Effects of gravel and poultry manure on some growth indices of cucumber and soil properties in the north west of Urmia Lake

Application of gravel for controlling evaporation is prevalent in soils of arid and semiarid regions. The objective of this field study was to investigate the interactional effects of gravel and poultry manure (PM) at different application rates on selected properties of cucumber and soil. A factorial experiment was carried out in Shabestar region based on completely randomized design with three replicates. The first factor was gravel at the rates of 0, 15, 30, 45 and 60 kg m-2 and the second was PM at the rates of 0, 250, 500, 750 and 1000 g m-2. Gravel was applied as surface mulch while PM was mixed into the top 20 cm of soil depth. Some growth indices of cucumber and soil properties were determined during and at the end of growth season. The highest rate of gravel significantly increased the yield (16.9%) and water use efficiency (WUE) (17%) of cucumber, aggregate stability (46.5%) and field water content (42.8%) of soil and significantly decreased CaCO3 (15.1%) and soil penetration resistance (59.3%) compared to the control. The highest rate of PM significantly increased the chlorophyll index (50.3%), yield (96.9%), fruit dry matter (60.3%), WUE (98%), organic carbon (64.4%), aggregate stability (150%), electrical conductivity (EC) (287.5%) and significantly decreased CaCO3 (27.8%) and soil pH (12.8%) relative to the control. Simultaneously, application of gravel and PM at the highest rate significantly increased the relative water content of leaf (14.8 to 24.4%) relative to the other treatments. Results showed that gravel mulch improves cucumber yield and soil physical quality by increasing water holding capacity of the soil. Also, PM at low and high rates can improve soil physical and chemical quality in the semiarid region by increasing the organic carbon and decreasing pH and CaCO3.