The effects of minimum and conventional tillage systems on maize grain yield and soil fertility in western Ethiopia. Tolessa Debele Dilalessa

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