S. A. Brandt

Oilseed crops for semiarid cropping systems in the Northern Great Plains

oilseed crop produced in the USA, canola is the dominant oil crop in Canada. The cool climatic conditions Oilseed crops are grown throughout the semiarid region of the characteristic of the Canadian prairies provide an ideal northern Great Plains of North America for use as vegetable and industrial oils, spices, and birdfeed. In a region dominated by winter environment for Brassica spp. oilseeds and flax (Table and spring wheat (Triticum aestivum L. emend. Thell.), the accep2) while the climate found in the USA is better suited tance and production of another crop requires that it both has an to the warm season crops like soybean and sunflower. agronomic benefit to the cropping system and improve the farmers’ In the northern Great Plains, soybean is a relatively economic position. In this review, we compare the adaptation and new crop finding a place in semiarid cropping systems rotational effects of oilseed crops in the northern Great Plains. Canola with the development of early maturing, low heat–unit (Brassica sp.), mustard (B. juncea and Sinapis alba L.), and flax cultivars (Miller et al., 2002). As a result, the vast major(Linum usitatissimum L.) are well adapted to cool, short-season conity of soybean production in both the USA and Canada ditions found on the Canadian prairies and northern Great Plains occurs in wetter regions east of the Great Plains. Howborder states of the USA. Sunflower (Helianthus annuus L.) and safflower (Carthamus tinctorius L.) are better adapted to the longer ever, for the other oilseed crops listed in Table 1, the growing season and warmer temperatures found in the northern and majority of production occurs within the northern Great central Great Plains states. Examples are presented of how agronomic Plains. practices have been used to manipulate a crop’s fit into a local environDiversification within cereal-based cropping systems ment, as demonstrated with the early spring and dormant seeding can be critical to breaking pest infestations that are management of canola, and of the role of no-till seeding systems in common with monoculture (Bailey et al., 1992, 2000; allowing the establishment of small-seeded oilseed crops in semiarid Elliot and Lynch, 1995; Holtzer et al., 1996; Krupinsky regions. Continued evaluation of oilseed crops in rotation with cereals et al., 2002). Results of crop rotation studies in the Great will further expand our understanding of how they can be used to Plains revealed that where oilseeds are adapted, their strengthen the biological, economic, and environmental role of the region’s cropping systems. Specific research needs for each oilseed inclusion in rotation with cereals could increase net recrop have been recommended. turns and reduce risk through improved production stability (Lafond et al., 1993; Dhuyvetter et al., 1996; Zentner et al., 2002). In addition, the yield of wheat was increased when following oilseeds in rotation, confirmO crops are grown throughout the semiarid region of the northern Great Plains of North ing that monoculture systems are the least effective America for use as vegetable and industrial oils, spices, means of optimizing wheat production (Lafond et al., and birdfeed. In a region dominated by winter and 1992; Brandt and Zentner, 1995; Anderson et al., 1999). spring wheat (Triticum aestivum L.), the acceptance and The use of minimum and no-till seeding systems has production of another crop requires that it both has an been found to provide an effective means of controlling agronomic benefit to the cropping system and improves soil erosion in various regions of the Great Plains (Black the farmers’ economic position. Given that most oilseed and Power, 1965; Lindwall and Anderson, 1981). Imcrops have an indeterminate growth habit, adaptation provements in seed yield with conservation tillage have is influenced by tolerance to high temperature and been reported as a result of increased levels of plantdrought stress and by crop management to take advanavailable water throughout the soil profile in the spring tage of optimum environmental conditions for flowering (Aase and Reitz, 1989; Brandt, 1992; Lafond et al., 1992) and seed fill. The increasing area of oilseed crop producand increased water use efficiency due to favorable mition is an indication of the success of plant breeders croclimate conditions created by standing stubble (Cutand agronomists in developing suitable cultivars and forth and McConkey, 1997). Some oilseed crops are production methods in this semiarid region (Table 1). small seeded, requiring good surface soil moisture for While soybean [Glycine max (L.) Merr.] is the major seed germination and crop establishment, as is effectively provided in direct-seeding systems in the northern A.M. Johnston, Potash and Phosphate Inst. of Canada, 12-425 PineGreat Plains. As a result, adoption of conservation tillhouse Dr., Saskatoon, SK, Canada S7K 5K2; D.L. Tanaka, USDAage management not only reduces soil loss by erosion, ARS, Northern Great Plains Res. Lab., Box 459, Mandan, ND 58554; but also can facilitate extending the crop rotation and P.R. Miller, Montana State Univ., Dep. of Land Resour. and Environ. Sci., P.O. Box 173120, Bozeman, MT 59717-3120; S.A. Brandt, Agric. allowing for diversification of the crops grown. Ecoand Agri-Food Can., Box 10, Scott, SK, Canada S0K 4A0; D.C. Nielnomic success with a diversified crop rotation has been sen, USDA-ARS, Cent. Great Plains Res. Stn., 40335 Country Rd. reported to be improved with the implementation of GG, Akron, CO 80720; G.P. Lafond, Agric. and Agri-Food Can., Box conservation tillage practices, such as minimum and zero760, Indian Head, SK, Canada S0G 2K0; and N.R. Riveland, North Dakota State Univ., Williston Res. Ext. Cent., 14120 Hwy. 2, Williston, tillage (Lafond et al., 1993; Rossetti et al., 1999; Zentner ND 58101-8629. Saskatoon Res. Cent. Publ. 1421. Received 1 Dec. et al., 2002). 2000. *Corresponding author (ajohnston@ppi-ppic.org). The objective of this review is to summarize information on the adaptation and production potential of some Published in Agron. J. 94:231–240 (2002).

Response of three Brassica species to high temperature stress during reproductive growth.

The effect of short periods of high temperature stress on the reproductive development and yield of three Brassica species were studied in a growth chamber experiment conducted for 2 yr. Two genotypes from Brassica juncea L. and one each from B. napus L. and B. rapa L. were grown under day/night temperatures of 20/15 °C till early flowering or early pod development, subjected to high temperature stress of 28/15 °C or 35/15 °C for 7 d and then allowed to recover at 20/15 °C. Species differed in optimum temperatures, with B. juncea and B. rapa having higher optimum temperature than B. napus. Dry matter was unaffected by moderate temperature stress, while it was reduced by high temperature stress. The 35/15 °C treatment was injurious to reproductive organs at different developmental stages of all three species. High temperatures at flowering affected yield formation more than high temperature at pod development. On the main stem, mean seed yield reduction due to heat stress was 89%, but partial compensation ...

Seeding rate, fertilizer level and disease management effects on hybrid versus open pollinated canola (Brassica napus L.)

New canola cultivars have much higher yield potential than conventional canola cultivars and changes in production practices may be needed to achieve optimum yield from these cultivars. Studies were conducted to investigate the influence of seeding rates (2.8, 5.6 and 8.4 kg ha-1), fertilizer level (67% – low, 100% – medium, 133% – high of the commercial recommendation) and fungicide application on growth, dry matter accumulation, seed yield and seed quality using two high-yielding canola cultivars [cv. Quantum, open pollinated (OP), and cv. Invigor™, hybrid (HYB)]. The studies were conducted from 1999 to 2001 at three sites in the Parkland region of the Canadian prairies. The two cultivars did not differ in their responses to seeding and fertilizer rates, or fungicide application. Plant density was lower for the HYB than the OP because the HYB had larger seeds, with fewer seeds per kilogram. Emergence declined slightly at high fertilizer levels in some site-years due to fertilizer induced seedling damage...

Cultivation and grassland type effects on light fraction and total organic C and N in a Dark Brown Chernozemic soil

Light fraction of organic matter is a source of nutrients for plants and a substrate for microbes, while total organic matter is critical for optimum physical conditions and retention of nutrients and other chemicals in soil. The objective of this study was to evaluate the effects of cultivation and grassland type on light fraction and total C and N in a Dark Brown Chernozemic soil. Three paired-sets of soil samples, in five replications, were collected from three cultivated field areas under annual crops [mostly wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.)] and from three adjacent grassland areas. The three sets were a 30-yr-old bromegrass (Bromus inermis Leyss.)/alfalfa (Medicago sativa L.) dominated stand cut annually for hay (Lm) and cultivated area 1 (Ct1), an unbroken native grass stand having no vegetation removed (Ng) and cultivated area 2 (Ct2) and a bromegrass/crested wheatgrass (A gropyron cristatum L. Gaertn.) dominated stand on a land reverted to grassland 60 yr ago having no ...

Nitrogen contribution of field pea in annual cropping systems. 2. Total nitrogen benefit

The total nitrogen (N) benefit of field pea (Pisum sativum) to a succeeding non-legume crop was measured in a small plot experiment at Scott, Saskatchewan in the moist Dark Brown soil climatic zone, and in a small plot and landscape experiment near Melfort, Saskatchewan in the moist Black soil climatic zone from 1993 to 1995. The total N benefit was calculated as the difference in net N mineralized from soil plus N in the above- and below-ground crop residue between field pea and non-legume stubble-cropped plots over the growing season. Landscape slope position did not affect the total N benefit of field pea to a succeeding wheat crop, and preseeding tillage had an inconsistent effect on the total N benefit between years. The direct N benefit of field pea aboveground residue available to the succeeding crop in the landscape experiment was a minor component of the total N benefit, which averaged 25 kg N ha−1. The total N benefit was equivalent to the N residual effect, defined as the amount of fertilizer N...

Blackleg disease of canola mitigated by resistant cultivars and four-year crop rotations in western Canada

Abstract 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.

REGRESSION MODEL FOR PREDICTING YIELD OF HARD RED SPRING WHEAT GROWN ON STUBBLE IN THE SEMIARID PRAIRIE

Soil testing laboratories require predictive equations to make accurate fertilizer recommendations to cereal producers in the Canadian prairies. We used results from two 12-yr experiments (one studying snow management × fertilizer rates, and the other a tillage experiment), conducted on a medium-textured Orthic Brown Chernozem at Swift Current, Saskatchewan, to develop a regression model to estimate grain yield of hard red spring wheat (Triticum aestivum L.) grown on stubble. Stepwise regression, with backward elimination, was used to develop the relationship:Y = 1006 + 10.53 WU − 0.017 WU2 + 5.52 FN − 0.095 FN2 − 33.16 SN + 0.436 SN2 − (0.112 FN × SN) + (0.057 FN × WU) + (0.159 SN × WU) − 1.26 DD (R2 = 0.89, P = 0.001, n = 262)where Y = grain yield (kg ha−1), WU = estimated water use (mm), SN = soil test N (kg ha−1), FN = rate of fertilizer N (kg ha−1), and DD = degree days >5 °C (°C-days). Water use was available spring water in the 0- to 1.2-m depth plus 1 May to 31 July precipitation + irrigation, and...

Effect of tillage and crop rotations on the light fraction organic carbon and carbon mineralization in Chernozemic soils of Saskatchewan

Light fraction of soil organic C (LFOC) represents a major portion of labile soil organic C (SOC) and is a key attribute of soil quality. Soil respiration (Cmin) is an important index depicting the potential activity of the labile SOC. Six field experiments, varying in duration (8 to 25 yr), in location (Brown, Dark Brown and Black Chernozemic soil zones of Saskatchewan) and soil texture, were conducted to evaluate the impact of tillage and crop rotations on crop production and soil quality. We sampled the 0-7.5-cm depth of soil in these experiments to determine the treatment effects on LFOC, the proportion of LFOC in the SOC (LFOC/SOC) and Cmin. Increasing the frequency of summer fallow in cropping systems decreased the LFOC in all soil zones; it also decreased the proportion of LFOC in SOC and Cmin. Tillage had little impact on LFOC in the Brown and Dark Brown Chernozemic soil zones, although it significantly decreased LFOC in the Black Chernozemic soil zone. Thus, crop rotation had a greater impact on ...

Adaptation of alternative pulse and oilseed crops to the semiarid Canadian Prairie: Seed yield and water use efficiency

Diversification and intensification of the cropping systems in the traditional wheat-fallow area of the semiarid Canadian prairie is necessary to improve sustainability. Selection of alternate crops to include in cropping systems requires information on production risks with different climate regimes. To understand water use/yield relationships of alternate crops, three pulse crops (leguminous grain crops) [chickpea (Cicer arietinum L.), pea (Pisum sativum L.) and lentil (Lens culinaris Medik.)], three oilseed crops [canola (Brassica napus L. and B. rapa L.) and mustard (B. juncea L.)], and one cereal crop [wheat (Triticum aestivum L.)] were studied under varying water regimes: during 1996–1998 under well-watered, rainfed, imposed drought conditions, and in 2001 under rainfed conditions. Generally, the relative ranking between crops for water use was maintained across water regimes, such that the crops separated into three general groups of water users (high: wheat, B. napus, mustard; medium: chickpea, B....

ACCUMULATION AND DISTRIBUTION OF NITRATE–NITROGEN AND EXTRACTABLE PHOSPHORUS IN THE SOIL PROFILE UNDER VARIOUS ALTERNATIVE CROPPING SYSTEMS

ABSTRACT Cropping systems can influence the accumulation and distribution of plant nutrients in the soil profile, which can affect their utilization efficiency by crops and pollution potential in the environment. A field experiment was conducted on a Dark Brown loam soil at Scott, Saskatchewan, Canada to assess the effects of input level, cropping diversity and crop phase on the accumulation and distribution of nitrate–nitrogen (N) and extractable phosphorus (P) in the soil profile at the end of 1995 to 2000 growing seasons. The 54 treatments were combinations of three input levels (organic—ORG, reduced—RED and high—HIGH), three cropping diversities (low diversity—LOW, diversified annual grains—DAG, and diversified annual and perennials—DAP), and six crop phases chosen from fallow (tillage-fallow or chem-fallow), green manure [lentil—Lens culinaris Medicus or sweet clover—Melilotus officinalis (L.) Lam], spring wheat (Triticum aestivum L.), canola (Brassica napus L. and Brassica rapa L.), fall rye (Secale cereale L.), field pea (Pisum sativum L.), spring barley (Hordeum vulgare L.), flax (Linum usitatissimum L.), oats (Avena sativa L.), and bromegrass (Bromus inermis Leyss), alfalfa (Medicago sativa Leyss) mixture hay. Soil was sampled from the 0–15, 15–30, 30–60, and 60–90 cm depths in each crop phase from 1995 to 2000, with additional depths 90–120, 120–150, 150–180, 180–210, and 210–240 cm taken from the wheat phase in 2000. In general, there were greater amounts of nitrate–N with HIGH input compared to ORG or RED inputs, especially under LOW diversity. The nitrate–N in various soil depths suggested some downward movement of nitrate–N to the deeper soil depths when HIGH input was compared to ORG input. In LOW cropping diversity, green manure or fallow usually had more nitrate–N in soil than other crop phases. In DAG and DAP cropping diversities, nitrate–N varied with crops and on average it had maximum concentration after wheat or canola in DAG and after hay followed closely by wheat in DAP. The ORG input level had greater nitrate–N than RED or HIGH inputs in some instances, most likely due to relatively low extractable P in soil for optimum crop growth under ORG input. Extractable P in the 0–15 and 15–30 cm soil depths tended to be greater under HIGH or RED inputs compared to the ORG input level in many cases. In summary, there was no consistent effect of cropping diversity on extractable P in soil under ORG input, but LOW diversity tended to show more extractable P compared to DAG and DAP diversities in some cases of RED and HIGH inputs. The green manure/fallow, HIGH input and LOW diversity treatments tended to result in higher nitrate–N and extractable P levels compared to the corresponding treatments, and the effects were more pronounced on nitrate–N than extractable P and in shallow compared to deeper soil layers.