Sustainable Agriculture Literature Review - Boulder County

! ! !!
"#$%&!'())!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!=+!>5?324!
Hybridization of Seeds
One of the most significant seed innovations was the development of hybrid crops in the
1930s, particularly corn. Hybridization allows breeders to enhance certain biological
characteristics more predictably and more quickly than natural selection (sometimes
termed “selection”). Corn, as an open-pollinated (OP) crop, was well suited to the
inbreeding-hybridization process. Hybrid corn seeds have their benefits for farmers,
which include: higher yield potential, greater uniformity immaturity, and resistance to
lodging making mechanization possible. The advantage of hybridization for seed firms is
that the enhanced vigor of the hybrid seeds is not transmitted to its offspring, requiring
farmers to buy new seed every year. The first seed company was organized for the
commercial production of hybrid corn in 1926, but hybrid corn production only began to
expand in the early 1930s. By 1960, the share of corn acreage cultivated with hybrid
seed in the U.S. had reached 95 percent and almost all OP corn cultivated in the U.S.
was replaced by hybrids by the 1960s. 491
Genetically Engineered Seeds
In conventional plant breeding, available genes and traits are limited due to sexual
incompatibility to other lines of the crop and their wild relatives. This restriction has led to
the development of genetic engineering, which in principle allows introducing valuable
traits of any organism (other plants, bacteria, fungi, animals, viruses) into the genome of
any plant. 492 Genetically engineered (GE) crops are classified into one of the three
categories: crops with enhanced input traits (herbicide tolerance, insect resistance, and
resistance to environmental stresses), crops with added value output traits (nutrientenhanced
seeds), and crops that are used for products (pharmaceuticals, bio-based
fuels, and other products). 493
Hybrid and GE seeds are patentable and therefore cannot be legally saved, and
replanted for the following year. 494 Although farmers might prefer GE seeds, because
their use may lead to higher yields and higher revenues, GE seeds are more expensive
than traditional seed. Because of the high research and development of agricultural
biotechnology, the extra costs of GE seed companies are passed on to the farmers.
This is one reason why the benefits of adopting GE crop practices vary. Another
example of how benefits can vary is if the level of insect infestation is high, the benefits
from Bacillus thuringiensis (Bt) GE seeds will be greater than if insect infestation was
low. 495
Use of GE seeds can affect farming practices by changing the type of tillage practiced.
For example, a possible benefit of herbicide tolerant (HT) crops is soil conservation,
through adoption of conservation tillage practices. Herbicide tolerant crops may allow
farmers to use post-emergent herbicides, such as glyphosate, and avoid pre-emergent
herbicides that would be incorporated into the soil. This is a possible benefit that needs
to be studied in practice to observe if soil health is actually improving as a result of GE
crops. 496 Herbicide tolerant soybeans have had a great impact on tillage practices.
According to the USDA, about 60 percent of HT soybean acres planted in 1997 used
conservation tillage, while only 40 percent of the conventional acres planted used
conservation tillage. HT soybean crops have had an even bigger effect on no-till
practices compared with conventional tillage, which are 40 percent and 20 percent of
acres planted respectively. 497
!
",&"
!,342#.5#6/1!78$.%3/23$1!
9.21$#23$1!:1;.1