Agriculture Reference
In-Depth Information
to reduce the number of soil-disturbing equipment passes and attendant potential
for surface erosion. Benefits of no-till include a decreased requirement for fos-
sil fuel, reduced loss of soil, nutrients, and pesticides in runoff water, better soil
water infiltration and water-holding capacity, and a more stable environment for
soil organisms. In the MCSE No-till system, the number of equipment passes has
been reduced by 26%—from 8.4 to 6.2 per year—as compared to the Conventional
system (Gelfand et al. 2010). Reduced soil disturbance has led to greater soil C
accumulation in the top 5 cm of soil in the No-till system (3.6 kg C m
−2
) compared
to the Conventional system (3.2 kg C m
−2
) (Syswerda et al. 2011). The Biologically
Based system also led to a greater soil C accumulation (3.8 kg C m
−2
), similar to the
No-till system, but as discussed in more detail below, this occurred despite frequent
soil disturbance from plowing and rotary hoeing for mechanical weed control.
One of the sustainability principles evaluated in the MCSE is the role of plant
diversity in agroecosystem performance, including net primary productivity (NPP),
nutrient retention, and ecosystem stability. Generally, positive relationships have
been shown among diversity, NPP, and other ecosystem services in grasslands and
other low nutrient, semi-managed, and natural systems (e.g., Hector et al. 1999;
Tilman et al. 2001; Hooper et al. 2005, 2012). In row-crop systems, biodiversity
is generally a function of crop rotation, intercropping, and inclusion of acces-
sory crops such as winter cover crops. In both long-term (Syswerda et al. 2011,
2012) and shorter-term comparisons (Drinkwater et al. 1998, Maeder et al. 2002),
more diverse organic systems have accumulated more soil organic matter and
leached less nitrate than paired systems under conventional management.
However, such comparisons cannot distinguish between the effects of plant
diversity per se and other management practices that differ among the experimental
systems. As a consequence, diversity has rarely been studied as a discrete factor
(Gross et al. 2015, Chapter 7 in this volume). The LFL and Biodiversity experi-
ments (Smith et al. 2008; Robertson and Hamilton 2015, Chapter 1 in this vol-
ume; Gross et al. 2015, Chapter 7 in this volume) were established at KBS to more
explicitly investigate the effects of plant diversity and rotational complexity in bio-
logically based cropped ecosystems (Sánchez et al. 2004, Snapp et al. 2010a).
The KBS Living Field Lab Experiment
The LFL was designed with input from a farmer advisory group and has played
an important role, especially in outreach at KBS. The aim of the LFL is to test
farm-relevant combinations of intensively managed systems where crop diversity
can be examined as a separate factor from other management factors (Sánchez et al.
2004). This allows comparison of common crop sequences such as continuous corn
vs. more diverse corn rotations. Management factors include nutrient sources (com-
binations of conventional fertilizer and composted manure) and weed control (con-
ventional herbicide inputs vs. mechanical cultivation).
The factorial, split-plot design of the LFL includes management regime
(Organic vs. Integrated Conventional) as a main plot system and plant biodiver-
sity (comparing one, two, three, and six plant species) as subplot treatments. The
Organic system relies on certified organic practices including the application of
