The effects of minimum and conventional tillage systems on maize grain yield and soil fertility in...
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The effects of minimum and conventional tillage systems on maize grain yield and soil
fertility in western Ethiopia
Tolessa Debele
5th World Congress on Conservation AgricultureIncorporating 3rd Farming System Conference
26 – 29 September 2011 Brisbane, Australia
Introduction• The major maize producing areas
high yield potential favorable environments.
• However, national average maize yield of 2.2 t/ha • The inability to increase yield is attributed to:
non-sustainable cropping practices, particularly plow- or hoe-based cultivation,
soil and water loss due to erosion and Declining soil fertility
• To overcome these inabilities: Various management practices have to be
considered
Introduction …• Generally, CT has been world-wide the basic tool
of cropping for centuries It has been therefore an integral part of traditional
and/or conventional agriculture. • However, the need to produce more food
for an increasing population with decreasing soil and water resources
►caused a shift to MT• MT is recognized for its role in conservation of
both soil and water on account of CRs remaining on the surface
Objectives
to evaluate the effects of tillage system, residue management and nitrogen fertilization on maize grain yield in western Ethiopia
To determine the effects of the integrated management practices on some soil fertility parameters.
Methodolgy• Experiments on integrated soil management practices
were conducted at five site for five-years in western Ethiopia.
• The experiments were laid out in a RCBD with three replications.
• Three tillage systems: MTRR = Minimum tillage with residue retention, MTRV = Minimum tillage with residue removal CT = conventional tillage
• Three N fertilization levels: Recommended rate i.e. 92 kg N/ha 25% less & 25% more than recommended rate
Methodology….• The experimental plots were kept permanent to observe
the carry-over effects over years • For the MTRR and MTRV treatments soil
disturbance was restricted to the absolute minimum, viz. the soil was disturbed only to place the seed in
the soil at the time of sowing. • In contrast, for CT treatments the soil was
plowed 3 times prior to sowing to obtain a suitable seedbed.
Results and discussion
Effects of tillage system on
Maize grain yield
Table 1. Climatic data of Bako research center Rainfall (mm) May Jun Jul Aug Sep Oct CS Annual
1990-99 146.1 214.1 254.1 231.7 141.4 70.8 1058 1244
2000 135.1 278.2 236.9 289.6 162.0 103.4 1205 1346
2001 161.3 219.3 328.9 264.3 96.7 92.7 1163 1354
2002 68.3 236.0 239.2 205.9 42.1 0.0 792 1041
2003 5.7 265.1 420.6 434.4 39.9 11.5 1177 1355
2004 14.1 268.6 225.5 257.8 85.2 43.5 895 1061
2000-04 76.9 253.4 290.2 290.4 85.2 50.2 1046 1231
Figure 1. Mean grain yield of five sites as affected by tillage systems. Bars for each year with the same letter are not significantly different at
5% probability.
0
1000
2000
3000
4000
5000
6000
7000
8000
2000 2001 2002 2003 2004 2000-2004
Years
Gra
in y
ield
(kg
ha
-1)
MTRR MTRV CT
a
aaaa
a
b
bbb
bb
a
cb
ba
b
Table 2. Effect of tillage system, residue management and N fertilization on maize grain yield
N levels Tillage system (T)
(kg/ha) MTRR MTRV CT Mean
69 5953 5595 5210 5586
92 6513 6173 5868 6185
115 6953 6450 6227 6543
Mean 6471 6073 5768
LSD(0.05) T or N = 394 T x N = ns
Effects of tillage system on
soil physical and chemical properties
0
5
10
15
20
25
30
0.0 0.5 1.0 1.5 2.0 PR (Mpa)
Soi
l de
pth
(cm
)
MTRR
MTRV
CT
ns
ns
ns
ns
LSD(0.05)
0.13
0.17
Figure 3. Effect of tillage system on penetrometer resistance (PR) of soil at different depths
0.0
7.5
15.0
22.5
30.0
5.3 5.4 5.5 5.6 5.7
Soil
dept
h (c
m)
pH
MT RRMT RVCT
LSD(0.05
0.14
ns
ns
ns
0.0
7.5
15.0
22.5
30.0
1.0 1.5 2.0 2.5 3.0
Soil
dept
h (c
m)
Organic C (%)
MTRRMTRVCT
LSD(0.0
ns0.17
ns
0.21
Figure 5. Effect of tillage systems on OC at four depth intervals
0.0
7.5
15.0
22.5
30.0
1.0 1.3 1.5 1.8 2.0N (g kg-1)
Soil
dept
h (c
m)
MTRRMTRVCT
ns
ns
ns
0.25
0.0
7.5
15.0
22.5
30.0
5 10 15 20 25
P (mg kg-1)
Soi
l dep
th (
cm)
MTRR
MTRV
CT
LSD(0.05) 2.0
ns
ns
ns
Figure 7. Effect of tillage systems on available P content of soils at four depth intervals
0.0
7.5
15.0
22.5
30.0
150 175 200 225 250
Soil
dept
h (c
m)
K (mg kg-1)
MTRR
MTRV
CT
LSD(0.05)
1917
ns
ns
Conclusions• On average, MTRR increased grain yield by:
6.6% as compared to MTRV and 12.2% as compared to CT
• MTRR increased maize grain yield particularly when maize crop faced terminal drought as compared to MTRV and CT.
• When crop residues are removed, it takes at least two years before adverse effects on grain yield reductions become evident
• When crop residues are retained on the surface, it requires at least two years before the beneficial influence on grain yield are realized.
Conclusions …
• The grain yield was not affected by the interaction of tillage system and N fertilization.
• Consequently, the recommended fertilizer rate of 92 kg N/ha for CT maize was also found adequate for MT maize.
Conclusions …• After 5 years the influence of the tillage systems
on PR, pH, organic C, total N, extractable P and K was confined to the upper 0-15cm which is the plow layer.
• In comparison with CT, MTRR resulted in a higher PR and lower pH which is alarming since both of them should be managed carefully for
sustainable cropping.
• However, MTRR resulted in higher contents of organic C, total N, extractable P and K which is reassuring since all of them can be very beneficial for
sustainable cropping.
The way forward• The results proved that MTRR can be introduced
successfully in the study area: when it coincides with fertilization of 92 kg
N/ha • However, MTRV is not an option at all to replace
CT from a soil quality point of view.• The replacement of CT with MTRR should
contribute to sustainable maize production in Ethiopia.
THANK YOU