Transcript Land Husbandry in Drought Prone Areas Msc.556

Zero (no) Tillage in the US
Land Husbandry in Drought Prone
areas: Msc. Module 556
Presented by Lemi Wani Jake
Definition
• Zero or No tillage system involves the direct
placement of seeds without prior seed
preparation. It is characterized by minimal soil
disturbance and stubble or crop residue
retention
History of Zero tillage
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No tillage was used in ancient times
The Incas in the Andes practised no tillage
In Brazil seeds were planted before tilling
Also practised for centuries in Mexico and
Central America
• In the US conservation tillage started in the
1930’s to alleviate wind erosion
• 1960: trials to kill weeds with Paraquat and to
use Atrazine for residue control carried out.
History (cont)
• 1961-2: no till demonstration farms established
• Kentucky farmers became first mechanized no
tillage farmers
• 1966: Allis Chalmers designed the flutted
coulter no tillage planter/seeder
History (cont)
• Area under no tillage in the US increased from
2.2 million ha in 1973 and 4.8 million in 1983
to nearly 20 million in 1974.
• Accounts for about 16% of the total cultivated
area.
World Adoption
World Adoption
country
USA
Area Total
(ha) area
%
19.3 16.3
Brazil
11.2
21.3
Argentina
7.3
32
Canada
4.1
----
Australia
1
----
Paraguay
0.79
52
Table 1: Leading countries
in the world
Benefits of No tillage
• Two characteristics give credit to no tillage:
• Stubble/residue retention and
• Minimal soil disturbance
• Stubble reduces impact of raindrop on soil,
runoff and the rate of evaporation.
• By so doing it protects the soil from wind and
water erosion and improves its water holding
capacity.
Benefits of No tillage
• Water infiltration into the soil is also increased.
• Undisturbed soil and abundance of crop
residue on the soil surface ensure high organic
matter content in the soil.
• In no tillage, macro aggregates protect soil
organic matter from microbial decomposition.
Benefits of no tillage
• Soil organic matter in turn encourages the
formation of more soil aggregates
• Soil structure which increases soil porosity is
improved in this way providing suitable
conditions for plant growth
• Conventional tillage also encourages the
formation of soil clods which are not stable
due to destruction of its organic matter fig. 2
Benefits of no tillage
• With time the soil particles in these clods
disperse and soil porosity is lost.
• Amount of organic matter is therefore higher
in no tillage treatments than in conventional
tillage treatments fig 3.
• Due to the high content of soil organic carbon
in no tilled soils, they tend to have high
proportions of stable soil macro-aggregates.
Fig 2.
Benefits of no tillage
Fig.3 Soil organic carbon
in various tillage
systems.
NT = No-till
CT = Chisel-till
MT = Mouldboard-till
Benefits of no tillage
• Soil organic carbon also increases the moisture
retention capacity of the soil.
• The amount of moisture held in the soil determines
the yield of a crop in dry weather
• In no tilled soils water losses by evaporation are
minimised and more water is held in the soil due to its
high organic matter content compared to
conventionally tilled soils which have low organic
carbon and high water losses by evaporation.
Benefits of no till
• Fertilizer use efficiency is ensured by the
amount of water available in the soil. Nutrients
in fertilizers are released in soluble form
• Adequate water in no till soils ensure nutrients
availability to plants which absorb them.
• No till treatments therefore give higher yields
than conventional treatments fig 4.
Benefits of No tillage
Fig 4.Fertilizer use efficiency of various
tillage systems.
Benefits of No-tillage
• Soil compaction is minimised in no-tillage because
tractor passes once during sowing.
• In conventional tillage, however, weights of
machinery and implements press soil particles
together reducing the proportion of macro-pores in
the soil. Soil aggregates break down and soil particles
are closely packed together. The bulk densities of
tilled soils are normally higher than those under notillage which are loose and encourage water
infiltration.
• However, bulk density decrease in no till soils occur
with time.
Benefits of No tillage
• No tillage increase microbial populations
• Plenty of food and less soil disturbance favour
earth worms populations increase.
• Earth worms improve soil porosity and
structure.
Corn growing on no-tilled soil
Benefits of No tillage
• Economics
• Machinery costs and labour costs are reduced: fuel,
depreciation, interests, insurance, housing,
maintenance, and time.
• Expenses are only related to fertilisers, herbicides,
sowing and pesticides.
• In the USA no till has reduced costs of soybeans
production by $ 14.18 per acre fig 5.
Benefits of No tillage
Fig.5.
Disadvantages of No tillage
• No tillage is risky
• Reports have shown decrease in crop yields in the
long term
• A Kentucky report indicated decrease in corn yields
under un-limed non-tilled soils compared to
mouldboard tilled soils
• Low yields in this case are attributed to increased
acidity due to build up of carbon and nitrogen near
the soil surface resulting from stubble (crop residue).
Disadvantages of No tillage
• In Central Indiana yield losses were attributed
to decline in soil fertility over a 12-year
period.
• Improved water infiltration has apparently
caused leaching of nutrients.
• In Central Minnesota there was a fall in corn
yields despite fertilizer and lime treatment and
application of herbicides and pesticides.
Disadvantages of No tillage
• It was established that soil type and bad
climate are responsible for yield decline.
• Very low temperatures under the residue retard
early growth in corn leading to lower harvest
• Also poorly drained soils reduces rate of
growth resulting in poor yields fig 6.
Disadvantages of No tillage
• Fig 6: Yield decrease in No till
system
Disadvantages of No tillage
• Weeds:
– Tillage generally kills weeds
– In no till soils weeds control is a problem
– Requires timely applications of herbicides before
and after sowing
– Herbicides commonly used in no tillage includes:
Gramoxone Extra, Atrazine, Bladex 4L, Dual 8E,
Lasso 4E, 2,4-D Ester, 2,4-D Amine etc…
– Rate of applications and timing are important to
maximise yields.
Disadvantages of No tillage
• Pests and Diseases
• Crop residue on non-tilled soils encourage outbreaks of pests and
diseases.
• This requires use of integrated pest management techniques such as
choice of suitable rotations, residue management, pesticides
application etc…
• Crop residue: interferes with sowing and causes a
condition known as allelopathy
• Allelopathy is the toxic effect on a crop due to decaying residue
from the same crop or similar species. Its effects are more likely to
occur when corn is followed by corn in a rotation.
• Well-planned rotation and removal of residues using no-till planters
is the solution.
Crop Rotation
• Effective management tool for no-tillage
systems when well-planned
• Bulky crop residue more manageable by rotating cereals
in alternation with legumes.
• Weeds can be easily controlled by herbicides- use of
broadleaf herbicides to control broadleaf weeds in
cereals.
• Lower risks of diseases and pests
• Rotation with forage crops like alfalfa
Conclusions
• No tillage is favoured due to its ability to conserve moisture
and reduce soil erosion resulting in efficient water use and
availability of nutrients
• Costs of production are also greatly reduced
• But is also risky involving factors that reduce yields.
• Proper integrated management techniques are required for it to
succeed once the decision to adopt no tillage is taken.
• Several farmers in the US have gone no till faced by a number
of challenges and realised its returns with time. To do this
requires patience and sound management practices.
• No till can be adopted in many other areas after all ancient
people practised no tillage farming alone.