عنوان مقاله [English]
Introduction Due to the inefficiency of some chemical fertilizers of trace elements, the high cost of import organic fertilizers containing these elements and also the lack of proper uptake of phosphorus in soils in arid and semi-arid regions, and the desire to produce better quality products, the use of organic matter enriched with nutrients such as phosphorus and iron seems essential. Therefore, the present study was conducted with the aim of comparing the effect of different levels of iron refuse and phosphate soil as an enrichment and investigating the interaction effects of enrichment on the growth components of tomato plants.
Materials and Methods To study the effect of compost enriched with iron refuse and phosphate soil on tomato plant, pot experimen was conducted with experimental treatments including compost enriched with iron refuse at three levels of 0, 5 and 20%, compost enriched with phosphate soil at three levels 0, 5% and 10%. To prepare the potting soil before applying the treatments, 10% by weight of sand was added to the soil. Iron refuse were prepared from the factory of National Iranian Steel Industrial Group and phosphate soil from Esfordi phosphate company and after air drying, the percentage of iron and total phosphorus were measured using standard methods (wet digestion). Compost prepared from green space wastes was also digest to investigate some chemical properties. Obtained data were performed analysed in factoriall in completely randomized design with three replications. Statistical analysis was performed using SPSS software and mean comparisons were performed by Duncan's multiple range test. Charts were drawn using Excel software.
Results and Discussion The results showed the highest plant height was observed in the treatment of 20% iron enrichment with 10% phosphorus enrichment at the rate of 57.9 cm. Comparisons of the mean effect of iron enrichment on total chlorophyll in tomato leaves showed that in general, with increasing the percentage of iron, total chlorophyll increased by 17.6 and 18.2%, respectively, compared to the control treatment. In other words, enrichment of compost with iron refuse increases the plant chlorophyll content by 39%, which is 34% for phosphorus enrichment. The maximum chlorophyll content of the plant was observed in the treatment of 20% iron enrichment with 10% phosphorus, which was not significantly different from the 20% iron enrichment treatment and 5% phosphorus enrichment treatment. Therefore, simultaneous enrichment of compost with iron and phosphorus can increase the quality of crops, especially leafy vegetables. According to the results, increasing the level of iron enrichment from zero to 20% caused 42.4% increase in plant dry weight, which is reported to be 24.9% for phosphorus enrichment. In general, as expected, with increasing the percentage of phosphorus in compost, the concentration of phosphorus in the shoot of tomato plant increased. Iron concentration in the plant increases by 10.9% with increasing phosphorus enrichment level from zero to 5%; In contrast, the use of phosphate soil at the level of 5% caused a decrease in zinc and copper concentrations of the plant by 21.5% and 15.2%, respectively. In many cases, the phosphorus and iron have reducing effects on each other due to the deposition of soluble iron in the form of insoluble phosphate compounds. According to the results of the present study, when an organic medium such as compost is used to add these two elements to the soil, the effect of organic matter on the formation of soluble chelates can increase the amount of avalable iron. Organic matter also has an undeniable effect on preventing the stabilization of phosphorus, which causes its release due to the direct decomposition of organic matter or the production of organic acids. Cupper was found to be more sensitive to increasing the amount of phosphorus in soil.
Conclusion The use of enriching compounds by improving plant nutritional conditions can lead to improve effects of organic amendments such as compost. The use of phosphate-enriched compost and iron refuse, increased the yield of tomato plants. According to the results, high levels of enrichment to some extent limit the uptake of zinc and copper, which is related to the interaction of elements with each other and changes in concentration ratios. Due to the lack of micronutrients in most crops and horticulture and the competition of elements in the soil, in many cases there is a decline in product quality, so it is suggested that following the present study, some studies to be conducted to investigate the simultaneous enrichment of other micronutrients such as zinc and copper and balance dose of enrichment so that maximum absorption is achieved simultaneously for all target elements. The use of waste from different sources to balance the enrichment of organic materials, in addition to reducing costs, will lead to the recycling of large volumes of waste.