Climate Change Adaptation - Climate Resilient Agriculture for Ensuring Food Security - page 227

Fig. 12.4 Happy seeder for sowing in presence of residues (Photo courtesy: CSISA (CIMMYT-IRRI), New Delhi)

left on the soil surface. Conservation tillage prac-
tices typically leave about one-third of crop resi-
due on the soil surface. This slows water
movement, which reduces the amount of soil ero-
sion. Conservation tillage is suitable for a range
of crops including grains, vegetables, root crops,
sugarcane, cassava, fruit, and vines.
Conservation tillage is a popular technology
in the Americas, with approximately 44 % prac-
ticed in Latin America. Studies suggest that there
is great potential to bring this technology to
Africa, Asia, and Eastern Europe, although limit-
ing factors have to be taken into account (Derpsch
2001 ). The most common conservation tillage
practices are no-till, ridge-till, and mulch-till.
No-till is a way of growing crops without dis-
turbing the soil. This practice involves leaving
the residue from last year's crop undisturbed and
planting directly into the residue on the seedbed.
No-till requires specialized seeding equipment
designed to plant seeds into undisturbed crop
residues and soil (Fig. 12.4 ). No-till farming
changes weed composition drastically. Faster
growing weeds may no longer be a problem in
the face of increased competition, but shrubs and
trees may begin to grow eventually. Cover crops -
“green manure” - can be used in a no-till system
to help control weeds. Leguminous cover crops

which are typically high in nitrogen can often
increase soil fertility.
In ridge-till practices, the soil is left undis-
turbed from harvest to planting and crops are
planted on raised ridges (Fig. 12.5 ). Planting
usually involves the removal of the top of the
ridge. Planting is completed with sweeps, disk
openers, coulters, or row cleaners. Residue is left
on the surface between ridges. Weed control is
accomplished with cover crops, herbicides, and/
or cultivation. Ridges are rebuilt during row
cultivation.
Mulch-till techniques involve disturbing the
soil between harvesting one crop and planting the
next but leaving around a third of the soil covered
with residues after seeding. Implements used for
mulch-till techniques include chisels, sweeps,
and fi eld cultivators.
Unpredictability of rainfall and an increase in
the mean temperature may affect soil moisture
levels leading to damages to and failures in crop
yields. Conservation tillage practices reduce risk
from drought by reducing soil erosion, enhancing
moisture retention, and minimizing soil impac-
tion. In combination, these factors improve resil-
ience to climatic effects of drought and fl oods.
Improved soil nutrient recycling may also help
combat crop pests and diseases.