CHAPTER I
INTRODUCTION
Agriculture is an art and science of growing crops that is satisfying the most fundamental need of man i.e., food has influenced the social and economic life of the people of India for centuries. Agriculture is and will be the backbone of Indian economy contributing to a significant part of the gross domestic product where two thirds of the population is either engaged directly or indirectly in farm related activities.
The dawn of the new millennium poses tough challenges to the farming community, producing more food to feed the burgeoning population from shrinking land and less water without eroding ecological foundations will be an uphill task. The surest means to take over this challenge is through environmentally sustainable farming methods, which are economically rewarding and intellectually stimulating. A strategy for integrated nutrient supply is evolved by using a judicious combination of chemical fertilizers, organic manures, green manures and biofertilizers.
India achieved self-sufficiency with rapid growth and development in food grain production from a mere 51.0 M.T. in fifties to 205.91 M.T. now. This was possible through co-operative effort made by farmers and scientists by bringing the research from laboratory to land. There has been number of reports from almost every state in the country that in spite of increased input the crop production has either levelled off or declining because of reduction in organic carbon content of soil. Soils are being constantly degraded and destroyed with profound economic costs. About 70% of our soils are deficient in organic carbon (less than 1%) and micronutrients deficiencies are being widely experienced throughout the country. Soil toxicity due to industrial effluents and use of chemicals and pesticides is affecting adversely both soil health and crop productivity (Paroda, 2001). In India it has been observed in large number of experiments that crop yields of important crops even with very high amounts of organic manures (20 to 30 t ha-1) do not equal those obtained with normal recommended dose of fertilizers (100-150 kg N, 40-60 kg P2O5 and 40-60 kg K2O ha-1). The crop yields are higher, when both are applied together. This is attributed to proper nutrient supply as well as creation of better soil physical and biological conditions.
Rice has a unique position in Indian economy. The rice industry in India has an extremely rich legacy. India is the world’s second largest rice producer and consumer next to China. It accounts for almost 22% of the total world paddy production (Anon., 1997). India is having the largest area under rice (43 million hectares) however the production is very low (86.10 M.T.) as compared to other rice growing countries of the world. Per capita consumption averages to around 86 kg per year. In Maharashtra rice ranks third in respect of area among cereals with 14.65 lakh hectares total area under rice with production of 18.79 lakh t however the average productivity is as low as 15 q ha-1. Rice occupies 4.6 lakh hectares in Konkan region with production of 8.7 lakh t and 23.0 q ha-1 average yields. The main reasons for low productivity are vagaries of nature, low fertilizer use efficiency, poor management and heavy infestation of weeds (Anon., 2002).
India occupies a premier position in global oilseed scenario accounting for 14% oilseed area and 8% of oilseeds production (Hegde, 1996). Oilseeds are rich sources of energy and nutrition. Edible oils and oil meals have an important role to play in relieving malnutrition and calorie nutrition of human and animal population. The oilseeds scenario has undergone a dramatic change in recent years where in the oilseed sector became a net foreign exchange earner leading to Yellow Revolution. Edible oil consumption is continuously rising reaching almost 12.5 kg per annum during 1998-99. For a projected population of 1180 million in 2010 the edible oilseeds with a per capita consumption of 15 kg work out to 17.7 M.T. equivalents to 51 M.T. of oilseeds.
India has the third largest oil economy in the world however India’s consumption of oils and fats has been low. Over the years there has been some increase in the per capita consumption of edible oils to 7 kg per year though it is much below the world average of 14.5 kg per person per year. The developed western world has an annual per capita consumption of 30 kg. To meet the future demands for oilseeds concerted efforts will have to be made to achieve the target of 10.49 M.T. of edible oil, which could be extracted from 34.63 M.T. of edible oilseeds production by 2020 A.D.
Indian mustard [Brassica juncea (L.) Czernj. & Cosson] commonly known as raya, rai and laha is one of the most important edible oilseed crops among the various oilseed crops ranking second in the world in rapeseed production. It occupies a prominent place being next to groundnut both in area and production meeting the fat requirement of about 50% population of the northern and eastern parts of India. India is one of the largest producers of mustard in the world having the area of about 6.85 million hectares, production 6.94 M.T. and productivity 10.13 q ha-1 during 1996-97. In Maharashtra the area and production during 1993-94 was 13 thousand hectares and 5 thousand t respectively with the productivity of 381 kg ha-1 (Patil et al., 1995). Frontline demonstration by the Directorate of Oilseeds Research on the field has shown that there is an immense potential to enhance productivity of mustard from the present level by adoption of recommended technologies (Prasad, 1994).
Mustard being a tap rooted crop with well spread lateral root system can be grown both under rainfed and irrigated conditions. It offers good scope for diversification of cropping pattern in rabi season particularly in areas where water is scarce. In Konkan region though it is cultivated for last 10 years the productivity is still low (333 kg ha-1). The principle causes of low productivity are lack of irrigation facilities, low use of fertilizers, late sowing time, weed menace and lack of plant protection measures. The importance of fertilizer is increasing the production of food grains and other crop is well recognized by the farmers (Anon., 1998). Farmers give recommended doses of fertilizer to the crop, but soils vary in fertility not only from hectare to hectare, but even from meter to meter. Soil fertility is also unstable from season to season. There may be increase or decrease in soil nutrient status due to cultivation and management practices on soil.
Fertilizers are costly input in modern agriculture. In future production costs of NPK fertilizers will become more costly and the demand for them will depend upon the ability of the farmers to pay for them. Economic rationality therefore dictates a more comprehensive approach to fertilizer utilization, incorporating soil test, field experimentation and economic evaluation of results (Anon., 1998). The continuous unbalanced use of fertilizers in intensive cropping system often leads to disproportionate nutrient availability and adverse effect on physical properties and chemical composition of soil, which finally results in declining crop yields. The integrated use of green manures, biofertilizers and chemical fertilizers can help to maintain optimum crop yields and required soil nutrient pool on sustained basis. Integrated plant nutrient approach is going to be the mainstay in the next millennium. Integrated plant nutrient supply system (IPNS) developed by the FAO is the maintenance or adjustment of soil fertility and of plant nutrient supply to an optimum level for sustaining the desired productivity through optimization of the benefits from all possible sources in an integrated manner.
Integrated nutrient management (INM) is a prescription for developing a durable IPNS. The INM is soil fertility sustaining practice because it enhances the availability of both applied and native soil nutrients during the growing season of the crops synchronizes the nutrient demand set by the plants both in time and space with supply of the nutrients from the labile soil and applied nutrient pools sustains and enhances chemical, biological and physical soil health and arrests degradation of soil, water and environmental quality by promoting carbon sequestration, minimizing the avoidable leakage of the fertilizer nutrients to the water bodies and atmosphere.
There is a vast scope for increasing nutrient supply through use of organic manures, green manures and adoption of proper crop sequences and these together can contribute significantly to the required nutrient pool. There is however no scope for reducing the consumption of chemical fertilizers since the level of crop productivity is not only to be maintained, but is to be increased in the coming years, which is presently not possible without the use of chemical fertilizers. The fertilizer use should be promoted till a full proof low input technology for higher productivity is available. Under the present Indian context the organic sources of nutrients should be considered as supplements to chemical fertilizers and not their substitutes (Mishra and Kapur, 1992).
The research on fertilizer use in our country was mainly confined to individual crops and fertilizer recommendations formulated on the basis of their responses. It is a well known fact that a crop is only a component of a cropping system and as such it has to be grown in some crop sequence. The fertilizer needs of a crop will vary depending upon the characteristics of the preceding crop in rotation. In this context it is also important to mention that besides the influence of preceding crops the fertilizers applied to one crop benefit to some extent the succeeding crops also because of their residual effects. For efficient fertilizer management it appears almost obligatory to evaluate precisely the role of preceding crops and also the residual effect of applied nutrients in sustaining the productivity of soils. Some attempts have been made recently to work out the relative fertilizer responses of various crops in different cropping systems. There is a need for system approach of nutrient supply to the system as a whole to increase the fertilizer use efficiency and economizing the use of costly mineral fertilizers. This can be attained by accounting the residual effect of the applied fertilizers and preceding crops. A technology package has to be developed depending upon the cropping system, soil type, ecological condition and socio economic conditions of the farmer. A study has thus been formulated to sustain the productivity of cropping and resource base with green manure and chemical fertilizers for studying productivity potential of hybrid rice-mustard cropping sequence with the following objectives.
1.
Effect
of organic manures and inorganic fertilizers on growth and yield of hybrid rice.
2.
Effect
of inorganic fertilizers on growth and yield of mustard.
3.
Residual
effect of organic manures and inorganic fertilizers applied to hybrid rice on
the succeeding mustard crop.
4.
Develop
suitable integrated nutrient management system for hybrid rice-mustard cropping
sequence.
5.
Effect
of organic manures and fertilizers on soil health and fertility changes in hybrid
rice-mustard cropping sequence.