Dryland irrigation increases accumulation rates of pedogenic carbonate and releases soil abiotic CO2

Agricultural fields in drylands are challenged globally by limited freshwater resources for irrigation and also by elevated soil salinity and sodicity. It is well known that pedogenic carbonate is less soluble than evaporate salts and commonly forms in natural drylands. However, few studies have evaluated how irrigation loads dissolved calcium and bicarbonate to agricultural fields, accelerating formation rates of secondary calcite and simultaneously releasing abiotic CO2 to the atmosphere. This study reports one of the first geochemical and isotopic studies of such “anthropogenic” pedogenic carbonates and CO2 from irrigated drylands of southwestern United States. A pecan orchard and an alfalfa field, where flood-irrigation using the Rio Grande river is a common practice, were compared to a nearby natural dryland site. Strontium and carbon isotope ratios show that bulk pedogenic carbonates in irrigated soils at the pecan orchard primarily formed due to flood-irrigation, and that approximately 20–50% of soil CO2 in these irrigated soils is calcite-derived abiotic CO2 instead of soil-respired or atmospheric origins. Multiple variables that control the salt buildup in this region are identified and impact the crop production and soil sustainability regionally and globally. Irrigation intensity and water chemistry (irrigation water quantity and quality) dictate salt loading, and soil texture governs water infiltration and salt leaching. In the study area, agricultural soils have accumulated up to 10 wt% of calcite after just about 100 years of cultivation. These rates will likely increase in the future due to the combined effects of climate variability (reduced rainfall and more intense evaporation), use of more brackish groundwater for irrigation, and reduced porosity in soils. The enhanced accumulation rates of pedogenic carbonate are accompanied by release of large amounts of abiotic CO2 from irrigated drylands to atmosphere. Extensive field studies and modelling approaches are needed to further quantify these effluxes at local, regional and global scales.

Heavy Metals in Agricultural Soils of National Capital Region, Delhi: Levels and Ecological Risk

This study was conducted to assess heavy metals concentrations in agricultural soils in the National Capital Region, Delhi. A total of 84 soil samples were collected from selected agricultural areas located near industries, national highways, state highways, Yamuna floodplain, residential complexes, and wastewater irrigated soils. Heavy metal concentrations, pH, and organic carbon (%) were analyzed in the collected soil samples. The average value of pH, and organic carbon (%) in the soil samples were 7.79±0.49 and 0.53±0.17 percent respectively. Average concentrations of heavy metals (mg kg-1) in the agricultural soils were found in the order of Fe > Al > Mn > Zn > Ni > Cr > Cu > Pb > Co > Cd with value as 14916.92, 13538.87, 277.16, 74.53, 35.34, 33.68, 22.94, 18.45, 1.88, and 0.92 . The concentrations of Zn, Ni, and Mn reported in the present study were several times higher than their concentration in Indian natural background soils. A significant potential ecological risk has been noticed in nearly all the agricultural soil samples except for the samples collected nearby residential areas. The contamination factor has shown that most of the soil samples were moderately contaminated with Mn, Ni, Fe, and Cr and some soil samples were considerably to strongly contaminated with Zn, Pb, Cd, and Ni. Wastewater irrigated soils showed a moderate to a strong degree of accumulation of Zn, Cd, and Ni.

Current State of Granulometric Composition of Irrigated Meadow-Serozem Soils of Azerbaijan

The article deals with the granulometric composition of irrigated-meadow-gray soils (Irrigic Calcisols). Along with the granulometric composition, the ratio of sand, dust and silt fractions was taken into account. The results of the analysis show that the uneven distribution of dependent silt particles supplied with irrigation water causes a variety in the granulometric composition of irrigated soils. At the same time, the differences in the granulometric composition of irrigated lands and raw soils were identified, and the reasons were studied.

UV treatment of agricultural plants in territories subject to salination of soil

An assessment of the influence of electrotechnology of ultraviolet irradiation of seeds and pre-sowing soil treatment and the creation, on their technological basis, of management and control of salt and nutritional regimes of irrigated soils has been carried out. Relative yield of field crops versus the concentration of toxic salts in the soil solution at full moisture capacity are shown. By results of experimental researches acting of UV irradiation on the amount of ammonifying bacteria in the soil under cotton for increasing the accumulation of the most mobile nitrate forms of nitrogen are defined.

Determination of model parameters of water-nutritional processes in soil for nitrogen compounds

Studies of development of an integrated model that allows calculating the whole range of processes necessary for predicting and managing the water and nutrient regimes of reclaimed soils are considered. Calculated values of the maximum concentrations of nitrate nitrogen in the topsoil during the growing season of plant for Tashkent’s region are shown. Values of field moisture capacity and wilting moisture of the main varieties of irrigated soils are defined.

Impact of irrigated and non-irrigated cropping systems on soil physicochemical properties in a small-scale irrigation farming system in Eastern Uganda

This study evaluated the impact of irrigation and cropping on soil physicochemical properties at Kyekide small scale irrigation farm in Jinja district, eastern Uganda. Treatments included Land-use systems under perennial and annual cropping with and without irrigation for over 20 years. The hypothesis was that there were insignificant differences in physicochemical properties of the soil under irrigated and non-irrigated cropping systems. Soil physical properties except hydraulic conductivity was not significantly different with irrigation and cropping. The pH of the soils ranged from moderately acidic to neutral pH (5.17-7.40), with irrigated soils tending to be more neutral than non-irrigated soils. SOM content was higher in the irrigated soils and perennial soils than in the non-irrigated and annual soils. The soils were moderately deficient in N and severely deficient in P (mean values =0.175% N and 1.183mg kg-1 P) compared with the critical of 0.2% and 15 mg kg-1, respectively. Irrigated soils had a significantly higher Na+ content than non-irrigated soils, with a mean value of 2.985cmol/kg. The K+, Ca2+, and Mg2+ contents were higher in irrigated and perennial soils than non-irrigated and annual soils. The study suggested monitoring the soils under an irrigation scheme to prevent degradation due to increased salt accumulation or chemical fertility decline. Overall, monitoring of soil quality is vital in irrigation schemes to monitor the impacts of water on the environment.

Adsorption of EDCs on Reclaimed Water-Irrigated Soils: A Comparative Analysis of a Branched Nonylphenol, Nonylphenol and Bisphenol A

Nonylphenol (NP) and bisphenol A (BPA) are two typical endocrine disrupter chemicals (EDCs) in reclaimed water. In this study, the adsorptions of NP, a branched NP (NP7) and BPA on reclaimed water-irrigated soils were studied by isothermal experiments, and the different environmental factors on their adsorptions were investigated. The results showed that the adsorptions of NP and NP7 on soils conformed to the Linear model, and the adsorption of BPA conformed to the Freundlich model. The adsorptions of NP, NP7 and BPA on soils decreased with increasing temperatures and pHs. Adsorption equilibrium constant (Kd or Kf) were maximum at pH = 3, temperature 25 °C and As(III)-soil, respectively. The adsorption capacity of NP, NP7 and BPA to soils under different cation valence were as follows: neutrally > divalent cations > mono-cations. Kd of NP7 on soil was less than that of NP under different pH and temperatures, while under different cation concentrations it was the inverse. Fourier Transform Infrared Spectrometer (FTIR) analysis showed alkyl chains of NP and BPA seemed to form van der Waals interactions with the cavity of soil. Results of this study will provide further comprehensive fundamental data for human health risk assessment of NP and BPA in soil.

Assessing the Long-Term Impact of Traditional Agriculture and the Mid-Term Impact of Intensification in Face of Local Climatic Changes

In the Mediterranean basin, edaphic salinization, sodification and alkalinization related to anthropic pressures and climatic changes may hinder the ecosystem sustainability. It is pertinent to study the mid and long-term variability of these soil characteristics in face off the macro agricultural system in use (i.e., irrigation or rain-fed). Four irrigated soils from the Caia Irrigation Perimeter (Portugal), Fluvisols, Luvisols, Calcisols and Cambisols were analysed in the mid-term, from 2002 to 2012, for its available Ca2+, Mg2+, K+ and Na+ content. Overall, Ca2+, K+ and Na+ significantly increased during the period of this study by 25%, 8% and 7%, respectively. Soil organic matter (SOM) and pH for the irrigated soils in the area were already assessed in previous studies with the overall SOM remaining constant (p ≥ 0.05) and pH increasing (p < 0.01) by 5%. We provide the predictive maps for Na+ and the CROSS predictive & HotSpot evolution map from 2002 to 2012. Rain-fed soils were analysed in the long-term, from 1965 to 2012, for their SOM, pH and non-acid cations (Ca2+, Mg2+, K+ and Na+) content. While SOM, pH and the exchangeable Ca2+, Mg2+ and K+ significantly increased (p < 0.01) by 23%, 8%, 60%, 21% and 193%, respectively, exchangeable Na+ significantly decreased (p < 0.01) by 50%. These results may be related to the local climate changes as, according to the Thornthwaite classification, it went from sub-humid with great water excess (C1B2s2b4) in the climate normal 1951/1980 to sub-humid with moderate water excess (C1B2sb4) in 1981/2010 to semi-arid with little to none water excess (DB2db4) in 1991/2020. The irrigated areas in this Mediterranean region are slowly departing from sustainable goals of soil conservation and better edaphic management and conservation practices, that address the registered climatic changes in the area, could be adopted.

Microplastics and Their Effect in Horticultural Crops: Food Safety and Plant Stress

The presence of micro and nanoplastics in the food chain constitutes an emergent multifactorial food safety and physiological stress problem, which must be approached with a strategic perspective since it affects public health when consuming products that have this pollutant, such as fish and crustaceans, fruits, and vegetables. In this review, the authors present the results by scientists from different disciplines who are dedicated to discovering their chemical constitution and origin, the contents of these microparticles in edible plants, the contamination of water-irrigated soils, the mechanisms that concentrate microplastics in these soils, methods to determine them, contamination of freshwater sources of cities, and the negative effect of nano and microplastics on various food products and their detrimental impact on the environment. Recent findings of plant uptake mechanisms complement this, but more research is needed.