Long-term effects of fertilizers and organic manures on the productivity of rice-wheat cropping system in West Bengal  P. K. Mani, A. L. Kundu, P. K. Sahu, and M. Pramanick

 

AICRP on Cropping Systems Research,Bidhan Chandra Krishi Viswavidyalaya,

Mohanpur, W.B.

 

The sustainability of the production system and yield trends can be interpreted in relation to changes in soil properties and climate through LTFE which provides constant management regime in defined treatments (Cassman et al., 1997).

The production and productivity in rice-wheat system is showing a declining trend in Indo-Gangetic plains of West Bengal. A field experiment on rice-wheat cropping system was conducted to develop suitable integrated nutrient supply system utilizing local organic resources in various combination with fertilizers for sustaining crop production on long-term basis

Objectives

            Quantify the substitution of N, P and K with FYM, Green Manure (Sesbania aculeata), and paddy straw in rice yield

         Residual and cumulative effect of substitution on the yield of succeeding wheat crop

   Bearings on soil fertility, Agronomic efficiency (AE), recovery efficiency (RE) and internal efficiency (IE) and soil quality vis-à-vis soil health.

 Assessing sustainability by measuring sustainable yield index (SYI)

 

Experimental detailsLocation : Mohanpur, W.B. (22046/ N, 88087/E)Year of start Kharif, 1986Design of the Expt RBD with 4 replicationsNo. of Treatments 12Soil Typic UstochreptCropping System Rice (IET-4094) –Wheat (UP-262)

_Agro-ecosystem Irrigated

Initial soil properties pH = 7.5, OC = 0.94%, total N = 0.054%, Available P and K =14.9 & 80 kg/ha

AEN (kg grain yield increaser per kg N applied)

= (GY+N –GY0N)/ FN, GY=grain yield, FN=fert. Nitrogen

REN (kg N taken up per kg N applied) = (UN+N – UN0N)/ FN , UN= uptake of nitrogen

IEN (kg grain per kg N taken up) =GY/UN total

Nutrient concentration (%) N P2O5 K2OFYM 0.66 0.20 0.30Paddy straw 0.40 0.20 0.30 Green Manure(Sesbania aculeata)

0.80 0.15 0.40

Table 1: Effect of different fertiliser treatments on mean rice and wheat yield Treatment

Treatment detailsYield of

rice(q/ha)

Yield of wheat (q/ha)

 

Kharif (rice) Rabi (Wheat)T1 N0P0K0 N0P0K0 15.03 9.96  

T2 N40P20K20 N50P30K20 26.53 19.38  

T3 N40P20K20 N100P60K40 28.34 27.48  

T4 N60P30K30 N75P40K30 31.67 26.88  

T5 N80P40K40 N100P60K40 34.44 28.91  

T6 T3+FYM N100P60K40 35.55 30.84  

T7 T4+FYM N75P40K30 37.64 29.18  

T8 T3+Straw N100P60K40 36.14 32.4  

T9 T4+Straw N75P40K30 35.81 28.75  

T10 T3+GM N100P60K40 37.84 31.65  

T11 T4+GM N75P40K30 37.76 28.53  

T12 FP(N50P30K20)LSD(P=0.05)

FP(N60P20K20) 27.701.95

23.871.81

 

Fig.1: Trends in grain yield of rice over the years between few treatments

0.010.020.030.040.050.0

1986 1991 1996 2001Years

Gra

in Y

ield

(q

/ha)

T1 T5 T6 T7

Table 2a: Effect of different fertiliser treatments on Nutrient efficiencies

Treat

Treatment details AE (rice)

AE (wheat)

 

Kharif(rice)

Rabi(Wheat) N P K N P K

        

    

 

T1 N0P0K0 N0P0K0 - - - - - -  

T2 N40P20K20 N50P30K20 29 57 57  

T3 N40P20K20 N100P60K40 33 67 6719 31 47

 

T4 N60P30K30 N75P40K30 27 55 5517 29 44

 

T5 N80P40K40 N100P60K40 24 48 4823 42 56

 

T6 T3+FYM N100P60K40 51 65 6519 32 47

 

T7 T4+FYM N75P40K30 37 7521 35 52

 

T8 T3+Straw N100P60K40 5375 26 48 64

 

T9 T4+Straw N75P40K30 3566 66 22 37 56

 

T10 T3+GM N100P60K40 5769 69 25 47

3662

 

T11 T4+GM N75P40K30 386876

6876

21

25 465462  

T12 FP FP 25 42 63 23 70 69  

Table 2b: Effect of different fertiliser treatments on Nutrient efficiencies

TrTreatment details Apparent nutrient

recovery (REN) (%)

Internal efficiency, IEN (kg kg-1)

Kharif

(rice)Rabi

(Wheat) (rice) (wheat) (rice) (wheat)             

T1 N0P0K0 N0P0K0 -

T2 N40P20K20 N50P30K20

- 27 24

T3 N40P20K20 N100P60K40

0.41 0.26 37 35

T4 N60P30K30 N75P40K30

0.50 0.69 38 25

T5 N80P40K40 N100P60K40

0.48 0.58 38 32

T6 T3+FYM N100P60K40

0.49 0.67 37 27

T7 T4+FYM N75P40K30

0.70 0.70 43 28

T8 T3+Straw N100P60K40

0.41 0.44 48 39

T9 T4+Straw N75P40K30

0.64 0.60 45 32

T10 T3+GM N100P60K40

0.49 0.50 43 36

T11 T4+GM N75P40K30

0.69 0.63 46 30

T12 FP FP0.530.39

0.560.19

4437

3435

Table 3: Effect of different fertiliser treatments on SYI

TreatTreatment details Sustainable Yield Index

SYI = (Y-)/Ymax

 

Kharif

(rice)

Rabi

(wheat) (rice)0.48

(wheat)         T1 N0P0K0 N0P0K0

0.43

 

T2 N40P20K20 N50P30K20 0.66  

T3 N40P20K20 N100P60K40 0.52  

T4 N60P30K30 N75P40K30 0.61  

T5 N80P40K40 N100P60K40 0.66  

T6 T3+FYM N100P60K40 0.63  

T7 T4+FYM N75P40K30 0.69  

T8 T3+Straw N100P60K40 0.63 0.66 

T9 T4+Straw N75P40K30 0.68  

T10 T3+GM N100P60K400.69

0.55 

T11 T4+GM N75P40K30 0.650.64

 

T12 FP FP 0.550.530.53  

0.34

0.56

0.57

0.55

0.58

0.56

Salient findings Application of NPK and its substitution with FYM, PS and GM increased the grain yield of rice and wheat significantly (Table 1).

50% substitution by organic manures along with RDF resulted similar AE of N in rice. AE of N was increased in wheat by residual effect.

The response of rice to the application of total RDF(80:40:40) and its 25% substitution with FYM and 50% with PS and GM were (1.94, 2.26, and 2.11t/ha), respectively. Substitution is effective and can save costly inorganic fertilizers.

Apparent recovery efficiency varies from 39% (FP) to70%(T6) indicates usefulness of organic manures as an INM strategy for sustaining productivity.

SYI in both Rice and wheat reflects higher in organically substituted treatments. Closeness to 1 indicates higher sustainability (Singh et al.,1990).

Tr 

Treatment details  pH

 Org.

Carbon(g.kg-1)

Available Nutrients(kg.ha-1)

Kharif(rice)

Rabi (Wheat)

N P K Zn(ppm)

    After 16 cycles of cropping sequences

T1 N0P0K0 N0P0K0 7.2 4.8 152 33.4 180 1.23T2 N40P20K20 N50P30K20 7.3 5.4 185T3 N40P20K20 N100P60K40 7.2 5.8

155 44.9172

3.47

T4 N60P30K30 N75P40K30 7.2 6.0157 40.2

1673.13

T5 N80P40K40 N100P60K40 7.2162 35.1

1893.85

T6 T3+FYM N100P60K40 7.37.0 165 51.4

1895.5

T7 T4+FYM N75P40K30 7.37.2 166 37.9

1673.81

T8 T3+Straw N100P60K40 7.27.0 168 49.9

1761.53

T9 T4+Straw N75P40K30 7.37.8 168 48.4 1.18

T10 T3+GM N100P60K40 7.17.6 160 41.2

43.0194176

0.94

T11 T4+GM N75P40K30 7.38.6 158

38.0 1892.12

T12 FP FP 7.48.46.3

160158 40.9 167

1.110.92

In rice-wheat rotations longer aerobic periods cause a more rapid and complete turnover of O.M. leading to decrease in SOM content (Fig.2) (Dobermann and Fairhurst, 2000).

higher production of CO2 and organic acids.

higher mobilisation of native soil P by the vigorous Sesbania root system and contribution through added biomass.

solubilizing action of certain organic acids produced during FYM decomposition and its greater capacity to hold K in the available form.

pH

SOM

P

K

Fig. 2 Organic Carbon-a sole indicator of soil quality

0

2

4

6

8

10

Initial T1 T2 T3 T4 T5 T6 T7 T8 T9

T10 T11 T12Treatment

Org

anic

ca

rbon

(g/k

g)

Soil quality is…

“the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation.”

(Karlen et al., 1997)(Karlen et al., 1997)

Soil Health vs Soil Quality

• Generally, soil health is synonymous with soil quality except:– Soil health includes only dynamic quality– Soil quality includes dynamic & inherent qualities

A soil may have poor inherent soil quality A soil may have poor inherent soil quality but still have good soil healthbut still have good soil health..

(Gregorich and Carter, 1997)(Gregorich and Carter, 1997)

Monitoring of Trends

Soi

l Qua

lity

Time

Aggrading

Sustaining

Degrading

Bas

elin

e

(Seybold et al., 1998)

Fig. 3: SQI through conventional method

-3500-3000-2500-2000-1500-1000-500

0500

1000

1 2 3 4 5

Treatment

SQI

1= control; 2 = T5 ; 3 = T7 ; 4 = T9 ; 5 =T11

The order of efficacy of different treatments for maintaining soil quality are as follows: NPK+FYM> NPK+GM>100% NPK>NPK+PS>Control (Fig.3). 1= control; 2 =T5; 3 =T7; 4 = T9; 5 =T11 (SQI developed by following the methods of Dalal and Moloney (2000), and adapted from Mandal et al., 2003 ).

Conclusion

25% substitution with FYM and 50% with GM / PS is effective for sustaining production level.

Thus integrated use of green/organic manures and chemical fertilizers is vital for the long-term sustainability of rice-wheat production system as well as soil quality in the Indo-Gangetic plains of West Bengal.

Thanks for your patience