KENT A MCVAYCROPPING SYSTEMS SPECIALIST

SOUTHERN AG RESEARCH CENTERMONTANA STATE UNIVERSITY

Crop Rotation Benefits

Harvested biomass production is a function of:

Energy InputEnergy captureLosses to competitionHarvest loss

Energy Input

All energy comes from the sun

Efficiency of energy conversion to biomass is dependent on crop management

C4 vs C3 Corn vs wheat

Grass vs legume Barley vs pea

So what is the optimum system for converting energy into biomass?

Full canopied forests, like this

Or Native rangeland

These convert a large portion of the energy received into biomass

Cropland Captures a Fraction of Total Energy

Although silage corn comes close !

So would sugarcane

www.farmphoto.com

What about Montana?

Rainfall limits production potentialAverage growing season limits most

production to C3 metabolism: wheat, barley, peas, canola

It will be hard to compete head to head against other less stressful environments. Targeting markets is a good idea e.g. high protein wheat Specialty crops like camelina for special purpose

industrial oils, or food grade oils, or pharmaceuticals Crops that have multiple markets. Peas for human or

animal consumption

Crop Rotation Benefits

Usually a positive yield responseChance to use alternate herbicides

Cleans up some weed problems

Disease pressure can be reducedIncreases diversity

Spreads out planting and harvesting dates More commodities to sell

Rotation Yield Benefits

Tanaka et al. 1999. Agron J. 97:385-390

Mandan, ND 1999

Previous crop Canola CrambeDry

bean Dry pea FlaxSaf-

flower Soy-beanSun-

flowerSpring wheat Barley

Canola

Crambe

Dry bean

Dry pea

Flax

Safflower

Soybean

Sunflower

Spring wheat

Barley

Year 1

Year 2

Rotation Yield Benefits

Tanaka et al. 1999. Agron J. 97:385-390

Mandan, ND 1999

Previous crop Canola CrambeDry

bean Dry pea FlaxSaf-

flower Soy-beanSun-

flowerSpring wheat Barley

----------------------------------------------- lbs / acre ------------------------------------------------------------

Canola 1413 1688 1241 2335 1639 1012 2032 1597 3591 4680

Crambe 1290 1769 968 2148 1605 869 2039 1738 3217 4981

Dry bean 1400 1559 1175 2550 1521 888 2237 1609 3308 4189

Dry pea 1530 2362 1216 2581 1430 1042 2112 1768 3114 4674

Flax 1543 1791 1131 2660 690 597 1995 769 3651 4617

Safflower 1220 1518 816 2532 1387 458 1735 1096 3031 4579

Soybean 1239 1649 1098 2300 1752 886 2501 1498 3466 4363

Sunflower 1363 1763 989 2610 1625 760 1951 1306 3388 4852

Spring wheat 1312 1879 758 3045 1571 1026 1844 1499 3428 4728

Barley 1480 2025 1332 2549 1641 1106 2090 1758 3385 4482

Rotation Yield Benefits

Mandan, ND 1999

Previous crop Canola Crambe

Dry bean

Dry pea Flax

Saf-flower

Soy-bean

Sun-flower

Spring wheat Barley

Rot. Benefit

Canola 1.00 0.95 1.06 0.90 2.38 2.21 0.81 1.22 1.05 1.04 1.26

Crambe 0.91 1.00 0.82 0.83 2.33 1.90 0.82 1.33 0.94 1.11 1.20

Dry bean 0.99 0.88 1.00 0.99 2.20 1.94 0.89 1.23 0.96 0.93 1.20

Dry pea 1.08 1.34 1.03 1.00 2.07 2.28 0.84 1.35 0.91 1.04 1.29

Flax 1.09 1.01 0.96 1.03 1.00 1.30 0.80 0.59 1.07 1.03 0.99

Safflower 0.86 0.86 0.69 0.98 2.01 1.00 0.69 0.84 0.88 1.02 0.98

Soybean 0.88 0.93 0.93 0.89 2.54 1.93 1.00 1.15 1.01 0.97 1.22

Sunflower 0.96 1.00 0.84 1.01 2.36 1.66 0.78 1.00 0.99 1.08 1.17

Spring wheat 0.93 1.06 0.65 1.18 2.28 2.24 0.74 1.15 1.00 1.05 1.23

Barley 1.05 1.14 1.13 0.99 2.38 2.41 0.84 1.35 0.99 1.00 1.33

Rot. Benefit 0.98 1.02 0.91 0.98 2.15 1.89 0.82 1.12 0.98 1.03 1.19

Tanaka et al. 1999. Agron J. 97:385-390

Rotation Yield Benefits

------------------ Year ---------------Rotation BenefitCrop 2003 2004 1999 2000

Flax 2.15 2.57 2.36G. Sorghum 2.35 2.35Corn 2.39 1.25 1.82Chickpea 0.97 2.58 1.77Safflower 1.89 1.33 1.61Sunflower 2.80 1.12 1.12 1.36 1.60Lentil 1.10 1.37 1.23Proso millet 1.30 1.06 1.18Barley 1.03 1.21 1.12Buckwheat 1.21 1.02 1.11Dry Pea 1.16 1.16 0.98 1.14 1.11Canola 1.06 0.92 0.98 1.29 1.06Wheat 1.03 0.84 0.98 1.16 1.00Crambe 1.02 0.99 1.00Dry bean 0.91 0.97 0.94Soybean 0.82 0.81 0.82

Tanaka et al. 1999. Agron J. 97:385-390

Alternate Herbicides

Wheat-Wheat What is the dominant weed? Downy Brome Wild oat

Wheat –Pea: Downy Brome easily controlled with herbicides like Select,

Assure, or Spartan during the Pea crop cycle

Note: Research at Bozeman showed wheat/pea/fallow rotation compared to continuous wheat decreased downy brome density from 60 to 10 plants/ft2

The Disease Triangle

Environment

Susceptible Host

Organism

Remember: All three must be present in order for the disease to be expressed

Increased Diversity

Growing more crops spreads out the workload Planting time Spraying time Harvest time

More diversity requires greater management skills Record keeping becomes even more critical Time management Rotation restrictions

More commodities greater flexibility in marketing

Crop Rotation Can Be Beneficial

Yield increasesReduced need for herbicides Reduced disease pressureDiversified markets and crop management