مجله مدیریت اراضی
سال پنجم شماره 2 (پاییز و زمستان 1396)

Agricultural land use change is one example of the cases in which the free market economy has failed to protect the environment. It stands only second to the current water shortage as the major problem of agriculture in present-day Iran. The problem of land use change has led to the degradation or even devastation of large portions of the cultivable area to pose serious threats to food security, self-sufficiency, and sustainable employment in rural communities with obvious grave social, cultural, and economic consequences. Protecting agricultural lands has become even more difficult due to the development pressures of both tourism and industry; the imminent water crisis; the declining agricultural productivity due to soil degradation; changes in rural lifestyle; and the absence of deterrent laws and the bureaucratic corruption. Study has revealed that low income levels, rising production costs that make agricultural production uneconomical, inefficient agricultural practices, difficulties in product marketing and sales, lack of funding, unrealistic increases in property prices, and increasing cost of living are important factors underlying the changes in land use. It has also been established that land use change causes such irreversible environmental damages as soil erosion and desertification; natural disasters including landslides, flooding and climate change, reduced vegetative cover, reduced biodiversity, and loss of soil fertility with such adverse environmental consequences as soil and water pollution by unauthorized industrial pollutants, especially along the rivers, coastal areas, and areas next to drinking and irrigation water resources. All of these ultimately lead to the gradual annihilation of agriculture that poses a serious threat to food security. In addition to its environmental impacts, land use change causes structural changes in the social, economic, and physical structures of rural areas. The dire consequences include income inequality and engraved social injustice and discrimination in rural areas, frustration and conflicts at the household level, cultural confrontations, loss of social and individual identity, increased tendency for immigration, reduced motivation for long-term agricultural planning, reducing numbers of sustainable and productive jobs, and ultimately irreversible social and cultural consequences. The present article addresses some of these aspects in detail.

The importantroleof soil fertility in food production warrants long-term monitoring to track changes in soil properties. Long-term soil tests are field trials conducted onpermanent plots that are regularly sampled to quantify soil changes over time scales of decades. This article intends to introducelong-term soil fertility testsusing permanent plots aimed atcollecting information on the effects of long-term soil fertility management practices on soil properties. Efforts are also made to develop a general methodologyfor future research. Mosttests on permanent plots in the past mainly focused on soil carbon concentrations over long-term periods to find that continuous applicationof organic matter toarable land led not only to improved soil physical and chemical properties but also toits enhanced biological activity.This is while organic modifiers, especially when improperly applied,may reportedly contributeto environmental pollution. So far few long-term soil tests have been conducted in Iran,most of which havemainly determinedthe residual effects of fertilizers containing single nutrient elements such asphosphorus, zinc, orpotassium. This lack of consistent tests and the scant information thus far obtained necessitate planningfor drastic and targetedtestson Iranian soils.Evaluation of long-term experiments revealed that it will be necessary to employsuch variedland management practicesof livestock manuring, proper crop rotation, and avoidance of severe tillage to enhancecarbon sequestration in soils. Finally, it was observed that the use of chemical fertilizers combined with organic and biological agentsis favorable to increased agricultural production and enhanced sustainable soil fertility.

The abundance ofnematodes in different ecosystems makes thema most desirable agentfor monitoringenvironmental pollution. They are,indeed, considered as the most promising candidates for bioindication of soil disturbances such as heavy metals pollution in the soil. Studies ofthe effects of such heavy metals as lead, cadmium, chromium, copper, nickel, zinc, and selenium on different nematode generain different trophic groups usingdiversityanalysis and nematode assemblage indices have shownconsiderable changes in the populations of certain genera of nematodeswith increasing concentration of each specificmetal. Despite theunique characteristics of nematodesinmonitoring soil pollution, it is difficult to generalize the effects of toxic metal pollutants on nematode assemblages in soil asthe outcome of such analyseslargely vary with ecosystem, spatial scale,andsuchlocal characteristics as pH, vegetative cover, and the composition of indigenous nematode fauna present in the soil. In the evaluation of nematode community indices, it is, therefore, preferable toremove the genera that lead to ambiguity in predictions and to restrictthe indices only to those belonging to known genera with already establishedsensitivity or response to specific types of disturbance. Thus, population index analyses will not only yield better predictions but will also be more cost-effective. Examples of practical and commercial applications ofnematode assemblage analysis in other countries formonitoring chemical pollution in aquatic habitats are available that can be usefully exploited toward applied researchto overcome the present limitations in using nematodes formonitoring soil heavy metal pollution in Iran.

Water scarcity and mismanagement of available water resources leads to water crisis that might be furtherheightened underdrought conditionswith dire environmental, social, and economic outcomes.The present study was implemented to determine the quantity of groundwater resources in the Lavar-Fin Plain,Bandar Abbas City, to identify and assess the consequences of indiscriminate groundwater withdrawals, and to developuseful solutions forthe problems ahead. For the purposes of this study,the meteorological, hydrologic, geological, and geographical data obtained on six observation wells in the study plain collected over a 20-year period (1995-2015) were analyzed to determine the overdraft, groundwater levels drop, and water deficit of the aquifer.It was foundthat the groundwater level underwent a drop of 4.28 meters (or, an annual average of 21 cm)over the 20-year study period. Given the fact that surface water resources account for 10% and groundwater resources account for about 90% of the abstractionin the regionand, further,that most of the withdrawal from groundwater resources is consumed for irrigation, it follows that the water table decline and its dire consequences can be abated by water conservation in theagriculture sector throughimproved irrigation systems along withsuch measures as raising public awareness of the imminent problems, raising users’ knowledge of water conservation methods, exercising accurate control measures to restrict water withdrawals through installing metering devices, issuing no new drillinglicenses, and changing cropping patternsin the region.

Root systems in citrus trees develop from rootstocks. They have, thus, direct effects on water and nutrient uptake and translocation. The present study was conducted to evaluate the effects of three rootstocks common in northern Iran (i.e., sour orange, Swingle citrumelo, and Troyer citrange) on the nutrient uptake, translocation, and accumulation (NAI) as well as their translocation indices (NTI). For this purpose, one-year old seedlings of sour orange, Swingle citrumelo, and Troyer citrange were cultivated in a loamy soil under glasshouse conditions. After six months, the seedlings were harvested to measure their dry weights as well as their leaf, stem, and root concentrations of phosphorus, potassium, calcium, iron, manganese, zinc, and copper. Also, the rootstocks investigated were discriminated based on their nutrient accumulation and translocation indices as determined by factor analysis. Results showed the superiority of Troyer citrange in terms of phosphorus and iron uptake; citrumelo in terms of potassium and copper uptake; and common sour orange in terms of calcium and manganese uptake. The order recorded for the rootstocks in terms of their nutrient accumulation indices was sour orange>Troyer citrange~Swingle citrumelo. It was also found that the nutrient translocation indices of the three citrus rootstocks decreased in the following order: Swingle citrumelo > Troyer citrange > sour orange. Clearly, the citrus rootstocks investigated exhibited differential nutritional behaviors and different capacities with respect to utilizing plant nutrient elements.

Despite the role played by the reuse of industrial effluentsin alleviating the shortage of irrigation water in dry regions such asIran, the irreversible damages to the environment as a result of uncontrolled discharge of effluents into the environment and agricultural landscannot be overlooked. Industrial effluent reusepresupposesthe knowledge of their quality and a careful investigation of their environmental impactssuch as soil, groundwater, and food contamination. The present study was conducted to investigateseasonal variations in the quality of thetreated industrial effluent from Isfahan Steel Complex during the period from April to March, 2007 and to determine its effects on groundwater resourcesas determined by the chemical composition of both the applied irrigation water and the seepage from the plant’s evaporation ponds intothe neighboringwater wells. For this purpose, samples were taken from both the industrial effluent and selected wells and analyzed for pH; EC; Nitrate; hardness; TSS; TDS; Cations including Na, Ca2, Mg2;anions including SO42-, CO32-, HCO3-, Cl-; and heavy metals including Pb, Cd, Cu, Fe, Cr, Mn, Co, and Zn. The results were compared with standard reference levels recommended for groundwater resources, irrigation water, and direct human consumption.The effluent studied was found appropriate neither for discharge into groundwater and absorption wells due to its quality characteristics of EC,N-NO3,BOD,COD,Cl, and SO42-concentrations that exceeded standard limits, nor for irrigation use due toits higher than standard concentrations of EC, SO42-, Cl,N-NO3, and TDSwhileits Cowas also higher (0.14 mg/l)than the standard limit of 0.05 mg/l (Environmental Protection Organization, 1984).Investigation of the effluent’s effects on groundwater resources revealed thatthe groundwater abstracted from the vicinity of Isfahan Steel Complex suffered from EC,TDS,N-NO3,HCO3-,SAR,Cl-,SO42- as well as Co(0.14 mg/l compared with the standard 0.05 mg/l) limitations.

Since metallic nanoparticles are widely used nowadays in industrial applications of nanotechnology, there is every possibility that they find their way into soils, especially through sewage sludge. Nanoparticle properties (e.g., size, shape, and surface charge) and those of the soil environment (e.g., pH, ionic strength, and clay content) affect the physical and chemical processes that lead to the dissolution, aggregation, and agglomeration of nanoparticles. This is while some of these specific interactions, particularly the roles played by different DOMs in the direct uptake of nanoparticles by soil organisms and the availability of different forms of engineered nanoparticles, have been scarcely ever investigated. Nanoparticulate mobility and bioavailability to microorganisms control their behavior in soil. However, little is known about the effects of dissolution, aggregation, and agglomeration processes on the toxicity of nanoparticles. Moreover, conflicting results have been reported by most studies, making it difficult to derive a clear picture of the processes involved. The present study provides an overview of the fate and transport of metal nanoparticles in soil.