 and 2012 produced significantly greater seed yield, straw yield and nutrient uptake, when compared to the control. In treatments where chemical fertilizers were also applied, in addition to organic amendments, ap- plication of N fertilizer increased seed yield, straw yield and nutrient uptake substantially when combined with wood ash fine in 2009, 2010, 2011 and 2012, wood ash granular in 2009, 2011 and 2012, and glycerol in 2009 and 2012 (moderate increase in 2012). In the chemical fertilizer treatments, there was a reduction in seed yield, straw yield and nutrient uptake of canola when only N fertilizer was applied compared to the control (significant in 2010 and 2011). Application of P along with N (NP) increased seed yield, straw yield and nutrient uptake of canola compared to N alone treatment, but was less than the NPS treatment in all years. Application of S along with N (NS) increased seed yield, straw yield and nutrient uptake of canola further compared to the NP treatment, but it was still lower than the NPS treatment in 2010 and 2011. In treatments receiving inorganic/mineral amendments in addition to chemical fertilizers, application of N + P fertilizers substantially increased seed yield, straw yield and nutrient uptake in treatments receiving gypsum and RRES in 2009, 2010, 2011 and 2012. This suggests the potential of gypsum and RRES in preventing S deficiency in organic crops when grown on S-deficient soils, provided other nutrients are not limiting in the soil for crop growth. Seed yield, straw yield and nutrient uptake with application of N and S fertilizers in combination with rock phosphate and/or Penicillium bilaiae were similar to N + S treatment in most cases, except in 2011 when application of finely-ground or powder rock phosphate in a combination with N + S produced significantly greater yield and nutrient uptake than N + S with granular rock phosphate. This suggests little contribution of rock phosphate and/or Penicillium bilaiae in improving yield and nutrient uptake of canola, and improves the performance of fine rock phosphate only evident in the third growing season in 2011, after three consecutive applications, but not in 2012. In conclusion, some organic amendments showed potential for improvement in organic crop production, and in some other cases highest yield and nutrient uptake were produced

Smith, E. G., Kutcher, H. R., Brandt, S. A., Ulrich, D., Malhi, S. S. and Johnston, A. M. 2013. The profitability of short-duration canola and pea rotations in western Canada. Can. J. Plant Sci. 93: 933–940. A long-term field study of canola and pea interval in rotations was used to determine the most profitable canola production systems. The duration between canola crops has been declining with most canola grown more often than the recommended once every 4 yr. Producers could be reducing their long-term profitability if the short-duration canola rotation results in increased disease and lower yield. A field study was conducted from 1998 to 2007 at Scott and from 1999 to 2006 at Melfort in Saskatchewan, Canada, to examine the long-term impact of shorter-duration canola and pea rotations. Canola and pea were grown continuously, or in rotations with wheat or flax for 2, 3, or 4 yr. Two canola types were used, one was a blackleg-susceptible conventional cultivar and the other a blackleg-resistant hybrid. The returns above variable costs for the production systems were determined over the last 4 yr of the study, the period of time when rotation impacts should be most evident in this study. The continuous canola and pea rotations were the least profitable rotations. Blackleg-susceptible canola had higher return when in rotations of 3 or 4 yr, compared with continuous or 2 yr. Blackleg-resistant hybrid canola had statistically similar returns for 2, 3 and 4-yr rotations, which were superior to continuous canola. Even with increased blackleg disease incidence and severity after several years of a short-duration canola rotation, the short-duration canola rotation was more profitable when growing the disease-resistant hybrid. With high canola prices, the returns from the short-duration canola rotations were as high, or higher, than rotations with more years between canola crops. The canola industry must recognize that producers have an economic incentive to use short-duration canola rotations and new systems (disease resistance and rotations) need to be developed within this context.

The objective of this study was to determine the impact of frequency of broad-leaf crops canola and pea in various crop rotations on pH, total organic C (TOC), total organic N (TON), light fraction organic C (LFOC) and light fraction organic N (LFON) in the 0 - 7.5 and 7.5 - 15 cm soil depths in autumn 2009 after 12 years (1998-2009) on a Dark Brown Chernozem (Typic Boroll) loam at Scott, Saskatchewan, Canada. The field ex-periment contained monoculture canola (herbicide tolerant and blackleg resistant hybrid) and monoculture pea compared with rotations that contained these crops every 2-, 3-, and 4-yr with wheat. There was no effect of crop rotation duration and crop phase on soil pH. Mass of TOC and TON in the 0 - 15 cm soil was greater in canola phase than pea phase in the 1-yr (monoculture) and 2-yr crop rotations, while the opposite was true in the 3-yr and 4-yr crop rotations. Mass of TOC and TON (averaged across crop phases,) in soil generally increased with increasing crop rotation duration, with the maximum in the 4-yr rotation while no difference in the 1-yr and 2-yr rotations. Mass of LFOC and LFON in soil was greater in canola phase than pea phase in the 1-yr, 2-yr and 3-yr rotations, but the opposite was true in the 4-yr rotation. There was no consistent effect of crop rotation duration on mass of LFOC and LFON. The N balance sheet over the 1998 to 2009 period indicated large amounts of unaccounted N for monoculture pea, suggesting a great potential for N loss from the soil-plant system in this treatment through nitrate leaching and/or denitrification. In conclusion, the findings suggest that the quantity of organic C and N can be maximized by increasing duration of crop rotation and by including hybrid canola in the rotation.

In the Canadian prairies, current recommendations allow growing of canola or pea once every 4 years on a particular field to effectively mange diseases, insects, and weeds, but producers are interested in increasing frequency of these crops to optimize economic returns. A 4-year (from 1999 and 2002) field experiment, with treatments consisting of rotations of monoculture canola and pea to rotations that contained these crops every 2, 3, and 4 years with wheat and flax, was conducted on a Black Chernozem (Udic Boroll) silty clay at Melfort, Saskatchewan, to determine the impact of frequency of broad-leaf crops canola and pea in various crop rotations on accumulation and distribution of nitrate nitrogen (N) and extractable phosphorus (P) in the soil profile after 4 years. Two cultivars of canola, an herbicide-tolerant blacklegresistant variety (hybrid) and a conventional (not herbicide tolerant) open-pollinated, blackleg-susceptible variety (OP), were included. Mean effects of crop rotation or rotation length on soil nitrate N were not significant, though the amount of soil nitrate N in different soil layers tended to be greatest with monocultures and least in the 4-year rotation with flax. Effects of crop phase (i.e., individual crops that make up the rotation) x crop rotation interactions on soil nitrate N were significant for all layers in the soil profile. The amounts of nitrate N in soil after canola, especially hybrid canola, were lowest in most crop rotations, suggesting the importance of canola in minimizing downward movement of nitrate N in the soil profile. Soil extractable P in the 0- to 15-cm layer was least with monocultures and greatest in the 4-year rotation with flax. There was a significant effect of crop phase on soil extractable P, but soil P levels varied with crop phase in different rotations. In conclusion, residual nitrate N in soil can be reduced by extending crop rotations and using high-yielding disease-resistant canola cultivars, most likely by improving crop yields.

Flexibility in crop rotation planning allows canola and pea producers to adapt to changing management practices and marketing opportunities. Current recommendations in western Canada are to follow a 1 in 4-yr rotation for canola or pea on a particular field, but producers are interested in increasing frequency of these crops. The objective of this study was to determine the impacts of frequency of broad-leaf crops canola and pea and fungicide application in various crop rotations on accumulation and distribution of nitrate nitrogen (N) and extractable phosphorus (P) in the soil profile after 8 yr on a Dark Brown Chernozem (Typic Boroll) loam at Scott, Saskatchewan. The field experiment (from 1998 and 2005) contained monoculture canola and monoculture pea compared with rotations that contained these crops every 2, 3, and 4 yr with wheat and/or flax. Two cultivars of canola were included, an herbicide-tolerant and blackleg-resistant hybrid, and a conventional (not herbicide tolerant) open-pollinated, blackleg-susceptible (OP) cultivar. Subplots were fungicide treatments that attempted to control both blackleg and sclerotinia stem rot in canola and mycosphaerella blight in pea. Residual soil nitrate N in most layers and extractable P in many layers were significantly affected by crop rotation or rotation length, with the greatest amounts after monocultures. Fungicide application resulted in decreased amount of residual soil nitrate N, but it had no effect on soil extractable P. Crop phase (i.e., individual crops that make up the rotation) had a significant effect on soil nitrate N in many crop rotations; for example, residual soil nitrate N tended to be greatest after pea or OP canola and also after flax in the 4-yr rotation with flax. Crop phase had no effect on soil extractable P in any crop rotation. The lower amounts of residual soil nitrate N were usually associated with greater cumulative seed yields, and more so with greater cumulative N removal in seed in various crop rotations and phases within rotations. In conclusion, the findings suggest that accumulation of residual nutrients in soil, especially nitrate N, can be minimized by extending crop rotations, using high-yielding disease-resistant canola cultivars, and applying fungicides in years with weather conditions conducive to diseases.

The impact of cropping system management on root and crown rot of spring wheat (Triticum aestivum L.) was examined on a Dark Brown Chernozem (Typic Boroll) soil in the Canadian Prairies. This systems approach tried to reflect the most common practices of organic and conventional producers in this region. The study consisted of a factorial combination of three input levels (high, with tillage, fertilizer and pesticides; reduced [RED], with conservation tillage, targeted fertilizer and weed control; and organic [ORG] with tillage and N-fixing legumes); and three levels of cropping diversity (low diversity with wheat and summerfallow or legume green manure fallow; diversified using annual grain crops; and diversified using annual grain crops and perennial forages). All rotations were 6 yr long. Subcrown internodes and crowns/lower culms of wheat plants were scored for discoloration, and fungi in discolored tissue were identified and quantified. Overall, input level had a greater impact on disease levels and fungal frequency than cropping diversity. Discoloration severity was lowest in the RED systems, which was attributed to lower percentage isolation of Cochliobolus sativus, the most common pathogen. Fusarium species varied with input level. The pathogens F. avenaceum and F. culmorum were most associated with RED and/or least associated with ORG systems, whereas the weak pathogen/saprophyte F. equiseti was most associated with ORG systems. Thus, ORG management helped to reduce populations of F. avenaceum and F. culmorum, two of the most important Fusarium pathogens in the Canadian Prairies.

Although producers' prime objective may be to increase net returns, many are also interested in conserving and enhancing the quality the soil, water and air resources through adopting more environmentally friendly production practices. This study compared non-renewable energy inputs, energy output, and energy use efficiency of nine dryland cropping systems comprised of a factorial combination of three methods of input management [high (HIGH), i.e., conventional tillage plus full recommended rates of fertilizer and pesticides; reduced (RED), i.e., conservation tillage plus reduced rates of fertilizer and pesticides; and organic (ORG), i.e., conventional tillage plus N-fixing legumes and non-chemical means of weed and pest control]; and three crop rotation systems with varying levels of cropping diversity [a fallow-based rotation with low crop diversity (LOW); a diversified rotation using annual cereal, oilseed and pulse grains (DAG): and a diversified rotation using annual grains and perennial forages (DAP)]. The study was conducted over the 1996-2007 period on a Dark Brown Chernozemic soil (Typic Boroll) in the Canadian Prairies. As expected, total direct plus indirect energy input was the highest for the HIGH and RED input treatments (3773 MJ ha(-1) year(-1)), and 50% less for ORG management. Most of the energy savings came from the non-use of inorganic fertilizers and pesticides in the ORG management treatments. Further, total energy use was the highest for the DAG treatments (3572 MJ ha(-1) year(-1)), and similar but about 18% lower for the DAP and LOW crop diversity treatments compared to DAG. Thus, overall, the HIGH/DAG and RED/DAG systems had the highest energy requirements (4409 MJ ha(-1) year(-1)) and ORG/DAP had the lowest (1806 MJ ha(-1) year(-1)). Energy output (calorimetric energy content) was typically the highest for the HIGH input treatments (26,541 MJ ha-1 year-'), was about 4% less with RED, and 37% less with ORG management. The latter reflected the lower crop yields obtained with organic management. Similarly, energy output was the highest for the DAP treatments (25,008 MJ ha(-1) year(-1)), about 5% less for DAG, and 20% less for the LOW crop diversity treatments. The higher energy output with the DAP treatments largely reflected that the entire harvested biomass of the forage crops was included in energy output, while for grain crops only the seed was included. The straw and crop residues from annual crops were returned to the land to protect the soil from erosion and to maintain soil organic matter as this is the recommended practice in this semi-arid region. In contrast to energy output and to net energy produced, energy use efficiency (measured as yield of grain plus forage produced per unit of energy input or as energy output/energy input ratio) was the highest for the ORG input treatments (497 kg of harvested production GJ(-1) of energy input, and an energy output/energy input ratio of 83). We obtained lower, but generally similar energy use efficiency for the HIGH and RED input treatments (392 kg GJ(-1) and ratio of 7.1). Thus, overall, ORG/DAP was the most energy efficient cropping system, while RED/LOW and RED/DAG generally ranked the lowest in energy use efficiency. Our findings support the current movement of producers toward ORG management as a means of reducing the reliance on non-renewable energy inputs and improving overall energy use efficiency of their cropping systems.Our results also suggestthat moving away from traditional monoculture cereal rotations that employ frequent summer fallowing, toward extended and diversified crop rotations that use reduced tillage methods, although resulting in an increase in energy output, will not significantly reduce the overall reliance on non-renewable energy inputs, nor enhance energy use efficiency, unless perennial legume forages and/or legume grain crops are included in the cropping mix. (C) 2010 Elsevier B.V. All rights reserved.

AbstractProducers in the semi-arid Dark Brown Chernozemic (Typic Boroll) soil zone of the Canadian Prairie are contemplating changes to land-use practices, moving away from conventional high-input production systems that specialize in one or two annual grain crops to more diversified and extended cropping systems that use reduced-input and organic management practices. This study examined the economic merits of nine cropping systems, consisting of a factorial combination of three input management methods and three levels of cropping diversity. It was conducted over the 1996–2007 period on a loam soil at Scott, Saskatchewan. The input treatments were: (1) high input (HIGH), which used conventional tillage and full recommended rates of fertilizers and pesticides ‘as required’; (2) reduced input (RED), which used conservation tillage and integrated weed and nutrient management practices in an effort to lower requirements for fuel, fertilizers and pesticides; and (3) organic input (ORG), which used tillage, non-chemical pest control, higher seeding rates, delayed seeding and legume crops to replenish soil nutrients. The crop diversity treatments included: (1) a fallow-based rotation with low crop diversity (LOW); (2) a diversified annual rotation of cereal, oilseed and pulse grains (DAG); and (3) a diversified rotation using annual grains and perennial forages (DAP). All crop rotations were 6 years in length. At the 2007 input costs and prices, average net returns and 12-year net present values were higher for organic than for non-organic treatments, with the ORG input/LOW crop diversity system being the most profitable (net returns=$234 ha−1yr−1and net present value=$1953 ha−1). Net returns averaged about 10% less for ORG/DAG compared to the most profitable system, and about 22% less for HIGH/DAG and RED/DAG (the best non-organic systems). The DAP treatments that included forage were not economically competitive with the other treatments, often producing economic losses. The relative profitability of the organic treatments was highly dependent on the existence of organic price premiums. When price premiums for organic crops were reduced to less than 70% of the 2007 levels, the organic treatments were less profitable than the comparable non-organic treatments. The organic treatments also experienced significantly lower (and often negative) net returns compared to the non-organic treatments during completion of the 3-year organic certification period. We estimated that it required 5–7 years after completion of certification for the organic treatments to break even with the comparable non-organic treatments. Thereafter the organic treatments produced consistently higher net earnings. Production costs averaged 16% lower with ORG management compared to the HIGH-input treatments, but we found little difference in total costs between the respective HIGH- and RED-input treatments. The organic treatments also displayed lower income variability than the non-organic treatments, with the ORG/LOW system being preferred by risk-averse producers, who do not subscribe to all-risk crop insurance, and with the ORG/LOW and ORG/DAG systems preferred by low and medium risk-averse producers when having the added financial protection from the Canada/Saskatchewan all-risk crop insurance program.

Differences in response to nitrogen (N) fertilizer will affect the production economics of field crops. Currently, there is limited information comparing the agronomic and economic performance of juncea canola (Brassica juncea L.) and sunflower (Helianthus annuus L.) to napus canola (Brassica napus L.) and flax (Linum ustitatissimum L.) in Saskatchewan under no-till practices. A study of these species was carried out at five Saskatchewan locations over 3 yr and included eight nitrogen rates. All four species had a curvilinear increase in grain yield as N rate increased with the largest yield response observed in napus canola to as much as 200 kg N ha-1. The majority of the increase in flax grain yield occurred as the N rate increased from 10 to 90 kg ha-1, while most of the increase in grain yield of juncea canola and sunflower occurred as N increased from 10 to 70 kg ha-1. Biplot analysis indicated that grain yield variation was reduced at and above 50 kg N ha-1 in flax, napus canola and juncea canola, but not in sunflower. Analysis indicated that a wide range of N rates would provide a similar adjusted gross return within each crop with the exact N range being determined by crop price and nitrogen cost. The N rate affected the kernel weight of sunflower but not the kernel weight of other crops. The protein concentration of all the species increased as N rate increased. Seed oil concentration tended to decrease as the N rate increased, but this was not consistent. In conclusion, higher yielding cultivars of sunflower and juncea canola are needed before they will replace a large acreage of flax or napus canola; however, in the drier regions of the Saskatchewan there is potential to expand sunflower production.Key words: Brassica juncea, Helianthus annuus, Brassica napus, Linum usitatissimum, nitrogen, economic analysis

Adverse weather is often associated with yield reduction of canola, also known as oilseed rape. Historical weather and crop yield data from Saskatchewan (SK) crop districts were analyzed with both simple correlation analysis and iterative principal components analysis. The analyses demonstrated the negative impacts of high temperatures and low precipitation, and the positive effects of greater-than-average precipitation, and to a lesser extent, cooler-than-average nocturnal temperatures. Iterative Chi-square analysis and iterative principal components analysis both showed that the beginning of July, which coincides with the early part of the flowering period of the crop in SK, was the critical time in which high temperatures (>30°C) and low precipitation led to yield loss.

Active optical sensors have potential as tools to increase N fertilizer use efficiency in crop production; however, empirical data are required to utilize the sensors for this purpose. Data were compiled from N fertilizer trials at five Canadian locations (2004-2007) to determine the feasibility of using optical sensors during the growing season to estimate the seed yield potential of canola (Brassica napus). The normalized difference vegetation index (NDVI) of each plot in each trial was measured using a hand-held optical sensor several times each season. The NDVI between the six-leaf stage and the beginning of flowering was divided by one of several different heat unit summations to normalize the measurements, and data were combined across locations. Linear and exponential regression analyses were completed for canola seed yield as a function of both the original and normalized NDVI measurements. When data from all locations were combined, NDVI was significantly correlated with canola seed yield (R 2 = 0.35; P < 0.001) and normalizing NDVI did not improve the correlation. Categorizing the locations by soil zone (Brown-Dark Brown and thin-Black-Black) and completing separate regression analyses for each group increased the correlation coefficients for NDVI and seed yield (R 2 = 0.36-0.43). Furthermore, dividing NDVI by the heat unit summations generally improved the correlation when the data were categorized by soil zone. The largest correlation coefficient occurred when NDVI was divided by growing degree days with a base temperature of 5°C (R 2 = 0.53-0.67). Our results show that optical sensors can be used to estimate canola yield potential early enough in the growing season to have potential as an N management tool.Key words: Normalized difference vegetation index, agriculture, precision, nitrogen use efficiency