Wheat Research Centre Bangladesh Agricultural Research Institute

Gazipur

Dr. Md. Ataur Rahman

Rice straw mulching and nitrogen requirement to improve productivity of no-

till wheat following rice in Bangladesh

M. A. Rahman, NCD Barma, T. P. Tiwari and J. G. Lauren

Why no-tillage? To conserve national resources.

Improve productivity, soil physics and many others.

But we at Wheat Research Centre, initiated no-till what with different objectives-

1. Reduce the time interval between rice harvest to wheat sowing thus ensure the proper time of wheat sowing.

2. To utilize the residual soil moisture.

What is our experience?

Soil moisture during seeding is the key factor for establishment of no-till wheat. In most cases soil moisture either higher or lower than the requirement.

In light textured soil, rapid dry up of top soil caused Poor stand establishment, Also Weed infestation was higher with Low nitrogen use efficiency Low productivity no till wheat.

No-till Wheat following rice No-till Maize following wheat

PTPR No-till rice (DSR) following maize

Attempts to address the constraints

Farmers remained with their traditional system. Preferred well till soil for upland crops and

Well puddling for wetland rice.

Crop residue has the multiple use, as feed and fuel.Also rice straw is used in thatching the rural huts. Thus the retention of crop residue is rare in Bangladesh.

What is about crop residue retention?

Under such a condition, we initiate an alternate approach of duel use of rice straw. For a short period as mulch and after withdrawing as fuel.

To examine whether mulching for a short period have the potentials in improving no-till wheat by - Conserving initial soil moisture.

- Controlling weed growth.

- Increasing nitrogen use efficiency.

Objectives

Experimental Design and treatments

Factorial RCBD

Mulch treatments

M0 = No mulching

M1 = Straw mulch @ 4.0 t ha-1 which withdrawn at 20 DAS

M2 = Straw mulch @ 4.0 t ha-1 that was retained on soil

Nitrogen levels

N0 = No nitrogen

N1 = 80 Kg ha-1

N2 = 120 Kg ha-1

N3 = 160 Kg ha-1

WRC, Dinajpur, 2007-08 and 2008-09, post-rice harvested paddy field.

LocationMethodology

Applied as 3 equal split during sowing seeds, 20 DAS and 35 DAS.

Soil Moisture in surface soil layers (0-15 cm) was monitored gravimetrically from sowing to 40 DAS at 5 days interval.

Weed sampling and biomass were measured at 20, 35 and 45 DAS.

Growth analysis of wheat roots (RLD and RWD) was carried out at anthesis stage of the crop.

N content in straw and grain was analyzed to determine N uptake and ANR (%).

ANR%= [(A – B)/C] × 100

Where, A is N uptake by the plant under the treatment of interest (kg/ha), B is N uptake by the plant under N0 treatment (kg/ha), and C is N applied for the treatment of interest (kg/ha)

Measurements

Fig. 1: Effect of mulch and N levels on surface soil moisture in time

10

15

20

25

30

35

1 5 10 15 20 25 30 35 40

Days after sowing

So

il m

ois

ture

(%

)

M0M1M2

2000-01

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40

Days after sowing

So

il m

oist

ure

(%

)

M0M1M2 2001-02

First year 2nd year

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40

Days after sowing

Soil

moi

stur

e (%

)N0N80N120N160

2001-02

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40

Days after sowing

Soi

l moi

stu

re (

%)

N0N80N120N160

2000-01

First year 2nd year

↑IR

↑IR

↑IR

↑IR

Fig. 2: Effect of mulch and N levels on weed growth

2nd Year

0

30

60

90

120

150

0 20 35 45

Days after sowing

Dry

mat

ter

(g m

-2)

N0N80N120N160

2nd Year

0

30

60

90

120

150

0 20 35 45

Days after sowing

Dry

mat

ter

(g m

-2)

M0

M1

M2

0

30

60

90

120

150

0 20 35 45

Days after sowing

Dry

mat

ter

(g m

-2)

N0N80N120N160

1st Year

0

30

60

90

120

150

0 20 35 45

Days after sowing

Dry

mat

ter

(g m

-2)

M0M1M2

1st Year

2nd Year

Fig. 3: Interaction effect of mulch and N levels on number of spikes/m2 of no-till wheat

100

150

200

250

300

350

N0 N80 N120 N160

Sp

ikes

/m2

M0 M1 M2

N levels

Table1: Root growth of no-till wheat at anthesis stage under different mulch and N levels

Treatment Shoot weight

(g/plant)

Root weight (g/plant)

Root weight density (mg/cc)

Root length density (cm/cc)

Mulch levels

M0 24.6 b 0.69 b 0.23 b 0.76 bM1 45.4 a 1.61 a 0.35 a 1.44 aM2 47.5 a 1.69 a 0.38 a 1.50 a

N levels

N0 19.29 d 0.82 b 0.15 b 1.05 cN80 38.45 c 1.40 a 0.31 a 1.21 bN120 46.20 b 1.44 a 0.33 a 1.49 aN160 52.54 a 1.45 a 0.36 a 1.33 ab

0

30

60

90

120

N0 N80 N120 N160

N u

pta

ke

(k

g/h

a)

M0 M1 M2

Fig. 4: Interaction effect of mulch and N levels on N uptake of no-till wheat

N levels

Treat-Treat-mentment

M0 M1 M2

N0 0.45 B d 0.72 A c 0.75 A c

N80 1.73 B c 2.58 A b 2.67 A b

N120 2.16 B b 3.72 A a 3.98 A a

N160 2.81 B a 3.81 A a 3.90 A a

Table 2: Effect of mulch and N levels on grain Table 2: Effect of mulch and N levels on grain yield of wheat (Mean of 2 years, in t hayield of wheat (Mean of 2 years, in t ha -1-1))

Capital letters to compare mulch effect under any N level and small lettering to compare N effect under any mulch level

Fig. 5: Nitrogen level Vs. grain yield relationship under different much treatments.

0

1

2

3

4

5

1 2 3 4

0

1

2

3

4

5

1 2 3 4

M2

Gra

in Y

ield

(kg

/ha)

0

1000

2000

3000

4000

0 80 120 160N (kg ha-1)

M0

0 80 120 160

0

1000

2000

3000

4000

5000

0 80 120 160

M1

N (kg ha-1)

y = 388 + 30.2x - 0.132x2

R2 = 0.898

Optimum N Dose = 115 kg ha-1

N (kg ha-1)

Gra

in Y

ield

(kg

/ha)

y = 364 + 27.1x - 0.111x2

R2 = 0.916

Optimum N Dose = 122 kg ha-1

y = 17.5x + 216

R2 = 0.965

Straw mulch conserves initial soil moisture and suppresses weed growth.

Mulch ensures plant establishment with higher spikes/m2.

Improves N-uptake and root proliferation of no-till wheat.

Mulching for a short period of 20 DAS is as effective as straw retention, in eliminating the production constraints and favoring the production factors of no-till wheat.

When the recommendation of straw retention is prohibited due to multiple need for straw, farmer’s could practice the alternate option of short term mulching.

Conclusion and Remarks Conclusion and Remarks

Acknowledgement

BARI Anthurium-1

BARI Gerbera-1

Thank you very much