Organic and mineral fertilizer effects on the yield and mineral contents of carrot (Daucus carota)

The conventional agriculture uses large quantities of synthetic fertilizers and pesticides to control diseases and to provide nutrients to crops. These practices may have led to a decrease in organic matter content and hence to a decline in soil quality. Organic fertilization is one of the oldest methods of soil cultivation. Every possible type of organic manuring has got vital importance for soil fertility preservation (Petróczki, 2004). Organic fertilizers are major components of organic farming, which offer an economically attractive and ecologically sound means of reducing external inputs and improving internal resources. Organic materials play key roles in terms of maintaining or improving soil fertility, soil organic matter and plant nutrition through the direct and indirect effects on microbial activity and nutrient availability (Clark et al. 1998). The European Union Landfill Directive (Council of European Union, 1999) required the Member States to reduce the amount of biodegradable waste and improve activities, such as recovery and recycling. Food waste is large component of the waste stream by weight and constitutes in Hungary. Hotels, restaurants, food chains, food factories produce a lot of tons of organic waste that may be composted. If these wastes can be composted to obtain a quality organic soil amendment with humified organic matter and the end product used as soil organic amendment or fertilizer, this may represent one of the alternatives for achieving the goal of ensuring integrated and sustainable waste management (Chang & Tin-En Hsu, 2008). While programs and facilities to manage any waste are well established, the management of food waste in collecting for treatment in central composting facilities is perhaps only in its infancy (Levis et al. 2010). Use of food waste compost can be a good alternative for increasing crop production by enhancing soil productivity. Food waste compost is generally higher in nutrient value and lower in contamination than most other types of compost, thus making it more valuable in the market (Roberts et al, 2007). Use of microbial preparations for enhancement of plant production is becoming a new practice in many countries (Rodriguez & Fraga, 1999; Higa, 1994). Bacterial fertilizers may contain different microorganisms, for example nitrogen fixing and phosphates solubilizing microorganisms. They have the ability to fix nitrogen from the air and to solubilize phosphate minerals and so make nitrogen and phosphorus available to plants. Biofertilizers may increase the soil microbial sources, improve crop nutrition conditions, may accelerate the decomposition of organic wastes, increase the availability of mineral nutrients, can dissolve soil phosphorus, potassium, can increase the nitrogen content of soil and may enhance the activities of beneficial microorganisms. Results of different studies with microbial inoculants have been highly variable. According to many researchers microbial inoculants are promising components of integrated