Soil quality plays an important role in the link between high production and sustainability of land resources and can affect the quality of air, water and environment. Assessing the impact of management practices under agricultural land uses on soil quality is one of the necessary processes to achieve sustainable soil management in agricultural ecosystems. Therefore, this research was carried out with the aim of investigating the effects of conventional agricultural management systems on soil quality in Zanjan province.

154 soil samples were collected from 77 farms in Zanjan province (27 sites in irrigated and 50 sites in rainfed) at 0-30 and 30-60 cm depths. Considering the main threats which are associated with soil in Zanjan province, 30 soil physical, chemical and biological properties were measured and evaluated as the soil quality indicators. Additive soil quality index was determined by integrating soil quality indicators. Statistical parameters were applied to compare conventional management approaches in irrigated and rain-fed land uses on soil quality.

Under rainfed land use, at 0-30 cm depth, the aggregate stability and saturated hydraulic conductivity were decreased 49.49% and 22.04% respectively compared to the irrigated land use. Soil bulk density in irrigated land use was 3.68% lower than rainfed land use. Organic carbon, microbial biomass carbon, soil respiration and carbon and nitrogen stock index were higher under irrigated than rainfed land use. Under rainfed land use, soil organic carbon was decreased 33.87% and 31.43%, at 0-30 cm and 30-60 cm depth respectively, compared to the irrigated land use. The electrical conductivity at 0-30 cm depth was 50.46% lower than irrigated land use. Under rainfed land use, available zinc was decreased 66.54% and 63.43%, at 0-30 cm and 30-60 cm depth respectively, compared to the irrigated land use. The metabolic quotient in rainfed land use was higher than the irrigated land use and was identified as an indicator of soil degradation in this study. The metabolic quotient was reduced in irrigated land use by 40% and 33.33% at 0-30 and 30-60 cm depth respectively, compared to the rainfed land use. A significant positive correlation was found between organic carbon and soil physical properties including aggregate stability and saturated hydraulic conductivity and soil biological properties including microbial biomass carbon and soil respiration. The additive soil quality index at 0-30 cm depth, was significantly higher in irrigated land use (0.64) than rainfed land use (0.55).

The results showed that in terms of soil productivity and quality, irrigated management has better conditions than rainfed management. However, higher soil electrical conductivity in irrigated land use indicates the necessity of better chemical fertilizer management and assessing water quality used for irrigating lands in Zanjan province. Soil organic carbon was identified as the most important indicator that influenced the quality of studied soils. Using efficient management approaches including conservational tillage, operating appropriate crop rotation and application of equivalent chemical and organic fertilizers which result in increasing soil organic material are essential for both land uses, particularly under rainfed farming.

The purposeof this studywas to Analyzing factors that effecting on rangeland degradation. Statistical population of this research consisted of whole farmer in Pirtaj district (N= 1600); from that 120 farmer were selected as sample using cluster sampling. The main tool to collect data was a researcher made questionnaire that Content validity of the questionnaire was approved, by a panel of experts and its reliability was confirmed by calculating Cronbach''s alpha coefficient (α≥ 0.74- 0.82). Data was analyzed by SPSS software. Results of correlation analysis indicated a positive statistically significant relationship between rainfed land with personal ownership, number of livestock and rangeland degradation. Also, there are negative and significant relationships between irrigated lands with personal ownership, garden size, and rangeland degradation. Results of stepwise regression showed that in generally garden size, amount of rainfed land with personal ownership, and amount of irrigated lands with personal ownership, has been defined 35.00% of rangeland degradation variances.

Evaluation of urban sewage for its feasibility and potentiality as sources of irrigation water and plant nutrient is need of the hour. In this context, a field experiment was laid out in split–split plot design with three replications. Main plots constituted two types of lands (fields irrigated with sewage and bore well water since 1992). Subplots were allotted with three sources of irrigation which consisted of sewage water alone, bore well water alone (good water) and conjunction of sewage and bore well water. And sub-subplot constituted of four fertilizer levels (no fertilizer, 50 % recommended rate of fertilizer (RRF), 75 % RRF and 100 % RRF.

Crop growth in terms of photosynthesis, net assimilation rate and dry matter production significantly increased in sewage-irrigated land compared to bore well-irrigated land. Similarly, significantly higher wheat grain yield (4370 kg ha−1), protein (12.88 %) and dry gluten (9.22 %) were obtained in field irrigated with sewage water compared to bore well-irrigated land. Sources of irrigation also differed significantly producing higher grain yield (4,100 kg ha−1), protein (12.81 %), dry gluten (8.97 %) in sewage irrigation compared to bore well water irrigation. Enhanced activity of dehydrogenase and phosphatase enzymes and organic carbon in sewage-irrigated field contributed more to available nutrient pool of soil. Pooled results of 2 years revealed that wheat roots accumulated significantly higher amount of Cr, Ni, Pb and Cd in sewage-irrigated land compared to bore well-irrigated land. The same trend was noticed in stem with respect to Cr and Ni. In general, concentration of heavy metals was higher in root followed by stem and lower in grain. The Pb concentration in plant parts (root, stem and grain) was not influenced by land type and sources of irrigation. None of the treatments did show accumulation of these heavy metals in wheat plant parts more than normal range found in food plants. The values of these metals were below the recommended maximum tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives, Summary and conclusions. In: 53rd Meeting, Rome, (1999).

Increased wheat grain yield in sewage-irrigated land compared to bore well-irrigated land was attributed to increased soil fertility that was a result of continuous sewage irrigation. Long-term irrigation of farm lands with wastewater leads to contamination of soil and plant system with heavy metals in the study area. Wastewater-irrigated soil showed significant (p < 0.05, p < 0.01) accumulation of heavy metals compared to the freshwater-irrigated soil indicating concern of their increased absorption in wheat plant. The accumulation of heavy metals in wheat plant was in the order of roots > stems > grains. However, all these heavy metals in plant system were lower than the recommended threshold level.

The Bakhtegan and Tashk lakes (SW Iran) have been rapidly drying up during since 2007. In the absence of sufficient data, impacts of changes in land use on drying up of the lakes remain as yet undetermined. At this study, an attempt has been made to determine the effect of land use changes on shrinking of the lakes. The changes in the area of Bakhtegan and Tashk lakes together with the area of irrigated lands during the last three decades were determined by remote sensing analysis. By beginning of 1987 until 2007, the area of irrigated lands was increased from 1253.01 to 2506.11 km2 at all plains in the basin. Since 2007, two different behaviors have been detected in the area of irrigated lands at the upstream and downstream sectors of the basin. At downstream, all plains have experienced a significant reduction in the area of agricultural lands, but a considerable extension was detected in the upstream plains, where the lands were mainly cultivated with rice. Results show that the Bakhtegan and Tashk lakes had completely dried up as a result of the combined effects of meteorological drought and irrigation development (particularly at the upstream part of the basin).

A system dynamic model is necessary to estimate the existing interactions between Urmia Lake and factors affecting it. In this study, the Predator-Prey model using system dynamics simulation has been developed for Urmia Lake Basin. The main advantage of this model is providing the balanced water allocation between stakeholders in order to have a sustainable water management system for the lake. Due to increasing the area of irrigated lands in the northwest of Iran, having an applicable and up-to-date method to reduce water consumption in agricultural part is unavoidable. A stock-flow model has been designed in this study, in which Urmia Lake and irrigated lands are considered as the prey and predator, respectively. Then, the effects of various factors on the water elevation fluctuations of the lake have been analyzed dynamically and the strategies for reducing the water consumption of agricultural part have been investigated carefully. The results of this study indicate that the reducing irrigated lands by 40%, improve irrigation efficiency by 21% and reducing the area of lake by 20% lead to increasing water level of the lake by 1.7, 0.8 and 0.5 meters, respectively. By applying these policies, the water level of the lake will increase about 4.3 meters and it will lead to better ecological condition.

Soil quality (SQ) index is used as a quantitative tool for assessing the impact of land use and management systems on soil condition. The aim of this study was to quantify SQ under agricultural ecosystems in Zanjan province using multivariate analyses. 154 soil samples were collected from 77 farms in Zanjan province (27 sites under irrigated and 50 sites under rain-fed land use) at 0-30 and 30-60 cm depths. 24 soil physical, chemical and biological properties were measured. Principal component analysis was used to identify minimum data set (MDS) for assessing SQ. Two groups of MDS were determined by considering physical, chemical and biological properties separately (MDS1), and by using all measured soil properties (MDS2). The capability of linear or non-linear approaches to develop SQ index was investigated. Four SQ indices were calculated using MDS1 and MDS2, linear and non-linear scoring methods. Total nitrogen, available phosphorus, sodium, zinc and copper, microbial biomass carbon, microbial quotient index, aggregate stability and bulk density were determined as the MDS1. Soil organic carbon, available phosphorus, sodium, zinc and copper, microbial quotient index, aggregate stability and sorptivity were identified as the MDS2. Both methods had enough efficiency to identify MDS for assessing SQ. The linear SQ indices (p˂0.001) showed higher capability than non-linear indices (p˂0.01) to differentiate SQ between rain-fed and irrigated land uses. The SQ index calculated using linear function and MDS1 indicated SQ of irrigated land use (0.524) had a better condition compared to rainfed land use (0.433). The SQ index calculated using MDS2 also indicated a similar trend between irrigated (0.551) and rainfed land use (0.433).