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Background: Cattle manure (CM) is the most common organic fertilizer used by farmers. However, its usually slow decomposition leads to the use of chemical fertilizers. Therefore, experiments on nano-and micro-sized particles of CM were conducted to evaluate the possibility of accelerating its decomposition in soil. Methods: The effects of a sole application of CM in different sizes (nano-, micro-, and natural-sized particles) in two ranges (5 and 20 Mg ha -1 ) and the combined application of CM and chemical fertilizers on the plant growth characteristics of soybean (cv. JS 335) were studied at Gorgan University. Nano-and micro-sized particles of CM were produced using a ball mill, and their half-life in soil was measured. Soil properties were measured before planting. Grain yield, 1000 grain weight, number of pods per plant, biological yield, plant height, and nutrient contents in plant shoot material were measured. Results:The results showed that the use of nano-sized particles of CM (nCM) caused a significant increase in yield and yield components. Increasing the amount of crushing resulted in an increased rate of CM mineralization and in proper nitration before the formation of nodes in the roots. A significantly higher yield was obtained with nCM than with chemical fertilizer, and due to the nCM particles' half-life in soil, the plants were allowed to absorb nutrients for a longer time period. Conclusion: The nCM has two major advantages over chemical fertilizers in that it does not release nutrients as quickly as chemical fertilizers and the loss of nutrients from soil is low.

Background: The application of biochar as a soil amendment has achieved popularity and has been found to improve considerably soil nutrient status and plant productivity in low fertile soils. Methods: This study used two different methods to apply sewage sludge and sewage sludge biochar with three replicates in a completely randomized block design. The experiment included (1) control, (2) mulch biochar (20 t/ha), (3) incorporated biochar (20 t/ha), (4) mulch sewage sludge (45 t/ha), and (5) incorporated sewage sludge (45 t/ha). This study aimed to investigate the potential benefits of sewage sludge and its biochar as mulch and incorporated into the top-soil for soil fertility, growth, yield, and shoot nutrient concentration of soybean and the effects of treatments on dry bulk density, water content, and mechanical resistance. Results:The results showed higher values of height, biological yield, grain yield, and number of pods in the biochar mulch treatments (116.5, 10627.01, 4180, and 71.2, respectively). Moreover, it was determined that the addition of biochar and sewage sludge to soil resulted in increased shoot nitrogen (N), phosphorous (P), and potassium (K) concentrations, soil P, soil K, and total soil N (TN) compared with the control plots. Results from this study also showed that biochar and sewage sludge had positive impacts on the physical properties of soil. Bulk density and soil mechanical resistance were decreased, and volumetric water content was increased. Conclusion: Heating sludge removed all pathogens. It is recommended that short-and long-term studies be conducted in the region to investigate further increases in the combined biochar and sewage sludge application rates. Keywords: Nitrogen (N), Phosphorous (P), Potassium (K), Pathogens Citation: Fathi Dokht H, Movahedi Naeini SA, Dordipour E, De Jong LW, Hezarjaribi E. Effects of sewage sludge and its biochar on soybean yield in fine-textured loess soil.

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