DBE MATRIC Grade 10 Agricultural Sciences Term 4 Lessons – National Senior Certificate (NSC)
Over 700 000 Matric learners will be taking part in this year’s National Senior Certificate (NSC) final Matric exams. Exams will begin in less than three weeks. So today we will be sharing Grade 10 Term 4 Lessons & Notes as released by the South Africa Department of Basic Education (DBE)
TOPIC
Plant studies: General classification and overview of fodder crops. Importance and economic value of plants in agriculture. Arable crops.
PURPOSE OF LESSON :
At the end of this lesson you should be able to know the following:
• Define concepts related to creative thinking and problem solving.
• Apply the knowledge and skills related to the topic
• Classification and overview of…
• The average production volumes of economically important crops / plants
• The main crop production regions in South Africa (arable crops, horticultural crops, pasture crops and timber production)
• The general economic importance and utilization of crops (arable crops, horticultural crops, pasture crops and
timber production)
• Criteria for successful crop production
• Agricultural crops
• Agricultural economy
• Arable crops:
• The climatic and soil requirements of arable crops
• The classification of the following arable crops:
Cereals (maize, wheat, sorghum); Oilseed crops (sunflower, soybeans); and Industrial crops (sugarcane, cotton).
INTRODUCTION
Content of term one must be linked to the current content:
• Agricultural Ecology, Interaction in Ecosystems and Ecological Farming, Pasture Ecology, Pasture or Field Management and Biomes of South Africa
The purpose of the following lesson is to discuss the content associated with “Plant Studies”:
CONCEPTS / SKILLS
Plant studies
Volume of agricultural production :
• Quantity of products produced at any given time
• Weather conditions have a direct effect on crop production
• Low producer prices also have an effect on production volume
Economic importance of crops :
• 5 Million people dependent on agriculture for jobs and income in SA
• SA has the ability to be self-sufficient, but relies on imports for total food supplies
• Wheat, rice, vegetables
• Export products: wine, deciduous fruit, citrus fruits, sugar, avocado pears
Criteria for successful crop production:
• Take climate into account
• Plant at the right time of year
• Cultivation method important
• Plant high quality seed that is disease free
• Correct fertilizer
• Consider water needs
• Apply integrated pest management
• Harvest at the right time
• Store crops properly
• Transport crops correctly
• Protect against water and wind losses
Crops:
• Definition: Plants grown on a large scale for agricultural purposes
Crops / Arable crops Cereal crops – maize, wheat, sorghum
Oilseeds – sunflowers, soybeans
Industrial crops – sugarcane, cotton
Horticultural crops Vegetables – roots, leaves, stems, fruits and flowers
Fruit – tropical, subtropical and deciduous fruit and citrus Flowers – fynbos, garden flowers, cut flowers, shrubs · indigenous crops
Forage crops / Pasture crops Legumes and grass fodder crops
Forest crops Hard and soft wood
Natural and Commercial Forests
Grain crops:
• Definition: Grain is grasses that are grown for their edible components of their seed; staple food.
• Maize is the most widely grown crop locally.
• Wheat is grown in the Western Cape and the Free State.
• In 2008, 2.1 million tons were produced on 748 000 ha, making it the second largest crop in South Africa after maize.
• Grain sorghum is mainly grown in the drier parts of the summer rainfall areas, for example Mpumalanga, the
Free State, Limpopo and North West.
Oilseeds:
• Definition: Cultivated for valuable oil in seeds (20-40%)
• Sunflower
• Soybean
• Canola
• Sunflower is grown in the Free State, North West, Limpopo and the high-lying parts of Mpumalanga.
• Soybean production in South Africa currently ranges from 45000 to 500 000 tons per year. It seems that Mpumalanga is the area that produces the largest amount of soybeans (about 42%).
Industrial crops / Industrial crops:
• Definition: Not necessarily for food production, but for industrial processes.
• Sugarcane: is cultivated in the moist, warm coastal areas and midlands of the country.
These areas range from Mpumalanga through KwaZulu-Natal and south to the Eastern Cape.
• Cotton: is grown in the warm regions of Limpopo, North West, Mpumalanga and Northern Cape.
Uses of crops / arable crops:
• Corn:most important grain crop in SA, staple food for most people. White maize for humans, yellow maize as
animal feed
• Wheat: bread production
• Sunflower seeds:for oil in cooking foods. Oilcake is an important source of protein in feed.
• Brown and white sugar: used as a food sweetener
Jobs:
• Many South Africans make a living from crop production.
• There is a large variety of jobs in crop production.
• Jobs range from temporary workers helping to harvest crops to permanent workers who work as managers and scientists.
• Seed farmers support several other industries.
• They pay laborers, buy fertilizer, support insurance companies and buy fuel and seeds.
• The crops harvested are sold locally and internationally.
• The farmer earns money to pay the farm workers.
• The farming community supports other businesses, for example shops, cooperatives and garages.
The climatic and soil requirements of crops:
Climate requirements of maize:
• Maize requires a significant amount of moisture.
• 500-750 mm well-distributed rain is needed for proper growth.
• Maize uses water economically and is a crop that is relatively drought resistant.
• After germination and beard formation, maize needs less moisture.
• More moisture is needed during the reproduction period.
• Less moisture is also needed when it becomes mature.
• Maize is a crop for hot weather and requires an average daily temperature of about 22 °C and a night temperature above 15 °C.
• Maize needs a significant amount of heat from germination to the flowering stage.
Basic requirements of maize:
• The preferred pH is 5.5-7, which is slightly acidic to neutral.
• The soil must be well drained and well balanced in terms of plant nutrients
• Loam soil, about 1 meter deep, with a high-water capacity is ideal.
• Soil without hard layers is preferable for good root penetration.
Sorghum:
• Most sorghum varieties grown originate in Africa.
• Sorghum is used in some cultures to make home-brewed beer.
• It is also a good feed for livestock
Climate requirements of sorghum:
• Sorghum requires an average temperature of at least 25 0C to produce the maximum yield in a given year.
• Maximum photosynthesis is achieved at daytime temperatures of at least 30.
• Night temperatures below 13 0C for more than a few days severely impaired grain production.
• Planting can only start when the soil temperature has reached 17 0C.
• The long growing season (90-120 days) causes yields to drop sharply if plants are not in the soil early enough.
• Sorghum has a waxy layer on the leaves and stems, which even in intense heat helps to keep water in the plant.
• Sorghum is a drought-resistant grain.
• The plants need in the early growth stage up to 70-100 mm of moisture every ten days.
• By the time the seed heads fill, optimal water conditions drop to 50 mm every ten days.
• Yields are not affected by short droughts because the heads form over longer periods of time.
Soil requirements of sorghum:
• Sorghum can be grown in many different soil types.
• Sorghum will produce the best yield on deep, fertile, well-drained loam soil.
• It’s doing pretty well. Good in shallow soil and under drought conditions.
• Sorghum can be successfully grown on clay, loam or sandy loam soil.
• Fertile, well-drained soil is important for optimal yields.
• Soil with a clay loam texture and a good water capacity is the least suitable for the cultivation of sorghum.
• The crop does well in soils with a pH of 6.0-8.5, because it can tolerate considerable salinity and alkalinity.
• Sorghum is sensitive to aluminum toxicity, and soils with an acid saturation higher than 20% can be a problem.
Wheat:
• Wheat is one of the world’s most important food crops and is one of the first plants to be cultivated.
• New wheat species have evolved because early farmers probably grained from.
• They selected the best wheat plants to plant next year’s crop.
Climatic requirements of wheat:
• Wheat is a crop that grows well in cool environments.
• It needs different temperatures at different stages of growth and development.
• Temperature requirements during germination may differ slightly from one variety to another.
• Optimal temperatures are 20-25 0C.
• At temperatures below or above the optimum temperatures, the germination of seeds slowly decreases.
• If the temperature is above 30 0C when it matures, forced maturity and loss of yield occur.
• Wheat is grown where the annual rainfall is 250 – 1 750 mm.
• Winter wheat is more resistant to cold and frost than spring wheat.
• The density of the vegetation cover and weather conditions will determine how much water is needed.
Sunflower:
Climate requirements of sunflowers:
• Sunflowers are an oilseed crop that is drought resistant.
• It requires a minimum soil temperature of 8 -12 0C during germination and when seedlings grow.
• Seedlings tolerate frost moderately well until it reaches the developmental stage of four to six leaves.
• In South Africa, a shortage of water is the most important factor limiting the production of sunflowers.
• It is important that the available water is used in the best possible way.
• The crop requires warm weather from the seedling stage.
• In drier areas, it is essential that as much water as possible is stored in the soil profile before planting time to limit the chance of a miso crop.
• In the seedling stage, sunflowers are very sensitive to wind damage.
• Cultivation on soil with a light texture that is susceptible to wind erosion should be avoided unless wind erosion is successfully combated.
Soil requirements of sunflowers:
• Sunflowers adapt relatively well to a wide variety of soil types.
• The optimum pH of the soil is 6.5-8.5.
• Sunflowers are very sensitive to high aluminum levels and should not be planted in soil with a pH lower than 4.6.
• Sunflowers prefer sandy loam to clay soils with good drainage and irrigation facilities.
• Most sunflowers in South Africa are planted on soil with a clay percentage of less than 20%.
• Sunflower plants have deep and finely branched taproot systems that can utilize water in deep soil layers (more than 2m deep).
• The crop often does well even in a dry season, especially in deeper soil.
• Due to the unique water use pattern and root system, the shallow soil of Westleigh, Escourt and Kroonstad and other duplex soils is suitable for the cultivation of sunflowers.
• Sunflowers are able to utilize water in the clay horizon of shallow soil.
Soybean:
• Soybeans originally come from China.
• It is a primary, inexpensive source of protein for animal feed.
• Soybeans can produce at least twice as much protein per hectare as any other important vegetable or grain.
Climate requirements of soybeans:
• The optimum temperature for soybeans is 20-30 0C, with a short day length.
• Soybeans need a minimum soil temperature of 12 -15 0C to germinate.
• Planting should be avoided during lower temperatures in winter.
• Soybeans need 400-500 mm of rain in a season for a good harvest.
• High moisture requirements are critical during germination, the flowering period and the pod stage.
• Dry weather is necessary to ripen.
• Soybeans can tolerate short periods of waterlogging, but the weathering of seeds is a serious problem during the rainy season.
• Temperatures below 21 °C and above 32 °C can reduce flower and pod formation.
• Needs a minimum soil temperature of 12-15 0C to germinate.
• Extreme temperatures above 40 0C are harmful to seed production.
The climatic and soil requirements of industrial crops:
Sugar cane
Climate requirements of sugarcane:
• A total rainfall of 1 100 -1500 mm is sufficient.
• During the active growing season, rainfall promotes the rapid growth of the sugarcane.
• During the ripening period, rainfall is not desirable because it causes poor juice quality and impedes the harvesting and transport of sugarcane.
• Growth is related to temperature.
• The optimum temperature for stem emergence is 32-38 0C
• Temperatures above 38 reduce the rate of photosynthesis and increase respiration.
• For ripening, low temperatures of about 12-14 0C are desired.
• Severe cold weather limits the emergence of buds.
• A high humidity (80-85%) promotes the elongation of sugarcane.
• Sugarcane loves sun.
• Climatic conditions that promote high sugar accumulation in the stem are:
• Dry weather with long periods of bright sunshine; .
• Cooler nights with a large variation in day length;
• Very little rainfall during the ripening period.
Basic requirements of sugarcane:
• Sugarcane does not require a specific type of soil.
• It can be successfully cultivated on different soil types, from sandy soil to clay, loam and heavy clay soils.
• Sugarcane will grow well in well-drained, deep loam soil with a
• Sugarcane can tolerate acidic as well as alkaline soils.
• Lime is needed if the pH is lower than 5.0, and the application of gypsum is necessary if the pH is higher than 9.5.
• Very sandy soil is not ideal because nematodes can occur and damage the roots.
Cotton
Climate requirements for cotton:
• Cotton is a tropical crop grown in the hot season.
• It can be grown profitably in regions with a rainfall of 850-1100 mm.
• Economic returns cannot be obtained in regions with a rainfall of less than 500 mm.
• 500 mm well-distributed rainfall is required for higher yields.
• Temperatures above 35 0C are not desirable for the cultivation of cotton.
• When the moisture supply is favorable, the cotton plant can survive very high temperatures for only short periods (43-45 0C).
• If temperatures remain high for a few days, the yields will be severely affected.
• High light intensity throughout the growing season is essential for satisfactory plant development.
Basic requirements of cotton:
• Cotton can grow in a wide variety of soil types.
• The highest cotton yields are usually obtained on alluvial soils.
• ʼn High cotton yield depends on favorable soil air and soil moisture conditions.
• The soil structure and texture are therefore very important.
• Cotton has a deep root system and requires deep soil to grow well.
• It can grow on a variety of soils with a pH of 5-8 and higher
• Cotton is generally considered to be fairly tolerant of brackish soil.
• With irrigation, cotton is usually grown on sandy loam to loam soil.
ACTIVITIES / ASSESSMENT
• Teacher must work through activities that the learners must complete at home.
• Answer the questions in the relevant textbooks.
CONSOLIDATION
• The lesson deals with the content as set out in the CAPS document.
• Learners who understand the content must apply the necessary knowledge and skills to successfully answer questions based on the curriculum content.
• Learners are able to use the knowledge and skills as a good basis for progressing to the next topic. (Horticultural crops)
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