Agriculture Reference
In-Depth Information
from the same area of land while reducing the negative environmental impacts and
at the same time increasing contributions to natural capital and the flow of envi-
ronmental services (Pretty 2008; Royal Society 2009; Conway and Waage 2010;
Godfray et al. 2010). Cropping systems such as rice-wheat in south Asia, which
happened to be the backbone of food security in the past, are now being challenged
on the basis of their high environmental costs. Thus, our notion of sustainability of
agricultural systems is shifting, and alternative practices and systems that reduce
negative externalities should be sought. Sustainable agricultural systems, by defini-
tion, are less vulnerable to shocks and stresses. It is now widely recognized that yield
gaps in cereal crops described previously result from agronomic failings, and that
future yield increases depend heavily on this science (Pretty et al. 2011). Many vari-
ants of CA have been adopted by farmers in the tropical/subtropical and temperate
regions of the world for improved yields. CA has steadily increased worldwide to
cover about 7% of the world arable land area (Derpsch and Friedrich 2009). CA is an
innovation process of developing appropriate CA implements able to plant in loose
and anchored residues, early maturing cultivars for the cropping system, and har-
nessing appropriate nutrient-water interactions through iterative fine-tuning of crop
production technologies. It must, however, be remembered that conservation tillage
(CT) and CA are not synonymous. CT refers to reduced tillage with some residues
left on the surface and others incorporated using a plough. In CA, tillage is drasti-
cally reduced or not practiced to incorporate the residues. Readers are also referred
to the use of terms such as resource conservation technologies (RCTs) wherein CA
is defined as a practical agricultural production system that strives to achieve accept-
able profits, and reduce labor and energy inputs while concurrently conserving and
(in time) enhancing environmental quality. All RCT practices may not fit into the
elements of CA but may still be useful to the farmers on economic grounds. Thus,
there is a need for flexibility in defining CA for operational purposes.
Zero-till/CA systems are not about precision planting without tillage by using
appropriate seed drill or planters. It is about management practices (weed, water,
nutrient and integrated pest management, etc.) that make zero-till technology suc-
cessful and provide added advantages to the farmers. The most common CA inter-
ventions are reduced (or no) till with residue (straw) retention on the field, resulting in
lessened erosion and increased aboveground and belowground biodiversity, improved
water penetration and available holding capacity, and greater stores of surface soil
carbon. The impact of the interventions/technologies can be maximized by the layer-
ing of more than one technology, one above the other, in the crop production chain.
However, quite often, circumstances constrain the farmers to overlook or jump some
points in the chain such as to suite their resource endowments and the field situa-
tions. This facilitates the farmers to adopt CA-based RCTs as per their conveniences.
This point is clarified in Figure 5.3 wherein a farmer not having access to a laser-
assisted precision land-leveling system and machinery to plant in loose residue can
still harness some benefits of CA practices by following the “better-bet” practices
shown in Figure 5.3. The “better- and best-bet” management practices for unpuddled
transplanted rice-zero-till wheat system has been explained through a schematic
view as a specific example. A farmer following some segments of the lower chain (−)
and some of the upper chain is only following a set of better-bet rather than a best-bet
