Well-known legumes include alfalfa, clover, peas, chickpeas, lentils, lupin bean, mesquite, carob, soybeans, peanuts and tamarind. A legume fruit is a simple dry fruit that develops from a simple carpel and usually dehisces (opens along a seam) on two sides.
Cereal Crops are members of the grass family grown for their edible starchy seeds.The important cereal crops produced in Canada are wheat, barley, oats, rye and corn; small hectarages of triticale and grain millets are grown.
Crop Rotation: The growing of different crops in succession on a piece of land to avoid exhausting the soil and to control weeds, pests, and diseases.
Legumes are potential sources of plant nutrients that complement and supplement inorganic fertilizers for cereal crops because of their ability to fix biological nitrogen (N) when included to the cropping systems. By fixing atmospheric N2, legumes offer the most effective way of increasing the productivity of poor soils either in monoculture, intercropping, crop rotations, or mixed cropping systems.
Crop rotation is a practice of rotating/changing the type of crops grown in the field each season or each year (or changing from crops to fallow). It is a key principle of conservation agriculture because it improves the soil structure and fertility, and because it helps control weeds, pests and diseases.
Intercropping is also an ancient practice, placed on the fringes of a ‘modern dominated by large areas of monocultured, resource-consuming and high-yielding crops. Intercropping is considered as a means to address some of the major problems associated with modern farming, including moderate yield, pest and pathogen accumulation, soil degradation and environmental deterioration, thereby helping to deliver sustainable and productive agriculture
Role of legume-cereal crop rotation:
There are the following role of this legume-cereal crop rotation. Legumes have long been recognized and valued as “soil building” crops. Growing legumes improves soil quality through their beneficial effects on soil biological, chemical and physical conditions. When properly managed, legumes will:
- Enhance the N-supplying power of soils
- Increase the soil reserves of organic matter
- Stimulate soil biological activity
- Improve soil structure
- Reduce soil erosion by wind and water
- Increase soil aeration
- Improve soil water-holding capacity
- Make the soil easier to till
The extent of these soil improvements depends mainly on the type of legume used, the quantity of plant material returned to the soil, and the soil and climate conditions.Annual grain legumes (pulse crops) generally have smaller and shorter-lived effects on soil quality than perennial forage legumes.
Legume cereal crop rotation with respect to climate change
Major cropping systems of Pakistan are wheat-cotton, wheat-rice and mixed cropping systems. These fixed/conventional cropping systems are much exhaustive and depleting the soil badly. Similarly delayed sowing of wheat is often observed in almost all of the cropping systems. As there is already time conflict, farmers have no time to maintain their soil health.
Farmers are still following traditional methods of farming. Current farming practices are a major source (19-29%) of anthropogenic greenhouse gas (GHG) emissions. Use of fertilizer particularly nitrogenous fertilizer is increasing at an alarming rate as it will be double up to 2050 (Galloway et al., 2008).
Production and application of synthetic fertilizers is energy intensive, with high CO2 and N2O emissions. N moves down to ground water and cause pollution and diseases (Tilman et al., 2001) while other losses contribute 30% nitric oxide and 70% of nitrous oxide emission; nitrous oxide is 300 times more potent than CO2 to cause global warming (IPCC, 2001).
Atmospheric N2O increases from 0.2 to 0.3% each year by continuous use of synthetic fertilizers. Sustainable agriculture is an ecofriendly system which has the potential to reduce GHG emissions and is an effective strategy for mitigating climate change and building robust soils that are better adapted to extreme weather conditions.