Effect of Sheep Manure and Its Produced Vermicompost and Biochar on the Properties of a Calcareous Soil after Barley Harvest

Conversion of manures to vermicompost and biochar may alleviate some negative effects of manure application to soil but the efficiency of the produced vermicompost and biochar as compared to their feedstocks is not well-known. In the current investigation, we compared the effects of sheep manure and its derived vermicompost and biochar (pyrolyzed at 400 degrees C for 4 h) on the properties of a calcareous soil that planted with five cultivars of barley (Behrokh, Khatam, Reyhaneh03, Fajr 30 and Nimrooz) for 60 days. Different soil properties and availability of nutrients and barley yield were determined after plant harvest. The biochar significantly increased barley yield rather than control (4.20 vs. 3.57 g pot(-1)), but sheep manure and vermicompost had no effect on it (3.51 and 3.37 g pot(-1), respectively). Fajr 30 and Nimrooz (3.52 and 3.42 g pot(-1), respectively) had significantly lower yield than other cultivars. Biochar increased soil pH up to 8.2. Soil salinity was increased by application of all organic materials (increase to 16-36%). Cation exchange capacity (CEC) and organic matter content of soil were also increased by all organic materials application (0.4-0.9 cmol kg(-1) and 0.33-0.50%, respectively). All organic materials increased total nitrogen (N), but this increase was the highest with sheep manure application (53%). The availability of phosphorus (P) and potassium (K) was increased significantly by application of all organic materials, and this increase was the highest with biochar application (19 and 309 mg kg(-1), respectively). Biochar application had no effect on the availability of micronutrients, but application of sheep manure and vermicompost increased the availability of iron (Fe) (0.62 and 0.48 mg kg(-1), respectively) and zinc (Zn) (0.18 and 0.37 mg kg(-1), respectively). Generally, organic materials may change the status of soil nutrients via change in soil pH, organic matter content, release of nutrients, increase in soil CEC and formation of soluble complex with nutrients.