o level notes for agriculture

Green manuring

Green manuring is the plowing under or soil incorporation of any green manure crops while they are green or soon after they flower. Green manures are forage or leguminous crops that are grown for their leafy materials needed for soil conservation.

Advantages of green manuring

1. Improves the soil fertility
2. Add nutrients and organic matters
3. Improves the soil structure
4. Improves soil aeration
5. Helps control insect/mite pests, nematodes, and diseases
6. Helps control weeds
7. Promotes habitat for natural enemies
8. Increases soil's biodiversity by stimulating the growth of beneficial microbes and other soil organisms

Green manure crops

Green manure crops	Seeding rate (kg/ha)	Green biomass (t/ha)	Dry biomass (t/ha)	Nitrogen content (%)	Nitrogen (kg/ha)	When to incorporate in the soil? (DAP)
Azolla	50-90	8-10	1.8-3		52	35
Cowpea	40	9-10	3-4	1.4-1.5	140-150	40-60
Lablab	7-18		5-7		220	45-60
Mustard	5-12			3.5		21-37
Pigeon pea	45-67	9-10	5-7			45-60
Sesbania	20-90		1.5-4	4.3	250-360	45-50
Soybean	30-56		5-7.4		310	45-60
Sun hemp	35-40	5-19	5.5-6	1.7	108	50-60
Sweet clover	30-40	12	6	2		40-50

Criteria for the selection of green manure crops

1. Fast growing
2. Produce abundant and succulent tops
3. Well adapted to the local condition
4. Can fix nitrogen in the soil

Reminders

1. Broadcast or sow the seeds after harvest
2. Cut the greens after flowering and plow them under
3. Sow or transplant the next crops 1-2 weeks after the incorporation of the green manure

Intercropping

Intercropping is the cultivation of two or more crops simultaneously on the same field. It also means the growing of two or more crops on the same field with the planting of the second crop after the first one has completed its development. The rationale behind intercropping is that the different crops planted are unlikely to share the same insect pests and diseased-causing pathogens and to conserve the soil.

Types of intercropping practices

·  Mixed or multiple cropping is the cultivation of two or more crops simultaneously on the same field without a row arrangement.

·  Relay cropping is the growing of two or more crops on the same field with the planting of the second crop after the first one has completed its development.
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·  Row intercropping is the cultivation of two or more crops simultaneously on the same field with a row arrangement.

·  Strip cropping is the cultivation of different crops in alternate strips of uniform width and on the same field. It has two types; contour strip cropping and field strip cropping. Contour strip cropping follows a layout of a definite rotational sequence and the tillage is held closely to the exact contour of the field. Field strip cropping has strips with uniform width that follows across the general slope of the land.

Advantages

1. Reduces the insect/mite pest populations because of the diversity of the crops grown. When other crops are present in the field, the insect/mite pests are confused and they need more time to look for their favorite plants.
2. Reduces the plant diseases. The distance between plants of the same species is increased because other crops (belonging to a different family group) are planted in between.
3. Reduces hillside erosion and protects topsoil, especially the contour strip cropping.
4. Attracts more beneficial insects, especially when flowering crops are included the the cropping system
5. Minimizes labor cost on the control of weeds. A mixture of various crops gives often a better coverage of the soil leaving less space for the development of weeds.
6. Utilizes the farm area more efficiently.
7. Results in potential increase for total production and farm profitability than when the same crops are grown separately.
8. Provides 2 or more different food crops for the farm family in one cropping season.

Trap cropping

Trap cropping is the planting of a trap crop to protect the main cash crop from a certain pest or several pests. The trap crop can be from the same or different family group, than that of the main crop, as long as it is more attractive to the pest. There are two types of planting the trap crops; perimeter trap cropping and row intercropping. Perimeter trap cropping (border trap cropping) is the planting of trap crop completely surrounding the main cash crop. It prevents a pest attack that comes from all sides of the field. It works best on pests that are found near the borderline of the farm. Row intercropping is the planting of the trap crop in alternating rows within the main crop.

Advantages of trap cropping

1. Lessens the use of pesticide
2. Lowers the pesticide cost
3. Preserves the indigenous natural enemies
4. Improves the crop's quality
5. Helps conserve the soil and the environment

Table 1. Examples of trap cropping practices

Trap crop	Main crop	Method of planting	Pest controlled
Alfalfa (Meyer, 2003)	Cotton	Strip intercrop	Lygus bug
Basil and marigold (MMSU, 2003)	Garlic	Border crops	Thrips
Castor plant (Hasse, 1986; 1987)	Cotton	Border crop	Heliotis sp.
Chervil (Ellis; Bradley, 1996)	Vegetables Ornamentals	Among plants	Slugs
Chinese cabbage, mustard, and radish (Facknath, 1997; Muniappan; Lali, 1997)	Cabbage	Planted in every 15 rows of cabbage	Cabbage webworm Flea hopper Mustard aphid
Beans and other legumes	Corn	Row intercrop	Leafhopper Leaf beetles Stalk borer Fall armyworm
Chick pea (Grundy; Short, 2003)	Cotton	Block trap crop at 20 plants/ sq m (Brown, 2002)	Heliotis sp.
Collards (Boucher; Durgy, 2003)	Cabbage	Border crop	Diamondback moth
Corn (Hasse, 1986; 1987)	Cotton	Row intercrop, planted in every 20 rows of cotton or every 10-15 m	Heliotis sp.
Cowpea (CIKS, 2000)	Cotton	Row intercrop in every 5 rows of cotton	Heliotis sp.
Desmodium (ICIPE, 2003)	Corn Cowpea Millet Sorghum	Row intercrop	Stemborer Striga
Dill and lovage (Ellis; Bradley, 1996)	Tomato	Row intercrop	Tomato hornworm
Green beans (Ellis; Bradley, 1996)	Soybean	Row intercrop	Mexican bean beetle
Horse radish (DA, Philippines, 1997)	Potato	Intercrop	Colorado potato beetle
Hot cherry pepper (Boucher; Durgy, 2003)	Bell pepper	Border crop	Pepper maggot
Indian mustard (Cornell University, 1995)	Cabbage	Strip intercrop in between cabbage plots	Cabbage head caterpillar
Marigold (French and African marigold) (Vann; Kirkpatrick; Cartwright, 2004) (Dofour; Guerena; Earles, 2003)	Solanaceous Crucifers Legumes Cucurbits	Row/strip intercrop	Nematodes
Medic, Medicago litoralis (Miles, C.; et al., 1996)	Carrot	Strip intercrop in between carrot plots	Carrot root fly
Napier grass (ICIPE, 2003)	Corn	Intercrop Border crop	Stemborer
Nasturtium (Ellis; Bradley, 1996)	Cabbage	Row intercrop	Aphids Flea beetle Cucumber beetle Squash vine borer
Okra (Hasse, 1986; 1987)	Cotton	Border crop	Flower cotton weevil
Onion and garlic	Carrot	Border crops or barrier crops in between plots	Carrot root fly Thrips
Radish (Ellis; Bradley, 1996)	Cabbage family	Row intercrop	Flea beetle Root maggot
Rye (OIKOS, 2003)	Soybean	Row intercrop	Corn seedling maggot
Sesbania (Naito, 2001)	Soybean	Row intercrop at a distance of 15 m apart	Stink bug
Sickle pod (OIKOS, 2003)	Soybean	Strip intercrop	Velvet bean caterpillar Green stink bug
Soybean	Corn	Row intercrop	Heliotis sp.
Sudan grass (ICIPE, 2003)	Corn	Intercrop Border crop	Stemborer
Sunflower (CIKS, 2000)	Cotton	Row intercrop in every 5 rows of cotton	Heliotis sp.
Tansy (DA, Philippines, 1997)	Potato	Intercrop	Colorado potato beetle
Tobacco (Hasse, 1986; 1987)	Cotton	Row intercrop, planted in every 20 rows of cotton	Heliotis sp.
Tomato (Makumbi, 1996)	Cabbage	Intercrop (Tomato is planted 2 weeks ahead at the plots' borders)	Diamondback moth
Vertiver grass (van de Berg, Undated)	Corn	Perimeter crop	Corn stalk borer

Tips for successful trap cropping

·  Make a farm plan. This will guide you on where the trap crops are to be sown or planted.

·  Learn to know and identify the pests.

·  Select a trap crop that is more attractive to the pest than the main crop. Ask for assistance from your local agriculturist.

·  Monitor your plants regularly.

·  Immediately control the pests that are found in the trap crop. Prune or remove the trap crops once the pest population is high, otherwise they will serve as the breeding ground and the pests will attack the rest of your farm.

·  Be ready to sacrifice your trap crop as an early crop and destroy them once pest infestation is high.

·  Always keep farm records.