JWSS - Journal of Water and Soil Science

The effects of dissolved organic matter (DOM), derived from compost, on the sorption of simazine by soils were studied using a batch equilibrium technique. Six soils with different organic carbon contents were investigated in this study. Simazine sorption isotherms on soils were described by the linear equation, and the distribution coefficients without DOM (K_d) or with DOM (K_d*) were obtained. Generally, the values of K_d*/K_d were initially increased and then decreased with raising DOM concentrations of 0-65 mg DOC·L in the soil-solution system form. Critical concentrations of DOM (DOM_np) were obtained, and the value of K_d* was equal to K_d. The presence of DOM with concentrations lower than DOM_np promoted simazine sorption on the soils (K_d* > K_d), whereas the presence of DOM with concentrations higher than DOM_np tended to inhibit the simazine sorption (K_d* < K_d). Interestingly, DOM_np for the tested soils was negatively correlated to the soil organic carbon content, and the maximum of K_d*/K_d (K_max) was correlated positively with the maximum of DOM sorption on the soil (X_max). Further investigations also showed that the presence of the hydrophobic fraction of DOM evidently promoted the simazine sorption on soils, whereas the presence of hydrophilic DOM fraction obviously tended to inhibit the simazine sorption.

Water scarcity is the most important factor constraining agricultural production all over the world and water shortage in agriculture must be established to use the deficit irrigation. In order to study the effects of the regulated deficit irrigation and partial root zone drying on the growth traits of Rosmarinus Officinalis L., an experiment was conducted in the center of seed and plant production of IranShahr municipality in 2017. The experiment treatments were arranged as a randomized complete block design with three replications. The irrigation regimes consisted of full irrigation, regulated deficit (RDI₇₅ and RDI₅₅) and partial root zone drying irrigation (PRD₇₅ and PRD₅₅). The results showed that deficit irrigation at 75 and 55 percent of full irrigation resulted in saving 18.6 and 34.3 percent of water consumption, respectively. Comparison of full irrigation and PRD₇₅ showed that dry weight, height of plants and number of shoots per plant were decreased by 6.7, 14.3 and 12.1 percent, respectively. However, proper development of root in PRD₇₅ increased 12.9 percent of water productivity. Therefore, by considering the problems of water scarcity, it is possible to provide PRD₇₅ as a superior treatment and a suitable strategy to cope with the water crisis in order to move towards a sustainable agricultural system.