Sustainable agriculture may be defined as the successful management of resources for agriculture to satisfy the changing human needs, while maintaining or enhancing the quality of environment and conserving natural resources.
Sustainable agriculture involves several techniques such as mixed farming, mixed cropping, crop rotation and crop selection.
- It can be defined as a system of farming on a particular form to sustain and satisfy the essential needs of the farmers. This includes crop production, raising of livestock, poultry, fish and bee keeping etc.
- A mixed farming system in which a farmer grows food crops such as rice and wheat together with fodder crops such as oat and sorghum is called a food-fodder farming system.
- A farming system in which fruit and fodder crops are grown is called a horti-pastoral system.
- A farming system in which crops are grown along with timber trees is called an agro-forestry system.
- The mixed cropping is growing of two or more crops simultaneously on the same piece of land.
- The basic objective of mixed cropping is minimising risk and insurance against crop failure due to abnormal weather condition.
- Growing two or more crops but in definite row pattern is known as intercropping. The objective is to increase productivity per unit area and time.
- Crop rotation is the practice of growing different crops in succession in the same field or soil.
- The fundamental aim is to increase the productivity, but it also helps to maintain the fertility and moisture content of the soil.
- A particular crop requires certain nutrients. If it is grown on the same soil year after year, the soil becomes deficient in these nutrients. Crop rotation resolves this problem. Usually a leguminous crop is grown between two cereal crops. Cereal crops take away nitrogenous compounds from the soil. The nitrogen-fixing bacteria in the roots of pulse crops restore these compounds.
- Crop rotation helps control pests and diseases too. When the same crop is grown in the same field over and over again, the pests specific to the crop get the right conditions to multiply more and more rapidly. When another crop is grown in between, their growth slows down because they do not find its favourable conditions.
A crop variety must possess several desirable characters such as high yield, superior quality, early maturing, resistance to important diseases, insect pests etc.
- Improvement of crop varieties is an important measure, which creates the genetic potential in crop plants for higher and better yield. Scientists involved in this work are called plant breeders, and the science of improving crop varieties is called plant breeding.
- The various approaches used are referred to as plant-breeding methods or techniques. These involve introduction of crop from another area; selection of plants with desired traits; hybridisation or cross-breeding plants with diverse desirable characters.
- A breeder selects from a population, such plants that have desirable characteristics. Seeds from only the selected plants are harvested and used to raise the next generation. This process is called
- selection. This step brings about improvement in the crop. Selection utilises the genetic variation present in a crop.
- Hybridisation refers to crossing between genetically dissimilar plants. This crossing may be intervarietal (between different varieties), interspecific (between two different species of the same genus) and intergeneric (between different genera). In plant breeding, intervarietal hybridisation is extensively used.