A field experiment was conducted at the Experimental Farm, Fac. of Agric., Al-Azhar Uni., Assiut, Egypt during two successive winter seasons of 2013/14 and 2014/15 to study the effect of poultry manure application (PM) and foliar application of humic acid (HA) on caraway plants growth and its yield constituents as well as some soil properties. Split plot design with three replicates was used. Four levels of PM (0, 10, 20 and 30 m3/fed) that were side banded in one dose before sowing and the recommended dose (RD) of NPK fertilizers were assigned to the main plots. Four humic acid levels ( 0, 1, 2 and 3 ml/L ) as foliar application were allocated to the sub- plots.
The results indicated that poultry manure, humic acid and recommended NPK dose treatments significantly increased vegetative traits (plant height, number of branches, and dry weight) of Caraway plants compared to untreated ones and could be arranged due to these increases in the order of poultry manure > recommended dose > humic acid. The highest values of vegetative traits, fruit and volatile oil yields in both season were recorded at highest level of both PM and HA (PM3HA3) followed by the recommended NPK dose with the highest level of HA (RDHA3) and then at the highest level of PM with the medium level of HA (PM3HA2). Moreover, poultry manure application, foliar application of humic acid and the recommended NPK dose significantly increased N, P, K, Fe, Mn and Cu contents of Caraway plants. Increasing the applied level of poultry manure or humic acid showed a positive effect on the soil organic matter content. The soil salinity (EC) were positively affected with using these studied materials since the EC of the soil increased with all treatments. On the other hand, the application of poultry manure or humic acid had a negative effect on the soil pH.