Economics of spring wheat production systems using conventional tillage management in the Brown soil zone Revisited

Transcription

1 Economics of spring wheat production systems using conventional tillage management in the Brown soil zone Revisited R. P. Zentner 1, C. A. Campbell 2, F. Selles 1, R. Lemke 1, B. G. McConkey 1, M. R. Fernandez 1, C. Hamel 1, and Y. T. Gan 1 1 Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, Box 1030 Swift Current, Saskatchewan, Canada S9H 3X2 ( zentnerr@agr.gc.ca); 2 Eastern Cereals and Oilseeds Research Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6. Received 17 November 2005, accepted 20 July Zentner, R. P., Campbell, C. A., Selles, F., Lemke, R., McConkey, B. G., Fernandez, M. R., Hamel, C. and Gan, Y. T Economics of spring wheat production systems using conventional tillage management in the Brown soil zone Revisited. Can. J. Plant Sci. 87: Producers in the semiarid Brown soil zone of the Canadian Prairies have historically used fallow (F)- based cropping systems with mechanical tillage methods to produce spring wheat (Triticum aestivum L.) (W). However, in the past two decades government policies and programs have changed, as have cropping practices, market opportunities, and weather patterns. This study re-examines the economic merits of these conventional cropping systems under today s conditions in regard to the optimal cropping frequency, value of applying N and P fertilizer at soil test rates, and the possible advantage of replacing monoculture wheat with lentil (Lens culinaris Medikus) (Lent) or flax (Linum usitatissimum L.) (Flx) grown in mixed rotations. The analysis draws on data from a long-term crop rotation experiment that was established in 1967 on an Orthic Brown Chernozem at the Semiarid Prairie Agricultural Research Centre at Swift Current, Saskatchewan. All cropping systems were managed using conventional tillage practices, which attempted to conserve as much surface crop residue as possible (i.e., stubble mulch tillage techniques were used). The findings for , a period characterized by above normal precipitation, were compared with those reported previously for the period when growing conditions were less favorable but more typical for this area. Net returns during were highest for W-Lent ($93 ha 1 yr 1 ) and lowest for F-Flx-W ($38 ha 1 yr 1 ). Net returns for well-fertilized F-W, F-W-W, F-W-W-W-W-W, and Cont W during this same period were similar, averaging about $52 ha 1 yr 1 or 44% less than for W-Lent. These results contrast with those reported for the previous 18-yr period when F-W and F-W-W generally produced higher net returns than Cont W. Within the F-W-W systems, the application of both N and P fertilizer increased the 18-yr ( ) mean net returns by $18 ha 1 yr 1 compared with application of N only, and by $32 ha 1 yr 1 compared with application of P only. For Cont W the application of N and P fertilizer increased the mean net returns by $71 ha 1 yr 1 compared with application of P only. These economic benefits from N and P fertilization were much higher than those reported in due to the more humid growing conditions and the increased rate of N fertilizer prescribed by the soil testing lab since Further, our findings showed that only if producers were highly risk averse, do not subscribe to all-risk crop insurance, or if the price for wheat was high or price for lentil low, would the monoculture wheat systems be preferred to W-Lent. However, producers who are highly risk averse would still opt for the cropping systems that included some summerfallow. Our findings support the recent trends in land use practices by area producers towards more diversified and intensive cropping systems which are less reliant on frequent fallowing. Key words: Crop rotations, wheat, lentil, flax, summerfallow, production costs, net returns, income variability Zentner, R. P., Campbell, C. A., Selles, F., Lemke, R., McConkey, B. G., Fernandez, M. R., Hamel, C. et Gan, Y. T Économique des systèmes de production du blé de printemps recourant aux méthodes classiques de travail du sol dans la zone des sols bruns un retour. Can. J. Plant Sci. 87: Les cultivateurs de la zone mi-aride de sols bruns des Prairies canadiennes utilisent depuis toujours des systèmes de culture sur jachère (J) avec travail mécanique du sol pour produire du blé de printemps (Triticum aestivum L.) (B). Toutefois, les politiques et les programmes gouvernementaux ont évolué au cours des vingt dernières années, comme l ont fait les pratiques agricoles, les débouchés commerciaux et les conditions climatiques. Cet article réexamine les avantages économiques de tels systèmes de production dans les conditions actuelles par rapport à une fréquence optimale des cultures, à l application d engrais N et P selon les résultats de l analyse des sols et à l utilité éventuelle de remplacer la monoculture du blé par un assolement avec la lentille (Lens culinaris Medikus) (LE) ou le lin (Linum usitatissimum L.) (LI). L analyse des auteurs repose sur les données d une expérience de longue haleine sur l assolement amorcée en 1967, sur un tchernoziom orthique brun au Centre de recherches agricoles de la région semi-aride des Prairies, à Swift Current (Saskatchewan). Tous les systèmes agricoles faisaient appel à des pratiques classiques de travail du sol tentant de conserver autant de résidus de culture que possible (à savoir, recourant à des techniques de transformation du chaume en paillis par enfouissement). Les résultats obtenus entre 1985 et 2002, période caractérisée par des précipitations supérieures à la normale, ont été comparés à ceux de la période , durant laquelle les conditions de croissance étaient plus difficiles mais plus typiques pour la région. Entre 1985 et 2002, le meilleur revenu net a été enregistré pour la rotation B-LE (93 $ par hectare annuellement), le revenu le plus faible venant de l assolement J-LI-B (38 $ par hectare annuellement). Durant la même période, le revenu net était similaire pour les rotations J- Abbreviations: F, summerfallow or fallow; W, spring wheat; Flx, flax; Lent, lentil; Cont, continuous; SEM, standard error of the mean; LSD, least significant difference. 27

2 28 CANADIAN JOURNAL OF PLANT SCIENCE B, J-B-B, J-B-B-B-B-B et la culture continue du B, tous avec une bonne fertilisation, soit autour de 52 $ par hectare annuellement, en moyenne, ou 44 % de moins que l assolement B-LE. Ces résultats contrastent avec ceux rapportés pour la période de 18 années antérieure où les rotations J-B et J-B-B donnaient un revenu net supérieur à celui de la monoculture du blé. Avec l assolement J- B-B, l application d engrais N et P accroît le revenu net moyen de 18 ans ( ) de 18 $ par hectare annuellement, comparativement au revenu net obtenu après application d un engrais N uniquement, et l augmente de 32 $ par hectare annuellement, comparativement à celui obtenu quand les amendements se limitent à un engrais P. Avec la culture continue du blé, l application d engrais N et P augmente le revenu net moyen de 71 $ par hectare annuellement, comparativement au revenu enregistré après application d engrais P seulement. Les avantages économiques de la bonification avec des engrais N et P sont nettement plus marqués qu entre 1967 et On le doit à la plus grande humidité durant la période végétative et au relèvement du taux de fertilisation N que recommande le laboratoire d analyse du sol depuis Par ailleurs, les auteurs ont constaté qu on ne devrait préférer la monoculture du blé à l assolement B-LE uniquement si le producteur se montre très réfractaire aux risques, s il n adhère pas à une assurance-récolte tous risques, voire si le prix du blé est élevé ou celui des lentilles trop bas. Les producteurs réfractaires aux risques devraient néanmoins opter pour des systèmes agricoles intégrant une jachère quelconque. Ces constatations confirment les tendances récentes de la région quant à la vocation des terres, à savoir l orientation vers des systèmes de culture plus diversifiés et plus intensifs n exigeant pas de jachères fréquentes. Mots clés: Assolements, blé, lentille, lin, jachère, coûts de production, revenu net, fluctuation des revenus Producers in the Brown soil zone of the Canadian prairies have historically included high proportions of summerfallow in their monoculture spring wheat (Triticum aestivum L.) rotations as a means of managing the inherent shortage of growing season precipitation (DePauw et al. 1986). These cropping systems, which also relied on extensive use of mechanical tillage methods, have been shown to maximize net farm income and to minimize financial risk under the economic conditions of the day (Zentner and Campbell 1988). However, changes in grain prices and input costs due to policy changes and new technologies have caused many producers to search for more varied and profitable cropping options (Smith et al. 2001; Campbell et al. 2002; Zentner et al. 2002). A long-term crop rotation experiment initiated in 1967 at the Semiarid Prairie Agricultural Research Centre in southwestern Saskatchewan was evaluated for economic performance in 1985 (Zentner and Campbell 1988). At the time, net returns were generally highest for the most frequently summerfallowed treatments like fallow-wheat (F-W) and F- W-W, with the risk of economic loss also being lowest for these systems. However, other analyses showed these frequently summerfallowed treatments to be more damaging to soil (Biederbeck et al. 1984), water (Campbell et al. 1984) and air (Curtin et al. 2002) quality than continuous wheat (Cont W). This prompted a modification in the experiment in 1985 to include a 6-yr F-W-W-W-W-W rotation to determine if the economic advantage of summerfallowing could be combined with the soil quality enhancing advantage of more frequent cropping. Further, during the first 18 yr of the experiment, growing season precipitation was typical of the semiarid prairies, being often below average so that crop response to N and P fertilizers was only marginal (Zentner and Campbell 1988); however, weather conditions have been more favorable during the last 18 yr ( ) and so has crop response to fertilizer (Campbell et al. 2005) and other inputs. The objectives of this paper were to re-evaluate the economic performance of cropping systems that use conventional management practices in this semiarid region with regard to the most optimal cropping frequency, value of applying N and P fertilizer at soil test rates, and the advantage of replacing monoculture wheat with pulse or oilseed crops grown in mixed rotations. MATERIALS AND METHODS Experimental Data Details of the design and management of this experiment have been reported (Campbell et al. 1983; Zentner and Campbell 1988; Campbell et al. 2004, 2005); therefore, only a brief review is presented here, together with a summary of some pertinent agronomic findings and some additional information and data specific to the objectives of this paper. The experiment was initiated in 1967 at the Agriculture and Agri-Food Canada Research Centre near Swift Current, Saskatchewan (50 17 N, W, and elevation 883 m), on slightly sloping land (<3%) that had been cropped using a F-W rotation with minimal fertilizer additions since The soil is a Swinton loam, an Orthic Brown Chernozem (Ayres et al. 1985), with organic C and N contents of 18 and 1.8 g kg 1 (0 15 cm depth), respectively, and a surface ph in water paste of 6.5. Twelve crop rotations were originally established on 81 plots in a randomized complete-block design with three replicates. In this paper we discuss nine of the rotations (Table 1). The wheat-lentil (Lens culinaris Medikus) (W- Lent) rotation was established in 1979 from two N and P fertilized Cont W systems that existed from 1967 to 1978, while the 6-yr F-W-W-W-W-W rotation was established in 1985 from two N and P fertilized continuous crop rotations (a) an Oat (Avena sativa L.) (hay)-w-w system and (b) a Flax (Linum usitatissimum L.)-W-W system, both of which existed from (Campbell et al. 1983). All phases of each rotation were present every year and each rotation was cycled on its assigned plots. Each plot was 10.5 m by 40 m. Commercial farm equipment was used to perform all field operations using stubble mulch tillage techniques to conserve as much surface crop residue as possible. The seedbeds for wheat and flax plots were typically prepared with one operation of a heavy-duty sweep cultivator with mounted harrows; in later years the flax plots also received a harrow-packing operation. For lentil, in years when a preemergent herbicide was soil incorporated, the seedbed

3 ZENTNER ET AL. ECONOMICS OF SPRING WHEAT PRODUCTION SYSTEMS IN THE SEMIARID PRAIRIE 29 Table 1. Crop rotations and fertilizer treatments Rotation sequence Fertilizer application Abbreviation Fallow-Wheat N and P F-W (N + P) Fallow-Wheat-Wheat N and P F-W-W (N + P) Fallow-Wheat-Wheat N only F-W-W (N only) Fallow-Wheat-Wheat P only F-W-W (P only) Fallow-Flax-Wheat N and P F-Flx-W (N + P) Fallow-Wheat-Wheat- Wheat-Wheat-Wheat z N and P F-W-W-W-W-W (N + P) Continuous wheat N and P Cont W (N + P) Continuous wheat P only Cont W (P only) Wheat-Lentil y N and P W-Lent (N + P) z Established in 1985 from N and P fertilized Oat(hay)-W-W and Flx-W-W systems. y Established in 1979 from two N and P fertilized Cont W systems. received a light discing followed by a cultivation and harrow-packing; in other years a shallow cultivation followed by harrow-packing was used. Crops were planted generally in early- to mid-may using a hoe press drill. Wheat was seeded at the recommended rate of 67 kg ha 1, flax at 31 kg ha 1, and lentil (large green) at kg ha 1. Recommended varieties were planted each year, but the cultivars changed as new ones became available (Campbell et al. 2004, 2005). The wheat seed was treated with a fungicide to control seed-borne and seedling diseases, while the lentil seed was- inoculated with an appropriate Rhizobium culture prior to planting. Fertilizer N and P were applied to crops in accordance with rotation specifications (Table 1) and the soil NO 3 -N (0 0.6 m depth) and soil-p ( m depth) levels in individual plots measured the previous fall (mid-october) (Campbell et al. 2004). Fertilizer N, as ammonium nitrate, was applied by broadcasting it in spring prior to seedbed preparation. From 1967 to 1990, we used N rates recommended by the soil testing laboratory at the University of Saskatchewan (Saskatchewan Soil Testing Laboratory 1990) with rates of N applied to bring the total mineral N level (soil test + fertilizer) to 65 kg ha 1 for wheat, 45 kg ha 1 for flax, and 22 kg ha 1 for grain lentil (assumes normal moisture conditions). In 1990, the soil testing laboratory recommendations for N were increased to 90 kg ha 1 of total N for wheat grown on fallow, 73 kg ha 1 for wheat grown on stubble, 62 kg ha 1 for flax grown on fallow, and were unchanged for grain lentil. Wheat grown on fallow (for treatments designated to receive N fertilizer) received about 8 kg N ha 1 yr 1 prior to 1991, and since then about 41 kg N ha 1 yr 1 due to the change in fertilizer guidelines and the more favorable growing season precipitation conditions that prevailed. Wheat grown on wheat stubble (for treatments designated to receive N fertilizer) received about 30 kg N ha 1 yr 1 prior to 1991 and about 50 kg N ha 1 yr 1 since then, while wheat grown on lentil stubble received 23 kg N ha 1 yr 1 from and about 39 kg N ha 1 yr 1 thereafter. Flax received an average of 6 and 11 kg N ha 1 yr 1 in the respective periods, while lentil received an average of about 14 kg N ha 1 yr 1. Phosphorus fertilizer (as monoammonium phosphate) was applied with the seed, with the designated treatments receiving 9 10 kg P ha 1 yr 1 Table 2. Summary of selected 2003 input costs and economic parameters Input item Cost Units Fuels Diesel 0.57 $ L 1 Gasoline 0.70 $ L 1 Fertilizers N - ammonium nitrate 0.78 $ kg 1 P 2 O $ kg 1 Herbicides z 2,4-D ester $ kg 1 Bromoxynil $ kg 1 Bromoxynil & MCPA ester (1:1) $ kg 1 Clodinafop-propargyl $ kg 1 Dicamba $ kg 1 Diclopfop methyl $ kg 1 Diclopfop methyl & bromoxynil (23:8) $ kg 1 Fenoxaprop-p-ethyl $ kg 1 Glyphosate $ kg 1 Glyphosate & dicamba (11:5) $ kg 1 Metribuzin $ kg 1 Sethoxydim $ kg 1 Sethoxydim & clopyralid & MCPA ester (9:1:5.6) $ kg 1 Tralkoxydim $ kg 1 Triallate $ kg 1 Trifluralin $ kg 1 Fungicides Chlorathalonil $ kg 1 Insecticides z Deltamethrin 1.73 $ g 1 Seed treatments and inoculants Carbathiin & thiram & lindane (8.9:10.1:12.9) 0.13 $ kg 1 Rhizobium 0.88 $ kg 1 Crop insurance premiums and (yield guarantees y ) Wheat on fallow - N & P fertilized (1562) $ ha 1 (kg ha 1 ) Wheat on fallow - N only or P only (1430) $ ha 1 (kg ha 1 ) Wheat on stubble - N & P fertilized 9.04 (1213) $ ha 1 (kg ha 1 ) Wheat on stubble - N only or P only 7.59 (912) $ ha 1 (kg ha 1 ) Flax on fallow (714) $ ha 1 (kg ha 1 ) Lentil on stubble (704) $ ha 1 (kg ha 1 ) Labor 9.00 $ h 1 Interest 8 % Other x $ ha 1 Machine Operations w Heavy-duty sweep cultivation (mounted harrow ) $ ha 1 Rodweed 6.34 $ ha 1 Disc $ ha 1 Broadcast 5.56 $ ha 1 Harrow-pack 7.51 $ ha 1 Land roll 7.56 $ ha 1 Hoe press drill $ ha 1 Spray (includes marker foam and water hauling) 8.30 $ ha 1 Swath 9.87 $ ha 1 Combine - wheat v $ ha 1 - flax v $ ha 1 - lentil v $ ha 1 Transport - field to farm to elevator v $ ha 1 z Costs are per unit of active ingredient. 70% yield coverage. x Includes land taxes, farm utilities and miscellaneous costs. w Includes fuel, oil, repairs, and machine overhead costs plus labor. v Costs are shown for a grain yield of 2500 kg ha 1.

4 30 CANADIAN JOURNAL OF PLANT SCIENCE Fig. 1. Effect of crop rotation and fertilizer on total wheat production for the and periods at Swift Current, Saskatchewan. in accordance with the general recommendations for the area and crop (Saskatchewan Agriculture 1988). Nitrogen in the P source was accounted for in the N rates cited. Weeds were controlled in-crop (as required) using the most common herbicides of the time and the full recommended application rates for the specific crops and area (Saskatchewan Agriculture Food and Rural Revitalization 2004). The continuous cropping systems required more use of non-selective herbicides than fallow-based rotations for periodic post-harvest control of quackgrass (Agropyron repens Beauv.). In early years, wheat typically received triallate (soil incorporated with seedbed tillage) for grassy weed control followed by bromoxynil plus MCPA applied in-crop for broadleaf weed control. More recently, diclofop methyl, tralkoxydim, clodinafop-propargyl, and/or bromoxynil plus MCPA were applied alone or in combination as required. Flax typically received diclopfop methyl, fenoxaprop-p-ethyl, sethoxydim, and/or bromoxynil plus MCPA depending upon the type and number of weeds present based on visual inspection of the plots. Lentil received trifluralin (spring applied and soil incorporated) in early years for grassy weed control; in later years sethoxydim was used. Metribuzin was applied to lentil in most years for broadleaf weed control. In 1982, the metribuzin destroyed the lentil crop, and in several other years short-term crop injury was observed with this herbicide. Since 1990, the metribuzin has been applied to lentil as a split application to minimize potential crop injury (Saskatchewan Agriculture, Food and Rural Revitalization 2004). Since the mid 1990s, lentil also received an application chlorathalonil for control of ascochyta blight (Ascochyta lentis) and anthracnose caused by Colletotrichum truncatum (Schw.). Crops were harvested at the full-ripe stage. Yield determinations were made by cutting a swath 5 m wide and 40 m long through the middle of the plot. The swath was left to air dry for 5 to 7 d to approximately 14% moisture content, after which the grain was harvested with a conventional combine equipped with an automated weighing system. Small 2.32-m 2 subplots were also hand-harvested from each plot and the grain analyzed for Kjeldahl N (Starr and Smith 1978). Grain protein content was taken as %N 5.7, and the values corrected to a constant moisture content of 13.5%. The straw was chopped and redistributed on the respective plots using chopper and spreader attachments on the combine. In the fall, after harvest, 2,4-D ester was applied to all plots to control winter annual weeds (no fall tillage was performed). Summerfallow plots received an average of four (range 2 to 5) tillage operations (using a cultivator or rodweeder) during the spring and summer periods, plus a fall application of 2,4-D ester to control weeds. Daily weather data were recorded at a meteorological station located 0.5 km west of the test site and are summarized in Campbell et al. (2005). Economic Analysis Costs of production and economic returns for each cropping system were determined annually using methods described by Zentner et al. (1990). Net return was defined as the income remaining after paying for all cash costs (i.e., seed,

5 ZENTNER ET AL. ECONOMICS OF SPRING WHEAT PRODUCTION SYSTEMS IN THE SEMIARID PRAIRIE 31 Table 3. Grain yields and grain protein concentrations by rotation phase and period at Swift Current, Saskatchewan Yield Protein y Yield Protein y Yield Protein y Rotation phase z Fert. (kg ha 1 ) (%) (kg ha 1 ) (%) (kg ha 1 ) (%) Grown on fallow F-(W) N + P 1898 ± ± ± ± ± ± 0.1 F-(W)-W N + P 1912 ± ± ± ± ± ± 0.1 F-(W)-W N only 1715 ± ± ± ± ± ± 0.1 F-(W)-W P only 1872 ± ± ± ± ± ± 0.2 F-(Flx)-W N + P 798 ± ± ± ± ± ± 0.2 F-(W)-W-W-W-W N + P NA NA 2668 x ± ± 0.2 NA NA Grown on stubble F-W-(W) N + P 1403 ± ± ± ± ± ± 0.2 F-W-(W) N only 1263 ± ± ± ± ± ± 0.2 F-W-(W) P only 1307 ± ± ± ± ± ± 0.2 F-Flx-(W) N + P 1376 ± ± ± ± ± ± 0.2 F-W-(W)-W-W-W N + P NA NA 1803 ± ± 0.5 NA NA F-W-W-(W)-W-W N + P NA NA 1774 ± ± 0.5 NA NA F-W-W-W-(W)-W N + P NA NA 1863 ± ± 0.5 NA NA F-W-W-W-W-(W) N + P NA NA 1883 ± ± 0.5 NA NA Cont (W) N + P 1354 ± ± ± ± ± ± 0.2 Cont (W) P only 1162 ± ± ± ± ± ± 0.2 (W)-Lent N + P NA NA 1824 ± ± 0.2 NA NA W-(Lent) N + P NA NA 1122 ± ± 0.2 NA NA z The rotation phase of interest is shown in parentheses. The ± values are the standard error of the means. y Corrected to 13.5% moisture. x Excludes 1985 when wheat grown on fallow was not yet in proper sequence. fertilizers, pesticides, machinery operation, crop insurance premiums, land taxes, interest, and miscellaneous expenses), labor, and ownership costs for machinery and grain storage; thus, it represents the residual return to management and equity in land. Net returns were computed and presented as annual values and as 18-yr mean values for the periods (previously analyzed, Zentner and Campbell 1988) and Riskiness of each cropping system was assessed using stochastic dominance analysis (Goh et al. 1989) to compare the probability distributions of net returns for groups of producers having low, medium, and high risk aversion as defined by Zentner et al. (1992). All purchased inputs and machine operations were valued and held constant at their 2003 cost levels (Table 2) (Saskatchewan Agriculture, Food and Rural Revitalization 2003a; University of Saskatchewan 2003). Participation in the Canada/Saskatchewan Crop Insurance Program was assumed to be at the 70% yield coverage level for all crops. Premium rates (at the base cost level) and payout criteria for Risk Area #10 of Saskatchewan were assumed (Table 2) (Saskatchewan Crop Insurance Corporation 2003). The analysis was also completed for the rotations assuming no participation in the all-risk crop insurance program to assess the effectiveness of this program in reducing the overall financial risk associated with use of the rotations. The research plot data were extrapolated to the farm-level using a 1295-ha representative farm with a typical complement of machinery and labor supply for each treatment. The net farm-gate prices for the grains (net of rail transportation and elevator handling costs) were taken at their respective 10-yr (1992/ /2002) mean values, namely $169 t 1 (standard deviation = $27 t 1 ) for wheat (13.5% protein), $266 t 1 (standard deviation = $47 t 1 ) for flax, and $334 t 1 (standard deviation = $48 t 1 ) for lentil (Saskatchewan Agriculture, Food and Rural Revitalization 2003b). The price for wheat was adjusted by treatment, replicate and year for grain protein content in accordance with the 2003 protein price schedule as established by the Canadian Wheat Board (Canadian Wheat Board 2003). The economic performance of the cropping systems was also evaluated for a range of product prices (representing two standard deviations lower to two standard deviations higher than their respective mean values) to test the sensitivity of the findings to changes in these price conditions. All economic results were expressed on a per hectare basis for the complete rotation systems, which includes the costs and returns for all cropped and summerfallow portions of each rotation, and for individual crops within each rotation treatment. The analysis was completed under the same economic assumptions for the full study period for the purpose of comparing the results from the recent 18- yr period ( ) with those reported earlier for the first 18-yr period ( ) (Zentner and Campbell 1988). All data were subjected to analysis of variance using a completely randomized block design with split plots. Rotations (or rotation-phase) were main plots and years were sub-plots (Gomez and Gomez 1984). All data were analyzed using the Proc GLM of SAS (SAS Institute, Inc. 1985). Significant differences among treatment means were determined by least significant difference (P = 0.10). RESULTS AND DISCUSSION Weather Conditions Growing season (May-August) precipitation (GSP) over the 36-yr period averaged 203 mm, which was near the long-

6 32 CANADIAN JOURNAL OF PLANT SCIENCE Table 4. Effect of crop rotation on total production costs by year and period Year Mean Mean Mean Crop rotation Fertilizer ($ ha 1 ) F-W N + P ± ± ± 2 F-W-W N + P ± ± ± 2 F-W-W N only ± ± ± 2 F-W-W P only ± ± 2 178± 3 F-Flx-W N + P ± ± ± 2 F-W-W-W-W-W N + P ± 4 NA NA Cont W N + P ± ± ± 5 Cont W P only ± ± ± 3 W-Lent N + P ± ± 7 z 292 ± 5 y Mean SEM LSD Rot Year (P < 0.10) = 12 z y Table 5. Effect of crop rotation on resource expenditures for the and periods F-W F-W-W F-W-W F-W-W F-Flx-W F-W-W-W-W-W Cont W Cont W W-Lent (N + P) (N + P) (N only) (P only) (N + P) (N + P) (N + P) (P only) (N + P) Resource category z ($ ha 1 ) Seed NA Fertilizer NA Pesticides NA Fuel & oil NA Repairs NA Crop insurance NA Other y NA Interest NA Labor NA Machine overhead NA Total cost NA SEM (total cost) NA z only. y Includes land taxes, farm utilities and miscellaneous costs.

7 ZENTNER ET AL. ECONOMICS OF SPRING WHEAT PRODUCTION SYSTEMS IN THE SEMIARID PRAIRIE 33 term (106-yr) mean of 210 mm for this region (Campbell et al. 2005). During the first 18 yr ( ) of the experiment, GSP averaged 176 mm or 16% lower than the longterm mean, and it was less than 80% of normal in 9 of 18 yr. In contrast, during the latter 18-yr period ( ), GSP averaged 230 mm and was near-normal to well-above normal in 13 of these years. There were 6 yr with severe drought conditions (1967, 1973, 1984, 1985, 1988, and 2001), which were equally distributed between the two periods. Thus overall, represents a period of generally favorable growing conditions for annual crops, compared with the more typical dry conditions experienced during the first 18 yr. Grain Yield and Protein Concentration As reported by Campbell et al. (2005), yields of N and P fertilized crops averaged 30 to 45% higher during than in (Table 3), with yields in the later period also being above the recent historical average for the Brown soil zone (Saskatchewan Agriculture, Food and Rural Revitalization 2003b). These relatively high yields were attributed to a combination of the more favorable weather conditions, higher rates of N fertilizer that were applied to crops since 1991 (Campbell et al. 2004, 2005), and to improved crop varieties and production technologies. Yields of N and P fertilized wheat grown on fallow during averaged 44% higher than comparable yields of wheat grown on stubble, reflecting the higher available soil water reserves under fallow (Campbell et al. 2004); during well-fertilized fallow wheat yields averaged 36% higher than comparable stubble wheat yields. Rotation length or cropping frequency had no effect on the yields of well-fertilized wheat grown on fallow or on stubble, as was also reported for the first 18-yr period (Zentner and Campbell 1988). Further, our data showed no significant yield advantage to growing wheat in mixed rotations with flax (Campbell et al. 2005) or lentil (Zentner et al. 2001) as compared with monoculture wheat, although there was a tendency for wheat grown after flax to yield slightly more than for wheat grown after wheat in the period. This latter effect may be due to the greater soil NO 3 -N found in the lower soil depths after flax (Campbell et al. 2005). The general lack of a significant rotational yield benefit with these crops was attributed to the fact that weeds and diseases are rarely a major problem under our semiarid growing conditions (Campbell et al. 2005). However, other short-term studies conducted in this same soil-climatic region during the 1990s have reported significant rotational benefits from growing wheat and durum (Triticum turgidum L.) on pulse and oilseed stubble (Miller et al. 2002, 2003; Gan et al. 2003). Applying recommended rates of N and P fertilizer to F- W-W, compared with applying N fertilizer alone (i.e., the response to the addition of P fertilizer), increased wheat yields during the period by an average of 22% when the crop was grown on fallow, and by 15% when it was grown on stubble (Table 3); this compares to yield increases from P fertilization for fallow and stubble wheat of about 11% during the drier period. Similarly, applying N and P fertilizer versus applying P fertilizer alone (i.e., response to N fertilizer) increased yields of wheat grown on fallow by 9% and increased stubble wheat yields by 48% during the period; in the drier 18-yr period the yield responses from N fertilization averaged 2% (non-significant) for wheat on fallow, and 7 and 17% for wheat grown on stubble in the F-W-W and Cont W rotations, respectively. These relative N responses reflect the observation that soil N is only occasionally deficient for wheat grown on fallow compared with when wheat is grown on stubble where it is deficient in most years (Campbell et al. 2005). In contrast, when the yields from the well-fertilized monoculture wheat systems were expressed as total grain production, the general rankings of the rotations were reversed (Figure 1). Total wheat production over the period was highest for Cont W (N + P) (18-yr total yield of kg ha 1 ) and lowest for F-W (N + P); the two under-fertilized F-W-W rotations, and Cont W (P only) had about 31% less total production than Cont W (N + P). The F-W-W (N + P) rotation produced 18% less wheat, while F-W-W-W-W-W (N + P) produced 9% less wheat than Cont W (N + P) over this period. Although total wheat production for the N and P fertilized systems averaged about 35% lower during than in , the relative productivity among these rotations were generally similar. In contrast, the relative productivity of the cropping systems that received N only or P only fertilizer were higher in than in (compared with the N and P fertilized system), reflecting the lower yield penalty incurred from not applying the recommended rates of both N and P fertilizer in the earlier period when moisture conditions were less favorable. Flax yields averaged 1160 kg ha 1 during (Table 3), similar to the historical average yield of flax for this region (Saskatchewan Agriculture, Food and Rural Revitalization 2003b), but 45% greater than for the period (Table 3). Lentil yields averaged 1122 kg ha 1 over the recent 18-yr period, comparable to the 10-yr historical average yield of lentil for Saskatchewan (Saskatchewan Agriculture, Food and Rural Revitalization 2003b). Grain protein concentrations of wheat were typically lower during than in , especially for stubble wheat, reflecting yield dilution by higher yields due to the more favorable growing conditions in the later period (Table 3). Grain protein concentrations tended to be higher when wheat was grown on fallow than on stubble, with the exception of wheat grown after flax or grain lentil, in part reflecting the higher available soil nitrates in fallow compared with stubble land (Campbell et al. 2005). The tendency for higher grain protein in wheat following flax compared with the monoculture wheat systems that received N fertilizer at seeding, likely reflects the higher soil NO 3 -N located in the cm depth under the flax system because of its shallower rooting depth (Campbell et al. 2005), while the grain protein advantage for wheat after lentil was attributed to better synchrony between N avail-

8 34 CANADIAN JOURNAL OF PLANT SCIENCE ability and N uptake by wheat and the contribution of N 2 fixed by the lentil in the W-Lent rotation compared with the monoculture wheat systems (Zentner et al. 2001). Production Costs and Breakeven Conditions Production costs (i.e., cash costs, labor, and machine overhead) for the cropping systems increased with cropping frequency, the application of N and P fertilizer, and the inclusion of lentil in the rotation, and decreased with the substitution of flax for wheat grown on fallow (Table 4). Total costs for the rotations averaged $10 30 ha 1 yr 1 higher during compared with the first 18-yr period (Table 4), reflecting the higher rates of N fertilizer applied since 1991, and greater herbicide requirements due to the more favorable growing conditions in the last 18 yr (Table 5). During the period, total costs for the N and P fertilized systems were lowest for F-W at $176 ha 1 yr 1 and highest for W-Lent at $296 ha 1 yr 1 (Table 4). Production costs for F-W-W (N + P) averaged $34 ha 1 yr 1 higher (19% more) than for F-W (N + P), while costs for F-W-W- W-W-W (N + P) averaged $64 ha 1 yr 1 higher (36% more) and costs for Cont W (N + P) averaged $102 ha 1 yr 1 higher (58% more). Replacing wheat grown on fallow with flax in a 3-yr rotation lowered production costs by an average of $19 ha 1 yr 1 in this period, reflecting savings in fertilizer and pesticide costs for the flax system (Table 5). In contrast, replacing wheat with lentil increased total costs by $18 ha 1 yr 1 compared with Cont W. This was due to higher crop insurance, seed and pesticide costs for lentil, and despite the lower N fertilizer costs for the lentil system (Table 5). Withholding N fertilizer reduced annual production costs for the rotation systems by $24 ha 1 for F-W-W and by $46 ha 1 for Cont W during the period (Table 4 and Table 5). Similarly, withholding P fertilizer in a F-W-W rotation reduced annual production costs by an average of $18 ha 1 in this period (Table 4). By comparison, Zentner et al. (2006) reported for an experiment being conducted on adjacent land on this same soil type, that the 2003-level production costs for N and P fertilized F-W-W, and Cont W, but managed using conservation tillage practices, averaged $229 and $285 ha 1 yr 1, respectively, over the period. The higher costs for F-W-W reported in the conservation tillage study reflect the increased costs associated with controlling weeds on fallow areas with (mainly) herbicides versus using primarily mechanical tillage. As reported by Zentner et al. (2002), costs for tilled fallow in the semiarid Brown soil zone are relatively low because of the few tillage operations that are required during the 21-mo fallow period. Although minimum- tillage and zero-tillage managed fallow areas do provide substantial savings in machine operation and labor (compared with conventional till), these are more than offset by higher expenditures for herbicides. In contrast, there is often little difference in total production costs between conventional and conservation tillage management for continuously cropped systems in this dry region, reflecting the small difference in cost between a single preseeding tillage operation to control weeds and prepare the seedbed with Table 6. Effect of crop rotation on unit costs of wheat production by period Crop rotation Fertilizer ( $ t 1 ) F-W N + P F-W-W N + P F-W-W N only F-W-W P only F-Flx z -W N + P F-W-W-W-W-W N + P 147 NA NA Cont W N + P Cont W P only W-Lent y N + P x 155 w z The unit cost for flax production averaged $347 t 1 during , $260 t 1 during , and $296 t 1 during y The unit cost for lentil production averaged $443 t 1 during , $293 t 1 during , and $331 t 1 during x w conventional tillage management, and one preseeding herbicide application to control weeds with zero tillage management (Zentner et al. 2002). Similarly, Walburger et al. (2004) reported for a Brown Chernozemic soil at Bow Island, Alberta, that the costs for seed, fertilizer, herbicides, fuel, and machine repair under conventional tillage management in the year 2000 averaged $103 for F-W, $125 for F- W-W, $114 for F-Flx-W, $168 for Cont W (all cropping systems were fertilized with 40 kg N ha 1 and 8.6 kg P ha 1 yr 1 ), and $148 ha 1 yr 1 for W-Lent (fertilized with 8.6 kg P yr 1, but no N). In our conventionally tilled study, expenditures for these same resources during the period averaged $89, $113, $97, $161 and $165 ha 1 yr 1 for well-fertilized F-W, F-W-W, F-Flx-W, Cont W, and W- Lent, respectively (Table 5). The unit cost for producing wheat and other grains as influenced by cropping system, or alternatively, the breakeven prices needed to recover production costs are shown in Table 6. When breakeven prices are lower than the market price for the products, producers make a profit. For example, the unit cost for wheat grown on fallow in the F- W (N + P) rotation averaged $159 t 1 during and $138 t 1 during , both of which were lower than the average market price for wheat (i.e., $170 t 1 at 13.6 % protein content). This bodes well for the potential of earning a positive net return from producing wheat in this manner. Overall, the breakeven prices for wheat were lower during than in the period and were greater for Cont W than for F-W or F-W-W. Further, the breakeven prices for wheat were lower when recommended rates of N and P fertilizer were applied as compared with withholding nutrients, especially under the more favorable weather conditions of the period. The breakeven price for flax averaged $347 t 1 during and $260 t 1 during , while the breakeven prices for lentil averaged $443 t 1 in and $293 t 1 in the following 18-yr period. The high breakeven price for lentil during reflects the crop failure in 1982 due to herbicide damage and the low yields in several other years due to

9 ZENTNER ET AL. ECONOMICS OF SPRING WHEAT PRODUCTION SYSTEMS IN THE SEMIARID PRAIRIE 35 drought conditions (Campbell et al. 1992). In our companion study at Swift Current (Zentner et al. 2006), we reported breakeven prices for wheat grown on N and P fertilized fallow and stubble using conservation tillage management to be $159 t 1 and $150 t 1, respectively, during In the more moist Dark Brown soil zone at Scott, Saskatchewan, Zentner et al. (1996) reported that breakeven prices to recover cash costs (excluding labor and machinery overhead costs) for N and P fertilized wheat production averaged $64 t 1 for F-W, $74 t 1 for F-W-W, and $97 t 1 for Cont W based on 1994 input costs. Unit production costs for the complete rotation systems evaluated by Walburger et al. (2004) were considerably lower than those reported in our current study because cost items such as land taxes, farm utilities, and miscellaneous costs were not included in their analysis. Net Returns At the base grain price levels, the mean net returns for the N and P fertilized rotations [i.e., income (including payouts from the all-risk crop insurance program) remaining after paying for production costs] were highest for W-Lent ($93 ha 1 yr 1 ) and lowest for F-Flx-W ($38 ha 1 yr 1 ) (Table 7). Net returns for well-fertilized F- W, F-W-W, F-W-W-W-W-W, and Cont W during this same period were similar, averaging about $52 ha 1 yr 1 or 44% less than for W-Lent. The influence of cropping frequency on mean net returns contrasts with those reported for these cropping systems during the drier period (Zentner and Campbell 1988; Table 7) when F-W and F-W- W generally produced the highest net returns, and Cont W and F-Flx-W earned significantly lower (and often negative) net returns. Further, the mean net returns for F- W-W, and to lesser extent Cont W, were higher than those we reported for these cropping systems in our companion experiment that used conservation tillage and snow management practices (Zentner et al. 2006). In that study, conducted in , net returns for the same product price and input cost conditions as used in the current analysis averaged $18 ha 1 yr 1 for F-W-W (N + P) and $41 ha 1 yr 1 for Cont W (N + P). This difference in performance of the rotations between studies directly reflects the higher yields, higher grain protein content, and lower production costs for wheat grown on fallow, and the higher grain protein content for wheat grown on stubble when conventional tillage was employed compared with when conservation tillage management was used. Although not analyzed statistically, yields of wheat grown on fallow during averaged 280 kg ha 1 higher and grain protein content averaged 0.6 percentage units higher with conventional tillage compared with conservation tillage practices. These advantages in yield and grain protein for wheat grown on fallow could not be explained by differences in spring soil water reserves between the two experiments (which averaged 255 and 280 mm/120 cm soil depth for conventional-till and conservation-till fallow, respectively). Nor could it be credited to differences in rates of fertilizer N applied (which averaged 29 and 37 kg ha 1 yr 1 for conventional and conservation tillage, respectively), nor to differences in spring soil N lev- Table 7. Effect of crop rotation on net returns by year and period for base price assumptions Year Mean Mean Mean Crop rotation Fertilizer ($ ha 1 ) F-W N + P ± 6 23 ± 4 37 ± 4 F-W-W N + P ± 7 23 ± 5 38 ± 5 F-W-W N only ± 7 18 ± 5 26 ± 4 F-W-W P only ± 6 19 ± 6 20 ± 4 F-Flx-W N + P ± 7 3 ± 5 18 ± 5 F-W-W-W-W-W N + P ± 8 NA NA Cont W N + P ± 12 4 ± 6 26 ± 7 Cont W P only ± 8 17 ± 6 20 ± 5 W-Lent N + P ± 12 7 ± 13 z 72 ± 10 y Mean SEM LSD Rot Year (P < 0.10) = 29 z y

10 36 CANADIAN JOURNAL OF PLANT SCIENCE Table 8. Effect of price changes on net returns of crop rotations by 18-yr period F-W F-W-W F-W-W F-W-W F-Flx-W F-W-W-W-W-W Cont W Cont W W-Lent Grain price Period (N + P) (N + P) (N only) (P only) (N + P) (N + P) (N + P) (P only) (N + P) ($ ha 1 ) Base ± 4 23 ± 5 18 ± 5 19 ± 6 3 ± 5 NA 4 ± 6 17 ± 6 NA ± 6 52 ± 7 34 ± 7 20 ± 6 38 ± 7 56 ± 8 49 ± ± 8 93 ± 12 High wheat ± 6 80 ± 7 69 ± 8 74 ± 8 21 ± 6 NA 63 ± 9 41 ± 9 NA ± ± ± ± 9 72 ± ± ± ± ± 14 Low wheat ± 3 34 ± 3 33 ± 3 35 ± 4 26 ± 4 NA 55 ± 4 76 ± 4 NA ± 3 26 ± 4 30 ± 4 43 ± 4 5 ± 6 29 ± 5 45 ± 7 84 ± 5 46 ± 10 High flax ± 4 23 ± 5 18 ± 5 19 ± 6 21 ± 6 NA 4 ± 6 17 ± 6 NA ± 6 52 ± 7 34 ± 7 20 ± 6 73 ± 9 56 ± 8 49 ± ± 8 93 ± 12 Low flax ± 4 23 ± 5 18 ± 5 19 ± 6 27 ± 4 NA 4 ± 6 17 ± 6 NA ± 6 52 ± 7 34 ± 7 20 ± 6 3 ± 6 56 ± 8 49 ± ± 8 93 ± 12 High lentil ± 4 23 ± 5 18 ± 5 19 ± 6 3 ± 5 NA 4 ± 6 17 ± 6 NA ± 6 52 ± 7 34 ± 7 20 ± 6 38 ± 7 56 ± 8 49 ± ± ± 15 Low lentil ± 4 23 ± 5 18 ± 5 19 ± 6 3 ± 5 NA 4 ± 6 17 ± 6 NA ± 6 52 ± 7 34 ± 7 20 ± 6 38 ± 7 56 ± 8 49 ± ± 8 45 ± 9 els in the 0 60 cm depth (which averaged 64 and 66 kg ha 1 for the respective management methods). However, spring soil NO 3 -N in the cm depth averaged 22 kg ha 1 higher for conventional-till than for the conservation-till managed fallow, suggesting that during the 21-mo fallow period more N was mineralized under conventional tillage and also that more of the N being mineralized was leached below the soil test depth (i.e., 0 60 cm) under conventional tillage management; further, that this extra N located at depth may have contributed to the higher grain yields and protein content of fallow wheat grown on conventional tillage (McConkey et al. 2003). For wheat grown on stubble in the F-W-W (N + P) rotation, the advantage in grain protein under conventional tillage management likely also reflects the higher available N levels in the cm soil depth (compared with conservation tillage management), since this N is well-positioned to increase grain protein (by up to 1 full percentage point in the current study) because it is taken up by the plants later in the growing season (near anthesis) when it influences grain protein more than grain yield (Selles et al. 1997). This extra soil N at depth is less evident for the Cont W (N + P) systems between the two experiments, likely reflecting less opportunity for any mineralized N to leach to depth under the normally dry soil conditions associated with continuous cropping (compared with rotations that include fallow), regardless of the tillage method used. This may also reflect less opportunity to mineralize N in the cold fall-to-spring period and with a difference of only one tillage operation between the two management methods when continuous cropping. The economic value of applying N and P fertilizer in accord with soil test recommendations was apparent in our results for (Table 7). Within the F-W-W systems, the application of both N and P fertilizer increased the 18-yr mean net returns by $18 ha 1 yr 1 compared with application of N only, but by $32 ha 1 yr 1 compared with application of P only, suggesting that producers who find it necessary to reduce inputs in such systems should reduce P before reducing N. For the Cont W systems, withholding N fertilizer reduced net returns by $71 ha 1 yr 1 in the period. The benefit of N and P in enhancing net returns was considerably greater in the more humid period than in the drier period. Most of this difference was likely due to the advantage in water more so than the increase in N applied because Campbell et al. (1997) have shown that the influence of water in determining wheat yields is about four times that of fertilizer N in this soil zone. However, other factors such as improved plant genetics and more effective and lower cost herbicides may have also contributed to the difference in economic response to fertilizers between study periods. On an annual basis, net returns were lowest and negative for most cropping systems in the drought years of 1985, 1988 and 2001, even with substantial payouts from the allrisk crop insurance program (Table 7). Net returns were highest for the W-Lent (N + P) rotation in 12 of the last 18 yr, while Cont W (N + P) produced the highest net returns in 3 of 18 yr and F-W (N + P) in 2 of 18 yr. The size and frequency of economic losses were lowest for F-W (N + P), and when losses occurred they generally increased with cropping intensity. The application of recommended rates of N and P fertilizer to F-W-W significantly increased net returns in 12 of 18 yr compared with withholding nutrient application; it generated similar net returns in 4 other years and lower net returns in only 2 yr. Within the Cont W systems, the application of recommended rates of N and P fertilizer significantly increased net returns (compared with P only) in 15 of 18 yr. Similar trends were observed for the Cont W systems during the period as in , but for the F-W-W systems the application of