P.C. Vanlalhluna1 , U.K. Sahoo2 and S. L. Singh2

1Department of Botany, Pachhunga University College (A constituent College of Mizoram University) Aizawl, Mizoram-796001, India

2Department of Forestry, School of Earth Sciences and Natural Resource Management,

Mizoram University, Aizawl-796 004, India

Growth and yield of agricultural crops intercropped under three multipurpose

trees (MPTs) in Mizoram, North-East India

INTRODUCTION 

→ Mizoram is geographically located between 21˚58' to 24˚35' N latitude and 92˚15' to 93˚29' E longitude.

• Geographycally the state occupies an area of 21081 sq. kms.

• Nearly 6000 sq. kms of the area is under jhum land uses, reckoning to 28.46% of the total geographical area.

• The state of Mizoram shares many of the attributes of mountainous regions elsewhere, such as a high degree of remoteness, inaccessibility, fragility, steep slopes, high biodiversity and a large number of impoverished people.

• The climate is humid subtropical characterized by high rainfall.

• Most of the precipitation (over 80%) occurs during May to September.

• The slope/gradient limit the cropping pattern in the state.

• Nearly 80% of the land is above 30% slope, further a major chunk of the land is under steep to very steep slope hills limiting these are not suitable for agricultural crops.

• However, the hilly terrain favours the agroforestry practices which could bring better crop productivity and sustainable land use.

MATERIALS AND METHODS

 Study area

- Mizoram University campus located at 15km south-west of Aizawl, the capital city of Mizoram

- 23°42' to 23°46' N latitude 92°38' to 92°42' E longitude and 845 m asl.

Average rainfall - 2500 mm and about 80% of the rainfall occurs between June to September.

Temperature - 20° to 30° C in summer and from 8° to 18° C in winter.

Soil - sandy loam with 51.24% sand, 20.71% silt 28.04% clay

Treatment 

Tree seedling - One year old Alnus nepalensis(23cm), Melia azadirach(35cm) Gmelina arborea(30cm) height and

0.46 cm, 0.49 cm and 1.25 cm collar diameter respectively were planted

Spacing - at a uniform 2.5 x 2.5 m spacing (plant to plant and row to row)

Design - Randomized Block Design (RBD)

Replication - (3) three replications.

Intercropped - Local varieties of ginger (Zingiber officinale) turmeric (Curcuma longa)and maize (Zea mays) Weeding - Three weeding were carried out.

first weeding (mid-June) second (mid-August) last (first week of October).

Chemical control measures - were not provided Irrigation of any sort

Crop was raised - rainfed condition.

Data recording Observation - on growth parameters were made on the tree species at six month interval using standard methods.

Crop productivity- October (maize) November (ginger & turmeric).

Soil samples - 0-15 cm soil depth.

Soils - air dried, processed and analysed for pH, organic carbon, available N, P and K using standard methods.

Soil moisture percent = (Fresh weight – Dry weight) x 100/ fresh weight.

Biomass production =Dry weight of sample/fresh weight of sample x Total fresh weight of plant.

Land equivalent ratio (LER) = Ci/Cs + Ti/Ts.

where, Ci = crop yield under intercropping, Cs = crop yield under sole cropping, Ti = tree yield under intercropping, Ts = tree yield under sole system.

RESULTS AND DISCUSSION

Species Growth after 3-year Green biomass productivity (kg/tree)Height (cm)

Girth/Collar diameter(cm)

Canopy(m)

Litter fall (t/ha)

Leaf Twigs Branch

Alnus nepalensisControl 86.13±1.10

 3.86±0.23 8.76±2.09 4.4±0.21 4.3±0.52 14.3±0.91 21.2±0.74

 

Ginger 106.46±0.17 3.91±0.21 10.85±2.02 4.6±0.23 4.5±0.41 15.2±0.52 23.3±0.23 

Turmeric 110.93±0.67 3.95±0.20 10.95±3.05 4.7±0.74 4.6±0.85 16.1±0.32 24.4±0.21 

Maize 128.73±1.35 4.00±0.08 11.06±3.11 4.7±0.11 4.6±0.21 16.3±0.50 25.3±0.23 

CD (P<0.05) 4.41 0.03 0.03 0.05 0.02 0.06 0.09 

Melia azedarach  Control 339.06±1.34 9.40±0.08 6.8.15±1.19 3.2±0.55 4.0±0.22 12.7±0.33 18.5±0.11

 

Ginger 356.53±1.73 9.54±0.11 7.9.56±2.12 3.5±0.25 4.3±0.62 14.3±0.41 19.0±0.14 

Turmeric 362.26±3.17 9.62±0.20 7.9.66±3.15 3.6±0.71 4.4±0.41 15.5±0.47 20.2±0.05 

Maize 380.33±0.29 9.74±0.15 8.03±2.13 3.7±0.21 4.5±0.33 16.6±0.03 21.2±0.07 

CD (P<0.05) 4.62 0.09 0.01 0.01 0.01 0.09 0.07 

Gmelina arborea 

Control 342.33±1.61 9.30±0.04 13.10±2.09 5.6±0.88 4.6±0.52 17.6±0.04 31.1±0.41 

Ginger 354.06±1.57 9.44±0.10 15.52±2.02 5.9±0.62 4.9±0.24 18.2±0.56 32.2±0.63 

Turmeric 359.33±1.07 9.52±0.15 15.62±1.25 6.0±0.29 4.8±0.01 19.0±0.04 33.0±0.25 

Maize 376.13±1.24 9.61±0.13 16.00±1.15 6.2±0.47 4.9±0.55 19.5±0.05 34.5±0.52 

CD (P<0.05) 4.58 0.06 0.08 0.08 0.05 0.04 0.03 

Table 1. Growth and productivity of the tree species over a 3-year period.

 Growth of plants and biomass productivity 

The growth differences were significant (P< 0.05) between the treatments.

The maximum height and collar diameter were attained by Melia azadirach intercrop plot (380.33 & 9.74 cm) > Gmelina arborea (376.13 & 249.61 cm) > Alnus nepalensis (128.73 & 4.00 cm).

It was observed that the tree height and collar diameter were always higher in the intercropped plots than that of the sole crops.

The canopy cover, litter fall and green biomass productivity were maximum in Gmelina arborea intercroped > Melia azadirach > Alnus nepalensis.

The plants under intercropped plots were always taller, thicker and have greater green biomass productivity. This may be due to their ability to retained more soil moisture and provided better microclimatic favouring growth performance  

Species pH Organiccarbon (g/kg)

Available nutrients 

N (%) P (kg/ha) K (kg/ha) 

Alnus nepalensisControl 4.8±0.21 5.2±0.45 0.52±0.03 25.08±0.02 149.22±0.02

Ginger 5.0±0.36 5.3±0.36 0.74±0.01 25.09±0.03 156.54±0.55 

Turmeric 5.1±0.05 5.4±0.21 0.73±0.01 26.78±0.05 156.55±0.49 

Maize 5.2±0.12 5.6±0.33 0.74±0.02 25.05±0.02 157.53±0.47 

CD (P<0.05) 0.06 0.92 0.02 0.03 0.73 

Melia azedarachControl 4.8±0.05 5.0±0.85 0.50±0.02 21.02±0.03 148.03±0.01

 Ginger 4.9±0.85 5.3±0.96 0.74±0.01 22.03±0.07 156.34±0.35

 Turmeric 5.0±0.23 5.5±0.56 0.73±0.01 23.04±0.31 156.57±0.49

 Maize 5.1±0.25 5.6±0.41 0.74±0.02 22.01±0.03 157.24±0.40

 CD (P<0.05) 0.04 1.02 0.03 0.02 0.72

 

Gmelina arboreaControl 5.0±0.24 5.4±0.27 0.51±0.11 33.01±0.05 148.08±0.04

 Ginger 5.1±0.01 5.6±0.09 0.73±0.01 34.02±0.02 155.34±0.51

 

Turmeric 5.2±0.32 5.6±0.25 0.73±0.01 35.04±0.01 156.54±0.50 

Maize 5.3±0.56 5.9±0.05 0.72±0.03 33.01±0.03 156.52±0.56 

CD (P<0.05) 0.03 0.09 0.03 0.02 0.73 

Table 2. Effect of tree cover on physico-chemical properties of soils over a 3-year period

Fertility status of the soil

The soil pH and organic carbon show a significant (P<0.05) variation between the treatments.

Similarly, the NPK content in the soil also varied significantly (P<0.05) between the treatment.

The NPK level in general was maximum under tree-crop interaction than in sole crop (control). More litter production and subsequent litter decomposition might have enriched soil with more nutrients level.

The order of the nutrient level in the field was maximum in maize > turmeric > ginger respectively.

Species Rhizome/ Grain yield (t.ha-1)

Density (ha-1)

AGB(g/plant)

Alnus nepalensis

Control 5.11±0.02 33,597.23±0.53 12.76±2.09

Ginger 6.22±0.08 45,619.53±0.05 13.85±2.02 

Turmeric 5.64±0.01 42,523.05±0.21 14.25±3.05 

Maize 7.07±0.02 47,295.85±0.85 15.06±3.11 

CD (P<0.05) 0.42 - 0.58 

Melia azedarach

Control 5.01±0.04 33,450.52±0.23 12.92±0.05 

Ginger 6.20±0.13 45,512.62±0.12 15.57±2.12 

Turmeric 5.62±0.05 42,510.32±0.52 15.66±3.15 

Maize 6.52±0.02 47,150.06±0.41 16.00±2.13 

CD (P<0.05) 0.35 - 0.42 

Gmelina arboreaControl 6.01±0.03 36,253.03±0.52 13.51±0.04

 

Ginger 6.18±0.06 45,850.85±0.23 15.52±2.02 

Turmeric 5.60±0.02 42,486.69±0.51 15.62±1.25 

Maize 6.21±0.05 45,986.32±0.45 16.03±1.15 

CD (P<0.05) 0.08 - 0.51 

Table 3. Yield of intercrops under different tree species over a 3-year period.

Crop yield  

The yield of crops differed significantly (P<0.05) between the treatments and was influenced by tree association.

Ginger (6.22 t.ha-1), turmeric (5.64 t.ha-1) and maize (7.07 t.ha-1) registered maximum yield under Alnus nepalensis > Melia azadirach > Gmelina arborea.

Maximum crop yield under Alnus nepalensis may be due to their ability to fix atmospheric nitrogen through symbiotic and non-symbiotic association conditions.

In general, the crop yield was found better under intercropped than control. This may be due more litter production and subsequent litter decomposition under trees favouring higher soil moisture and nutrients retention contributed to higher crop yield

Parameters Ginger Turmeric Maize

Number of finger/cob

Control 5.93±0.02 5.73±0.01 7.22±0.02

Alnus nepalensis 6.70±0.01 6.58±0.02 7.01±0.01

Melia azedarach 6.60±0.03 6.47±0.01 6.99±0.03

Gmelina arborea 6.49±0.04 6.33±0.03 5.72±0.01

CD (P<0.05) 0.88 0.84 0.64

Finger size/length of cob (cm)

Control 6.80x5.71 4.59x4.13 16.92±0.03

Alnus nepalensis 8.27x7.99 6.65x6.31 16.71±0.02

Melia azedarach 8.22x7.91 6.52x6.26 16.34±0.02

Gmelina arborea 8.21x7.83 6.35x6.20 16.31±0.01

CD (P<0.05) - - -

Table 4. Intercrop growth under different tree species (after 3-year)

Crop productivity Crop growth differed significantly (P<0.05) between the treatments.

Better finger size and higher finger number were recorded in Alnus nepalensis > Melia azadiranch> Gmelina arborea.

Better finger size and higher finger number under Alnus nepalensis may be due to their ability to fixed atmospheric nitrogen through symbiotic and non-symbiotic association condition.

It was also observed that better finger size and higher number of finger were observed in tree-crop intercropped plot than control. This may be due to higher quantities of leaf fall and decay of root biomass in intercropped plots than sole crops.

Species Land Equivalent Ratio 

Crop Tree Total 

Alnus nepalensisGinger 1.21 1.10 2.31

 Turmeric 1.10 1.13 2.23

 Maize 1.38 1.16 2.54

 Melia azedarach

Ginger 1.23 1.06 2.29 

Turmeric 1.11 1.13 2.24 

Maize 1.30 1.20 2.50 

Gmelia arborea

Ginger 1.02 1.03 2.05 

Turmeric 0.93 1.06 1.99 

Maize 1.03 1.10 2.13 

Table 5. Land Equivalent Ratio of different agroforestry systems in Mizoram.

Land equivalent ratio

It was observed that land equivalent ratio was found to be more than unity (1) in all the treated plot. This showed that there is advantages in tree-crop interaction.

Land equivalent ratio (LER) was found maximum in Alnus nepalensis(2.54) intercroped plot > Melia azidarach(2.50) > Gmelina arborea(2.13). 

Studies on tree-crop interaction are very vital for prescribing suitable agroforestry models in hilly region like Mizoram where there is an urgent need for finding suitable farming practices alternative to shifting cultivation (jhum).

The present findings suggest that introduction of multipurpose trees along with agricultural crops could bring a change to the prevaling widely practiced old-age traditional Jhum and may result in better crop yield and sustainable land use.

CONCLUSIONS

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