Agriculture Reference
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found that weed control and maize yields with rotary hoeing plus in-row
weeding were equivalent to an herbicide control treatment in two years, but
lower in the third due to untimely rotary hoeing. Inter-row cultivation plus
row flaming provided yields and weed control equivalent to appropriate her-
bicide programs in maize, set onion, and cabbage, but not in direct-seeded
onion (Geier & Vogtmann, 1988; Ascard, 1990; Netland, Balvoll & Holmøy,
1994).
Most recent studies of mechanical weed control have focused on cultiva-
tion in conjunction with banded or reduced rates of herbicides. These inte-
grated systems have generally performed well (Kouwenhoven, Wevers & Post,
1991; Eadie et al ., 1992; Hartzler et al ., 1993; Mulder & Doll, 1993; Buhler et
al ., 1994; Mt. Pleasant, Burt & Frisch, 1994; Parks et al ., 1995; Mulugeta &
Stoltenberg, 1997), with some exceptions (Snipes & Mueller, 1992; Buhler,
Gunsolus & Ralston, 1993). Bridgemohan & Brathwaite (1989) found inter-
row cultivation better than any herbicide for control of Rottboellia cochinchinen-
sis in maize.
Often, cultivation has improved weed control or decreased the impact of
weeds on yield even when herbicides were applied at full rates (Glaz, Ulloa &
Parrado, 1989; Steckel, DeFelice & Sims, 1990; Shaw, Newsom & Smith, 1991;
Buhler et al .,1994; Mt.Pleasant,Burt & Frisch,1994; Steckel & DeFelice,1995;
Newsom & Shaw, 1996). Even when weeds have been effectively controlled by
chemicals or hand-weeding,cultivation often increases yield, presumably due
to better management of soil moisture or improved root growth (Prihar & Van
Doren, 1967; Russel, Fehr & Mitchell, 1971; Hauser, Cecil & Dowler, 1973;
Whitaker, Heinemann & Wischmeier, 1973; Johnson, 1985; Snipes & Mueller,
1992; Snipes et al ., 1992).
Contrary to frequently voiced concerns that higher labor expenses make
mechanical weeding uncompetitive with herbicides, analyses show that costs
for the two approaches are often similar (Mulder & Doll, 1993; Schweizer,
Westra & Lybecker, 1994; Mohler, Frisch & Mt. Pleasant, 1997). Moreover,
integrated systems using cultivation with reduced rate or banded herbicides
often provide equivalent yield at lower cost than chemical control alone (Bicki,
Wax & Sipp, 1991; Mulder & Doll, 1993). Although replacement of a substan-
tial proportion of herbicide use with cultivation is often economically profit-
able on a per hectare basis, cultivation is difficult on large, specialized farms
because labor and machinery are often insufficient for timely operations.
Forces driving such inefficiencies are discussed in Chapter 11.
Surprisingly, cultivation often requires less energy than typical herbicide
programs. This is because most herbicides require large amounts of energy
for feed stocks, process energy, packaging, and transportation (Pimentel,
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