عنوان مقاله [English]
In recent years, the effect of exogenous organic amendments on soil properties and plant growth characteristics has received renewed attention. Although the utilization of mineral fertilizers could be viewed as the best solution in terms of plant productivity, this approach is often inefficient in the long-term in tropical ecosystems due to the limited ability of low-activity clay soils to retain nutrients. Intensive use of agrochemicals in agricultural systems is also known to have irreversible effects on soil and water resources.
The use of organic and biological fertilizers are important strategies to reduce harmful effects of chemical fertilizers in sustainable management of agroecosystems.
Spent mushroom compost is the residual compost waste generated by the mushroom production industry. It is readily available and its formulation generally consists of a combination of wheat straw, dried blood, horse manure and ground chalk, composted together. It is an excellent source of humus, although much of its nitrogen content will have been used up by the composting and growing mushrooms. It remains, however, a good source of general nutrients, as well as a useful soil conditioner.
Most mineral soils contain mycorrhizal fungi, but often at levels that are too low for adequate colonization, especially in disturbed soils. Mycorrhizae are host specific and will only colonize certain plants; so in some soils, there are no native mycorrhizae that will benefit these plants. Therefore, most plants would benefit from mycorrhizae addition to the soil. Symbiosis begins when fungal spores germinate and emerging thread linke structures, called hyphae, enters the epidermis of plant roots. After colonization of the root, the fungus sends out a vast network of hyphae throughout the soil to form a greatly enhanced absorptive surface area. This results in improved nutrient acquisition and uptake by plant roots, particularly elemental phosphorus, zinc, manganese and copper and water. In return, the plant provides carbohydrates for the fungi.
Materials and methods
In order to study the effect of mushroom compost and mycorrhiza on yield of garlic (Allium sativum L.), a split plot experiment based on RCBD design with three replications was conducted in 2010-11 growing season in research farm of Ferdowsi University of Mashhad, Iran. Mycorrhiza (Glomus mosseae) (use and non-use) and spent mushroom compost levels (SMC) (0, 20, 40, 60, 80, 100 t ha-1) were considered as the main and sub factors. In order to determine the physic-chemical properties of soil, sampling was done at a depth of 0 to 30 cm. Distance on and between rows was considered 10 and 20 cm, respectively. In order to weeds control, manual weeding was done three times. At the end of the growing season, economic yield, biological yield, plant height, shoot dry weight, bulb diameter, bulblet weight per plant, bulblet volume per plant and bulblet number per plant were measured. Analysis of variance was done with SAS Ver 9.1 software.
Result and discussion
The results showed that the effect of different levels of mushroom compost was significant on the most studied traits, but mycorrhiza had no significant effect on yield and yield components of garlic. Based on the results, highest diameter and length of the bulb and bulblets were observed in application of 100 t ha-1 SMC. The highest economic yield (12760 kg ha-1) was observed in application of 100 t ha-1 SMC, so that the application of SMC increased economic yield by 48 percent compared to control. The highest dry matter production and harvest index also were observed in application of 100 t ha-1 SMC.
Organic and biological fertilizers are among the most significant resources for development of agricultural soil quality and increase in the yield of different medicinal plants. It has been reported that this ecological inputs provide favorable conditions for plant growth and development through improvement of physical, chemical and biological properties of the soil (Cabrera et al., 2009), therefore, it can be concluded that improvement of the most studied traits in the present study were due to use of organic fertilizers.
In general, the results showed that it seems use of SMC can improve quantitative and qualitative characteristics of garlic, thus it can be considered as a suitable alternative to chemical fertilizers.