Impact of Applied Humic and Fulvic Acids on the Soil Physic-Chemical Properties and Cucumber Productivity Under Protected Cultivation Conditions

A greenhouse experiment was carried out on a cucumber crop (Cucumber sativus) cultivated in a clay loam soil at Bahtim, Agricultural Research Station during the growing season of 2010 to study the effect of humic and fulvic acids on physico-chemical properties and cucumber yield. The experiment contained two active organic acids treatments, i.e., humic acids as K-humate or fulvic acids as K-fulvate were used as soil application and foliar spray as solely treatment or incorporated together at five rates of 0, 5, 10, 15 and 20 L fed-1 from humic or fulvic acids as soil application or (0, 50, 100, 150 and 200 ppm) as foliar spray as compared with the combined treatment on some physical properties i.e., bulk density, total porosity, moisture constants (field capacity, wilting point and available water), hydraulic conductivity and chemical properties i.e., pH, EC, organic matter and availability of N, P and K in clay loam soil. On the other side, the positive effect of these treatments on cucumber yield and its content of nutrients were taken into consideration. Generally, results indicated that application of organic acids as soil application incorporated with foliar spray was more effective on improving soil and plant parameters under studied, followed by soil and foliar application as solely treatment, especially at the fourth rate of 20 L fed-1as soil application and 200 ppm as foliar spray. However, the obtained results showed that, the addition of humic or fulvic acids were positively affect on cucumber fruit yield as well as its contents of carbohydrate, protein % and NPK. Also, the best applied method for humic or fulvic acid was achieved when they was added as soil application combined with foliar spray, however, the greatest values of fruit yield of cucumber, total or soluble carbohydrate, protein % and NPK content in both shoot and fruit were obtained at the takes of 15 L fed-1 and 150 ppm for humic and fulvic acids as soil application combined with foliar spray, respectively.