Non-Peer ReviewedThe benefit of standing stubble for wheat and pulse growth and yield is dependent upon the height of the stubble. Taller stubble traps more snow and creates a better microclimate for seedlings growth than short or cultivated stubble. Since information on the effect of stubble management on the in-crop microclimate of canola was lacking, a three year field study was conducted at Swift Current. Short (15cm) and tall stubble (30cm) effect on microclimate and seed yield were compared with that of cultivated stubble. The microclimate parameters included wind velocity, soil, air, and plant temperatures, solar radiation, and relative humidity. Microclimate observations indicated lower wind speed near the soil surface and lower soil temperatures in tall compared to cultivated stubble. Surprisingly, the stem temperature of canola seeded in tall stubble was higher than cultivated stubble. Biomass production and water use efficiency increased for tall standing stubble compared to cultivated stubble. Tall stubble increased mean seed yield by 9 and 19% compared to short and fall cultivated plots, respectively. The results indicated that a combination of improved microclimate was responsible for the yield increase

Angadi, S.V.

Cutforth, H.W.

McConkey, B.G.

English

eCommons@USASK

Stubble and seeding management to improve microclimate and seed yield of canola

University of Saskatchewan Research Archive

Stubble and Seeding Management to Improve Microclimate andSeed Yield of CanolaS.V. Angadi*, H.W. Cutforth and B.G. McConkeySemiarid Prairie Agricultural Research Centre, Swift Current, SK S9H 3X2(*Ph# 306-778-7276     email:angadis@em.agr.ca)Key Words: Tall Stubble, Microclimate, Temperature, Wind, Seed YieldAbstractThe benefit of standing stubble for wheat and pulse growth and yield is dependent upon the heightof the stubble. Taller stubble traps more snow and creates a better microclimate for seedlings growththan short or cultivated stubble. Since information on the effect of stubble management on the in-crop microclimate of canola was lacking, a three year field study was conducted at Swift Current.Short (15cm) and tall stubble (30cm) effect on microclimate and seed yield were compared with thatof cultivated stubble. The microclimate parameters included wind velocity, soil, air, and planttemperatures, solar radiation, and relative humidity. Microclimate observations indicated lower windspeed near the soil surface and lower soil temperatures in tall compared to cultivated stubble.Surprisingly, the stem temperature of canola seeded in tall stubble was higher than cultivated stubble.Biomass production and water use efficiency increased for tall standing stubble compared tocultivated stubble. Tall stubble increased mean seed yield by 9 and 19% compared to short and fallcultivated plots, respectively. The results indicated that a combination of improved microclimate wasresponsible for the yield increase.IntroductionStanding stubble increases snow trapping compared to conventional fallow. The amount of snowtrapped is directly proportional to stubble height. Therefore, the practice of using taller standingstubble compared to cultivated stubble can increase the water supply to the crops.Tall standing stubble reduces wind speed, solar radiation reaching the soil surface and maintains soiltemperature cooler than fallow (Cutforth and McConkey 1997). The altered energy balance reducedwater lost by evaporation. The major changes in microclimate are noticed early in the growingseason, when the crop canopies are small and cannot regulate evaporation loss on their own. The microclimate also has direct effects on the crop (Cutforth and McConkey 1997). Compared tocultivated stubble, there are several reasons why evaporation of water from tall stubble treatmentsis reduced , two of which are reduced turbulent air mixing due to reduced wind velocity and reducedsolar radiation. However, while evaporation is reduced, plant photosynthesis is not. Greater biomassaccumulation in tall stubble compared to cultivated/fallow plots has been reported (Cutforth andMcConkey 1997). Compared to cultivated stubble treatments, the cumulative result of allmicroclimatic alterations by tall stubble was to increase yield of wheat and pulses at Swift Current.No information is available on the benefit of tall stubble for canola. Therefore, a large scale field trialwas planned with the following objectives: 1) To study the effect of stubble management onmicroclimate under a canola canopy, 2) To determine the stubble management effect on canola yieldand water use efficiency.Materials and MethodsA field study was conducted on a Swinton loam soil (Orthic Brown Chernozem) (Ayres et al. 1985)at the Agriculture and Agri-Food Canada, Semiarid Prairie Agricultural Research Centre (SPARC),Swift Current for three seasons (1998-1999, 1999-2000 and 2000-2001). The plot size was 15m x45m. A Glyphosate tolerant Argentine canola cv. ‘Arrow’ was seeded with a Flexicoil 5000 Airseeder with Flexi-Coil “Stealth” knives (Flexi-Coil Ltd, Saskatoon, SK, S7K 3S5) at 23-cm rowspacing. A seeding rate of 9.5 kg ha-1 was used to attain an acceptable stand of canola. Fertilizer ratewas 84 kg N ha-1, 22 kg P ha-1 and 22 kg S ha-1, of which 78 kg N and all of S was broadcasted in thespring and the remaining N and all P was mid row banded at seeding. Post emergent Glyphosateapplications kept the experimental area weed free.Three stubble heights (Tall, $30 cm; Short, 15 cm; and cultivated) were established in the fall.Stubble treatments were imposed on wheat grown on fallow, which was harvested using a headerequipped combine to leave stubble taller than 30. The fall cultivated plot was slowly (<5 km h-1)worked with a tandem disc followed by harrow-packers. About one-half of the standing stubble wasburied with the remaining residue lying flat on the soil surface. The short stubble (15 cm high) in fallwas deployed by cutting the tall stubble with an haybine without windrowing.The microclimate measurements were restricted to one replication in each year. Soil temperatureswere measured with thermistors at 0.05, 0.10 and 0.30 m depths. Air temperatures were measuredwith double shielded and passively aerated copper-constantan thermocouples at 0.15, 0.50 and 1.00m above ground. Wind velocity at 0.15, 0.50, 1.00 and 2.00 m above surface was measured withanemometers (Wind Sentry and Gill 3 Cup anemometers, RM Young Company, Traverse City, MI).Solar radiation above the canopy (only in one plot) and solar radiation reaching the soil surface(approximately 7cm above the ground) were measured using 1 m long tube solarimeters (“Monteithpattern” tube solarimeter, Delta-T Devices Ltd. Cambridge, UK). Temperature measurements werereplicated at 3 to 4 locations within the plot. Wind velocity and solar radiation readings were madeat only one place. Before harvest, 1.82 m row lengths from each quarter were hand harvested to measure biomassproduction. Seed yields were measured with a full-size MF 550 combine (AGCO Corporation, 4205River Green Parkway, Duluth, GA 30096) after windrowing; the  middle swath in each plot (5.5mx 18m) was used for seed yield estimation. Water use efficiency was calculated as the amount ofwater used to produce a unit of seed.Results and DiscussionMicroclimateAmong the microclimatic parameters measured, soil temperature at 5 cm depth, wind velocity at 15cm height and solar radiation at ground level were significantly influenced by stubble height. Theprevious results indicate that the above parameters may have the greatest effect on transpiration,evaporation and water use efficiency (Cutforth and McConkey 1997).The horizontal wind speed at 2m had a significant role in modifying the effect of stubblemanagement on wind speed near the soil surface (Fig.1). At low wind speed (<5 m s-1), stubblemanagement had no effect on wind profile. As the wind velocity increased to moderate levels (5 to15 m s-1), tall stubble reduced wind speed closure to soil surface more than cultivated or shortstubble. At high wind speed (>15 m s-1), the efficiency of tall stubble to reduce wind speed furtherimproved and short stubble also had lower wind speed than cultivated plot. This suggests that theefficiency of standing stubble in reducing wind speed close to soil surface increases with stubbleheight and prevailing wind speed. The temperature profiles indicated higher soil temperature under cultivated conditions compared tostubble conditions during the growing season (data not presented). However, when temperaturerange was compared, the cultivated plot had a wider range than stubble plots (Fig. 2). Again,comparing the temperature profile at different wind speeds indicated that when wind speed at 2mis low, the air temperature range at 15 cm height widened in the order of short>tall>cultivatedstubble. The soil temperature also showed similar trends, although the magnitude was small. Theeffect of stubble management on soil or air temperature was maximum close to the soil surface. Asthe wind speed increased, the effect of stubble management on the temperature profile was reduced.This suggests that the effect of stubble management is only observed in the absence of convectiveenergy.Plant TemperaturePlant temperature was measured by inserting a small thermocouple into the stem of canola seedlingsat the10-15 cm height. Plants in tall stubble were warmer than plants in cultivated plots (Fig. 3). Theeffect was more significant when the solar radiation levels were high. Under, cloudy conditions theeffect was reduced significantly.Effect on Crop Growth and YieldStubble management had a significant effect on the biomass production (Table 1). Comparing across2 years, tall stubble plots tended to produce the most biomass, while the biomass from the shortstubble treatments was intermediate to tall and cultivated stubble. Visual observations indicated thatearly growth of canola in tall stubble was better than in cultivated stubble, which supported the earlydevelopment of wheat in a tall stubble of corn (Sharratt, 2002).Similar to biomass, seed yield was greatly influenced by stubble management and seedingmanagement. Pooled over two years, tall stubble treatment produced 9 and 19% higher seed yieldcompared to short and cultivated plots. Short stubble plots were statistically similar to tall stubbleor cultivated plots. Thus, the improved microclimate under tall stubble enabled canola to use watermore efficiently to produce higher yields compared to cultivated plots.AcknowledgmentsThe research was financed by Saskatchewan Canola Development Commission, SaskatchewanAgriculture Development Fund and AAFC-Matching Investment Initiative. We also thank DougJudiesch, Don Sluth, Evan Powell, Jason Newton and other summer students for technical help.ReferencesCutforth, H.W. and B.G. McConkey. 1997. Stubble height effects on microclimate, yield and wateruse efficiency of spring wheat grown in a semiarid climate on the Canadian Prairies. Can.J. Plant Sci. 77:359-366.Sharratt B.S. 2002b. Corn stubble height and residue placement in the northen US corn belt I. Springmicroclimate and wheat development. Soil Till Res. 64:243-252.Table 1 Effect of stubble and seeding management on mean biomass production and seed yieldof Argentine canola (cv. Arrow) during 1999 and 2000 at Swift Current.Treatments SeedingLate Fall Early Spring Late Spring MeanBiomass (kg ha-1)Tall Stubble 7995 6621 5314 6643aShort (Fall) 7902 6639 5061   6634abCultivated (Fall) 7661 5897 4735 6097bMean   7852a   6386b   5035cSeed Yield (kg ha-1)Tall Stubble 2201 1823 1548 1857aShort (Fall) 1952 1677 1480   1703abCultivated (Fall) 1750 1537 1388 1558bMean   1968a   1679b   1472cFig. 2 Effect of stubble management on the soil and air temperature profiles in the early stages ofcanola at low (<5 m s-1), moderate (5-15 m s-1) and high (>15 m s-1) wind velocities measured 2m above the soil surface at Swift Current in 2000.Fig. 1 Effect of stubble management on the wind profiles in the early stages of canola at low (<5m s-1), moderate (5-15 m s-1) and high (>15 m s-1) wind velocities measured 2 m above the soilsurface at Swift Current in 2000.Fig 3.  Effect of tall and cultivated plots on canola plant temperature on three contrasting days atSwift Current in 2001.

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Stubble and seeding management to improve microclimate and seed yield of canola

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