Intercropping is the agricultural practice of cultivating two or more crops in the same space at the same time. A practice often associated with sustainable agriculture and organic farming, intercropping is one form of poly culture, using companion planting principles. It is commonly used in tropical parts of the world and by various indigenous peoples, but in the mechanized agriculture of Europe, North America, and parts of Asia it is far less widespread. Intercropping may benefit crop yield or control of some kind of pest, or may have other agronomic benefits.
Mono cropping is the agricultural practice of growing the same crop year after year on the same land, without crop rotation through other crops. Mono cropping is most frequently practiced in industrialized countries' agricultural systems; maize (corn), soybeans and wheat are three common crops often grown using mono cropping techniques. It is increasingly being done in developing countries as genetically modified organisms (GMO) and industrial farming are displacing native crops and local farmers.
While economically a very efficient system, allowing for specialization in equipment and crop production, mono cropping is also controversial, as it often leads to depletion of the nutrients of the soil and problems with weeds and pesticides. These in turn lead to the mono cropping system being dependent on pesticides and artificial fertilizers. It also leaves the crop more susceptible to disease as genetic similarity between plants makes them equally vulnerable.
In agriculture, multiple cropping is the practice of growing two or more crops in the same space during a single growing season. It is a form of polyculture. It can take the form of double-cropping, in which a second crop is planted after the first has been harvested, or relay cropping, in which the second crop is started amidst the first crop before it has been harvested. A related practice, companion planting, is sometimes used in gardening and intensive cultivation of vegetables and fruits. One example of multi-cropping is tomatoes + onions + marigold; the marigolds repel some tomato pests. Multiple cropping is found in many agricultural traditions. In the cultivation of rice, multiple cropping requires effective irrigation, especially in areas with a dry season. Rain that falls during the wet season permits the cultivation of rice during that period, but during the other half of the year, water cannot be channeled into the rice fields without an irrigation system. The Green Revolution in Asia led to the development of high-yield varieties of rice, which required a substantially shorter growing season of 100 days, as opposed to traditional varieties, which needed 150 to 180 days. Due to this, multiple cropping became more prevalent in Asian countries. One kind of multiple cropping is intercropping, where an additional crop is planted in the spaces available between the main crop.
Organic farming is the form of agriculture that relies on crop rotation, green manure, compost, biological pest control, and mechanical cultivation to maintain soil productivity and control pests, excluding or strictly limiting the use of synthetic fertilizers and synthetic pesticides, plant growth regulators, livestock feed additives, and genetically modified organisms. The organic movement began in the early 1930s and early 1940s as a reaction to agriculture's growing reliance on synthetic fertilizers. Artificial fertilizers had been created during the 18th century, initially with super phosphates and then ammonia derived fertilizers mass-produced using the Haber-Bosch process developed during World War I. These early fertilizers were cheap, powerful, and easy to transport in bulk. Similar advances occurred in chemical pesticides in the 1940s, leading to the decade being referred to as the 'pesticide era'.
Traditional systems already combine various mixtures of livestock species and crops. The challenge is to increase the productivity of traditional systems, so they produce a higher usable biomass while conserving the natural resources on which the whole agricultural system depends. Crop-livestock integration increases the overall productivity of ecosystems, since livestock can use otherwise unusable parts of plants and crop by-products. Conversely, crops can utilize the livestock manure as a source of plant nutrients. Crop-livestock integration also increases sustainability. It is the flow of energy and materials that determine the stability of slopeland ecosystems. Closed systems in which nutrients and energy are recycled are much more sustainable than an open system which leaks nutrients, and which needs higher inputs to maintain its productivity in the long term.
The integration of crops and livestock is a promising agricultural system for low-income small-scale farmers. A great advantage of crop-livestock integration is that it uses diverse resources such as fodder legumes, crop residues and livestock manure in a system of nutrient recycling. Livestock provide a high level of profit per unit of labor input, plus valuable manure for use as fertilizer. Livestock also have the great advantage of being relatively easy to market compared to harvested crops. There is a steady demand for livestock products, with relatively high and stable prices. Another great advantage of livestock production in slopeland agriculture is that the animals can walk to market. This is a considerable benefit in remote areas with poor roads, where farmers would otherwise find it very difficult to market what they produce. In such areas, livestock may be the only feasible source of cash income. The way forward seems to be highly productive mixtures of species, including a range of complementary crops at different levels in the canopy, and forage species as livestock feed. Similarly, slash and burn agriculture is undergoing a transition to sedentary cultivation. For unimproved systems, this is a process of impoverishment, with progressively lower yields and worsening weed and erosion problems. Livestock can also be integrated into slopeland reforestation programs, particularly in the early stages of tree growth.
Soilless culture is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, or mineral wool. Some of the reasons why hydroponics is being adapted around the world for food production are the following:
1. No soil is needed 2. The water stays in the system and can be reused, lower water costs 3. It is possible to control the nutrition levels 100% lower nutrition costs 4. No nutrition pollution in the environment because of the controlled system 5. Stabile and high yields
Pest and diseases are easier to get rid of than in soil because of the containers mobility Today, soilless culture is an established branch of agronomy. Progress has been rapid, and results obtained in various countries have proved it to be thoroughly practical and to have very definite advantages over conventional methods of horticulture. The two chief merits of the soil-less cultivation of plants are, first, much higher crop yields, and second, hydroponics can be used in places where in-ground agriculture or gardening is not possible.
The Soilless conditions (presence of fertilizer and high humidity) create an environment that stimulates salmonella growth. Another disadvantage is pathogens attacks including damp-off due to Verticillium wilt caused by the high moisture levels associated with hydroponics and overwatering of soil based plants.