The BHU Future Farming Centre

Information - Crop Management - Production

Corn, Bean, Squash Intercrop Experiment, 2002-03

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Background

Beans, Maize and Squash are frequently planted together as part of an intercropping system in the highland subtropics of Central America.  This apparently has several advantages, particularly for the maize, which performs as well as or better than it does alone. 

Choice of varieties is very important for this type of experiment.  In Mexico where this practice was established the combination is between specific varieties of corn beans and squash. 

Results from a famous experiment near Tabasco in Mexico are presented in Table 1 below

TABLE 1: Yields and Total Biomass of Maize, Beans, and Squash (kg/ha) in Polyculture as Compared with Several Densities (plants/ha) of each crop in monoculture (from Gliessman l998)

Crop

Monoculture

Polyculture

Maize

 

 

 

 

 

Density

33,000

40,000

66,600

100,000

50,000

Yield

990

1,150

1,230

1,170

1,720

Biomass

2,823

3,119

4,487

4,871

5,927

Beans

 

 

 

 

 

Density

56,800

64,000

100,000

133,200

40,000

Yield

425

740

610

695

110

Biomass

853

895

843

1,390

253

Squash

 

 

 

 

 

Density

1,200

1,875

7500

30,000

3,330

Yield

15

215

430

225

80

Biomass

241

841

1,254

802

478

Total polyculture yield

 

 

1,910

Total polyculture biomass

 

 

6,659

There are several approaches to analysing the relationships and relative yield within these intercropping systems.  Here we will look at the treatments outlined in the table below;

Maize

100%

(flour)

Blue Hopi

1

Beans

100%

(dry)

Pinto

2

Squash

100%

(non running)

Sweet Mama

3

 

 

 

 

 

Maize bean squash

100%

 

 

4

Maize bean squash

75%

 

 

5

Maize bean squash

50%

 

 

6

Three replicates were made of each of the six treatments

 

100%

75%

50%

 

Inrow

Interow

Density(plants/m2)

Inrow

Interow

Density(plants/m2)

Inrow

Interow

Density(plants/m2)

corn

0.3

0.45

7.41

0.4

0.45

5.56

0.6

0.45

3.70

beans

0.15

0.45

14.8

0.2

0.45

11.1

0.3

0.45

7.41

squash

0.45

0.45

4.94

0.6

0.45

3.70

0.9

0.45

2.47

Crops were planted on a grid where the rows of corn, beans and squash were 0.15m offset from each other to minimise early competition between species.

Due to season length and low germination considerations the maize corn was grown as cell transplants, while the squash and beans being short season plants were direct seeded.  None of the plots were weeded so the yield effects of weed suppression could be expressed.

Results

Unfortunately each of the treatments was highly variable between reps.  This meant little opportunity to separate the means but also gave the polycultures a greater opportunity to compensate where one crop did poorly.

 Direct relative yield results are illustrated in the table below.

Cropping System

Squash

Bean

Corn

% relative yield

 

Monocrop Maize

 

 

100%

100%

b

Monocrop Beans

 

100%

 

100%

b

Monocrop Squash

100%

 

 

100%

b

Polyculture 100%

61%

19%

90%

170%

a

Polyculture 75%

59%

19%

94%

172%

a

Polyculture 50%

57%

21%

70%

148%

a

The Mexican experience had a cumulative relative yield or land efficiency ratio (LER) of 1.73 for this cropping combination when compared to optimal planting densities.  Other subsistence farming intercrop combinations have shown results of up to 2.82 with recently designed combinations (Altieri 2002)

BHU

monoculture

polyculture

Maize

100%

100%

75%

50%

Density

74074

74074

55556

37037

Yield

4389

3963

4111

3062

%CV

31%

Beans

Density

148148

148148

111111

74074

Yield

3498

1244

1279

1399

%CV

32%

Squash

Density

49383

49383

37037

24691

Yield

36214

22016

21193

20576

%CV

23%

Total polyculture yield

27223

26583

25037

%CV

15%

5%

20%

Yield stability was higher with the polycultures as opposed to the monocultures as can be seen by the coefficient of variation (%CV).  A lower %CV means less variation relative to the yield, so polyculture crops had a LER that varied by 5 – 20% while monoculture crops varied by 23 – 32%.

Similar intercrops have been used on European organic farms to produce cereal legume stock feed mixes e.g. oats and peas (Lampkin 1990).  There is potential for the use of this type of system to produce food directly for humans as well.

One of the additional advantages of the corn-bean-squash intercrop system is the additional biomass produced (Gliessman, 1998).  The additional biomass produced has the potential for stock food or for ‘feeding’ the soil.  Unfortunately, biomass production was not examined in this experiment.

Conclusion

Polycultures have the potential to increase yields and sustainability in many parts of the world.  This type of system could be designed to fit the New Zealand context. 

References

Alteri, M. A. 2002.

Gliessman, S.R. 1998. Agroecology: ecological process in sustainable agriculture. Ann Arbor Press, Michigan.

Lampkin N, 1990.  Organic Farming. Farming Press Books, Ipswich.