Salinization Of Farmland Research Articles

Advances in deciphering salt tolerance mechanism in maize

Maize (Zea mays L.) is a global cereal crop whose demand is projected to double by 2050. Along with worsening of farmland salinization, salt stress has become a major environmental threat to the sustainability of maize production worldwide. Accordingly, there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize. As salt tolerance is a complex trait regulated by multiple genes, and maize germplasm varies widely in salt tolerance, efforts have been devoted to the identification and application of quantitative-trait loci (QTL) for salt tolerance. QTL associated with ion regulation, osmotic tolerance, and other aspects of salt tolerance have been discovered using genome-wide association studies (GWAS), linkage mapping, and omics-based approaches. This review highlights recent advances in the molecular-level understanding of salt stress response in maize, in particular in (a) the discovery of salt-tolerance QTL, (b) the mechanisms of salt tolerance, (c) the development of salt-tolerant maize cultivars, and (d) current challenges and future prospects.

Calcium chloride priming reverses the effect of salinity stress on α-amylase activity during seed germination in Vigna radiata

Farmland salinization is a global issue that is causing significant agricultural losses. Seeds of Vigna radiata were treated 200 mM NaCl, CaCl2 + 200 mM NaCl and control (distilled water). 200 mM NaCl treatment had a considerable negative impact on seed germination and seeds were unable to germinate. Reduction in seed germination was correlated with low α-amylase activity after 96 h of incubation as compared to control seeds. Seed priming with CaCl2 increased seed germination upto 84% after 96 h of incubation under salinity stress. CaCl2 treatment increasesα-amylase activity by 45% as compared to control at 96 h of incubation under salinity stress at 200 mM of NaCl. CaCl2 treatment rescue seed germination in Vigna radiata under salinity stress by increasing α-amylase activity.

Assessing the Long-Term Evolution of Abandoned Salinized Farmland via Temporal Remote Sensing Data

Salinization in arid or semiarid regions with water logging limits cropland yield, threatening food security. The highest level of farmland salinization, that is, abandoned salinized farmland, is a tradeoff between inadequate drainage facilities and sustainable farming. The evolution of abandoned salinized farmlands is closely related to the development of cropping systems. However, detecting abandoned salinized farmland using time-series remote sensing data has not been investigated well by previous studies. In this study, a novel approach was proposed to detect the dynamics of abandoned salinized farmland using time-series multispectral and thermal imagery. Thirty-two years of temporal Landsat imagery (from 1988 to 2019) was used to assess the evolution of salinization in Hetao, a two-thousand-year-old irrigation district in northern China. As intermediate variables of the proposed method, the crop-specific planting area was retrieved via its unique temporal vegetation index (VI) pattern, in which the shape-model-fitting technology and the K-means cluster algorithm were used. The desert area was stripped from the clustered non-vegetative area using its distinct features in the thermal band. Subsequently, the abandoned salinized farmland was distinguished from the urban area by the threshold-based saline index (SI). In addition, a regression model between electrical conductance (EC) and SI was established, and the spatial saline degree was evaluated by the SI map in uncropped and unfrozen seasons. The results show that the cropland has constantly been expanding in recent decades (from 4.7 × 105 ha to 7.1 × 105 ha), while the planting area of maize and sunflower has grown and the area of wheat has decreased. Significant desalinization progress was observed in Hetao, where both the area of salt-affected land (salt-free area increased approximately 4 × 105 ha) and the abandoned salinized farmland decreased (reduced from 0.45 × 105 ha to 0.19 × 105 ha). This could be mainly attributed to three reasons: the popularization of water-saving irrigation technology, the construction of artificial drainage facilities, and a shift in cropping patterns. The decrease in irrigation and the increase in drainage have deepened the groundwater table in Hetao, which weakens the salt collection capacity of the abandoned salinized farmland. The results demonstrate the promising possibility of reutilizing abandoned salinized farmland via a leaching campaign where the groundwater table is sufficiently deep to stop salinization.

Geotextile covering: Potential technique for farmland salinization control

AbstractThis paper investigated fabric coverings, exploring their ability to remove salt from saline soils. Soil columns filled with saline soil were saturated with saltwater, then covered with four kinds of fabric materials (nylon, cotton, geotextile [150 g m−2], and gauze). The soil columns were heated under infrared lights for 25 days. The microstructural characteristics of the fabric materials before and after the experiments, as well as the crystallization conditions on the soil surface, were examined using scanning electron microscope (SEM). The results demonstrated that both hydrophilicity and structure of fabrics affect salt removal efficiency. Although salt quantity removed by geotextile (111.54 g m−2) was less than gauze (293.89 g m−2), geotextile showed greater potential on salt removal considering long‐term evaporation. To further investigate the performance of geotextile material on salt removal, the experiment was repeated with commercially available geotextiles with areal densities of 200, 300, 400, and 500 g m−2. The 500 g m−2 geotextile could remove 368.15 g m−2 of salt, much more than salt removed with geotextiles of density 150, 200, 300, and 400 g m−2 (111.54, 61.57, 102.05, and 102.34 g m−2, respectively), which further proved that fabric structure had great influence on salt removal. These results demonstrated that geotextile covering with optimized fabric structure could be a promising and environmentally friendly technique for farmland salinization control.

Model Prediction of Secondary Soil Salinization in the Keriya Oasis, Northwest China

Significant anthropogenic and biophysical changes have caused fluctuations in the soil salinization area of the Keriya Oasis in China. The Driver-Pressure-State-Impact-Response (DPSIR) sustainability framework and Bayesian networks (BNs) were used to integrate information from anthropogenic and natural systems to model the trend of secondary soil salinization. The developed model predicted that light salinization (vegetation coverage of around 15–20%, soil salt 5–10 g/kg) of the ecotone will increase in the near term but decelerate slightly in the future, and that farmland salinization will decrease in the near term. This trend is expected to accelerate in the future. Both trends are attributed to decreased water logging, increased groundwater exploitation, and decreased ratio of evaporation/precipitation. In contrast, severe salinization (vegetation coverage of around 2%, soil salt ≥20 g/kg) of the ecotone will increase in the near term. This trend will accelerate in the future because decreased river flow will reduce the flushing of severely salinized soil crust. Anthropogenic factors have negative impacts and natural causes have positive impacts on light salinization of ecotones. In situations involving severe farmland salinization, anthropogenic factors have persistent negative impacts.

Actual Condition of Vertical Drainage for Farmland Salinization in Republic of Uzbekistan

Actual Condition of Vertical Drainage for Farmland Salinization in Republic of Uzbekistan

Climate Change Mitigation: The Role of Agriculture

The paper examined available information on the contribution of agriculture toward climate change, the effect of climate change on agriculture and the mitigation potentials of agriculture on climate change. Findings reveal that agriculture contributes to climate change majorly by the emission of methane, nitrous oxide and carbon (iv) oxide. Climate change affects agriculture through temperature rises which affect both crop and animal production, rising sea levels which causes farm land salinization and flooding and pests/diseases infestation. The mitigation potential of agriculture relies on sustainable agricultural practices which include organic farming, agro biodiversity, better land and water management practices, composting, vermicomposting, integrated pest management, cover cropping, mulching, use of bio fuel/bio energy, reduction of fertilizer use, crop rotations and soil conserving tillage which reduce soil erosion. For effective climate change mitigation through agriculture, the following recommendations were made (i) there is need for a systematic redirection of investment, funding, research and policy focus towards sustainable agriculture (ii) agricultural policies that encourage farming by subsidizing safe and sustainable farm inputs should be encouraged (iii) extension services should promote awareness-raising about sustainable agriculture and (iv) sustainable agriculture should be integrated into all level of the education system.

Climate Change and Sustainable Agriculture in Nigeria: Challenges and Opportunities

Context: Climate change has become one of the most serious challenges facing the world- its people, the environment and its economies. It is believed that the changes in the climate are attributable to emissions of GHGs that result from human activities. Agriculture, as one of the activities of man, emits a substantial amount of these GHGs and in turn negatively impacted by climate change. Climate change ravages agricultural production yet offers some opportunities to agriculture. Aims: The paper reviewed available information on the challenges and opportunities of climate change to sustainable agriculture in Nigeria. Results and Conclusions: Review shows that climate change affects sustainable agriculture through temperature rises which leads to the decline in both crop and animal yield, rising sea levels which causes farm land salinization and flooding. Some of the opportunities climate change offers include potentials for increasing links/linkages across different stakeholder/actors, opportunity for agriculture to play a leading role in climate change mitigation and diversification of farmers’ incomes. The paper concludes that the few opportunities climate change offers should be maximized.

Water Problems in Central Asia

We review water-related issues in Central Asia's Syr Darya and Amu Darya River basins as seen in changes in water management and climatic trends. We start by clarifying these problems in basins that are basically in an arid region where water circumstances as a source is unstable and water rights and use among riparian countries are highly discrepant. Results of the examinations on water management clarified 4 major issues: (1) problems affecting countries downstream, such as water shortages in summer and artificial flood damage in winter; (2) problem of irrigation water distribution in the Fergana Valley; (3) the salinization of farmland in middle and lower riparian reaches; and (4) deterioration in Aral Sea and neighboring ecosystems due to drastically lowered water levels. An analysis of the impact of climate change on local hydrological systems pointed up potential new indications: (5) trends in global warming triggering earlier snow melts and floods; and (6) trend in the warming prompting earlier vegetative activity. We conclude by recommending concrete measures for appropriate irrigation and better water management.

Causes of farmland salinization and remedial measures in the Aral Sea basin—Research on water management to prevent secondary salinization in rice-based cropping system in arid land

In the Lower Syr Darya region of the Aral Sea basin, secondary salinization of irrigated lands has been a crucial problem. To clarify the mechanism of secondary salinization, studies on water and salt behavior were conducted in an irrigation block where a rice-based cropping system has been practiced. Results of on-site studies are summarized as follows: (1) since the performance of land-leveling for rice cultivation was extremely poor, the water level was maintained high enough to submerge the highest portion of each plot, and this causes wastage of irrigation water and salt accumulation. (2) A large portion of water introduced to rice plots tends to be released into field drains. (3) Due to excessive irrigation of rice plots with slightly saline river water, dissolved salts were mainly deposited in upland plots in the block and its periphery. Changes in salt accumulation rates were dependent upon the scale of annual changes in the farmland areas that were converted from the upland condition to submerged condition in a process of crop rotation. (4) A remarkable finding was obtained on salt behavior in saturated shallow soil layers of rice plots. An initial decrease in soil water salinity in the shallow layer is due to the leaching effects of infiltration during the initial stage, and the subsequent gradual increase is more likely a consequence of mixing with the saline water that remains in the finer soil pores combined with the concentration effects of crop water uptake, and the upward flow from the lower layers due to occasional interruption and resumption of irrigation water supply. (5) Because seepage water from rice plots flows underneath the field drain, the rise of the groundwater table and salt accumulation were accelerated in the adjacent upland plots. Thus, mixed cropping with rice and upland crops based on a crop rotation system in an irrigation block accelerates waterlogging and salt accumulation in upland plots. Based on these results, several remedial measures were recommended to overcome problems on secondary salinization as follows: (1) avoid mixed cropping with rice and upland crops, and unify either upland crops or rice in an irrigation block to control groundwater table; (2) decrease conveyance and field application losses through improved canal construction and management performance, introduction of canal lining, and improved land-leveling performance; (3) maintain and operate drainage canals to enhance function, particularly installation of subsurface tile drainage for enhancing subsurface drainage function and management of drainage outfall for minimizing environmental degradation caused by saline drainage water in the downstream area; (4) develop a design and management technique of evaporation pond for better effluent management and reuse of drainage water at the outfall of each irrigation block; (5) reduce the water supplied for rice and its use for other crops, or returning the saved water to the river for downstream users including returning to the environment; (6) conclude international water and/or drainage rights agreements among riparian countries and enactment of a basin-wide management regulation to control water withdrawal and drainage.

Use of conditional probability networks for environmental monitoring

Causal or conditional probability networks (CPNs) are shown to provide a natural framework for combining a time sequence of classified satellite images with other maps for environmental monitoring. The key features of CPNs are described by way of application to an example involving the monitoring of salinization of farmland over time using satellite images and an ancillary dataset derived from a digital terrain model. It is shown that CPNs can be used to improve mapping accuracies by incorporating knowledge about the spatial and temporal variation of the map classes of interest. The methods provide a practical solution to the challenging problem of mapping and monitoring salt in farmland. The representation and propagation of uncertainty within this framework is discussed, as well as the spatial and temporal prediction of images and maps.

Image Fusion with Conditional Probability Networks for Monitoring the Salinization of Farmland

We show how a series of satellite images can be used in conjunction with data derived from a digital terrain model to monitor salinity in farmland. A conditional probability network (CPN) is constructed to produce salinity maps by combining uncertain information in images with uncertain knowledge or rules, where the rules are of a temporal and spatial nature. A specific model for extending conditional probability networks to handle the case of spatial context is given. To implement this model requires minor modifications to existing code for handling nonspatial CPN's.