A. M. Johnston

Nitrogen fertilization management for no-till cereal production in the Canadian Great Plains: a review

Nitrogen (N) is the nutrient most limiting crop production in all areas of the world and is generally applied to soil in the largest quantity. A review of the research on N fertilization management for no-till cereal production in the Canadian Great Plains, on mainly Chernozem and Gray soils, was done to illustrate the management practices which can be used to optimize the N use efficiency so as to minimize the N loss from root zone and environmental damage. Applied N is subject to loss by volatilization, immobilization, denitrification and leaching in soil and its efficiency of use by plants is governed by soil and climatic factors, fertilizer material, and soil, crop and fertilizer management practices. Overall efficiency of applied N has been <70%. Reducing tillage intensity modifies both the demand of crops for N due to changes in yield potential, and the supply of N due to changes in N cycling and losses. Consequently, it may be necessary to compensate for this by adjusting the fertilizer rate. Fertilizer use efficiency may also change with changes in tillage management, microclimate, microbial activity and distribution of fertilizer relative to crop residue. Placing the fertilizer in a band reduces contact with soil microorganisms, reducing immobilization of both ammonium (NH4) and nitrate (NO3). Banding also slows the conversion of urea to NH3 and NH4 to NO3, which can reduce losses by denitrification and leaching. The use of the urease inhibitor n-(n-butyl) thiophosphoric triamide (NBPT) shows promise in improving the efficiency of surface-applied urea-containing fertilizers in no-till systems and reducing seedling damage from seed-placed fertilizers. Ultimately, any N fertilization package has advantages and disadvantages. In selecting the optimum fertilizer management system for a farming operation, the balance between rate of application, cost and availability of equipment, soil disturbance, seedbed quality, moisture conservation, time and labor constraints and fertilizer use efficiency must be considered. The “best” management system is not fixed, but depends on the major limiting factors on each individual farm.

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).

Changes in total, mineralizable and light fraction soil organic matter with cropping and tillage intensities in semiarid southern Alberta, Canada

Abstract There has been a trend toward increased cropping intensity and decreased tillage intensity in the semiarid region of the Canadian prairies. The impact of these changes on sequestration of atmospheric CO 2 in soil organic carbon (C) is uncertain. Our objective was to quantify the changes in total, mineralizable and light fraction organic C and nitrogen (N) due to the adoption of continuous cropping and conservation tillage practices. We sampled three individual long-term experiments at Lethbridge, Alberta, in September 1992: a spring wheat ( Triticum aestivum L.)-fallow tillage study, a continuous spring wheat tillage study and a winter wheat rotation-tillage study. Treatments had been in place for 3–16 years. In the spring wheat-fallow study, different intensities (one-way disc > heavy-duty cultivator > blade cultivator) of conventional tillage (CT) were compared with minimum tillage (MT) and zero tillage (ZT). After 16 years, total organic C was 2.2 Mg ha −1 lower in more intensively worked CT treatments (one-way disc, heavy-duty cultivator) than in the least-intensive CT treatment (blade cultivator). The CT with the blade cultivator and ZT treatments had similar levels of organic C. The CT treatments with the one-way disc and heavy-duty cultivator had light fraction C and N and mineralizable N amounts that were about 13–18% lower than the CT with the blade cultivator, MT or ZT treatments. In the continuous spring wheat study, 8 years of ZT increased total organic C by 2 Mg ha −1 , and increased mineralizable and light fraction C and N by 15–27%, compared with CT with a heavy-duty cultivator prior to planting. In the winter wheat rotation-tillage study, total organic C was 2 Mg ha −1 higher in a continuous winter wheat (WW) rotation compared with that in a winter wheat-fallow rotation. The lack of an organic C response to ZT on the WW rotation may have been due to moldboard plowing of the ZT treatment in 1989 (6 years after establishment and 3 years before soil sampling), in an effort to control a severe infestation of downy brome ( Bromus tectorum L.). Our results suggest that although relative increases in soil organic matter were small, increases due to adoption of ZT were greater and occurred much faster in continuously cropped than in fallow-based rotations. Hence intensification of cropping practices, by elimination of fallow and moving toward continuous cropping, is the first step toward increased C sequestration. Reducing tillage intensity, by the adoption of ZT, enhances the cropping intensity effect.

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...

Inoculant formulation and fertilizer nitrogen effects on field pea: Nodulation, N2 fixation and nitrogen partitioning

Field pea (Pisum sativum L.) acreage has expanded rapidly in the past 10 yr in the Peace River Region of Alberta as well as western Canada. Understanding nitrogen dynamics of Rhizobium inoculants and applied N will provide farmers opportunities to improve N nutrition of field pea. Field experiments were conducted (a) to compare the effects of soil inoculation using granular inoculant, and seed inoculation using peat powder and liquid inoculants with an uninoculated check, on field pea nodulation and N2 fixation, and (b) to determine whether starter N is required by field pea to enhance N2 fixation. The effects of inoculant formulation on nodule number, N accumulation and N2 fixation were in the order: granular > peat powder > liquid = uninoculated. Field pea, from soil-applied inoculant, accumulated more N prior to and during podfilling than field pea with seed-applied inoculant. Fertilizer N application rates < 40 kg N ha-1 had no significant effects on biomass N at flatpod, indicating that starter N was...

Inoculant Formulation and Fertilizer Nitrogen Effects on Field Pea: Crop yield and Seed Quality

Appropriate rhizobial inoculation and fertility management can increase field pea (Pisum sativa) seed yield and improve yield stability in western Canada. The objective of this study was to determine the effect of inoculation method and N fertilizer application on pea seed yield and quality. The effects of soil inoculant (granular) and seed-applied inoculant (peat powder or liquid) used with and without urea-N application on field pea were investigated in the Peace River region of Western Canada. At low applied N rates, field pea biomass was significantly higher for soil-applied inoculant as compared to seed-applied inoculant. Soil-applied inoculant resulted in 15, 18, 9 and 0% higher pea biomass yield at the flatpod stage than seed-applied inoculant at 0, 20, 40 and 80 kg N ha-1, respectively. Averaged over all N rates, soil-applied inoculant resulted in 17, 50, and 56% higher pea seed yield than peat inoculant, liquid inoculant, or the uninoculated check, respectively. Soil-applied inoculant increased t...

Sulphur fertilizer and tillage effects on canola seed quality in the Black soil zone of western Canada

Field studies in Manitoba, Saskatchewan and Alberta over 3 yr evaluated immediate and residual effects of source, timing and placement of su lphur (S) fertilizers on canola quality under reduced (RT) and conventional tillage (CT). Oil concentration of canola seed increased and chlorophyll content decreased with application of plant-available forms of S fertilizer if soils were deficient in available sulphate-S. Therefore, canola seed quality was improved by correction of S deficiencies. The magnitude and consistency of fertilizer effects reflected the sulphate availability of the fertilizer source applied, with ammonium sulphate having a greater effect than the bentonite-elemental S product, Tiger 90®, in the year of application. Effects on seed N concentration were inconsistent, but decreases in seed N concentration occasionally occurred with correction of an S deficiency, reflecting an inverse relationship between seed yield or seed oil concentration and seed N concentration. Seed S concentration genera...

Comparative nitrogen response and economic evaluation for optimum yield of hybrid and open-pollinated canola

Plant breeders have dramatically improved the yield potential of new canola cultivars. To achieve optimum yield with such cultivars, particularly hybrids, may require changes to fertilizer management practices that were established prior to development of these cultivars. We investigated the influence of N fertilizer rate (0, 30, 60, 90, 120, and 150 kg N ha-1) on plant density, days to flowering, length of flowering stage, days to maturity, biomass, seed yield and quality, and economic returns of two canola cultivars (Quantum, a high-yielding open-pollinated; and InVigor® 2663, a high-yielding hybrid) on a Dark Brown (Scott), a Thick Black (Melfort), and a Thin Black (Indian Head) Chernozem soil in Saskatchewan in 2000 and 2001. Plant density was slightly lower for InVigor 2663 than Quantum due to larger seed size of the former. InVigor 2663 tended to take more days to flowering and had shorter flowering stage duration compared with Quantum, but the two cultivars showed no consistent difference for the n...

Effect of nitrogen, seeding date and cultivar on oat quality and yield in the eastern Canadian prairies

The proportion of oat (Avena sativa L.) being used for race horses and human consumption has increased over the past 15 yr. The objective of this study was to evaluate the effects of N, seeding date and cultivar on grain yield components, grain yield and grain quality of oat under a direct seeding system. Four N rates, three seeding dates and two cultivars were tested at Indian Head, Melfort, and Canora, SK, and Brandon, MB. Yield was more responsive to increasing N rates from 15 and 80 kg ha-1 when oat was seeded in early May versus early June. Panicles plant-1 was the yield component that accounted for most of the yield increase achieved from increasing rates of N, while kernel weight was the yield component that decreased as the rate of N increased. Physical seed quality decreased (plump seed decreased and thin seed increased) with delayed seeding and greater N fertilizer rates. Nitrogen fertilizer and seeding date had a much larger effect on the quality of CDC Pacer than AC Assiniboia. Combining early...

Early seeding dates improve oat yield and quality in the eastern prairies

Demand for high quality oat (Avena sativa L.) for consumption by humans and race horses has increased, leading to increased oat production on the Canadian prairies. Little information exists on the best management practices for producing high-quality, high-yielding oat using direct seeding systems and cropping practices developed and adopted over the past 15 yr. The objective of this study was to determine the effect of early seeding on grain yield and quality of oat cultivars currently grown in the eastern prairie region. Four seeding dates and four cultivars were tested at Indian Head, Melfort, and Brandon over 3 yr. Moving the seeding date from mid-June to early May increased oat yield, seeds per panicle, kernel weight, test weight and plump seed by 76, 33, 10, 13 and 11%, respectively, when averaged across all locations and years. This increase in yield and quality was probably due to improved environmental conditions and a reduction in crown rust infection (Puccina coronata Corda). Crown rust has a l...