Annexure
Non-point Source Pollution:
In recent year, however, it has become clear that a large portion of the contaminant load to surface and ground waters originates from the land around these waters (e.g. farm field, city street), rather than from specific point sources. This is because non-point source pollution is intimately linked to the hydrologic cycle and particularly drainage from storm events. Rainfall that reaches the land surface has a limited number of subsequent pathways. It either can soak or move over the top of the land surface. The force of moving storm water (runoff) over the land surface provides the energy for the movement of contaminant to receiving water (e.g. river, lakes, estuaries). The only other mode of movement of Nonpoint source contaminant would be wind; however, this transport mode would result in significantly smaller Nonpoint source pollutant loads to water bodies. Also Nonpoint source contaminants are not necessarily significantly different from point source contaminants. In facts, Nonpoint source can generate both traditional and toxic contaminants. In pristine areas, for form anthropogenic influences, aquatic ecosystem receives inputs of natural Nonpoint source contaminants (sediments). However, because rainfall and snowmelt event are the primary driving forces, the movement of Nonpoint source contaminant is more erratic and less frequent and the duration is shorter, than the typically more continuous point source discharges. Most previous experience regarding Nonpoint source contamination has focused on plant nutrient (Phosphorus, Nitrogen) and sediments. Also Nonpoint source pollution contaminants including heavy metals and synthetic organic chemicals, this latter substance may be even more importat, especially in regard to their potential effects on human health. In the agricultural areas, where pesticides and herbicides, nutrients, heavy metals and macro pollutants can be components of Nonpoint source runoff.
Characteristics of Non-point Source Pollution:
- Highly dynamic, occurs at intervals closely related to hydrologic cycle.
- Variability of values can range across several orders of magnitude, one order of magnitude and between regions.
- Most severe water quality impacts occur during or after storm events.
- Entry points to receiving water usually cannot be identified typically arises from extensive land areas.
- Difficult to quantify with traditional techniques.
- Primary water quality parameters are sediments, nutrient, heavy metals, synthetic organics, pH (acidity) and
- Control programmers involve individuals not normally considered in pollution control programmes.
The Magnitude of non point source contaminant loads depends on the following factor as;
- Drainage basin Physiography
- Type and chemistry of soil
- Type and extent of vegetative cover
- Density of drainage channels
- Types and quantities of materials applied to the land surface.
- Duration of the dry period proceeding the rainfall events and
- Volume, intensity and quality of rainfall.
Types of Nonpoint Source Pollution:
- Sediments (erosion)
- Plant nutrients (Phosphorus, Nitrogen)
- BOD, COD
- Heavy metals
- Synthetic organic chemicals
- Dissolved solids (Salinity)
- Microorganisms (bacteria) and metabolic products
- Acidifying compound and
- Macro pollutants (large debris)
Cropping Pattern And Nutrient: Crop Relationship:
Nitrogen is known as the plant nutrient. Air is the primary source of Nitrogen for plant nutrition and only leguminous crops can directly use this free Nitrogen with the help of symbiotic bacteria of the genus Rhizobium. Other pant derives from the soil their Nitrogen in the soil by the action of microorganism on the soil organic matter. Nonsymbiotic microorganisms can fix free nitrogen of the air and make it available to plant in ammonium and nitrate forms. Nitrogen encourages the vegetative development of plant by imparting and healthy green colour to the leaves. It also controls, to some extent, the efficient utilization of phosphorus and potassium. Its deficiency retard growth and root development, turns the foliage yellowish or pale green, hasten maturity, causes the shriveling of grains and lower crop yield. The older leaves are affected first. An excess of nitrogen produces leathery, dark green leaves and succulent growth. It also delay the maturation of plants, impairs the delay the maturation of plants, impairs the quality of the crops like barley, potato, tobacco, sugar cane and fruits. Phosphorus influences the vigour of plant and improves the quality of crops. It also increases resistance to disease and strengthens the stem of cereals plants, thus reducing their tendency to lodge. When applied to leguminous crops, it hasteus and encourage the development of nitrogen fixing nodule bacteria. If P is deficient in the soil, plant fail to make a quick start, do not develop a satisfactory root system, remain stunted and sometimes develop a tendency to show a reddish or purplish discolouration of the stem and foliage oming to an abnormal increase in the sugar contact and the formation of autocyanin.
Pluses from an essential part of the Indian diet and are grown commonly as pure crops in rotation or mixed with cereals, oilseeds and fibre crops. Root and stubble of these pulse legumes return to the soil small quantities of organic matter rich in nitrogen. The inclusion of groundnut in the cotton-Jowar rotation of central, southern and western India, the growing of quick maturing variety of Mung before Wheat in U.P and Wheat and RabiJowar in Marathwada Division. The sowing of peas in the standing crop of irrigated cotton in U.P and the sowing of sunhemp in the standing paddy crops in A.P, Tamilnadu and Karnataka state, or of Val in the coastal paddy areas of Maharashtra are valuable practice for soil improvement. All these leguminous crops leaves the soil in a better physical conditions and richer in nitrogen. The intercropping of cotton with groundnut or with tur in central and southern parts of country. The growing of wheat, mixed peas and grams in northern and central India. Rotation normally, the Rabiwheat is followed in the Kharif by crops such as maize, Jowar, bajara, cotton and arhar. Sometimes, some of the green manure crops, such as sanai, moong, guar, lobia or hubam clover, are sown immediately after Kharif ton enrich the soil. Gram, lineed, barley and mustard are also included in the rotations. With the recent emphasis on intensive agriculture and with the availability of photo-intensive crops verities, the rotation patterns have undergone some changes. In Punjab, Haryana and western U.P rice has become an important crop in the Kharif. It is followed by wheat. In eastern India, wheat has become an important crop and is grown extensively after rice on land, which is left either fallow or put under ‘boro’ rice. In some state, like West Bengal, the rice-wheat-jute rotation has become common. The sugar cane – wheat rotation is also common in northern India. When irrigation is available a legume crop is grown in between two cereal crops to enrich the soil as well as to get the needed pulses. In the black soil of central and peninsular India, unirrigated wheat is rotated with Jowar, bajra or cotton in Kharif in the preceding year. The growing of quick maturing crops, such as mung, generally, onion, coriander and even groundnut or early sown maize as catch crops before wheat is fairly common. The irrigated wheat is rotated with a variety of garden crops and /or irrigated rice, RabiJowar, ragi etc.