soil nutrients

Introduction and Goal:

Soil is one of the most important components of the earth and has a number of functions and ecosystem services that are essential for sustainable life on the planet. Soil loss due to erosion occurs almost all over the world and reduces the productivity of natural ecosystems such as forests, rangelands, and agricultural lands. The present study investigated the role of rainfall duration on runoff and soil nutrients under different plant species in the Chogha Sabz Park, Ilam Province.

In this study the amount of runoff was determined in afforested stands (Cupressus sempervirens L.), natural Quercus brantii Lindl. forest, and control treatment based on the representative stand principle in burned and unburned conditions. The rainfall simulator was installed in a 2 m2 plot during 15 and 30 min of rainfall with a constant intensity of 80 mm/h. This study investigated the effect of species type on the amount of runoff, sediment, and nutrients. The basic characteristics, including soil texture, litter depth, and pH, were also measured and the results were analyzed using one-way variance test and comparison of means was performed using Duncan's multiple range test.

The results of the runoff study in the experimental plots of the prescribed fire treatment and the comparison of the studied species in the time intervals showed that in different intervals, fire caused an increase in the amount of runoff, so that in a 30-min interval in the control plot, a runoff of 17 l was produced, which was a significant increase compared to the two stands of Cupressus sempervirens L. and Quercus brantii Lindl. Also, the highest amount of total sediment in the 30-min interval in the control plot was 108.15 g, and its lowest amount was 52.64 g in the 15-min interval in the coniferous species of Cupressus sempervirens L. On the other hand, in the unburned condition, it was determined that the highest amount of runoff in the studied area was in the 15- and 30-min intervals in the control plot, with amounts of 5 and 17 l, respectively. Simultaneous examination of runoff and sediment in the experimental plots showed that the trends in both were similar and that as runoff increased, sediment also increased.

Conclusion and Suggestions:

According to the results of this study, it was determined that changes in the natural areas of the Zagros, such as fires, can increase the process of runoff production, causing the loss of nutrients in the soil and changing the chemical properties of the soil. It is suggested that the effect of adding organic soil amendments or cover on soil, runoff and sediment properties after fire be investigated and simulated.

The present paper investigates soil valuation and explores the intricacies associated with the development of a standard framework for a sound soil valuation system. Drawing upon a review of studies conducted across the world, we identify the techniques commonly used in estimating the economic value of soil that best suits the conditions in Iran. The ‘ecosystem services’ and ‘total economic value’ (TEV) frameworks are being currently employed for economic valuation of environmental resources and that of soil as the main component of the environment. A variety of methods have been developed for estimating the economic profits of ecosystem services and the costs arising from ecosystem degradation. In most cases, base cost estimation involves replacement cost, opportunity cost, damage cost avoid, and replacement cost methods. Study of the implementation of these methods as well as their associated requirements including soil nutrient content and current land use as well as soil conservation and watershed management practices in use reveal that the above methods can be effectively implemented because not only the required infrastructure but also the necessary data are currently available at the state-level. A salient feature of these methods is that they guarantee more tangible and calculable advantages, basic significance for environmental resources, and non-recurrent concerns about environmental commodities; care must, however, be taken in the measurement system employed for the monetary value of resources during environmental assessment since only investment and labor revenues are taken into account while the revenues due to the exploitation of vital resources and services are ignored and never ever included in the absence of a pricing policy, which obviously causes the values of natural resources to remain unaccounted for in economic estimations.