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Peanut Farming January 05, 2018

Intercropping and Crop Rotation

INTERCROPPING
Intercropping is the growing of two or more crops together in proximity on the same land. As a result, two or more crops are managed at the same time. It differs from crop rotation in which two or more crops are grown one after the other. There are at least four types of intercropping according to spatial arrangement (Sullivan, 2003).

ROW INTERCROPPING
ROW INTERCROPPING is the growing of two or more crops at the same time with at least one crop planted in rows. In farms grown to perennial crops, annual crops like corn, rice and pineapple are commonly grown as intercrop between the rows of the main crop. This strategy is an efficient way of maximizing the use of farm land by utilizing vacant spaces while at the same time suppressing the growth of weeds during the juvenile stage of the main crop.

With annuals, the component crops are planted at the same time or the other crop(s) are planted during the juvenile stage of growth (before flowering) of the first crop. In India, pigeon pea is traditionally planted with sorghum. The pigeon pea starts flowering after the sorghum plants are harvested. In the United States, velvet bean or cowpea is planted in standing corn at the last corn cultivation. When the corn plants mature, the corn stalks become natural trellis for the beans or peas. Both the corn and the intercrop are harvested together.

STRIP INTERCROPPING

STRIP INTERCROPPING is the growing of two or more crops together in strips wide enough to allow separate production of crops using mechanical implements, but close enough for the crops to interact. Examples of successful strip intercropping practices in the United States are: alternating strips of wheat, corn and soybean 6 rows wide each; oat, corn and soybean; and 6 rows of corn with 12 rows of soybean.

MIXED INTERCROPPING OR MIXED CROPPING is the growing of two or more crops at the same time with no distinct row arrangement.

RELAY INTERCROPPING OR RELAY CROPPING is a system in which a second crop is planted into an existing crop when it has flowered (reproductive stage) but before harvesting. There is thus a minimum temporal overlap of two or more crops. The relay crop should be fairly tolerant to shade and trampling. Examples of relay crops are cassava, cotton, sweet potato and sesban with corn; chickpea, lentil and wheat with upland rice.

IN CROP ROTATION OR SEQUENTIAL CROPPING, two or more crops are grown one after the other in the same piece of land. It is advantageous that the succeeding crop belongs to a family different from that of the previous crop. The period of crop rotation may be for two to three years or longer. Farm income significantly increased by alternating lowland rice with high-value crops like garlic, onion, melons, bell pepper and other vegetables.

ADVANTAGES OF CROP ROTATION COMPARED TO MONOCULTURE
In addition to increased crop yields and profit, the following are the advantages of crop rotation over monoculture, the continuous growing of a single crop.

1. Better control of weeds. Crop rotation is intended to break the life cycle and suppress the growth of weeds. The sequential planting of different crops may check the development of any weed species and reduce weed growth especially if cover crops or green manures (click to read Cover Crops in Tropical Crop Farming) and tall-growing row crops are used as component rotation crops. It improves the soil structure Some crops have strong, deep roots. They can break up hardpans, and tap moisture and nutrients from deep in the soil. Others have many fine, shallow roots. They tap nutrients near the surface and bind the soil. They form many tiny holes so that air and water can get into the soil. Planting the same crop season after season encourages certain weeds, insects and diseases. Planting different crops breaks their life cycle and prevents them from multiplying.
2. Better control of pests and diseases. Some pests and causal organisms of plant diseases are host specific. They attack certain crop species or those belonging to the same family but not others. For example, the problem with rice stem borer will continue if rice is not rotated with other crops of a different family. This is because food will be always available to the pest. However, if legume is planted as the next crop, then corn, beans and bulbs, the build up of the pest will be disrupted because they will be deprived of food.
3. Improved soil structure and organic matter content. The alternate planting of deep and shallow rooted plants will break up the soil and reduce the effects of plow pan. The planting of soybean, other grain legumes, sweet potato and vegetables will return sufficient quantities of plant residues to the soil as their leaves drop on the ground or body parts are left on the field after harvest, instead of being burned as is commonly practiced with sugarcane. Green manures will add significant amounts of organic matter.
4. Improved soil fertility. The continuous growing of a single crop will result to the depletion of certain soil nutrients. With crop rotation, soil fertility will be promoted through alternate planting of crops having different nutrient needs. This will prevent the depletion of any one essential element present in the soil. Leguminous plants, because of their ability to accumulate nitrogen by fixing it from the air in association with Rhizobium bacteria, will improve soil fertility. Legumes (such as groundnuts and beans) fix nitrogen in the soil. When their green parts and roots rot, this nitrogen can be used by other crops such as maize. The result is higher, more stable yields, without the need to apply expensive inorganic fertilizer.

It produces different types of output Growing a mix of grain, beans, vegetables and fodder means a more varied diet and more types of produce to sell.

It reduces risk A single crop may fail because of drought. It may be attacked by pests. Or its market price may be low when time comes to sell it. Producing several different crops reduces these risks.

Cropping systems
You can choose from many different types of crops, and you can plant them in different combinations. Here are some options:

Monocropping
This is where the field is used to grow only one crop season after season. This has several disadvantages: it is difficult to maintain cover on the soil; it encourages pests, diseases and weeds; and it can reduce the soil fertility and damage the soil structure. So avoid monocropping if you can. It is much better to rotate crops, or use intercropping or strip cropping.

Sequential cropping
This involves growing two crops in the same field, one after the other in the same year. In some places, the rainy season is long enough to grow two crops: either two main crops, or one main crop followed by a cover crop. Growing two crops may also be possible if there are two rainy seasons, or if there is enough moisture left in the soil to grow a second crop. If the crops are different, this is a crop rotation.

Intercropping
This means growing a two or more crops in the same field at the same time. It is possible to do this in different ways:

• Broadcasting the seeds of both crops, or dibbling the seeds without any row arrangement. This is called mixed intercropping. It is easy to do but makes weeding, fertilization and harvesting difficult. Individual plants may compete with each other because they are too close together.
• Planting the main crop in rows and then broadcasting the seeds of the intercrop (such as a cover crop).
• Planting both the main crop and the intercrop in rows. This is called row intercropping. The rows make weeding and harvesting easier than with mixed intercropping.

A possible problem is that the intercrop may compete with the main crop for light, water and nutrients. This may reduce the yields of both crops.

Strip cropping
This involves planting broad strips of several crops in the field. Each strip is 3–9 m wide. On slopes, the strips can be laid out along the contour to prevent erosion. The next year, the farmer can rotate crops by planting each strip with a different crop.

Strip cropping has many of the advantages of intercropping: it produces a variety of crops, the legume improves the soil fertility, and rotation helps reduce pest and weed problems. The residues from one strip can be used as soil cover for neighboring strips. At the same time, strip cropping avoids some of the disadvantages of intercropping: managing the single crop within the strip is easy, and competition between the crops is reduced.

Relay cropping
This is growing one crop, then planting another crop (usually a cover crop) in the same field before harvesting the first. This helps avoid competition between the main crop and the intercrop. It also uses the field for a longer time, since the cover crop usually continues to grow after the main crop is harvested.

Crop rotation This means changing the type of crops grown in the field each season or each year (or changing from crops to fallow). Crop rotation is a key principle of conservation agriculture because it improves the soil structure and fertility, and because it helps control weeds, pests and diseases.

Crop rotation is one of the oldest and most effective cultural control strategies. It means the planned order of specific crops planted on the same field. It also means that the succeeding crop belongs to a different family than the previous one. The planned rotation may vary from 2 or 3 year or longer period.

Some insect pests and disease-causing organisms are hosts' specific. For example, rice stem borer feeds mostly on rice. If you don't rotate rice with other crops belonging to a different family, the problem continues as food is always available to the pest. However, if you plant legume as the next crop, then corn, then beans, then bulbs, the insect pest will likely die due to absence of food.

Advantages of crop rotation

1. Prevents soil depletion
2. Maintains soil fertility
3. Reduces soil erosion
4. Controls insect/mite pests. Crop rotation as a means to control to insect pests is most effective when the pests are present before the crop is planted have no wide range of host crops; attack only annual/biennial crops; and do not have the ability to fly from one field to another.
5. Reduces reliance on synthetic chemicals
6. Reduces the pests' build-up
7. Prevents diseases
8. Helps control weeds

Useful tips in planning crop rotation

1. Know the family where your crops belong to make sure that you plant on the next cropping a crop that belongs to a different family than the previous one.
   

   Family	Common names
   Allium	Chive, garlic, leek, onion, shallot
   Cucurbit (Gourd family)	Bitter gourd, bottle gourd, chayote cucumber, ivy gourd, luffa gourd, melons pumpkins, snake gourd, squash, wax gourd
   Crucifer (Brassica)	Bok choy (petchay), broccoli, Brussels sprouts,  cabbage, Chinese cabbage, cauliflower, collard, kale, kohlrabi, mustard, radish,turnip, watercress
   Legume	Common beans, black bean, broad bean (Fava), clover, cowpea, garbanzo, hyacinth bean, kidney bean, Lima bean, lintel, mungbean, peanut, pigeon pea, pinto bean, runner bean, snap pea, snow pea, soybean, string bean, white bean
   Aster	Lettuce, artichoke
   Solanaceous (Nightshade family)	Potato, tomato, pepper, eggplant
   Grains and cereals	Corn, rice, sorghum, wheat, oat, barley, millet
   Carrot family	Carrot, celery, dill, parsnip, parsley
   Root crops	Cassava, sweet potato, taro, yam, water chestnut
   Mallow family	Cotton, okra

2. Make a list of the crops you want to grow by also taken into consideration the market's demand of your produce. For example, plant leafy vegetable on the first cropping season, next fruit vegetables, then root crops, then legumes, then small grains.
3. Grow legumes before grains or cereals.
4. Practice green manuring.
5. Always keep farm records.