Pakistan is a country nestling 117 m people, situated in monsoonal subtropics between 24-37o N and 60-75o E. The country is divided into four federating units; Punjab, Sindh, Baluchistan and NWFP (North West Frontier Province). The economy of Pakistan agrarian in character, agriculture continues to be the single largest sector, a dominant driving force for growth with deep impact on socio-economic set up and the main source of livelihood for 66 percent of the country's population around which socio-economic privileges and deprivation revolve. At present it accounts for 21.8 percent of the GDP and employs 44.7 percent of the total work force. As such agriculture is at the center of the national economic policies and has been designated by the Government as the engine of national economic growth and poverty reduction. Agriculture contributes to growth as a supplier of raw materials to industry as well as generating buoyant market for expansion of industrial products and also making substantial contribution to Pakistan's exports earnings and national economic growth. Thus any improvement in agriculture was not only helping country's economic growth to rise at a faster rate but was also benefiting a large segment of the country's population (Anonymous, 2008-09).
The diversity in natural resources, climate, people and socio-economic conditions has given rise to varying farming systems in Pakistan. The cropping systems are nutrient exhausting in Pakistan and soil nutrients in the natural resource base are dwindling faster than they are being replaced. Nutrients and organic matter in the soil have been depleted and crop yields have steadily decreased. Out of a total geographical area of 79.6 million hectare, only 22 million hectares are being cultivated. About 80% of the cultivated area is irrigated while the remaining is rain-fed (Anonymous, 2007).
Intercropping tenders farmers the opportunity to engage nature's principle of diversity on their farms. Many different intercrop systems are discussed, including mixed intercropping, strip cropping, and traditional intercropping arrangements. Intercrops can be more productive than growing pure stands. Pakistan is a subtropical country having adequate land resources with high intensity of sunlight for plant growth. Therefore, possibility of raising two or more crops on the same piece of land in a year needs to be explored for effective and efficient utilization of these natural resources. Intercropping is being considered to utilize these resources in an efficient way and is also most economical production system as it increases the production per unit area and time. Presently, interest in intercropping is increasing among the small growers because of their diversified needs and low farm income from the monocropping system. Recent evidence suggests that there are substantial advantages of legumes intercropping which are achieved not by means of costly inputs but by the simple expedient of growing crops together in an appropriate geometry (Nazir et al.,1997, Ahmad & Saeed, 1998). When legumes are grown in association with non-legumes, there is often advantage to the non-legumes from nitrogen fixed by the legumes from nitrogen fixed by the legumes (Saeed et al., 1997).
Intercropping of cereals and grain legumes is a neglected theme in agricultural science and practice in both conventional and organic farming system (Dahlmann, and Von Fragstein 2006). Intercropped legumes fix most of their nitrogen from the atmosphere and not compete with maize for nitrogen resources (Adu-Gyamfi et al.2007; Vesterager et al.2008). Cereal-legume intercropping plays an important role in subsistence food production in both developed and developing countries, especially in situations of limited water resources (Tsubo et al. 2005; Amanullah et al. 2006and Egbe, & Adeyemo, 2007). Intercropping cereals and grain legumes can be very potential for both organic and conventional farmers (Prins and de Wit 2005). As land under cultivation is shrinking thus it is imperative to increase per acre yield by adopting practices like better management of soil, soil fertility and intercropping systems. Intercropping is a wise pre- time management for increasing potentiality of soil and production per unit area as well as income as it provides security against potential losses due to monoculture. Moreover, there is a need for increased production of pulses and cereals as we are deficient in proteins and carbohydrates in our daily diet and huge amount of foreign exchange is spent annually on the import of these commodities.
The cost of inorganic fertilizer is very exorbitant that the resource poor farmers cannot afford even a single bag to apply their crops for lack of financial resources. Poultry manure is currently considered a low value fertilizer material as it contains high nitrogen, phosphorus, potassium and other essential nutrients. In contrast to mineral fertilizer, it adds organic matter to soil which improves soil structure, nutrient retention, aeration, soil moisture holding capacity and water infiltration( Deksissa et al;2008). Similarly, poultry manure supplies P more readily to plants than other organic manure sources (Garg and Bahla, 2008). Poultry manure is discounted in comparison to chemical fertilizer for various reasons, including difficulty of handling, availability, specific storage requirements, nutrient imbalance, etc. Organic matter produced by organic fertilizers has a strong, positive effect on moisture holding capacity, improvements in aggregation and structure (Sharif et al., 2004). Organic fertilizes including farmyard manure, poultry manure, sheep manure, and bio-fertilizer may be used for crop production as a substitute of chemical fertilizers (Khan et al., 2005 & Ayoola et al. 2007`). Organic fertilizers supply all the essential elements necessary for growth though not in equal proportion, and are readily decomposed by soil microorganisms (Afzal et al., 2005). Positive effects of organic waste on soil were reported in several studies (Odlare et al.2007 and Jedidi et al 2004). Furthermore biological, chemical and organic manures can be used to sustain productivity of land. The recent energy crisis and hike in prices the inorganic fertilizers necessitate the use of organic manures and bio-fertilizers in crop production.
Poultry manure has long been recognized as the most desirable organic fertilizer, as it improves soil fertility by adding both major and essential plant nutrients as well as soil organic matter which improves moisture and nutrient retention. Poultry manure is an excellent organic fertilizer, as it contains high nitrogen, phosphorus, potassium and other essential nutrients. In contrast to mineral fertilizer, it adds organic matter to soil which improves soil structures, nutrient retention, aeration, soil moisture holding capacity, and water infiltration (Deksissa et al., 2008). Poultry litter is a suitable N source for corn, and continuous application of poultry litter in excesses of what the crop can utilize on an agricultural land may lead to accumulation of P which will ultimately leach and affect the receiving water quality (Norman et al., 2003; Collins et al., 2008). The rising cost of inorganic fertilizers coupled with their inability to condition the soil has directed attention to organic manures in recent times. The manure so produced is disposed of in several ways, including burning. However, some farmers are aware of the beneficial effects of poultry manure and its release of nutrients for a good response in plant growth.
Maize (Zea mays L.) is the world's most widely grown cereal and is the primary staple food in many developing countries. Most farmers intercrop to maximize land use and diversify their food consumption (DARTS 1998; Shaxson and Tauer 1992). Maize has a high yield potential and is suited to a wide range of climates. At present it is cultivated on an area of 1.11 million hectares with total production of 4.03 million tons showing 11.9 % increase of production than that of preceding year due to adequate and timely application of inputs (Anonymous, 2008-09). It possesses a remarkable diversity of vegetative types, having a wide range of ecological adaptation. The unique energy capturing capability and efficient use of CO2 as C4 plant has made it capable of producing maximum grain yield per unit area as compared to other cereal crops. Maize is the world's third most important crop after rice and wheat. Diversified uses of maize worldwide include: maize grain; starch products; corn oil; baby foods; popcorn; maize-based food items; maize flour; forage for animals; maize stalks providing dry season feed for farm animals. It is potentially yielding cereal and is of great importance to the rural farming community in Pakistan.
Mungbean (Vigna radiata) and mashbean (Vigna mungo) are important pulse crops grown and consumed in Pakistan. Legume crops also support the growth of cereal crops by improving organic matter and physical characteristics of soil (Aslam & Mehmood, 2003). The 6 billion people on earth consume an average of nearly 11 g of nitrogen (N) per person per day, or about 24 million tonnes of N globally per year (Fink et al., 1999). Worldwide, legumes are grown on approximately 250 million hectares and they fix about 90 million tones of N2 per year (Kinzig and Socolow, 1994).The legumes have a central role to play in a productive and sustainable agriculture. Legumes grown in less fertile soil could improve the soil health by fixing atmospheric N and may partially supplement the use of inorganic fertilizers (Safdar et al.,2005 & Ghosh et al 2007). Current trend of increased demand and prices of pulses like mungbean and mash has created the opportunity for the farmers to increase their farm income which can help to alleviate poverty in rural areas. National average yield of mungbean is 0.63 t ha-1 with area 231.1 thousand hectares. National average yield of mungbean is 0.49 t/ha with area 31.5 thousand hectares.The production of mungbean and mashbean decreased by 20.8 % and 4.6%. The decreased in these crops is due to reduction of area of mungbean and mashbean 6 % and3.1 % respectively (Anonymous 2008-09).
Thus the best way of simultaneous increase in cereals and pulses productivity is to grow these crops in association with each other. However, with rapid increase in population and less chance of bringing new lands under cultivation, intercropping seems to be only way to increase productivity and land use intensity. Canopy structures and root systems of cereal crops are generally different from those of legume crops. The formative phase is comparatively greater in cereal crops than in legume crops. In cereal-legume intercropping, cereal crops form relatively higher canopy structures than legume crops and the roots of cereal crops grow to a greater depth than those of legume crops. This indicates that the component crops probably have differing spatial and temporal use of environmental resources such as radiation, water and nutrients (Willey, 1990). Therefore, this cropping system may help improve productivity of low external input farming, which depends largely on natural resources such as rainfall and soil fertility.
So in the present situation of preponderance of land fragmentation, surplus farm family labour, overlapping of growing season of crops, low productivity of most of the crops and practice of subsistence farming, intercrops reigns to be a promising strategy for increasing crop productivity particularly at small farm level in Pakistan (Bhatti et al., 2008). In dry land crop production, the most limiting factor is water (rainfall and irrigation) availability, and it is thus necessary to improve crop water-use efficiency. The key can be found in reduced soil temperature and retained soil moisture. The solution may then lie in traditional cropping techniques, such as intercropping and mulching (Wilken, 1972; Baldy and Stigter, 1997). Intercropping is one of the types of mulching, often referred to as live mulching.
The main reason for using a multiple cropping system is the fact that it involves integrating crops using space and labour more efficiently (Baldy and Stigter, 1997). Biophysical reasons include better utilization of environmental factors, greater yield stability in variable environments and soil conservation practices. Socio-economic reasons include the magnitude of inputs and outputs and their contribution to the stabilization of household food supply (Beets, 1982).
Soaring outlay of crop husbandry, diminishing soil fertility, appalling environment, shrinking land under pulses and public health are important reasons for use of organic manures, bio-fertilizers and offer the solution for sustainable and environmentally safe, economically feasible, socially viable and ecologically sustainable production system. A system that integrates different practices of soil fertility maintenance is required. This will include the use of mineral fertilizers, organic manures and intercropping. Therefore, study was devised to evaluate economic efficiency of different cereal-legume based cropping systems and the associated beneficial effects, such as higher productivity per unit area, greater monetary returns and enhancing land use efficiency, under rainfed conditions of Pothowar tract. The objectives of this research study were aimed to
* Compare potential of biological, chemical and organic fertility combinations for crop growth and yield under different cropping systems for Pothowar tract
* Determine residual effect of the cropping systems and fertility treatments on the soil and subsequent crop (for sustainable production system)
* Evaluate economic efficiency of different fertility protocols and cereal-legume based cropping systems under rainfed conditions
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