Agrisilviculture/Silviagriculture/Agrosilviculture (Shifting Cultivation)
This system involves the conscious and deliberate use of land for the concurrent production of agricultural crops including tree, crops and forest crops. Based on the nature of the components this system can be grouped into various forms:
a) Improved fallow species in shifting cultivation
b) Taungya system
c) Multispecies tree gardens
d) Alley cropping (Hedgerow inter-cropping)
e) Multipurpose trees and shrubs on farmlands
f) Crops combination with plantation crops
g) Agroforestry for fuelwood production
h) Shelter belts
i) Wind breaks
j) Soil conservation hedges etc.
a) Improved fallow species in shifting cultivation:Shifting cultivation:
- It is prevalent in many parts of Africa, Latin America, South-East Asia and Indian subcontinent.
- In India it is prevalent in Assam, Meghalaya, Jharkhand, Manipur, Orissa, Nagaland, Chattisgarh, M.P., Arunanchal Pradesh, Andhra Pradesh, Mizoram, Tripura, Kerala, West Bengal, Sikkim.
- It is known as ‘jhuming’ in North-east, ‘khallu / kurwa’ in Jharkhand and ‘dahiya’ or ‘podo’ in Orissa, Andhra Pradesh.
- In this system, forest patch is selected and cleared felled. The herbs, shrubs and twigs and branches (slashed vegetation) are burnt .Cultivation of crops is done for a few years until soil fertility declines. The site is than abandoned (fallow period) and new patch is selected for cultivation of crops. The site is again cultivated after giving rest for few years.
- Earlier the fallow cycle was of 20–30 year. However, due to increasing requirement for cultivation of land due to population pressure, fallow period has reduced from 25–30 years to 2–3 years which has broken down the resilience of ecosystem and the land is increasingly deteriorating. Thus now shifting cultivation has become source of ecological degradation, soil erosion and converting good forests into wastelands.
Plate 3.2 Shifting cultivationEffect of shifting cultivation
- Deforestation and denudation of hill slopes-in secondary succession, area is occupied by weeds, useless shrubs etc
- Soil erosion which leads to soil and nutrient losses, silting of reservoirs and streams, reduction in water-yield and landslips and landslides
- Shifting cultivation adversely affects cation exchange capacity and physical properties of soil. It leads to lowering of organic matter and lowering the total quantity of sesquioxides, iron, aluminum, calcium, potassium, phosphorus, etc.
- Increases soil pH and reducing microbial activity
- More weed growth and lower crop yield
- No opportunity for infrastructural development
Controlling shifting cultivation
- Motivate public for permanent agriculture by opening demonstration centers for improved agricultural practices, good quality seed, manuring, irrigation, weeding use of improved tools, terracing etc.
- Earning goodwill of local people: By engaging them in forest work and training them to undertake shifting cultivation on scientific lines.
- Arable land can be provided to the tribals for carrying out agriculture and also to settle in the area; a few schemes are being implemented under integrated tribal development programme
- Legal measures: on steep slopes, near to roadside etc
- Using land according to its capability
- Provision of alternative management
- Development of animal husbandry and dairy farming
- Training of artisans and development of handicrafts
- Employment in forest works and other industries
- Providing communication facilities
- Providing economic assistance for houses and agriculture operations
Improved fallow species in shifting cultivation:
- Fallows are crop land left without crops for periods ranging from one season to several years.
- The objective of improved fallow species in shifting cultivation is to recover depleted soil nutrients. Once the soil has recovered, crops are reintroduced for one or more season.
- The best species for the fallow system should induce good nitrogen fixation in the soil.
- The main aim of the fallow is to maintain or restore soil fertility and reduce erosion; some plants can be introduced primarily for their economic value.
- Plants included in improved fallows should be compatible with future crops, free of any negative physical or chemical effects on the soil and not in competition with the crops to be planted later on the same site.