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Soils vary greatly in their organic matter content. For all practical purposes the organic matter content of the soil parallels the soil N content. The C/N ratio of soil organic matter generally falls in the range of 10 to 12. Because of the ease with which Kjeldahl determination can be made, N is often used as an index of soil organic matter content.

3.1. Composition of Organic Matter in Soil

Organic matter constitutes 1 to 6% of the topsoil weight of most upland soils. In a typical grassland soil, 5 to 6% of organic matter may be present in the top 15 cm. Top soils with less than 1% organic matter are mostly limited to desert regions. On the contrary, the organic matter content of soils in low, wet areas may be as high as 90% or even more. Soils with more than 12 - 18% organic carbon (approximately 20 - 30% organic matter) are called organic soils.

Soil organic matter makes up only a few per cent of most soils, but it has a great deal of influence on soil properties and on agricultural productivity.

2.1. Quantity of Organic Matter

Based on the content of organic matter, soils are identified as mineral or organic. Mineral soils dominate most of the world’s cultivated land and may contain anything from a trace to 30 per cent of organic matter. Organic soils are naturally rich in organic matter, chiefly due to climatic reasons. Although they contain more than 30 per cent organic matter, it is precisely for this reason that they are not vital cropping soils.

The term soil organic matter (SOM) includes any material that is produced originally by soil organisms (plant or animal) that is returned to the soil and undergoes decomposition process. At any point in time, it consists of an array of materials, ranging from the intact original tissues of plants and animals to the substantially decomposed mixture of materials known as humus (Fig.1.1). Most soil organic matter originates from plant tissues. Plant residues contain 60 - 90 per cent of moisture and the remaining dry matter consists mostly of carbon, oxygen, hydrogen, with smaller amounts of sulphur, nitrogen, phosphorus, potassium, calcium and magnesium. Though present in small amounts, these nutrients are of great significance from the standpoint of soil fertility.

Organic manures

Anand Swarup (1992) stated that application of green manures along with rice husk increased the concentrations of N, P, Zn, Mn and Fe and decreased the Na concentration of rice in a reclaimed sodic soil. Kolambe and Patel (1994) reported that application of organic amendments along with phosphorus increased the uptake of phosphorus at different growth stages of rice.

Talashilkar and Chavan (1997) reported that incorporation of 10 t of Glyricidia ha^-1 and application of 100 per cent RDF recorded the highest total N uptake by rice over three successive years. Mishra and Sharma (1997) found that application of 100 per cent NPK + 10 t FYM ha^-1 resulted in highest total uptake of NPK by rice. Mahapatra etal. (1997) revealed that application of 80 kg N ha^-1 through green manure alone or through combined use of green manure and urea increased the total uptake of N by rice over application of fertilizers alone.

The uptake of Mg by rice plant was highest when fertilizer was applied in combination with vermicompost (Jadhav etal, 1997). Pattanayak etal. (2001) also reported the highest Ca uptake in the treatments that received green manuring of dhaincha. Sriramachandrasekharan (2001) who reported the highest Fe uptake of rice with green manuring of Sesbania aculeata.

Debele et al. (2001) reported that the application of FYM enriched with 10% rock phosphate + gypsum with PSB and PSF @ 500 g inoculums t^-1 of FYM increased the nutrient uptake of maize. The higher nutrient uptake of 227 kg N ha^-1, 59.5 kg P ha^-1 and 227 kg K ha^-1 recorded with the application of enriched FYM @ 2 t ha^-1.

In the global scenario, the increasing energy crisis and consequent escalation of chemical fertilizer prices along with increasing risk associated with soil degradation have reviewed interest in bio-resources for attaining soil health and sustainable crop production. The use of organic manures, bio-fertilizers and chemical fertilizers will augment the efficiency of combined application of nutrients to maintain a high level of soil productivity and rice production (Thakuria et al., 1991; Prasad et al., 1995). Several experimental evidences showed that the combination of various bio-resources with chemical fertilizers improved the rice production in sustainable way (Roy and Jha, 1987; Subba Rao, 1995; Mahapatra et al., 1997; Suresh et al., 2001).

The bio-resources application in the soil is known to improve the biological properties of the soil. Several earlier reports show a spur in microbial populations or increased microbial biomass carbon and the enhanced enzymatic activities with the incorporation of bio-resources in soil (Perucci, 1990; Goyal et al., 1993; Bonde et al., 2004).

Microbial populations

Indigenous microbial populations in soil are of fundamental importance for an eco system functioning, through determining nutrient cycling, organic matter decomposition and energy flow (Doran and Zeiss, 2000).

Secondary nutrients

Secondary nutrients includes Calcium, magnesium, and sulfur. Crop plants requires secondary nutrients in moderate quantity for crop growth and yield. Their requirement by plant is less than the macro nutrients. Sulphur and Magnesium requirement of crops are very similar to the Phosphorus needs. Calcium is required in higher amount than Phosphorus. Calcium and magnesium are mostly deficient in acid and alkali soils. In India S deficiencies are found in almost 40 per cent of the cultivated soil. Under intensive cropping system, the use of higher amount of nitrogenous fertilizer without secondary and micro nutrients and lesser use of organic manures are the major reason for the secondary and micro nutrient deficiency in soil.

Potassium availability in most of the coastal salt affected soils of India is rich except when the soils are low in clay content (Bandyopadhyay et al., 1985). Plants grown under high salinity may show K deficiency due to the antagonistic effect of Na on K absorption and / or disturbed Na / K ratio. Under such conditions application of K is also known to reduce the adverse effect of salinity and sodicity on crop growth (Qadar, 1995). Singh et al. (1980) reported that the addition of FYM increased the K concentration in the soil. Swarup (1987) reported that the incorporation of green manure increased the available N, P and K status of the soil. Available P and K remarkably increased to a tune of 30 and 44 per cent respectively by the application of coir waste (Santhi et al., 1991).

Experiments at Central Soil Salinity Research Institute (CSSRI), Kamal, India showed that alkali soils are not always high in available P and rice and wheat significantly responded to addition of P (Pathak et al., 1975).

The availability of phosphorus in soil either native or added is limited by fixation and precipitation mechanisms. The organic acids released during decomposition of organic matter influences the soil pH, form stable complexes with cations responsible for P fixation and thus increases the availability (Tiwari et al., 1980).

The use of bulky organic manures (Maurya and Ghosh, 1972; Chaudhary et al., 1981) and green manures (Prabhakar et al., 1972; Sharma et al., 2000) has been found very beneficial for P management of saline and alkali soils as these improve the soil physical condition and the availability of soil phosphates.

It is generally observed that N, P and Zn content in soil decreases with increasing soil salinity. Nutrient imbalances created by continuous use of chemical fertilizers, particularly nitrogenous fertilizer alone, combined with sub optimal rates of other nutrients or total omission of other nutrients are the primary causes for unsustainable yields of crops in saline soil. A sustainable approach for nutrient management in salt affected soils should therefore include balanced use of organic, inorganic and biological sources of nutrients (Bandyopadhyay and Rao, 2001). Organic amendments are known to facilitate the reclamation of sodic soils and better nutrition of crops (Anand swarup, 1992).

The coastal salt affected soils are low in productivity due to various soil fertility constraints that affect the crop growth and yield. The high salt content &/or high pH cause changes in solubility, availability and efficiency of plant nutrients, besides deteriorating the physical condition of soil. The soil biology (microbial population and enzymatic activities) also severely affected in these salt affected soils. The bio-resources are known to improve soil physical, chemical & biological properties of the soil. The maximization of rice production and considerable improvement in quality and composition of rice in coastal salt affected soil with the use of bio-resources have been reported by several research workers.

Around the world, nearly one billion people live along the 3,12,000 Km long coastline. The Indian coastline runs around 8,129 Km distributed along nine coastal states, two groups of islands and two union territories. The coastal ecosystem of India forms a very valuable resource community, supporting the livelihood security of several million rural poor and also contributing the national economy in a large measure. The latest estimates by National Bureau of Soil Survey and Land Use Planning (NBSS & LUP), Nagpur, India, using Global Assessment of Soil Degradation (GLASOD) guidelines indicate that the coastal area in the country is spread over an area of 11.8 million hectares (Mishra, 2005). Yadav et al. (1983) have reported about 3.1 M ha and 2.1 lakh ha of coastal salinity in India and Tamilnadu respectively.

Potato is an important crop of the world and grown in almost all the states in India. Apart from India, potato is grown in more than 100 countries but the intensity of cultivation varies considerably. For example in the Netherlands 19.6% of the total arable land is cultivated with potatoes. The figures for Germany, Peru and USA are 10.1%, 5.6% and less than 1% respectively. India ranks fourth in area (1.29 m ha) and third in production (25.23 m ton) in the world. The productivity of potato depends mainly on the quality and quantity of planting materials and the agronomic management practices adopted. Most of developing countries including India experience release of high yielding varieties, development of adequate agronomic and pest control measures but the gap between supply and demand of good quality adequate quantity seed has to be the major constraint in increasing its productivity. 

5.1 Jute Seed Production

Jute ranks secand next to cotton as the most important natural fibre and it recognized as the ‘golden fibre’. Its products being biodegradable and environment friendly in contrast to synthetic substitutes, a renewed interest in this natural fibre has been generated in the recent past throughout the world. Important characteristics of jute fibre are its silky lustures, high tensile strength, low extensibility, considerable heat resistance. Because of its great abundance and shortage of cotton, jute is blended with cotton and jute/cotton blended yarns are produced mainly to take advantage of the lower price of jute fibre (Doraiswamy et al, 1998). Several diversified product is also made from jute. Since currently the paper industry has been using it as a raw material for paper. It is also being used in geotextile. The jute sticks are largely used as fuel and also for making gun powder.

3.1 Redgram or Pigeon Pea

In any production programme, the importance of quality seed needs hardly be emphasized. In fact, the major bottleneck in the pigeon pea cultivation programme is the restricted or poor availability of quality seeds of the desirable varieties. The seed has been considered as the ‘vehicle of change’. With better attention paid to their interaction among water, fertilizer and seed of improved varieties, the production can be maximized. Although a numbers of improved varieties of pigeon pea have been released since 1970, organized seed production programmes have been rather limited. Most of our national efforts in this direction continue to be centralized on cereal crops like wheat, rice and hybrid millets. Moreover, the benefits of the current research will not reach the farmers unless large-scale seed multiplication programmes are organized.

4.1 Mustard

The principle oil yielding rape seed and mustard sp. cultivated in India are

4.1.1 Land Requirement

Select seed field on which the Brassica sp. was not grown in the previous season unless the crop in the previous season was of the same variety and was grown from certified seed. To avoid disease control it is necessary to fallow a 3-4 year crop rotation so that a given field is selected one in every 3-4 years. In addition select field should be well drained, leveled and suitable for Brassica cultivation.

2.1 Rice

Rice is the staple food for the largest number of people on the Earth. According to an estimate, the global rice production must reach 800 million tonne from the present 91.04 million tonne in 2005-06 to meet the demand in 2025. It’s area is 37% of the total area under food grains as against 20% under wheat, another important food crop. But globally it stands next to wheat in harvested area. As the irrigated rice contributes more than 75 per cent of the total rice production, enhancing its yield potential would be key to meeting the global rice requirement for an additional 215 million tonne. To achieve the target yield, rice varieties with a yield advantage of about 20 per cent over popular and widely adapted rice varieties under tropical conditions must be developed. Experience in China, India, Vietnam, Philippines, Bangladesh and several other countries clearly indicates that hybrid rice technology offers readily available option to meet this challenge. 

Current Status of Seed Production

Organized seed production in India became possible with the formation of National Seed Corporation (NSC) during 1963, which paved the way for a sound seed industry to come as a consequence of the introduction of hybrid technology during 1961-65. The release of high yielding dwarf varieties of wheat and rice by the 1960’s gave further impetus to the growth of the seed industry in the country. For the total area under cultivation of 26.7 m ha and 65 per cent of the area) insect, disease and weeds (10-40 per cent loss) and also poor shelf-life. Hybrid technology have defined solution in several crop plants specially vegetables, cotton, rice etc. with the development of appropriate hybridization and seed production. In 1990-91, the area planted to ‘bought seed’ was about 10.35 per cent. The total ‘bought seed’ was estimated at around 5.91 lakh tonnes valued at Rs 679.80 crores. 

These beans are mostly found in China, Korea, Japan, India, Sri Lanka, Madagascar, and Indonesia, and are not frequently cultivated for commercial purposes. Sword bean pods can reach a length of over a foot and a width of one to two inches. It is grown as a minor vegetable for local use throughout South and Southeast Asia, particularly in India, Sri Lanka, and Myanmar. Sword bean is typically planted as an annual vegetable crop because it is a perennial climbing legume. Sword bean is grown for its soft pods, which can be eaten raw or cooked.