Crop Production and Management
Agriculture: The science of farming is called agriculture. Farming including cultivation of plants and rearing of animals for food and other beneficial items (like wool, cotton, beverages, etc.) is called agriculture. Agriculture is the main occupation of the majority of people in India. Due to this, most of the people in India live in rural areas.
Crop: When plants of the same kind are grown and cultivated at one place on a large scale commercially, they are called a crop.
Types of Crops in India
India is a vast country where diverse practices of farming are seen in different parts. But crops in India can be divided into two main types, which are as follows:
Kharif: Kharif crops are grown in the rainy season, i.e. during monsoon. Kharif crops are usually sown in June and harvested in September. Kharif crops need high temperature and plenty of rainfall to grow properly. Paddy, maize, soya bean, groundnut and cotton are the examples of Kharif crop. Paddy is the main Kharif crop in India.
Rabi: Rabi crops are grown in the winter season. Rabi crops are sown in October and harvested in March. Rabi crops need mild temperature and moderate water to grow properly. Wheat, gram, mustard, pea and linseed are the examples of Rabi crop. Wheat is the main Rabi crop in India.
Various tasks; which a farmer needs to do during the cultivation of crops are collectively called agricultural practices. Activities which are part of agricultural practices are as follows:
- Preparation of soil
- Adding manure and fertilizer
- Protecting from weeds
Preparation of Soil
The first step of cultivation is the preparation of the soil. This is done by loosening and turning the soil. A plough is used for this purpose. If the soil becomes too hard then farmer may resort to watering the soil before ploughing.
Traditionally, animal-drawn ploughs have been used by farmers. Nowadays, tractor-drawn ploughs are used for this purpose. A tractor helps in saving time and labour.
The soil may contain many big lumps even after ploughing. The lumps are broken with the help of a hoe. Sometimes the farmer may add manure before ploughing; in order to properly mix the manure with soil.
The seeds are sown in the field after ploughing. A farmer needs to separate damaged seeds from good seeds. The seeds should be sown at proper gaps and at the proper depth. The proper gap between seeds and proper depth in the soil ensures adequate sunlight, moisture, air and nutrients to the growing plants. Seeds can be shown by any of the following methods:
Broadcasting: This is a traditional method of sowing seeds. In this method, seeds are sprayed on the field manually, i.e. by hand. Broadcasting is only effective on plots of small size.
Traditional Seed Drill: A seed drill is composed of a funnel which has a long and pointed neck. The seed drill is attached to the plough-shaft. When the seeds are kept in the funnel they drop gradually through the neck; when the field is being ploughed. The pointed end of the neck of seed drill pierces the soil and thus seeds go deep into the soil. Seed drill helps in saving time when the farmer needs to sow a farm of large size.
Modern Seed Drill: The design of modern seed drill has evolved from the traditional seed drill. It contains many hollow and pointed tubes which are fitted on a huge frame of iron. All the tubes are connected to a huge container at the top. Seeds are kept in the container so that seeds can drop through the hollow tubes. Tractor-driven seed drills help in sowing seeds on large farms in less time.
Adding Manure and Fertilizers
We know that plants take nutrients from the soil and thus exhaust the soil's most of the nutrients with the passage of time. Manures and fertilizers need to be added to soil to replenish the plant nutrients.
Manure is prepared by decomposition of plant and animal waste. Farm waste is dumped in the field and is left to decompose. Sometimes, the farm waste may be covered with a layer of soil to hasten the process of decomposition. Sometimes, the help of earthworm is also taken to hasten the process. Farmers also make compost pits to prepare manure.
Fertilizers are chemicals which contain a specific plant nutrient. Fertilizers are made in factories and a pack of fertilizer may contain any one nutrient or a mixture of more than one nutrient. Urea, ammonium sulphate, superphosphate, potash and NPK (Nitrogen, Phosphorus and Potassium) are the examples of fertilizers.
Plants need plenty of water to grow. Farmers need to supply water to crops at regular intervals. This practice is called irrigation. Different types of crop require different amount and frequency of irrigation. Kharif crops need more water than Rabi crops.
Sources of Irrigation: Wells, tube-wells, ponds, lakes, rivers, canals, etc.
Traditional Methods of Irrigation: In traditional method, human or animal labour is used.
- Moat (Pulley System): This is composed of a pulley and a rope. A bucket is tied to one end of the rope. Another end of the rope is pulled through over the pulley in order to draw water.
- Chain Pump: Chain pump is composed of a wheel which is turned with the help of a chain. Many circular discs are fitted along with the chain. Movement of discs along with the chain helps in drawing water.
- Dhekli: Dhekli is composed of a long wooden beam which turns around a lever. A bucket is fitted at the longer end of the beam. The shorter end is pressed and raised by foot to fill and lift water.
- Rahat: Rahat is also called Persian Wheel because it came from Persia. Rahat is composed of a big wheel with buckets fitted on the rim. Rahat is turned with the help of cattle; which helps in drawing water from a reservoir.
Manual pumps are now being replaced by motor-driven pumps. Such motors are powered either by electricity or by a diesel engine.
Modern Methods of Irrigation:
Sprinkler System: The sprinkler system is composed of a series of pipelines. Vertical sprinklers are fitted at suitable gaps on the pipes. The water is pushed through the pipes with the help of a pump. The nozzle of the sprinkler keeps on rotating. It results in a jet of water being sprinkled on plants. Sprinkler system is ideal for irrigation on uneven land.
Drip Irrigation: In this system, pipes are laid near the base and along the queue of plants. The pipes have small holes at frequent gaps. The holes facilitate gradual dripping of water on the base of plants. This method is ideal for areas which are suffering from the shortage of water.
Protection from Weeds
Weeds: Any unwanted plant which grows along with crops is called weed. While some weeds are poisonous, many are not harmful. However, weeds compete with plants for various resources; like sunlight, air, water and nutrients. Weeds hamper the normal growth of plants. Hence, removal of weeds is necessary for a good harvest.
Weeding: Removal of weeds is called weeding. Weeding is usually done manually or by using a trowel. Weeds are also removed during ploughing. Weedicides are the chemicals which destroy weeds. 2, 4 – D is an example of weedicide. Weedicides are sprayed before flowering and seeding in the weeds. A farmer needs to take precautions to prevent any harm from weedicide. The farmer needs to wear protective clothes and masks while spraying a weedicide.
Harvesting involves cutting the mature crop. Traditionally, harvesting is done manually by using sickles. Combine harvesters are used on large farms. A combine harvester does harvesting and threshing at one go.
Threshing: Separation of grains from the harvested crop is called threshing. Threshing is done by threshing machine or by cattle.
Winnowing: Separation of grains and chaff is called winnowing. Winnowing is done manually or by machines.
Proper storage of harvested crop is necessary to prevent the damage from moisture and pests. Grains are generally dried in the sun before being stored. Silos of different sizes are used for storing grains. Fruits and vegetables and other perishable items are stored in cold storage. Pesticides are also used while storing grains.
Nitrogen Cycle – A Biogeochemical Cycle
Nitrogen plays a vital role in the survival of all living organisms. It is one of the primary nutrients and component of biomolecules such as chlorophyll, DNA, and proteins. Nitrogen is the most abundant element present in the atmosphere. Even though it is widely available, it acts as a scarce resource. Only when used in ammonia, it can be used by primary producers such as plants.
The simple diagram of the nitrogen cycle is as shown below.
Nitrogen gas (N2) exists in both organic and inorganic forms. Therefore it undergoes various types of transformation in order to maintain a balance in the ecosystem. The important transformations that nitrogen supports are nitrogen fixation, assimilation, ammonification, nitrification, and denitrification process. The conversion of this gas into its oxidation states plays an important role in maintaining the ecological balance.
The processes involved in a complete nitrogen cycle are:
Atmospheric nitrogen is converted into the usable form by lightning strikes or symbiotic bacteria which are known as Diazotrophs. These bacteria consist of a nitrogenase enzyme which has the capability to combine gaseous nitrogen with hydrogen to form ammonia.
When plants or animal die organic nitrogen is again released back into the soil. Bacteria or fungi present in the soil convert them back into ammonium. This process is also called as mineralization.
Primary producers take in this gas from the soil with the help of their roots in the form of amino acids, nitrite ions, nitrate ions or ammonium ions. This way it enters the food cycle when the consumers eat the plants.
In this process, the ammonia is converted into nitrate by the presence of bacteria in the soil. Ammonia is oxidized to form nitrites by bacteria such as Nitrosomonas species. Nitrates are converted into nitrates by Nitrobacter. This conversion is very important as ammonia gas is toxic to plants.
In order to complete the nitrogen cycle, the nitrites are reduced back to inert nitrogen gas in this process. This is done by bacterial species such as Clostridium and Pseudomonas in the absence of oxygen.