Farming Systems Design 2007 - International Environmental ...

Farming Systems Design 2007
Field-farm scale design and improvement
greater under zero- than conventional tillage, but for other crops, tillage system had less influence on
productivity than management system or rotation. Ecological management reduced weed biomass at
harvest (Table 2). Wild oat (Avena fatua), green foxtail (Setaria viridis), kochia (Kochia scoparia), and
Russian thistle (Salsola iberica) were the principal weed species present at harvest. Regression
analyses of yield by weed biomass at harvest resulted in highly significant and negative relationships
for wheat and pea, indicating that weed competition had a large impact on grain yield.
Table 1. Mean grain yields from spring wheat, pea and corn, and forage yield from barley
in two management and tillage systems, and four crop rotations, 2005-2006.
Parameter Spring wheat Pea Barley hay Corn
kg ha -1
Tillage system
Conventional tillage 3078 2412 5276 b 3357
Zero tillage 2968 2237 6335 a 3854
Management system
Conventional 3412 a † 2162 b 5149 b 3643
Ecological 2634 b 2489 a 6462 a 3568
Rotation
Continuous SW 2434 b - - -
SW-pea 3167 a 1979 b - -
SW-barley hay-pea 3335 a 2473 a 6133 -
SW-barley hay-corn-pea 3154 a 2522 a 5478 3606
†
Means within columns and parameters followed by different letters differ at P=0.05.
Table 2. Mean weed biomass at harvest from four crops in two management and tillage systems,
and four crop rotations, 2005-2006.
Parameter Spring wheat Pea Barley hay Corn
Weed biomass, kg ha -1
Tillage system
Conventional tillage 240 498 12
Zero tillage 274 733 10
Management system
Conventional 416 a † 729 767 16
Ecological 98 b 502 397 5
Rotation
Continuous SW 547 a - - -
SW-pea 209 b 966 a - -
SW-barley hay-pea 59 b 354 b 367 -
SW-barley hay-corn-pea 213 b 527 b 796 11
† Means within columns and parameters followed by different letters differ at P=0.05.
Conclusions
Early results from this long-term study indicate that ecological management and diversified rotations
improve spring wheat and pea yield, in part through increasing crop competitiveness with weeds.
However, additional research years across a range of environmental conditions are required for
confirmation.
References
Anderson, R., A multi-tactic approach to manage weed population dynamics in crop rotations. 2005. Agron. J.
97, 1579-1583.
Lenssen, A., et al., Cropping sequence and tillage system influences annual crop production and water use in
semiarid Montana, USA, 2007a. Field Crops Res. 100, 32-43.
Lenssen, A., et al., Diversified cropping systems in semiarid Montana: nitrogen use during drought, 2007b. Soil
Tillage Res. 94, 362-375.
Sainju, U, et al., Carbon sequestration in dryland soils and plant residue as influenced by crop rotation and
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